xref: /freebsd/contrib/llvm-project/llvm/lib/Analysis/InlineCost.cpp (revision 7ef62cebc2f965b0f640263e179276928885e33d)
1 //===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements inline cost analysis.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Analysis/InlineCost.h"
14 #include "llvm/ADT/STLExtras.h"
15 #include "llvm/ADT/SetVector.h"
16 #include "llvm/ADT/SmallPtrSet.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/Statistic.h"
19 #include "llvm/Analysis/AssumptionCache.h"
20 #include "llvm/Analysis/BlockFrequencyInfo.h"
21 #include "llvm/Analysis/CodeMetrics.h"
22 #include "llvm/Analysis/ConstantFolding.h"
23 #include "llvm/Analysis/InstructionSimplify.h"
24 #include "llvm/Analysis/LoopInfo.h"
25 #include "llvm/Analysis/MemoryBuiltins.h"
26 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
27 #include "llvm/Analysis/ProfileSummaryInfo.h"
28 #include "llvm/Analysis/TargetLibraryInfo.h"
29 #include "llvm/Analysis/TargetTransformInfo.h"
30 #include "llvm/Analysis/ValueTracking.h"
31 #include "llvm/Config/llvm-config.h"
32 #include "llvm/IR/AssemblyAnnotationWriter.h"
33 #include "llvm/IR/CallingConv.h"
34 #include "llvm/IR/DataLayout.h"
35 #include "llvm/IR/Dominators.h"
36 #include "llvm/IR/GetElementPtrTypeIterator.h"
37 #include "llvm/IR/GlobalAlias.h"
38 #include "llvm/IR/InstVisitor.h"
39 #include "llvm/IR/IntrinsicInst.h"
40 #include "llvm/IR/Operator.h"
41 #include "llvm/IR/PatternMatch.h"
42 #include "llvm/Support/CommandLine.h"
43 #include "llvm/Support/Debug.h"
44 #include "llvm/Support/FormattedStream.h"
45 #include "llvm/Support/raw_ostream.h"
46 #include <climits>
47 #include <limits>
48 #include <optional>
49 
50 using namespace llvm;
51 
52 #define DEBUG_TYPE "inline-cost"
53 
54 STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed");
55 
56 static cl::opt<int>
57     DefaultThreshold("inlinedefault-threshold", cl::Hidden, cl::init(225),
58                      cl::desc("Default amount of inlining to perform"));
59 
60 // We introduce this option since there is a minor compile-time win by avoiding
61 // addition of TTI attributes (target-features in particular) to inline
62 // candidates when they are guaranteed to be the same as top level methods in
63 // some use cases. If we avoid adding the attribute, we need an option to avoid
64 // checking these attributes.
65 static cl::opt<bool> IgnoreTTIInlineCompatible(
66     "ignore-tti-inline-compatible", cl::Hidden, cl::init(false),
67     cl::desc("Ignore TTI attributes compatibility check between callee/caller "
68              "during inline cost calculation"));
69 
70 static cl::opt<bool> PrintInstructionComments(
71     "print-instruction-comments", cl::Hidden, cl::init(false),
72     cl::desc("Prints comments for instruction based on inline cost analysis"));
73 
74 static cl::opt<int> InlineThreshold(
75     "inline-threshold", cl::Hidden, cl::init(225),
76     cl::desc("Control the amount of inlining to perform (default = 225)"));
77 
78 static cl::opt<int> HintThreshold(
79     "inlinehint-threshold", cl::Hidden, cl::init(325),
80     cl::desc("Threshold for inlining functions with inline hint"));
81 
82 static cl::opt<int>
83     ColdCallSiteThreshold("inline-cold-callsite-threshold", cl::Hidden,
84                           cl::init(45),
85                           cl::desc("Threshold for inlining cold callsites"));
86 
87 static cl::opt<bool> InlineEnableCostBenefitAnalysis(
88     "inline-enable-cost-benefit-analysis", cl::Hidden, cl::init(false),
89     cl::desc("Enable the cost-benefit analysis for the inliner"));
90 
91 static cl::opt<int> InlineSavingsMultiplier(
92     "inline-savings-multiplier", cl::Hidden, cl::init(8),
93     cl::desc("Multiplier to multiply cycle savings by during inlining"));
94 
95 static cl::opt<int>
96     InlineSizeAllowance("inline-size-allowance", cl::Hidden, cl::init(100),
97                         cl::desc("The maximum size of a callee that get's "
98                                  "inlined without sufficient cycle savings"));
99 
100 // We introduce this threshold to help performance of instrumentation based
101 // PGO before we actually hook up inliner with analysis passes such as BPI and
102 // BFI.
103 static cl::opt<int> ColdThreshold(
104     "inlinecold-threshold", cl::Hidden, cl::init(45),
105     cl::desc("Threshold for inlining functions with cold attribute"));
106 
107 static cl::opt<int>
108     HotCallSiteThreshold("hot-callsite-threshold", cl::Hidden, cl::init(3000),
109                          cl::desc("Threshold for hot callsites "));
110 
111 static cl::opt<int> LocallyHotCallSiteThreshold(
112     "locally-hot-callsite-threshold", cl::Hidden, cl::init(525),
113     cl::desc("Threshold for locally hot callsites "));
114 
115 static cl::opt<int> ColdCallSiteRelFreq(
116     "cold-callsite-rel-freq", cl::Hidden, cl::init(2),
117     cl::desc("Maximum block frequency, expressed as a percentage of caller's "
118              "entry frequency, for a callsite to be cold in the absence of "
119              "profile information."));
120 
121 static cl::opt<int> HotCallSiteRelFreq(
122     "hot-callsite-rel-freq", cl::Hidden, cl::init(60),
123     cl::desc("Minimum block frequency, expressed as a multiple of caller's "
124              "entry frequency, for a callsite to be hot in the absence of "
125              "profile information."));
126 
127 static cl::opt<int>
128     InstrCost("inline-instr-cost", cl::Hidden, cl::init(5),
129               cl::desc("Cost of a single instruction when inlining"));
130 
131 static cl::opt<int>
132     MemAccessCost("inline-memaccess-cost", cl::Hidden, cl::init(0),
133                   cl::desc("Cost of load/store instruction when inlining"));
134 
135 static cl::opt<int> CallPenalty(
136     "inline-call-penalty", cl::Hidden, cl::init(25),
137     cl::desc("Call penalty that is applied per callsite when inlining"));
138 
139 static cl::opt<size_t>
140     StackSizeThreshold("inline-max-stacksize", cl::Hidden,
141                        cl::init(std::numeric_limits<size_t>::max()),
142                        cl::desc("Do not inline functions with a stack size "
143                                 "that exceeds the specified limit"));
144 
145 static cl::opt<size_t>
146     RecurStackSizeThreshold("recursive-inline-max-stacksize", cl::Hidden,
147                        cl::init(InlineConstants::TotalAllocaSizeRecursiveCaller),
148                        cl::desc("Do not inline recursive functions with a stack "
149                                 "size that exceeds the specified limit"));
150 
151 static cl::opt<bool> OptComputeFullInlineCost(
152     "inline-cost-full", cl::Hidden,
153     cl::desc("Compute the full inline cost of a call site even when the cost "
154              "exceeds the threshold."));
155 
156 static cl::opt<bool> InlineCallerSupersetNoBuiltin(
157     "inline-caller-superset-nobuiltin", cl::Hidden, cl::init(true),
158     cl::desc("Allow inlining when caller has a superset of callee's nobuiltin "
159              "attributes."));
160 
161 static cl::opt<bool> DisableGEPConstOperand(
162     "disable-gep-const-evaluation", cl::Hidden, cl::init(false),
163     cl::desc("Disables evaluation of GetElementPtr with constant operands"));
164 
165 namespace llvm {
166 std::optional<int> getStringFnAttrAsInt(const Attribute &Attr) {
167   if (Attr.isValid()) {
168     int AttrValue = 0;
169     if (!Attr.getValueAsString().getAsInteger(10, AttrValue))
170       return AttrValue;
171   }
172   return std::nullopt;
173 }
174 
175 std::optional<int> getStringFnAttrAsInt(CallBase &CB, StringRef AttrKind) {
176   return getStringFnAttrAsInt(CB.getFnAttr(AttrKind));
177 }
178 
179 std::optional<int> getStringFnAttrAsInt(Function *F, StringRef AttrKind) {
180   return getStringFnAttrAsInt(F->getFnAttribute(AttrKind));
181 }
182 
183 namespace InlineConstants {
184 int getInstrCost() { return InstrCost; }
185 
186 } // namespace InlineConstants
187 
188 } // namespace llvm
189 
190 namespace {
191 class InlineCostCallAnalyzer;
192 
193 // This struct is used to store information about inline cost of a
194 // particular instruction
195 struct InstructionCostDetail {
196   int CostBefore = 0;
197   int CostAfter = 0;
198   int ThresholdBefore = 0;
199   int ThresholdAfter = 0;
200 
201   int getThresholdDelta() const { return ThresholdAfter - ThresholdBefore; }
202 
203   int getCostDelta() const { return CostAfter - CostBefore; }
204 
205   bool hasThresholdChanged() const { return ThresholdAfter != ThresholdBefore; }
206 };
207 
208 class InlineCostAnnotationWriter : public AssemblyAnnotationWriter {
209 private:
210   InlineCostCallAnalyzer *const ICCA;
211 
212 public:
213   InlineCostAnnotationWriter(InlineCostCallAnalyzer *ICCA) : ICCA(ICCA) {}
214   void emitInstructionAnnot(const Instruction *I,
215                             formatted_raw_ostream &OS) override;
216 };
217 
218 /// Carry out call site analysis, in order to evaluate inlinability.
219 /// NOTE: the type is currently used as implementation detail of functions such
220 /// as llvm::getInlineCost. Note the function_ref constructor parameters - the
221 /// expectation is that they come from the outer scope, from the wrapper
222 /// functions. If we want to support constructing CallAnalyzer objects where
223 /// lambdas are provided inline at construction, or where the object needs to
224 /// otherwise survive past the scope of the provided functions, we need to
225 /// revisit the argument types.
226 class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
227   typedef InstVisitor<CallAnalyzer, bool> Base;
228   friend class InstVisitor<CallAnalyzer, bool>;
229 
230 protected:
231   virtual ~CallAnalyzer() = default;
232   /// The TargetTransformInfo available for this compilation.
233   const TargetTransformInfo &TTI;
234 
235   /// Getter for the cache of @llvm.assume intrinsics.
236   function_ref<AssumptionCache &(Function &)> GetAssumptionCache;
237 
238   /// Getter for BlockFrequencyInfo
239   function_ref<BlockFrequencyInfo &(Function &)> GetBFI;
240 
241   /// Profile summary information.
242   ProfileSummaryInfo *PSI;
243 
244   /// The called function.
245   Function &F;
246 
247   // Cache the DataLayout since we use it a lot.
248   const DataLayout &DL;
249 
250   /// The OptimizationRemarkEmitter available for this compilation.
251   OptimizationRemarkEmitter *ORE;
252 
253   /// The candidate callsite being analyzed. Please do not use this to do
254   /// analysis in the caller function; we want the inline cost query to be
255   /// easily cacheable. Instead, use the cover function paramHasAttr.
256   CallBase &CandidateCall;
257 
258   /// Extension points for handling callsite features.
259   // Called before a basic block was analyzed.
260   virtual void onBlockStart(const BasicBlock *BB) {}
261 
262   /// Called after a basic block was analyzed.
263   virtual void onBlockAnalyzed(const BasicBlock *BB) {}
264 
265   /// Called before an instruction was analyzed
266   virtual void onInstructionAnalysisStart(const Instruction *I) {}
267 
268   /// Called after an instruction was analyzed
269   virtual void onInstructionAnalysisFinish(const Instruction *I) {}
270 
271   /// Called at the end of the analysis of the callsite. Return the outcome of
272   /// the analysis, i.e. 'InlineResult(true)' if the inlining may happen, or
273   /// the reason it can't.
274   virtual InlineResult finalizeAnalysis() { return InlineResult::success(); }
275   /// Called when we're about to start processing a basic block, and every time
276   /// we are done processing an instruction. Return true if there is no point in
277   /// continuing the analysis (e.g. we've determined already the call site is
278   /// too expensive to inline)
279   virtual bool shouldStop() { return false; }
280 
281   /// Called before the analysis of the callee body starts (with callsite
282   /// contexts propagated).  It checks callsite-specific information. Return a
283   /// reason analysis can't continue if that's the case, or 'true' if it may
284   /// continue.
285   virtual InlineResult onAnalysisStart() { return InlineResult::success(); }
286   /// Called if the analysis engine decides SROA cannot be done for the given
287   /// alloca.
288   virtual void onDisableSROA(AllocaInst *Arg) {}
289 
290   /// Called the analysis engine determines load elimination won't happen.
291   virtual void onDisableLoadElimination() {}
292 
293   /// Called when we visit a CallBase, before the analysis starts. Return false
294   /// to stop further processing of the instruction.
295   virtual bool onCallBaseVisitStart(CallBase &Call) { return true; }
296 
297   /// Called to account for a call.
298   virtual void onCallPenalty() {}
299 
300   /// Called to account for a load or store.
301   virtual void onMemAccess(){};
302 
303   /// Called to account for the expectation the inlining would result in a load
304   /// elimination.
305   virtual void onLoadEliminationOpportunity() {}
306 
307   /// Called to account for the cost of argument setup for the Call in the
308   /// callee's body (not the callsite currently under analysis).
309   virtual void onCallArgumentSetup(const CallBase &Call) {}
310 
311   /// Called to account for a load relative intrinsic.
312   virtual void onLoadRelativeIntrinsic() {}
313 
314   /// Called to account for a lowered call.
315   virtual void onLoweredCall(Function *F, CallBase &Call, bool IsIndirectCall) {
316   }
317 
318   /// Account for a jump table of given size. Return false to stop further
319   /// processing the switch instruction
320   virtual bool onJumpTable(unsigned JumpTableSize) { return true; }
321 
322   /// Account for a case cluster of given size. Return false to stop further
323   /// processing of the instruction.
324   virtual bool onCaseCluster(unsigned NumCaseCluster) { return true; }
325 
326   /// Called at the end of processing a switch instruction, with the given
327   /// number of case clusters.
328   virtual void onFinalizeSwitch(unsigned JumpTableSize,
329                                 unsigned NumCaseCluster) {}
330 
331   /// Called to account for any other instruction not specifically accounted
332   /// for.
333   virtual void onMissedSimplification() {}
334 
335   /// Start accounting potential benefits due to SROA for the given alloca.
336   virtual void onInitializeSROAArg(AllocaInst *Arg) {}
337 
338   /// Account SROA savings for the AllocaInst value.
339   virtual void onAggregateSROAUse(AllocaInst *V) {}
340 
341   bool handleSROA(Value *V, bool DoNotDisable) {
342     // Check for SROA candidates in comparisons.
343     if (auto *SROAArg = getSROAArgForValueOrNull(V)) {
344       if (DoNotDisable) {
345         onAggregateSROAUse(SROAArg);
346         return true;
347       }
348       disableSROAForArg(SROAArg);
349     }
350     return false;
351   }
352 
353   bool IsCallerRecursive = false;
354   bool IsRecursiveCall = false;
355   bool ExposesReturnsTwice = false;
356   bool HasDynamicAlloca = false;
357   bool ContainsNoDuplicateCall = false;
358   bool HasReturn = false;
359   bool HasIndirectBr = false;
360   bool HasUninlineableIntrinsic = false;
361   bool InitsVargArgs = false;
362 
363   /// Number of bytes allocated statically by the callee.
364   uint64_t AllocatedSize = 0;
365   unsigned NumInstructions = 0;
366   unsigned NumVectorInstructions = 0;
367 
368   /// While we walk the potentially-inlined instructions, we build up and
369   /// maintain a mapping of simplified values specific to this callsite. The
370   /// idea is to propagate any special information we have about arguments to
371   /// this call through the inlinable section of the function, and account for
372   /// likely simplifications post-inlining. The most important aspect we track
373   /// is CFG altering simplifications -- when we prove a basic block dead, that
374   /// can cause dramatic shifts in the cost of inlining a function.
375   DenseMap<Value *, Constant *> SimplifiedValues;
376 
377   /// Keep track of the values which map back (through function arguments) to
378   /// allocas on the caller stack which could be simplified through SROA.
379   DenseMap<Value *, AllocaInst *> SROAArgValues;
380 
381   /// Keep track of Allocas for which we believe we may get SROA optimization.
382   DenseSet<AllocaInst *> EnabledSROAAllocas;
383 
384   /// Keep track of values which map to a pointer base and constant offset.
385   DenseMap<Value *, std::pair<Value *, APInt>> ConstantOffsetPtrs;
386 
387   /// Keep track of dead blocks due to the constant arguments.
388   SmallPtrSet<BasicBlock *, 16> DeadBlocks;
389 
390   /// The mapping of the blocks to their known unique successors due to the
391   /// constant arguments.
392   DenseMap<BasicBlock *, BasicBlock *> KnownSuccessors;
393 
394   /// Model the elimination of repeated loads that is expected to happen
395   /// whenever we simplify away the stores that would otherwise cause them to be
396   /// loads.
397   bool EnableLoadElimination = true;
398 
399   /// Whether we allow inlining for recursive call.
400   bool AllowRecursiveCall = false;
401 
402   SmallPtrSet<Value *, 16> LoadAddrSet;
403 
404   AllocaInst *getSROAArgForValueOrNull(Value *V) const {
405     auto It = SROAArgValues.find(V);
406     if (It == SROAArgValues.end() || EnabledSROAAllocas.count(It->second) == 0)
407       return nullptr;
408     return It->second;
409   }
410 
411   // Custom simplification helper routines.
412   bool isAllocaDerivedArg(Value *V);
413   void disableSROAForArg(AllocaInst *SROAArg);
414   void disableSROA(Value *V);
415   void findDeadBlocks(BasicBlock *CurrBB, BasicBlock *NextBB);
416   void disableLoadElimination();
417   bool isGEPFree(GetElementPtrInst &GEP);
418   bool canFoldInboundsGEP(GetElementPtrInst &I);
419   bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
420   bool simplifyCallSite(Function *F, CallBase &Call);
421   bool simplifyInstruction(Instruction &I);
422   bool simplifyIntrinsicCallIsConstant(CallBase &CB);
423   bool simplifyIntrinsicCallObjectSize(CallBase &CB);
424   ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);
425 
426   /// Return true if the given argument to the function being considered for
427   /// inlining has the given attribute set either at the call site or the
428   /// function declaration.  Primarily used to inspect call site specific
429   /// attributes since these can be more precise than the ones on the callee
430   /// itself.
431   bool paramHasAttr(Argument *A, Attribute::AttrKind Attr);
432 
433   /// Return true if the given value is known non null within the callee if
434   /// inlined through this particular callsite.
435   bool isKnownNonNullInCallee(Value *V);
436 
437   /// Return true if size growth is allowed when inlining the callee at \p Call.
438   bool allowSizeGrowth(CallBase &Call);
439 
440   // Custom analysis routines.
441   InlineResult analyzeBlock(BasicBlock *BB,
442                             SmallPtrSetImpl<const Value *> &EphValues);
443 
444   // Disable several entry points to the visitor so we don't accidentally use
445   // them by declaring but not defining them here.
446   void visit(Module *);
447   void visit(Module &);
448   void visit(Function *);
449   void visit(Function &);
450   void visit(BasicBlock *);
451   void visit(BasicBlock &);
452 
453   // Provide base case for our instruction visit.
454   bool visitInstruction(Instruction &I);
455 
456   // Our visit overrides.
457   bool visitAlloca(AllocaInst &I);
458   bool visitPHI(PHINode &I);
459   bool visitGetElementPtr(GetElementPtrInst &I);
460   bool visitBitCast(BitCastInst &I);
461   bool visitPtrToInt(PtrToIntInst &I);
462   bool visitIntToPtr(IntToPtrInst &I);
463   bool visitCastInst(CastInst &I);
464   bool visitCmpInst(CmpInst &I);
465   bool visitSub(BinaryOperator &I);
466   bool visitBinaryOperator(BinaryOperator &I);
467   bool visitFNeg(UnaryOperator &I);
468   bool visitLoad(LoadInst &I);
469   bool visitStore(StoreInst &I);
470   bool visitExtractValue(ExtractValueInst &I);
471   bool visitInsertValue(InsertValueInst &I);
472   bool visitCallBase(CallBase &Call);
473   bool visitReturnInst(ReturnInst &RI);
474   bool visitBranchInst(BranchInst &BI);
475   bool visitSelectInst(SelectInst &SI);
476   bool visitSwitchInst(SwitchInst &SI);
477   bool visitIndirectBrInst(IndirectBrInst &IBI);
478   bool visitResumeInst(ResumeInst &RI);
479   bool visitCleanupReturnInst(CleanupReturnInst &RI);
480   bool visitCatchReturnInst(CatchReturnInst &RI);
481   bool visitUnreachableInst(UnreachableInst &I);
482 
483 public:
484   CallAnalyzer(Function &Callee, CallBase &Call, const TargetTransformInfo &TTI,
485                function_ref<AssumptionCache &(Function &)> GetAssumptionCache,
486                function_ref<BlockFrequencyInfo &(Function &)> GetBFI = nullptr,
487                ProfileSummaryInfo *PSI = nullptr,
488                OptimizationRemarkEmitter *ORE = nullptr)
489       : TTI(TTI), GetAssumptionCache(GetAssumptionCache), GetBFI(GetBFI),
490         PSI(PSI), F(Callee), DL(F.getParent()->getDataLayout()), ORE(ORE),
491         CandidateCall(Call) {}
492 
493   InlineResult analyze();
494 
495   std::optional<Constant *> getSimplifiedValue(Instruction *I) {
496     if (SimplifiedValues.find(I) != SimplifiedValues.end())
497       return SimplifiedValues[I];
498     return std::nullopt;
499   }
500 
501   // Keep a bunch of stats about the cost savings found so we can print them
502   // out when debugging.
503   unsigned NumConstantArgs = 0;
504   unsigned NumConstantOffsetPtrArgs = 0;
505   unsigned NumAllocaArgs = 0;
506   unsigned NumConstantPtrCmps = 0;
507   unsigned NumConstantPtrDiffs = 0;
508   unsigned NumInstructionsSimplified = 0;
509 
510   void dump();
511 };
512 
513 // Considering forming a binary search, we should find the number of nodes
514 // which is same as the number of comparisons when lowered. For a given
515 // number of clusters, n, we can define a recursive function, f(n), to find
516 // the number of nodes in the tree. The recursion is :
517 // f(n) = 1 + f(n/2) + f (n - n/2), when n > 3,
518 // and f(n) = n, when n <= 3.
519 // This will lead a binary tree where the leaf should be either f(2) or f(3)
520 // when n > 3.  So, the number of comparisons from leaves should be n, while
521 // the number of non-leaf should be :
522 //   2^(log2(n) - 1) - 1
523 //   = 2^log2(n) * 2^-1 - 1
524 //   = n / 2 - 1.
525 // Considering comparisons from leaf and non-leaf nodes, we can estimate the
526 // number of comparisons in a simple closed form :
527 //   n + n / 2 - 1 = n * 3 / 2 - 1
528 int64_t getExpectedNumberOfCompare(int NumCaseCluster) {
529   return 3 * static_cast<int64_t>(NumCaseCluster) / 2 - 1;
530 }
531 
532 /// FIXME: if it is necessary to derive from InlineCostCallAnalyzer, note
533 /// the FIXME in onLoweredCall, when instantiating an InlineCostCallAnalyzer
534 class InlineCostCallAnalyzer final : public CallAnalyzer {
535   const bool ComputeFullInlineCost;
536   int LoadEliminationCost = 0;
537   /// Bonus to be applied when percentage of vector instructions in callee is
538   /// high (see more details in updateThreshold).
539   int VectorBonus = 0;
540   /// Bonus to be applied when the callee has only one reachable basic block.
541   int SingleBBBonus = 0;
542 
543   /// Tunable parameters that control the analysis.
544   const InlineParams &Params;
545 
546   // This DenseMap stores the delta change in cost and threshold after
547   // accounting for the given instruction. The map is filled only with the
548   // flag PrintInstructionComments on.
549   DenseMap<const Instruction *, InstructionCostDetail> InstructionCostDetailMap;
550 
551   /// Upper bound for the inlining cost. Bonuses are being applied to account
552   /// for speculative "expected profit" of the inlining decision.
553   int Threshold = 0;
554 
555   /// The amount of StaticBonus applied.
556   int StaticBonusApplied = 0;
557 
558   /// Attempt to evaluate indirect calls to boost its inline cost.
559   const bool BoostIndirectCalls;
560 
561   /// Ignore the threshold when finalizing analysis.
562   const bool IgnoreThreshold;
563 
564   // True if the cost-benefit-analysis-based inliner is enabled.
565   const bool CostBenefitAnalysisEnabled;
566 
567   /// Inlining cost measured in abstract units, accounts for all the
568   /// instructions expected to be executed for a given function invocation.
569   /// Instructions that are statically proven to be dead based on call-site
570   /// arguments are not counted here.
571   int Cost = 0;
572 
573   // The cumulative cost at the beginning of the basic block being analyzed.  At
574   // the end of analyzing each basic block, "Cost - CostAtBBStart" represents
575   // the size of that basic block.
576   int CostAtBBStart = 0;
577 
578   // The static size of live but cold basic blocks.  This is "static" in the
579   // sense that it's not weighted by profile counts at all.
580   int ColdSize = 0;
581 
582   // Whether inlining is decided by cost-threshold analysis.
583   bool DecidedByCostThreshold = false;
584 
585   // Whether inlining is decided by cost-benefit analysis.
586   bool DecidedByCostBenefit = false;
587 
588   // The cost-benefit pair computed by cost-benefit analysis.
589   std::optional<CostBenefitPair> CostBenefit;
590 
591   bool SingleBB = true;
592 
593   unsigned SROACostSavings = 0;
594   unsigned SROACostSavingsLost = 0;
595 
596   /// The mapping of caller Alloca values to their accumulated cost savings. If
597   /// we have to disable SROA for one of the allocas, this tells us how much
598   /// cost must be added.
599   DenseMap<AllocaInst *, int> SROAArgCosts;
600 
601   /// Return true if \p Call is a cold callsite.
602   bool isColdCallSite(CallBase &Call, BlockFrequencyInfo *CallerBFI);
603 
604   /// Update Threshold based on callsite properties such as callee
605   /// attributes and callee hotness for PGO builds. The Callee is explicitly
606   /// passed to support analyzing indirect calls whose target is inferred by
607   /// analysis.
608   void updateThreshold(CallBase &Call, Function &Callee);
609   /// Return a higher threshold if \p Call is a hot callsite.
610   std::optional<int> getHotCallSiteThreshold(CallBase &Call,
611                                              BlockFrequencyInfo *CallerBFI);
612 
613   /// Handle a capped 'int' increment for Cost.
614   void addCost(int64_t Inc) {
615     Inc = std::max<int64_t>(std::min<int64_t>(INT_MAX, Inc), INT_MIN);
616     Cost = std::max<int64_t>(std::min<int64_t>(INT_MAX, Inc + Cost), INT_MIN);
617   }
618 
619   void onDisableSROA(AllocaInst *Arg) override {
620     auto CostIt = SROAArgCosts.find(Arg);
621     if (CostIt == SROAArgCosts.end())
622       return;
623     addCost(CostIt->second);
624     SROACostSavings -= CostIt->second;
625     SROACostSavingsLost += CostIt->second;
626     SROAArgCosts.erase(CostIt);
627   }
628 
629   void onDisableLoadElimination() override {
630     addCost(LoadEliminationCost);
631     LoadEliminationCost = 0;
632   }
633 
634   bool onCallBaseVisitStart(CallBase &Call) override {
635     if (std::optional<int> AttrCallThresholdBonus =
636             getStringFnAttrAsInt(Call, "call-threshold-bonus"))
637       Threshold += *AttrCallThresholdBonus;
638 
639     if (std::optional<int> AttrCallCost =
640             getStringFnAttrAsInt(Call, "call-inline-cost")) {
641       addCost(*AttrCallCost);
642       // Prevent further processing of the call since we want to override its
643       // inline cost, not just add to it.
644       return false;
645     }
646     return true;
647   }
648 
649   void onCallPenalty() override { addCost(CallPenalty); }
650 
651   void onMemAccess() override { addCost(MemAccessCost); }
652 
653   void onCallArgumentSetup(const CallBase &Call) override {
654     // Pay the price of the argument setup. We account for the average 1
655     // instruction per call argument setup here.
656     addCost(Call.arg_size() * InstrCost);
657   }
658   void onLoadRelativeIntrinsic() override {
659     // This is normally lowered to 4 LLVM instructions.
660     addCost(3 * InstrCost);
661   }
662   void onLoweredCall(Function *F, CallBase &Call,
663                      bool IsIndirectCall) override {
664     // We account for the average 1 instruction per call argument setup here.
665     addCost(Call.arg_size() * InstrCost);
666 
667     // If we have a constant that we are calling as a function, we can peer
668     // through it and see the function target. This happens not infrequently
669     // during devirtualization and so we want to give it a hefty bonus for
670     // inlining, but cap that bonus in the event that inlining wouldn't pan out.
671     // Pretend to inline the function, with a custom threshold.
672     if (IsIndirectCall && BoostIndirectCalls) {
673       auto IndirectCallParams = Params;
674       IndirectCallParams.DefaultThreshold =
675           InlineConstants::IndirectCallThreshold;
676       /// FIXME: if InlineCostCallAnalyzer is derived from, this may need
677       /// to instantiate the derived class.
678       InlineCostCallAnalyzer CA(*F, Call, IndirectCallParams, TTI,
679                                 GetAssumptionCache, GetBFI, PSI, ORE, false);
680       if (CA.analyze().isSuccess()) {
681         // We were able to inline the indirect call! Subtract the cost from the
682         // threshold to get the bonus we want to apply, but don't go below zero.
683         Cost -= std::max(0, CA.getThreshold() - CA.getCost());
684       }
685     } else
686       // Otherwise simply add the cost for merely making the call.
687       addCost(CallPenalty);
688   }
689 
690   void onFinalizeSwitch(unsigned JumpTableSize,
691                         unsigned NumCaseCluster) override {
692     // If suitable for a jump table, consider the cost for the table size and
693     // branch to destination.
694     // Maximum valid cost increased in this function.
695     if (JumpTableSize) {
696       int64_t JTCost =
697           static_cast<int64_t>(JumpTableSize) * InstrCost + 4 * InstrCost;
698 
699       addCost(JTCost);
700       return;
701     }
702 
703     if (NumCaseCluster <= 3) {
704       // Suppose a comparison includes one compare and one conditional branch.
705       addCost(NumCaseCluster * 2 * InstrCost);
706       return;
707     }
708 
709     int64_t ExpectedNumberOfCompare =
710         getExpectedNumberOfCompare(NumCaseCluster);
711     int64_t SwitchCost = ExpectedNumberOfCompare * 2 * InstrCost;
712 
713     addCost(SwitchCost);
714   }
715   void onMissedSimplification() override { addCost(InstrCost); }
716 
717   void onInitializeSROAArg(AllocaInst *Arg) override {
718     assert(Arg != nullptr &&
719            "Should not initialize SROA costs for null value.");
720     SROAArgCosts[Arg] = 0;
721   }
722 
723   void onAggregateSROAUse(AllocaInst *SROAArg) override {
724     auto CostIt = SROAArgCosts.find(SROAArg);
725     assert(CostIt != SROAArgCosts.end() &&
726            "expected this argument to have a cost");
727     CostIt->second += InstrCost;
728     SROACostSavings += InstrCost;
729   }
730 
731   void onBlockStart(const BasicBlock *BB) override { CostAtBBStart = Cost; }
732 
733   void onBlockAnalyzed(const BasicBlock *BB) override {
734     if (CostBenefitAnalysisEnabled) {
735       // Keep track of the static size of live but cold basic blocks.  For now,
736       // we define a cold basic block to be one that's never executed.
737       assert(GetBFI && "GetBFI must be available");
738       BlockFrequencyInfo *BFI = &(GetBFI(F));
739       assert(BFI && "BFI must be available");
740       auto ProfileCount = BFI->getBlockProfileCount(BB);
741       if (*ProfileCount == 0)
742         ColdSize += Cost - CostAtBBStart;
743     }
744 
745     auto *TI = BB->getTerminator();
746     // If we had any successors at this point, than post-inlining is likely to
747     // have them as well. Note that we assume any basic blocks which existed
748     // due to branches or switches which folded above will also fold after
749     // inlining.
750     if (SingleBB && TI->getNumSuccessors() > 1) {
751       // Take off the bonus we applied to the threshold.
752       Threshold -= SingleBBBonus;
753       SingleBB = false;
754     }
755   }
756 
757   void onInstructionAnalysisStart(const Instruction *I) override {
758     // This function is called to store the initial cost of inlining before
759     // the given instruction was assessed.
760     if (!PrintInstructionComments)
761       return;
762     InstructionCostDetailMap[I].CostBefore = Cost;
763     InstructionCostDetailMap[I].ThresholdBefore = Threshold;
764   }
765 
766   void onInstructionAnalysisFinish(const Instruction *I) override {
767     // This function is called to find new values of cost and threshold after
768     // the instruction has been assessed.
769     if (!PrintInstructionComments)
770       return;
771     InstructionCostDetailMap[I].CostAfter = Cost;
772     InstructionCostDetailMap[I].ThresholdAfter = Threshold;
773   }
774 
775   bool isCostBenefitAnalysisEnabled() {
776     if (!PSI || !PSI->hasProfileSummary())
777       return false;
778 
779     if (!GetBFI)
780       return false;
781 
782     if (InlineEnableCostBenefitAnalysis.getNumOccurrences()) {
783       // Honor the explicit request from the user.
784       if (!InlineEnableCostBenefitAnalysis)
785         return false;
786     } else {
787       // Otherwise, require instrumentation profile.
788       if (!PSI->hasInstrumentationProfile())
789         return false;
790     }
791 
792     auto *Caller = CandidateCall.getParent()->getParent();
793     if (!Caller->getEntryCount())
794       return false;
795 
796     BlockFrequencyInfo *CallerBFI = &(GetBFI(*Caller));
797     if (!CallerBFI)
798       return false;
799 
800     // For now, limit to hot call site.
801     if (!PSI->isHotCallSite(CandidateCall, CallerBFI))
802       return false;
803 
804     // Make sure we have a nonzero entry count.
805     auto EntryCount = F.getEntryCount();
806     if (!EntryCount || !EntryCount->getCount())
807       return false;
808 
809     BlockFrequencyInfo *CalleeBFI = &(GetBFI(F));
810     if (!CalleeBFI)
811       return false;
812 
813     return true;
814   }
815 
816   // Determine whether we should inline the given call site, taking into account
817   // both the size cost and the cycle savings.  Return std::nullopt if we don't
818   // have suficient profiling information to determine.
819   std::optional<bool> costBenefitAnalysis() {
820     if (!CostBenefitAnalysisEnabled)
821       return std::nullopt;
822 
823     // buildInlinerPipeline in the pass builder sets HotCallSiteThreshold to 0
824     // for the prelink phase of the AutoFDO + ThinLTO build.  Honor the logic by
825     // falling back to the cost-based metric.
826     // TODO: Improve this hacky condition.
827     if (Threshold == 0)
828       return std::nullopt;
829 
830     assert(GetBFI);
831     BlockFrequencyInfo *CalleeBFI = &(GetBFI(F));
832     assert(CalleeBFI);
833 
834     // The cycle savings expressed as the sum of InstrCost
835     // multiplied by the estimated dynamic count of each instruction we can
836     // avoid.  Savings come from the call site cost, such as argument setup and
837     // the call instruction, as well as the instructions that are folded.
838     //
839     // We use 128-bit APInt here to avoid potential overflow.  This variable
840     // should stay well below 10^^24 (or 2^^80) in practice.  This "worst" case
841     // assumes that we can avoid or fold a billion instructions, each with a
842     // profile count of 10^^15 -- roughly the number of cycles for a 24-hour
843     // period on a 4GHz machine.
844     APInt CycleSavings(128, 0);
845 
846     for (auto &BB : F) {
847       APInt CurrentSavings(128, 0);
848       for (auto &I : BB) {
849         if (BranchInst *BI = dyn_cast<BranchInst>(&I)) {
850           // Count a conditional branch as savings if it becomes unconditional.
851           if (BI->isConditional() &&
852               isa_and_nonnull<ConstantInt>(
853                   SimplifiedValues.lookup(BI->getCondition()))) {
854             CurrentSavings += InstrCost;
855           }
856         } else if (Value *V = dyn_cast<Value>(&I)) {
857           // Count an instruction as savings if we can fold it.
858           if (SimplifiedValues.count(V)) {
859             CurrentSavings += InstrCost;
860           }
861         }
862       }
863 
864       auto ProfileCount = CalleeBFI->getBlockProfileCount(&BB);
865       CurrentSavings *= *ProfileCount;
866       CycleSavings += CurrentSavings;
867     }
868 
869     // Compute the cycle savings per call.
870     auto EntryProfileCount = F.getEntryCount();
871     assert(EntryProfileCount && EntryProfileCount->getCount());
872     auto EntryCount = EntryProfileCount->getCount();
873     CycleSavings += EntryCount / 2;
874     CycleSavings = CycleSavings.udiv(EntryCount);
875 
876     // Compute the total savings for the call site.
877     auto *CallerBB = CandidateCall.getParent();
878     BlockFrequencyInfo *CallerBFI = &(GetBFI(*(CallerBB->getParent())));
879     CycleSavings += getCallsiteCost(this->CandidateCall, DL);
880     CycleSavings *= *CallerBFI->getBlockProfileCount(CallerBB);
881 
882     // Remove the cost of the cold basic blocks.
883     int Size = Cost - ColdSize;
884 
885     // Allow tiny callees to be inlined regardless of whether they meet the
886     // savings threshold.
887     Size = Size > InlineSizeAllowance ? Size - InlineSizeAllowance : 1;
888 
889     CostBenefit.emplace(APInt(128, Size), CycleSavings);
890 
891     // Return true if the savings justify the cost of inlining.  Specifically,
892     // we evaluate the following inequality:
893     //
894     //  CycleSavings      PSI->getOrCompHotCountThreshold()
895     // -------------- >= -----------------------------------
896     //       Size              InlineSavingsMultiplier
897     //
898     // Note that the left hand side is specific to a call site.  The right hand
899     // side is a constant for the entire executable.
900     APInt LHS = CycleSavings;
901     LHS *= InlineSavingsMultiplier;
902     APInt RHS(128, PSI->getOrCompHotCountThreshold());
903     RHS *= Size;
904     return LHS.uge(RHS);
905   }
906 
907   InlineResult finalizeAnalysis() override {
908     // Loops generally act a lot like calls in that they act like barriers to
909     // movement, require a certain amount of setup, etc. So when optimising for
910     // size, we penalise any call sites that perform loops. We do this after all
911     // other costs here, so will likely only be dealing with relatively small
912     // functions (and hence DT and LI will hopefully be cheap).
913     auto *Caller = CandidateCall.getFunction();
914     if (Caller->hasMinSize()) {
915       DominatorTree DT(F);
916       LoopInfo LI(DT);
917       int NumLoops = 0;
918       for (Loop *L : LI) {
919         // Ignore loops that will not be executed
920         if (DeadBlocks.count(L->getHeader()))
921           continue;
922         NumLoops++;
923       }
924       addCost(NumLoops * InlineConstants::LoopPenalty);
925     }
926 
927     // We applied the maximum possible vector bonus at the beginning. Now,
928     // subtract the excess bonus, if any, from the Threshold before
929     // comparing against Cost.
930     if (NumVectorInstructions <= NumInstructions / 10)
931       Threshold -= VectorBonus;
932     else if (NumVectorInstructions <= NumInstructions / 2)
933       Threshold -= VectorBonus / 2;
934 
935     if (std::optional<int> AttrCost =
936             getStringFnAttrAsInt(CandidateCall, "function-inline-cost"))
937       Cost = *AttrCost;
938 
939     if (std::optional<int> AttrCostMult = getStringFnAttrAsInt(
940             CandidateCall,
941             InlineConstants::FunctionInlineCostMultiplierAttributeName))
942       Cost *= *AttrCostMult;
943 
944     if (std::optional<int> AttrThreshold =
945             getStringFnAttrAsInt(CandidateCall, "function-inline-threshold"))
946       Threshold = *AttrThreshold;
947 
948     if (auto Result = costBenefitAnalysis()) {
949       DecidedByCostBenefit = true;
950       if (*Result)
951         return InlineResult::success();
952       else
953         return InlineResult::failure("Cost over threshold.");
954     }
955 
956     if (IgnoreThreshold)
957       return InlineResult::success();
958 
959     DecidedByCostThreshold = true;
960     return Cost < std::max(1, Threshold)
961                ? InlineResult::success()
962                : InlineResult::failure("Cost over threshold.");
963   }
964 
965   bool shouldStop() override {
966     if (IgnoreThreshold || ComputeFullInlineCost)
967       return false;
968     // Bail out the moment we cross the threshold. This means we'll under-count
969     // the cost, but only when undercounting doesn't matter.
970     if (Cost < Threshold)
971       return false;
972     DecidedByCostThreshold = true;
973     return true;
974   }
975 
976   void onLoadEliminationOpportunity() override {
977     LoadEliminationCost += InstrCost;
978   }
979 
980   InlineResult onAnalysisStart() override {
981     // Perform some tweaks to the cost and threshold based on the direct
982     // callsite information.
983 
984     // We want to more aggressively inline vector-dense kernels, so up the
985     // threshold, and we'll lower it if the % of vector instructions gets too
986     // low. Note that these bonuses are some what arbitrary and evolved over
987     // time by accident as much as because they are principled bonuses.
988     //
989     // FIXME: It would be nice to remove all such bonuses. At least it would be
990     // nice to base the bonus values on something more scientific.
991     assert(NumInstructions == 0);
992     assert(NumVectorInstructions == 0);
993 
994     // Update the threshold based on callsite properties
995     updateThreshold(CandidateCall, F);
996 
997     // While Threshold depends on commandline options that can take negative
998     // values, we want to enforce the invariant that the computed threshold and
999     // bonuses are non-negative.
1000     assert(Threshold >= 0);
1001     assert(SingleBBBonus >= 0);
1002     assert(VectorBonus >= 0);
1003 
1004     // Speculatively apply all possible bonuses to Threshold. If cost exceeds
1005     // this Threshold any time, and cost cannot decrease, we can stop processing
1006     // the rest of the function body.
1007     Threshold += (SingleBBBonus + VectorBonus);
1008 
1009     // Give out bonuses for the callsite, as the instructions setting them up
1010     // will be gone after inlining.
1011     addCost(-getCallsiteCost(this->CandidateCall, DL));
1012 
1013     // If this function uses the coldcc calling convention, prefer not to inline
1014     // it.
1015     if (F.getCallingConv() == CallingConv::Cold)
1016       Cost += InlineConstants::ColdccPenalty;
1017 
1018     LLVM_DEBUG(dbgs() << "      Initial cost: " << Cost << "\n");
1019 
1020     // Check if we're done. This can happen due to bonuses and penalties.
1021     if (Cost >= Threshold && !ComputeFullInlineCost)
1022       return InlineResult::failure("high cost");
1023 
1024     return InlineResult::success();
1025   }
1026 
1027 public:
1028   InlineCostCallAnalyzer(
1029       Function &Callee, CallBase &Call, const InlineParams &Params,
1030       const TargetTransformInfo &TTI,
1031       function_ref<AssumptionCache &(Function &)> GetAssumptionCache,
1032       function_ref<BlockFrequencyInfo &(Function &)> GetBFI = nullptr,
1033       ProfileSummaryInfo *PSI = nullptr,
1034       OptimizationRemarkEmitter *ORE = nullptr, bool BoostIndirect = true,
1035       bool IgnoreThreshold = false)
1036       : CallAnalyzer(Callee, Call, TTI, GetAssumptionCache, GetBFI, PSI, ORE),
1037         ComputeFullInlineCost(OptComputeFullInlineCost ||
1038                               Params.ComputeFullInlineCost || ORE ||
1039                               isCostBenefitAnalysisEnabled()),
1040         Params(Params), Threshold(Params.DefaultThreshold),
1041         BoostIndirectCalls(BoostIndirect), IgnoreThreshold(IgnoreThreshold),
1042         CostBenefitAnalysisEnabled(isCostBenefitAnalysisEnabled()),
1043         Writer(this) {
1044     AllowRecursiveCall = *Params.AllowRecursiveCall;
1045   }
1046 
1047   /// Annotation Writer for instruction details
1048   InlineCostAnnotationWriter Writer;
1049 
1050   void dump();
1051 
1052   // Prints the same analysis as dump(), but its definition is not dependent
1053   // on the build.
1054   void print(raw_ostream &OS);
1055 
1056   std::optional<InstructionCostDetail> getCostDetails(const Instruction *I) {
1057     if (InstructionCostDetailMap.find(I) != InstructionCostDetailMap.end())
1058       return InstructionCostDetailMap[I];
1059     return std::nullopt;
1060   }
1061 
1062   virtual ~InlineCostCallAnalyzer() = default;
1063   int getThreshold() const { return Threshold; }
1064   int getCost() const { return Cost; }
1065   int getStaticBonusApplied() const { return StaticBonusApplied; }
1066   std::optional<CostBenefitPair> getCostBenefitPair() { return CostBenefit; }
1067   bool wasDecidedByCostBenefit() const { return DecidedByCostBenefit; }
1068   bool wasDecidedByCostThreshold() const { return DecidedByCostThreshold; }
1069 };
1070 
1071 // Return true if CB is the sole call to local function Callee.
1072 static bool isSoleCallToLocalFunction(const CallBase &CB,
1073                                       const Function &Callee) {
1074   return Callee.hasLocalLinkage() && Callee.hasOneLiveUse() &&
1075          &Callee == CB.getCalledFunction();
1076 }
1077 
1078 class InlineCostFeaturesAnalyzer final : public CallAnalyzer {
1079 private:
1080   InlineCostFeatures Cost = {};
1081 
1082   // FIXME: These constants are taken from the heuristic-based cost visitor.
1083   // These should be removed entirely in a later revision to avoid reliance on
1084   // heuristics in the ML inliner.
1085   static constexpr int JTCostMultiplier = 4;
1086   static constexpr int CaseClusterCostMultiplier = 2;
1087   static constexpr int SwitchCostMultiplier = 2;
1088 
1089   // FIXME: These are taken from the heuristic-based cost visitor: we should
1090   // eventually abstract these to the CallAnalyzer to avoid duplication.
1091   unsigned SROACostSavingOpportunities = 0;
1092   int VectorBonus = 0;
1093   int SingleBBBonus = 0;
1094   int Threshold = 5;
1095 
1096   DenseMap<AllocaInst *, unsigned> SROACosts;
1097 
1098   void increment(InlineCostFeatureIndex Feature, int64_t Delta = 1) {
1099     Cost[static_cast<size_t>(Feature)] += Delta;
1100   }
1101 
1102   void set(InlineCostFeatureIndex Feature, int64_t Value) {
1103     Cost[static_cast<size_t>(Feature)] = Value;
1104   }
1105 
1106   void onDisableSROA(AllocaInst *Arg) override {
1107     auto CostIt = SROACosts.find(Arg);
1108     if (CostIt == SROACosts.end())
1109       return;
1110 
1111     increment(InlineCostFeatureIndex::SROALosses, CostIt->second);
1112     SROACostSavingOpportunities -= CostIt->second;
1113     SROACosts.erase(CostIt);
1114   }
1115 
1116   void onDisableLoadElimination() override {
1117     set(InlineCostFeatureIndex::LoadElimination, 1);
1118   }
1119 
1120   void onCallPenalty() override {
1121     increment(InlineCostFeatureIndex::CallPenalty, CallPenalty);
1122   }
1123 
1124   void onCallArgumentSetup(const CallBase &Call) override {
1125     increment(InlineCostFeatureIndex::CallArgumentSetup,
1126               Call.arg_size() * InstrCost);
1127   }
1128 
1129   void onLoadRelativeIntrinsic() override {
1130     increment(InlineCostFeatureIndex::LoadRelativeIntrinsic, 3 * InstrCost);
1131   }
1132 
1133   void onLoweredCall(Function *F, CallBase &Call,
1134                      bool IsIndirectCall) override {
1135     increment(InlineCostFeatureIndex::LoweredCallArgSetup,
1136               Call.arg_size() * InstrCost);
1137 
1138     if (IsIndirectCall) {
1139       InlineParams IndirectCallParams = {/* DefaultThreshold*/ 0,
1140                                          /*HintThreshold*/ {},
1141                                          /*ColdThreshold*/ {},
1142                                          /*OptSizeThreshold*/ {},
1143                                          /*OptMinSizeThreshold*/ {},
1144                                          /*HotCallSiteThreshold*/ {},
1145                                          /*LocallyHotCallSiteThreshold*/ {},
1146                                          /*ColdCallSiteThreshold*/ {},
1147                                          /*ComputeFullInlineCost*/ true,
1148                                          /*EnableDeferral*/ true};
1149       IndirectCallParams.DefaultThreshold =
1150           InlineConstants::IndirectCallThreshold;
1151 
1152       InlineCostCallAnalyzer CA(*F, Call, IndirectCallParams, TTI,
1153                                 GetAssumptionCache, GetBFI, PSI, ORE, false,
1154                                 true);
1155       if (CA.analyze().isSuccess()) {
1156         increment(InlineCostFeatureIndex::NestedInlineCostEstimate,
1157                   CA.getCost());
1158         increment(InlineCostFeatureIndex::NestedInlines, 1);
1159       }
1160     } else {
1161       onCallPenalty();
1162     }
1163   }
1164 
1165   void onFinalizeSwitch(unsigned JumpTableSize,
1166                         unsigned NumCaseCluster) override {
1167 
1168     if (JumpTableSize) {
1169       int64_t JTCost = static_cast<int64_t>(JumpTableSize) * InstrCost +
1170                        JTCostMultiplier * InstrCost;
1171       increment(InlineCostFeatureIndex::JumpTablePenalty, JTCost);
1172       return;
1173     }
1174 
1175     if (NumCaseCluster <= 3) {
1176       increment(InlineCostFeatureIndex::CaseClusterPenalty,
1177                 NumCaseCluster * CaseClusterCostMultiplier * InstrCost);
1178       return;
1179     }
1180 
1181     int64_t ExpectedNumberOfCompare =
1182         getExpectedNumberOfCompare(NumCaseCluster);
1183 
1184     int64_t SwitchCost =
1185         ExpectedNumberOfCompare * SwitchCostMultiplier * InstrCost;
1186     increment(InlineCostFeatureIndex::SwitchPenalty, SwitchCost);
1187   }
1188 
1189   void onMissedSimplification() override {
1190     increment(InlineCostFeatureIndex::UnsimplifiedCommonInstructions,
1191               InstrCost);
1192   }
1193 
1194   void onInitializeSROAArg(AllocaInst *Arg) override { SROACosts[Arg] = 0; }
1195   void onAggregateSROAUse(AllocaInst *Arg) override {
1196     SROACosts.find(Arg)->second += InstrCost;
1197     SROACostSavingOpportunities += InstrCost;
1198   }
1199 
1200   void onBlockAnalyzed(const BasicBlock *BB) override {
1201     if (BB->getTerminator()->getNumSuccessors() > 1)
1202       set(InlineCostFeatureIndex::IsMultipleBlocks, 1);
1203     Threshold -= SingleBBBonus;
1204   }
1205 
1206   InlineResult finalizeAnalysis() override {
1207     auto *Caller = CandidateCall.getFunction();
1208     if (Caller->hasMinSize()) {
1209       DominatorTree DT(F);
1210       LoopInfo LI(DT);
1211       for (Loop *L : LI) {
1212         // Ignore loops that will not be executed
1213         if (DeadBlocks.count(L->getHeader()))
1214           continue;
1215         increment(InlineCostFeatureIndex::NumLoops,
1216                   InlineConstants::LoopPenalty);
1217       }
1218     }
1219     set(InlineCostFeatureIndex::DeadBlocks, DeadBlocks.size());
1220     set(InlineCostFeatureIndex::SimplifiedInstructions,
1221         NumInstructionsSimplified);
1222     set(InlineCostFeatureIndex::ConstantArgs, NumConstantArgs);
1223     set(InlineCostFeatureIndex::ConstantOffsetPtrArgs,
1224         NumConstantOffsetPtrArgs);
1225     set(InlineCostFeatureIndex::SROASavings, SROACostSavingOpportunities);
1226 
1227     if (NumVectorInstructions <= NumInstructions / 10)
1228       Threshold -= VectorBonus;
1229     else if (NumVectorInstructions <= NumInstructions / 2)
1230       Threshold -= VectorBonus / 2;
1231 
1232     set(InlineCostFeatureIndex::Threshold, Threshold);
1233 
1234     return InlineResult::success();
1235   }
1236 
1237   bool shouldStop() override { return false; }
1238 
1239   void onLoadEliminationOpportunity() override {
1240     increment(InlineCostFeatureIndex::LoadElimination, 1);
1241   }
1242 
1243   InlineResult onAnalysisStart() override {
1244     increment(InlineCostFeatureIndex::CallSiteCost,
1245               -1 * getCallsiteCost(this->CandidateCall, DL));
1246 
1247     set(InlineCostFeatureIndex::ColdCcPenalty,
1248         (F.getCallingConv() == CallingConv::Cold));
1249 
1250     set(InlineCostFeatureIndex::LastCallToStaticBonus,
1251         isSoleCallToLocalFunction(CandidateCall, F));
1252 
1253     // FIXME: we shouldn't repeat this logic in both the Features and Cost
1254     // analyzer - instead, we should abstract it to a common method in the
1255     // CallAnalyzer
1256     int SingleBBBonusPercent = 50;
1257     int VectorBonusPercent = TTI.getInlinerVectorBonusPercent();
1258     Threshold += TTI.adjustInliningThreshold(&CandidateCall);
1259     Threshold *= TTI.getInliningThresholdMultiplier();
1260     SingleBBBonus = Threshold * SingleBBBonusPercent / 100;
1261     VectorBonus = Threshold * VectorBonusPercent / 100;
1262     Threshold += (SingleBBBonus + VectorBonus);
1263 
1264     return InlineResult::success();
1265   }
1266 
1267 public:
1268   InlineCostFeaturesAnalyzer(
1269       const TargetTransformInfo &TTI,
1270       function_ref<AssumptionCache &(Function &)> &GetAssumptionCache,
1271       function_ref<BlockFrequencyInfo &(Function &)> GetBFI,
1272       ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE, Function &Callee,
1273       CallBase &Call)
1274       : CallAnalyzer(Callee, Call, TTI, GetAssumptionCache, GetBFI, PSI) {}
1275 
1276   const InlineCostFeatures &features() const { return Cost; }
1277 };
1278 
1279 } // namespace
1280 
1281 /// Test whether the given value is an Alloca-derived function argument.
1282 bool CallAnalyzer::isAllocaDerivedArg(Value *V) {
1283   return SROAArgValues.count(V);
1284 }
1285 
1286 void CallAnalyzer::disableSROAForArg(AllocaInst *SROAArg) {
1287   onDisableSROA(SROAArg);
1288   EnabledSROAAllocas.erase(SROAArg);
1289   disableLoadElimination();
1290 }
1291 
1292 void InlineCostAnnotationWriter::emitInstructionAnnot(
1293     const Instruction *I, formatted_raw_ostream &OS) {
1294   // The cost of inlining of the given instruction is printed always.
1295   // The threshold delta is printed only when it is non-zero. It happens
1296   // when we decided to give a bonus at a particular instruction.
1297   std::optional<InstructionCostDetail> Record = ICCA->getCostDetails(I);
1298   if (!Record)
1299     OS << "; No analysis for the instruction";
1300   else {
1301     OS << "; cost before = " << Record->CostBefore
1302        << ", cost after = " << Record->CostAfter
1303        << ", threshold before = " << Record->ThresholdBefore
1304        << ", threshold after = " << Record->ThresholdAfter << ", ";
1305     OS << "cost delta = " << Record->getCostDelta();
1306     if (Record->hasThresholdChanged())
1307       OS << ", threshold delta = " << Record->getThresholdDelta();
1308   }
1309   auto C = ICCA->getSimplifiedValue(const_cast<Instruction *>(I));
1310   if (C) {
1311     OS << ", simplified to ";
1312     (*C)->print(OS, true);
1313   }
1314   OS << "\n";
1315 }
1316 
1317 /// If 'V' maps to a SROA candidate, disable SROA for it.
1318 void CallAnalyzer::disableSROA(Value *V) {
1319   if (auto *SROAArg = getSROAArgForValueOrNull(V)) {
1320     disableSROAForArg(SROAArg);
1321   }
1322 }
1323 
1324 void CallAnalyzer::disableLoadElimination() {
1325   if (EnableLoadElimination) {
1326     onDisableLoadElimination();
1327     EnableLoadElimination = false;
1328   }
1329 }
1330 
1331 /// Accumulate a constant GEP offset into an APInt if possible.
1332 ///
1333 /// Returns false if unable to compute the offset for any reason. Respects any
1334 /// simplified values known during the analysis of this callsite.
1335 bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) {
1336   unsigned IntPtrWidth = DL.getIndexTypeSizeInBits(GEP.getType());
1337   assert(IntPtrWidth == Offset.getBitWidth());
1338 
1339   for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
1340        GTI != GTE; ++GTI) {
1341     ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
1342     if (!OpC)
1343       if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand()))
1344         OpC = dyn_cast<ConstantInt>(SimpleOp);
1345     if (!OpC)
1346       return false;
1347     if (OpC->isZero())
1348       continue;
1349 
1350     // Handle a struct index, which adds its field offset to the pointer.
1351     if (StructType *STy = GTI.getStructTypeOrNull()) {
1352       unsigned ElementIdx = OpC->getZExtValue();
1353       const StructLayout *SL = DL.getStructLayout(STy);
1354       Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
1355       continue;
1356     }
1357 
1358     APInt TypeSize(IntPtrWidth, DL.getTypeAllocSize(GTI.getIndexedType()));
1359     Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
1360   }
1361   return true;
1362 }
1363 
1364 /// Use TTI to check whether a GEP is free.
1365 ///
1366 /// Respects any simplified values known during the analysis of this callsite.
1367 bool CallAnalyzer::isGEPFree(GetElementPtrInst &GEP) {
1368   SmallVector<Value *, 4> Operands;
1369   Operands.push_back(GEP.getOperand(0));
1370   for (const Use &Op : GEP.indices())
1371     if (Constant *SimpleOp = SimplifiedValues.lookup(Op))
1372       Operands.push_back(SimpleOp);
1373     else
1374       Operands.push_back(Op);
1375   return TTI.getInstructionCost(&GEP, Operands,
1376                                 TargetTransformInfo::TCK_SizeAndLatency) ==
1377          TargetTransformInfo::TCC_Free;
1378 }
1379 
1380 bool CallAnalyzer::visitAlloca(AllocaInst &I) {
1381   disableSROA(I.getOperand(0));
1382 
1383   // Check whether inlining will turn a dynamic alloca into a static
1384   // alloca and handle that case.
1385   if (I.isArrayAllocation()) {
1386     Constant *Size = SimplifiedValues.lookup(I.getArraySize());
1387     if (auto *AllocSize = dyn_cast_or_null<ConstantInt>(Size)) {
1388       // Sometimes a dynamic alloca could be converted into a static alloca
1389       // after this constant prop, and become a huge static alloca on an
1390       // unconditional CFG path. Avoid inlining if this is going to happen above
1391       // a threshold.
1392       // FIXME: If the threshold is removed or lowered too much, we could end up
1393       // being too pessimistic and prevent inlining non-problematic code. This
1394       // could result in unintended perf regressions. A better overall strategy
1395       // is needed to track stack usage during inlining.
1396       Type *Ty = I.getAllocatedType();
1397       AllocatedSize = SaturatingMultiplyAdd(
1398           AllocSize->getLimitedValue(),
1399           DL.getTypeAllocSize(Ty).getKnownMinValue(), AllocatedSize);
1400       if (AllocatedSize > InlineConstants::MaxSimplifiedDynamicAllocaToInline)
1401         HasDynamicAlloca = true;
1402       return false;
1403     }
1404   }
1405 
1406   // Accumulate the allocated size.
1407   if (I.isStaticAlloca()) {
1408     Type *Ty = I.getAllocatedType();
1409     AllocatedSize = SaturatingAdd(DL.getTypeAllocSize(Ty).getKnownMinValue(),
1410                                   AllocatedSize);
1411   }
1412 
1413   // FIXME: This is overly conservative. Dynamic allocas are inefficient for
1414   // a variety of reasons, and so we would like to not inline them into
1415   // functions which don't currently have a dynamic alloca. This simply
1416   // disables inlining altogether in the presence of a dynamic alloca.
1417   if (!I.isStaticAlloca())
1418     HasDynamicAlloca = true;
1419 
1420   return false;
1421 }
1422 
1423 bool CallAnalyzer::visitPHI(PHINode &I) {
1424   // FIXME: We need to propagate SROA *disabling* through phi nodes, even
1425   // though we don't want to propagate it's bonuses. The idea is to disable
1426   // SROA if it *might* be used in an inappropriate manner.
1427 
1428   // Phi nodes are always zero-cost.
1429   // FIXME: Pointer sizes may differ between different address spaces, so do we
1430   // need to use correct address space in the call to getPointerSizeInBits here?
1431   // Or could we skip the getPointerSizeInBits call completely? As far as I can
1432   // see the ZeroOffset is used as a dummy value, so we can probably use any
1433   // bit width for the ZeroOffset?
1434   APInt ZeroOffset = APInt::getZero(DL.getPointerSizeInBits(0));
1435   bool CheckSROA = I.getType()->isPointerTy();
1436 
1437   // Track the constant or pointer with constant offset we've seen so far.
1438   Constant *FirstC = nullptr;
1439   std::pair<Value *, APInt> FirstBaseAndOffset = {nullptr, ZeroOffset};
1440   Value *FirstV = nullptr;
1441 
1442   for (unsigned i = 0, e = I.getNumIncomingValues(); i != e; ++i) {
1443     BasicBlock *Pred = I.getIncomingBlock(i);
1444     // If the incoming block is dead, skip the incoming block.
1445     if (DeadBlocks.count(Pred))
1446       continue;
1447     // If the parent block of phi is not the known successor of the incoming
1448     // block, skip the incoming block.
1449     BasicBlock *KnownSuccessor = KnownSuccessors[Pred];
1450     if (KnownSuccessor && KnownSuccessor != I.getParent())
1451       continue;
1452 
1453     Value *V = I.getIncomingValue(i);
1454     // If the incoming value is this phi itself, skip the incoming value.
1455     if (&I == V)
1456       continue;
1457 
1458     Constant *C = dyn_cast<Constant>(V);
1459     if (!C)
1460       C = SimplifiedValues.lookup(V);
1461 
1462     std::pair<Value *, APInt> BaseAndOffset = {nullptr, ZeroOffset};
1463     if (!C && CheckSROA)
1464       BaseAndOffset = ConstantOffsetPtrs.lookup(V);
1465 
1466     if (!C && !BaseAndOffset.first)
1467       // The incoming value is neither a constant nor a pointer with constant
1468       // offset, exit early.
1469       return true;
1470 
1471     if (FirstC) {
1472       if (FirstC == C)
1473         // If we've seen a constant incoming value before and it is the same
1474         // constant we see this time, continue checking the next incoming value.
1475         continue;
1476       // Otherwise early exit because we either see a different constant or saw
1477       // a constant before but we have a pointer with constant offset this time.
1478       return true;
1479     }
1480 
1481     if (FirstV) {
1482       // The same logic as above, but check pointer with constant offset here.
1483       if (FirstBaseAndOffset == BaseAndOffset)
1484         continue;
1485       return true;
1486     }
1487 
1488     if (C) {
1489       // This is the 1st time we've seen a constant, record it.
1490       FirstC = C;
1491       continue;
1492     }
1493 
1494     // The remaining case is that this is the 1st time we've seen a pointer with
1495     // constant offset, record it.
1496     FirstV = V;
1497     FirstBaseAndOffset = BaseAndOffset;
1498   }
1499 
1500   // Check if we can map phi to a constant.
1501   if (FirstC) {
1502     SimplifiedValues[&I] = FirstC;
1503     return true;
1504   }
1505 
1506   // Check if we can map phi to a pointer with constant offset.
1507   if (FirstBaseAndOffset.first) {
1508     ConstantOffsetPtrs[&I] = FirstBaseAndOffset;
1509 
1510     if (auto *SROAArg = getSROAArgForValueOrNull(FirstV))
1511       SROAArgValues[&I] = SROAArg;
1512   }
1513 
1514   return true;
1515 }
1516 
1517 /// Check we can fold GEPs of constant-offset call site argument pointers.
1518 /// This requires target data and inbounds GEPs.
1519 ///
1520 /// \return true if the specified GEP can be folded.
1521 bool CallAnalyzer::canFoldInboundsGEP(GetElementPtrInst &I) {
1522   // Check if we have a base + offset for the pointer.
1523   std::pair<Value *, APInt> BaseAndOffset =
1524       ConstantOffsetPtrs.lookup(I.getPointerOperand());
1525   if (!BaseAndOffset.first)
1526     return false;
1527 
1528   // Check if the offset of this GEP is constant, and if so accumulate it
1529   // into Offset.
1530   if (!accumulateGEPOffset(cast<GEPOperator>(I), BaseAndOffset.second))
1531     return false;
1532 
1533   // Add the result as a new mapping to Base + Offset.
1534   ConstantOffsetPtrs[&I] = BaseAndOffset;
1535 
1536   return true;
1537 }
1538 
1539 bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) {
1540   auto *SROAArg = getSROAArgForValueOrNull(I.getPointerOperand());
1541 
1542   // Lambda to check whether a GEP's indices are all constant.
1543   auto IsGEPOffsetConstant = [&](GetElementPtrInst &GEP) {
1544     for (const Use &Op : GEP.indices())
1545       if (!isa<Constant>(Op) && !SimplifiedValues.lookup(Op))
1546         return false;
1547     return true;
1548   };
1549 
1550   if (!DisableGEPConstOperand)
1551     if (simplifyInstruction(I))
1552       return true;
1553 
1554   if ((I.isInBounds() && canFoldInboundsGEP(I)) || IsGEPOffsetConstant(I)) {
1555     if (SROAArg)
1556       SROAArgValues[&I] = SROAArg;
1557 
1558     // Constant GEPs are modeled as free.
1559     return true;
1560   }
1561 
1562   // Variable GEPs will require math and will disable SROA.
1563   if (SROAArg)
1564     disableSROAForArg(SROAArg);
1565   return isGEPFree(I);
1566 }
1567 
1568 /// Simplify \p I if its operands are constants and update SimplifiedValues.
1569 bool CallAnalyzer::simplifyInstruction(Instruction &I) {
1570   SmallVector<Constant *> COps;
1571   for (Value *Op : I.operands()) {
1572     Constant *COp = dyn_cast<Constant>(Op);
1573     if (!COp)
1574       COp = SimplifiedValues.lookup(Op);
1575     if (!COp)
1576       return false;
1577     COps.push_back(COp);
1578   }
1579   auto *C = ConstantFoldInstOperands(&I, COps, DL);
1580   if (!C)
1581     return false;
1582   SimplifiedValues[&I] = C;
1583   return true;
1584 }
1585 
1586 /// Try to simplify a call to llvm.is.constant.
1587 ///
1588 /// Duplicate the argument checking from CallAnalyzer::simplifyCallSite since
1589 /// we expect calls of this specific intrinsic to be infrequent.
1590 ///
1591 /// FIXME: Given that we know CB's parent (F) caller
1592 /// (CandidateCall->getParent()->getParent()), we might be able to determine
1593 /// whether inlining F into F's caller would change how the call to
1594 /// llvm.is.constant would evaluate.
1595 bool CallAnalyzer::simplifyIntrinsicCallIsConstant(CallBase &CB) {
1596   Value *Arg = CB.getArgOperand(0);
1597   auto *C = dyn_cast<Constant>(Arg);
1598 
1599   if (!C)
1600     C = dyn_cast_or_null<Constant>(SimplifiedValues.lookup(Arg));
1601 
1602   Type *RT = CB.getFunctionType()->getReturnType();
1603   SimplifiedValues[&CB] = ConstantInt::get(RT, C ? 1 : 0);
1604   return true;
1605 }
1606 
1607 bool CallAnalyzer::simplifyIntrinsicCallObjectSize(CallBase &CB) {
1608   // As per the langref, "The fourth argument to llvm.objectsize determines if
1609   // the value should be evaluated at runtime."
1610   if(cast<ConstantInt>(CB.getArgOperand(3))->isOne())
1611     return false;
1612 
1613   Value *V = lowerObjectSizeCall(&cast<IntrinsicInst>(CB), DL, nullptr,
1614                                  /*MustSucceed=*/true);
1615   Constant *C = dyn_cast_or_null<Constant>(V);
1616   if (C)
1617     SimplifiedValues[&CB] = C;
1618   return C;
1619 }
1620 
1621 bool CallAnalyzer::visitBitCast(BitCastInst &I) {
1622   // Propagate constants through bitcasts.
1623   if (simplifyInstruction(I))
1624     return true;
1625 
1626   // Track base/offsets through casts
1627   std::pair<Value *, APInt> BaseAndOffset =
1628       ConstantOffsetPtrs.lookup(I.getOperand(0));
1629   // Casts don't change the offset, just wrap it up.
1630   if (BaseAndOffset.first)
1631     ConstantOffsetPtrs[&I] = BaseAndOffset;
1632 
1633   // Also look for SROA candidates here.
1634   if (auto *SROAArg = getSROAArgForValueOrNull(I.getOperand(0)))
1635     SROAArgValues[&I] = SROAArg;
1636 
1637   // Bitcasts are always zero cost.
1638   return true;
1639 }
1640 
1641 bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) {
1642   // Propagate constants through ptrtoint.
1643   if (simplifyInstruction(I))
1644     return true;
1645 
1646   // Track base/offset pairs when converted to a plain integer provided the
1647   // integer is large enough to represent the pointer.
1648   unsigned IntegerSize = I.getType()->getScalarSizeInBits();
1649   unsigned AS = I.getOperand(0)->getType()->getPointerAddressSpace();
1650   if (IntegerSize == DL.getPointerSizeInBits(AS)) {
1651     std::pair<Value *, APInt> BaseAndOffset =
1652         ConstantOffsetPtrs.lookup(I.getOperand(0));
1653     if (BaseAndOffset.first)
1654       ConstantOffsetPtrs[&I] = BaseAndOffset;
1655   }
1656 
1657   // This is really weird. Technically, ptrtoint will disable SROA. However,
1658   // unless that ptrtoint is *used* somewhere in the live basic blocks after
1659   // inlining, it will be nuked, and SROA should proceed. All of the uses which
1660   // would block SROA would also block SROA if applied directly to a pointer,
1661   // and so we can just add the integer in here. The only places where SROA is
1662   // preserved either cannot fire on an integer, or won't in-and-of themselves
1663   // disable SROA (ext) w/o some later use that we would see and disable.
1664   if (auto *SROAArg = getSROAArgForValueOrNull(I.getOperand(0)))
1665     SROAArgValues[&I] = SROAArg;
1666 
1667   return TTI.getInstructionCost(&I, TargetTransformInfo::TCK_SizeAndLatency) ==
1668          TargetTransformInfo::TCC_Free;
1669 }
1670 
1671 bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
1672   // Propagate constants through ptrtoint.
1673   if (simplifyInstruction(I))
1674     return true;
1675 
1676   // Track base/offset pairs when round-tripped through a pointer without
1677   // modifications provided the integer is not too large.
1678   Value *Op = I.getOperand(0);
1679   unsigned IntegerSize = Op->getType()->getScalarSizeInBits();
1680   if (IntegerSize <= DL.getPointerTypeSizeInBits(I.getType())) {
1681     std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Op);
1682     if (BaseAndOffset.first)
1683       ConstantOffsetPtrs[&I] = BaseAndOffset;
1684   }
1685 
1686   // "Propagate" SROA here in the same manner as we do for ptrtoint above.
1687   if (auto *SROAArg = getSROAArgForValueOrNull(Op))
1688     SROAArgValues[&I] = SROAArg;
1689 
1690   return TTI.getInstructionCost(&I, TargetTransformInfo::TCK_SizeAndLatency) ==
1691          TargetTransformInfo::TCC_Free;
1692 }
1693 
1694 bool CallAnalyzer::visitCastInst(CastInst &I) {
1695   // Propagate constants through casts.
1696   if (simplifyInstruction(I))
1697     return true;
1698 
1699   // Disable SROA in the face of arbitrary casts we don't explicitly list
1700   // elsewhere.
1701   disableSROA(I.getOperand(0));
1702 
1703   // If this is a floating-point cast, and the target says this operation
1704   // is expensive, this may eventually become a library call. Treat the cost
1705   // as such.
1706   switch (I.getOpcode()) {
1707   case Instruction::FPTrunc:
1708   case Instruction::FPExt:
1709   case Instruction::UIToFP:
1710   case Instruction::SIToFP:
1711   case Instruction::FPToUI:
1712   case Instruction::FPToSI:
1713     if (TTI.getFPOpCost(I.getType()) == TargetTransformInfo::TCC_Expensive)
1714       onCallPenalty();
1715     break;
1716   default:
1717     break;
1718   }
1719 
1720   return TTI.getInstructionCost(&I, TargetTransformInfo::TCK_SizeAndLatency) ==
1721          TargetTransformInfo::TCC_Free;
1722 }
1723 
1724 bool CallAnalyzer::paramHasAttr(Argument *A, Attribute::AttrKind Attr) {
1725   return CandidateCall.paramHasAttr(A->getArgNo(), Attr);
1726 }
1727 
1728 bool CallAnalyzer::isKnownNonNullInCallee(Value *V) {
1729   // Does the *call site* have the NonNull attribute set on an argument?  We
1730   // use the attribute on the call site to memoize any analysis done in the
1731   // caller. This will also trip if the callee function has a non-null
1732   // parameter attribute, but that's a less interesting case because hopefully
1733   // the callee would already have been simplified based on that.
1734   if (Argument *A = dyn_cast<Argument>(V))
1735     if (paramHasAttr(A, Attribute::NonNull))
1736       return true;
1737 
1738   // Is this an alloca in the caller?  This is distinct from the attribute case
1739   // above because attributes aren't updated within the inliner itself and we
1740   // always want to catch the alloca derived case.
1741   if (isAllocaDerivedArg(V))
1742     // We can actually predict the result of comparisons between an
1743     // alloca-derived value and null. Note that this fires regardless of
1744     // SROA firing.
1745     return true;
1746 
1747   return false;
1748 }
1749 
1750 bool CallAnalyzer::allowSizeGrowth(CallBase &Call) {
1751   // If the normal destination of the invoke or the parent block of the call
1752   // site is unreachable-terminated, there is little point in inlining this
1753   // unless there is literally zero cost.
1754   // FIXME: Note that it is possible that an unreachable-terminated block has a
1755   // hot entry. For example, in below scenario inlining hot_call_X() may be
1756   // beneficial :
1757   // main() {
1758   //   hot_call_1();
1759   //   ...
1760   //   hot_call_N()
1761   //   exit(0);
1762   // }
1763   // For now, we are not handling this corner case here as it is rare in real
1764   // code. In future, we should elaborate this based on BPI and BFI in more
1765   // general threshold adjusting heuristics in updateThreshold().
1766   if (InvokeInst *II = dyn_cast<InvokeInst>(&Call)) {
1767     if (isa<UnreachableInst>(II->getNormalDest()->getTerminator()))
1768       return false;
1769   } else if (isa<UnreachableInst>(Call.getParent()->getTerminator()))
1770     return false;
1771 
1772   return true;
1773 }
1774 
1775 bool InlineCostCallAnalyzer::isColdCallSite(CallBase &Call,
1776                                             BlockFrequencyInfo *CallerBFI) {
1777   // If global profile summary is available, then callsite's coldness is
1778   // determined based on that.
1779   if (PSI && PSI->hasProfileSummary())
1780     return PSI->isColdCallSite(Call, CallerBFI);
1781 
1782   // Otherwise we need BFI to be available.
1783   if (!CallerBFI)
1784     return false;
1785 
1786   // Determine if the callsite is cold relative to caller's entry. We could
1787   // potentially cache the computation of scaled entry frequency, but the added
1788   // complexity is not worth it unless this scaling shows up high in the
1789   // profiles.
1790   const BranchProbability ColdProb(ColdCallSiteRelFreq, 100);
1791   auto CallSiteBB = Call.getParent();
1792   auto CallSiteFreq = CallerBFI->getBlockFreq(CallSiteBB);
1793   auto CallerEntryFreq =
1794       CallerBFI->getBlockFreq(&(Call.getCaller()->getEntryBlock()));
1795   return CallSiteFreq < CallerEntryFreq * ColdProb;
1796 }
1797 
1798 std::optional<int>
1799 InlineCostCallAnalyzer::getHotCallSiteThreshold(CallBase &Call,
1800                                                 BlockFrequencyInfo *CallerBFI) {
1801 
1802   // If global profile summary is available, then callsite's hotness is
1803   // determined based on that.
1804   if (PSI && PSI->hasProfileSummary() && PSI->isHotCallSite(Call, CallerBFI))
1805     return Params.HotCallSiteThreshold;
1806 
1807   // Otherwise we need BFI to be available and to have a locally hot callsite
1808   // threshold.
1809   if (!CallerBFI || !Params.LocallyHotCallSiteThreshold)
1810     return std::nullopt;
1811 
1812   // Determine if the callsite is hot relative to caller's entry. We could
1813   // potentially cache the computation of scaled entry frequency, but the added
1814   // complexity is not worth it unless this scaling shows up high in the
1815   // profiles.
1816   auto CallSiteBB = Call.getParent();
1817   auto CallSiteFreq = CallerBFI->getBlockFreq(CallSiteBB).getFrequency();
1818   auto CallerEntryFreq = CallerBFI->getEntryFreq();
1819   if (CallSiteFreq >= CallerEntryFreq * HotCallSiteRelFreq)
1820     return Params.LocallyHotCallSiteThreshold;
1821 
1822   // Otherwise treat it normally.
1823   return std::nullopt;
1824 }
1825 
1826 void InlineCostCallAnalyzer::updateThreshold(CallBase &Call, Function &Callee) {
1827   // If no size growth is allowed for this inlining, set Threshold to 0.
1828   if (!allowSizeGrowth(Call)) {
1829     Threshold = 0;
1830     return;
1831   }
1832 
1833   Function *Caller = Call.getCaller();
1834 
1835   // return min(A, B) if B is valid.
1836   auto MinIfValid = [](int A, std::optional<int> B) {
1837     return B ? std::min(A, *B) : A;
1838   };
1839 
1840   // return max(A, B) if B is valid.
1841   auto MaxIfValid = [](int A, std::optional<int> B) {
1842     return B ? std::max(A, *B) : A;
1843   };
1844 
1845   // Various bonus percentages. These are multiplied by Threshold to get the
1846   // bonus values.
1847   // SingleBBBonus: This bonus is applied if the callee has a single reachable
1848   // basic block at the given callsite context. This is speculatively applied
1849   // and withdrawn if more than one basic block is seen.
1850   //
1851   // LstCallToStaticBonus: This large bonus is applied to ensure the inlining
1852   // of the last call to a static function as inlining such functions is
1853   // guaranteed to reduce code size.
1854   //
1855   // These bonus percentages may be set to 0 based on properties of the caller
1856   // and the callsite.
1857   int SingleBBBonusPercent = 50;
1858   int VectorBonusPercent = TTI.getInlinerVectorBonusPercent();
1859   int LastCallToStaticBonus = InlineConstants::LastCallToStaticBonus;
1860 
1861   // Lambda to set all the above bonus and bonus percentages to 0.
1862   auto DisallowAllBonuses = [&]() {
1863     SingleBBBonusPercent = 0;
1864     VectorBonusPercent = 0;
1865     LastCallToStaticBonus = 0;
1866   };
1867 
1868   // Use the OptMinSizeThreshold or OptSizeThreshold knob if they are available
1869   // and reduce the threshold if the caller has the necessary attribute.
1870   if (Caller->hasMinSize()) {
1871     Threshold = MinIfValid(Threshold, Params.OptMinSizeThreshold);
1872     // For minsize, we want to disable the single BB bonus and the vector
1873     // bonuses, but not the last-call-to-static bonus. Inlining the last call to
1874     // a static function will, at the minimum, eliminate the parameter setup and
1875     // call/return instructions.
1876     SingleBBBonusPercent = 0;
1877     VectorBonusPercent = 0;
1878   } else if (Caller->hasOptSize())
1879     Threshold = MinIfValid(Threshold, Params.OptSizeThreshold);
1880 
1881   // Adjust the threshold based on inlinehint attribute and profile based
1882   // hotness information if the caller does not have MinSize attribute.
1883   if (!Caller->hasMinSize()) {
1884     if (Callee.hasFnAttribute(Attribute::InlineHint))
1885       Threshold = MaxIfValid(Threshold, Params.HintThreshold);
1886 
1887     // FIXME: After switching to the new passmanager, simplify the logic below
1888     // by checking only the callsite hotness/coldness as we will reliably
1889     // have local profile information.
1890     //
1891     // Callsite hotness and coldness can be determined if sample profile is
1892     // used (which adds hotness metadata to calls) or if caller's
1893     // BlockFrequencyInfo is available.
1894     BlockFrequencyInfo *CallerBFI = GetBFI ? &(GetBFI(*Caller)) : nullptr;
1895     auto HotCallSiteThreshold = getHotCallSiteThreshold(Call, CallerBFI);
1896     if (!Caller->hasOptSize() && HotCallSiteThreshold) {
1897       LLVM_DEBUG(dbgs() << "Hot callsite.\n");
1898       // FIXME: This should update the threshold only if it exceeds the
1899       // current threshold, but AutoFDO + ThinLTO currently relies on this
1900       // behavior to prevent inlining of hot callsites during ThinLTO
1901       // compile phase.
1902       Threshold = *HotCallSiteThreshold;
1903     } else if (isColdCallSite(Call, CallerBFI)) {
1904       LLVM_DEBUG(dbgs() << "Cold callsite.\n");
1905       // Do not apply bonuses for a cold callsite including the
1906       // LastCallToStatic bonus. While this bonus might result in code size
1907       // reduction, it can cause the size of a non-cold caller to increase
1908       // preventing it from being inlined.
1909       DisallowAllBonuses();
1910       Threshold = MinIfValid(Threshold, Params.ColdCallSiteThreshold);
1911     } else if (PSI) {
1912       // Use callee's global profile information only if we have no way of
1913       // determining this via callsite information.
1914       if (PSI->isFunctionEntryHot(&Callee)) {
1915         LLVM_DEBUG(dbgs() << "Hot callee.\n");
1916         // If callsite hotness can not be determined, we may still know
1917         // that the callee is hot and treat it as a weaker hint for threshold
1918         // increase.
1919         Threshold = MaxIfValid(Threshold, Params.HintThreshold);
1920       } else if (PSI->isFunctionEntryCold(&Callee)) {
1921         LLVM_DEBUG(dbgs() << "Cold callee.\n");
1922         // Do not apply bonuses for a cold callee including the
1923         // LastCallToStatic bonus. While this bonus might result in code size
1924         // reduction, it can cause the size of a non-cold caller to increase
1925         // preventing it from being inlined.
1926         DisallowAllBonuses();
1927         Threshold = MinIfValid(Threshold, Params.ColdThreshold);
1928       }
1929     }
1930   }
1931 
1932   Threshold += TTI.adjustInliningThreshold(&Call);
1933 
1934   // Finally, take the target-specific inlining threshold multiplier into
1935   // account.
1936   Threshold *= TTI.getInliningThresholdMultiplier();
1937 
1938   SingleBBBonus = Threshold * SingleBBBonusPercent / 100;
1939   VectorBonus = Threshold * VectorBonusPercent / 100;
1940 
1941   // If there is only one call of the function, and it has internal linkage,
1942   // the cost of inlining it drops dramatically. It may seem odd to update
1943   // Cost in updateThreshold, but the bonus depends on the logic in this method.
1944   if (isSoleCallToLocalFunction(Call, F)) {
1945     Cost -= LastCallToStaticBonus;
1946     StaticBonusApplied = LastCallToStaticBonus;
1947   }
1948 }
1949 
1950 bool CallAnalyzer::visitCmpInst(CmpInst &I) {
1951   Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1952   // First try to handle simplified comparisons.
1953   if (simplifyInstruction(I))
1954     return true;
1955 
1956   if (I.getOpcode() == Instruction::FCmp)
1957     return false;
1958 
1959   // Otherwise look for a comparison between constant offset pointers with
1960   // a common base.
1961   Value *LHSBase, *RHSBase;
1962   APInt LHSOffset, RHSOffset;
1963   std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
1964   if (LHSBase) {
1965     std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
1966     if (RHSBase && LHSBase == RHSBase) {
1967       // We have common bases, fold the icmp to a constant based on the
1968       // offsets.
1969       Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
1970       Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
1971       if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
1972         SimplifiedValues[&I] = C;
1973         ++NumConstantPtrCmps;
1974         return true;
1975       }
1976     }
1977   }
1978 
1979   // If the comparison is an equality comparison with null, we can simplify it
1980   // if we know the value (argument) can't be null
1981   if (I.isEquality() && isa<ConstantPointerNull>(I.getOperand(1)) &&
1982       isKnownNonNullInCallee(I.getOperand(0))) {
1983     bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE;
1984     SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType())
1985                                       : ConstantInt::getFalse(I.getType());
1986     return true;
1987   }
1988   return handleSROA(I.getOperand(0), isa<ConstantPointerNull>(I.getOperand(1)));
1989 }
1990 
1991 bool CallAnalyzer::visitSub(BinaryOperator &I) {
1992   // Try to handle a special case: we can fold computing the difference of two
1993   // constant-related pointers.
1994   Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1995   Value *LHSBase, *RHSBase;
1996   APInt LHSOffset, RHSOffset;
1997   std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
1998   if (LHSBase) {
1999     std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
2000     if (RHSBase && LHSBase == RHSBase) {
2001       // We have common bases, fold the subtract to a constant based on the
2002       // offsets.
2003       Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
2004       Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
2005       if (Constant *C = ConstantExpr::getSub(CLHS, CRHS)) {
2006         SimplifiedValues[&I] = C;
2007         ++NumConstantPtrDiffs;
2008         return true;
2009       }
2010     }
2011   }
2012 
2013   // Otherwise, fall back to the generic logic for simplifying and handling
2014   // instructions.
2015   return Base::visitSub(I);
2016 }
2017 
2018 bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) {
2019   Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
2020   Constant *CLHS = dyn_cast<Constant>(LHS);
2021   if (!CLHS)
2022     CLHS = SimplifiedValues.lookup(LHS);
2023   Constant *CRHS = dyn_cast<Constant>(RHS);
2024   if (!CRHS)
2025     CRHS = SimplifiedValues.lookup(RHS);
2026 
2027   Value *SimpleV = nullptr;
2028   if (auto FI = dyn_cast<FPMathOperator>(&I))
2029     SimpleV = simplifyBinOp(I.getOpcode(), CLHS ? CLHS : LHS, CRHS ? CRHS : RHS,
2030                             FI->getFastMathFlags(), DL);
2031   else
2032     SimpleV =
2033         simplifyBinOp(I.getOpcode(), CLHS ? CLHS : LHS, CRHS ? CRHS : RHS, DL);
2034 
2035   if (Constant *C = dyn_cast_or_null<Constant>(SimpleV))
2036     SimplifiedValues[&I] = C;
2037 
2038   if (SimpleV)
2039     return true;
2040 
2041   // Disable any SROA on arguments to arbitrary, unsimplified binary operators.
2042   disableSROA(LHS);
2043   disableSROA(RHS);
2044 
2045   // If the instruction is floating point, and the target says this operation
2046   // is expensive, this may eventually become a library call. Treat the cost
2047   // as such. Unless it's fneg which can be implemented with an xor.
2048   using namespace llvm::PatternMatch;
2049   if (I.getType()->isFloatingPointTy() &&
2050       TTI.getFPOpCost(I.getType()) == TargetTransformInfo::TCC_Expensive &&
2051       !match(&I, m_FNeg(m_Value())))
2052     onCallPenalty();
2053 
2054   return false;
2055 }
2056 
2057 bool CallAnalyzer::visitFNeg(UnaryOperator &I) {
2058   Value *Op = I.getOperand(0);
2059   Constant *COp = dyn_cast<Constant>(Op);
2060   if (!COp)
2061     COp = SimplifiedValues.lookup(Op);
2062 
2063   Value *SimpleV = simplifyFNegInst(
2064       COp ? COp : Op, cast<FPMathOperator>(I).getFastMathFlags(), DL);
2065 
2066   if (Constant *C = dyn_cast_or_null<Constant>(SimpleV))
2067     SimplifiedValues[&I] = C;
2068 
2069   if (SimpleV)
2070     return true;
2071 
2072   // Disable any SROA on arguments to arbitrary, unsimplified fneg.
2073   disableSROA(Op);
2074 
2075   return false;
2076 }
2077 
2078 bool CallAnalyzer::visitLoad(LoadInst &I) {
2079   if (handleSROA(I.getPointerOperand(), I.isSimple()))
2080     return true;
2081 
2082   // If the data is already loaded from this address and hasn't been clobbered
2083   // by any stores or calls, this load is likely to be redundant and can be
2084   // eliminated.
2085   if (EnableLoadElimination &&
2086       !LoadAddrSet.insert(I.getPointerOperand()).second && I.isUnordered()) {
2087     onLoadEliminationOpportunity();
2088     return true;
2089   }
2090 
2091   onMemAccess();
2092   return false;
2093 }
2094 
2095 bool CallAnalyzer::visitStore(StoreInst &I) {
2096   if (handleSROA(I.getPointerOperand(), I.isSimple()))
2097     return true;
2098 
2099   // The store can potentially clobber loads and prevent repeated loads from
2100   // being eliminated.
2101   // FIXME:
2102   // 1. We can probably keep an initial set of eliminatable loads substracted
2103   // from the cost even when we finally see a store. We just need to disable
2104   // *further* accumulation of elimination savings.
2105   // 2. We should probably at some point thread MemorySSA for the callee into
2106   // this and then use that to actually compute *really* precise savings.
2107   disableLoadElimination();
2108 
2109   onMemAccess();
2110   return false;
2111 }
2112 
2113 bool CallAnalyzer::visitExtractValue(ExtractValueInst &I) {
2114   // Constant folding for extract value is trivial.
2115   if (simplifyInstruction(I))
2116     return true;
2117 
2118   // SROA can't look through these, but they may be free.
2119   return Base::visitExtractValue(I);
2120 }
2121 
2122 bool CallAnalyzer::visitInsertValue(InsertValueInst &I) {
2123   // Constant folding for insert value is trivial.
2124   if (simplifyInstruction(I))
2125     return true;
2126 
2127   // SROA can't look through these, but they may be free.
2128   return Base::visitInsertValue(I);
2129 }
2130 
2131 /// Try to simplify a call site.
2132 ///
2133 /// Takes a concrete function and callsite and tries to actually simplify it by
2134 /// analyzing the arguments and call itself with instsimplify. Returns true if
2135 /// it has simplified the callsite to some other entity (a constant), making it
2136 /// free.
2137 bool CallAnalyzer::simplifyCallSite(Function *F, CallBase &Call) {
2138   // FIXME: Using the instsimplify logic directly for this is inefficient
2139   // because we have to continually rebuild the argument list even when no
2140   // simplifications can be performed. Until that is fixed with remapping
2141   // inside of instsimplify, directly constant fold calls here.
2142   if (!canConstantFoldCallTo(&Call, F))
2143     return false;
2144 
2145   // Try to re-map the arguments to constants.
2146   SmallVector<Constant *, 4> ConstantArgs;
2147   ConstantArgs.reserve(Call.arg_size());
2148   for (Value *I : Call.args()) {
2149     Constant *C = dyn_cast<Constant>(I);
2150     if (!C)
2151       C = dyn_cast_or_null<Constant>(SimplifiedValues.lookup(I));
2152     if (!C)
2153       return false; // This argument doesn't map to a constant.
2154 
2155     ConstantArgs.push_back(C);
2156   }
2157   if (Constant *C = ConstantFoldCall(&Call, F, ConstantArgs)) {
2158     SimplifiedValues[&Call] = C;
2159     return true;
2160   }
2161 
2162   return false;
2163 }
2164 
2165 bool CallAnalyzer::visitCallBase(CallBase &Call) {
2166   if (!onCallBaseVisitStart(Call))
2167     return true;
2168 
2169   if (Call.hasFnAttr(Attribute::ReturnsTwice) &&
2170       !F.hasFnAttribute(Attribute::ReturnsTwice)) {
2171     // This aborts the entire analysis.
2172     ExposesReturnsTwice = true;
2173     return false;
2174   }
2175   if (isa<CallInst>(Call) && cast<CallInst>(Call).cannotDuplicate())
2176     ContainsNoDuplicateCall = true;
2177 
2178   Function *F = Call.getCalledFunction();
2179   bool IsIndirectCall = !F;
2180   if (IsIndirectCall) {
2181     // Check if this happens to be an indirect function call to a known function
2182     // in this inline context. If not, we've done all we can.
2183     Value *Callee = Call.getCalledOperand();
2184     F = dyn_cast_or_null<Function>(SimplifiedValues.lookup(Callee));
2185     if (!F || F->getFunctionType() != Call.getFunctionType()) {
2186       onCallArgumentSetup(Call);
2187 
2188       if (!Call.onlyReadsMemory())
2189         disableLoadElimination();
2190       return Base::visitCallBase(Call);
2191     }
2192   }
2193 
2194   assert(F && "Expected a call to a known function");
2195 
2196   // When we have a concrete function, first try to simplify it directly.
2197   if (simplifyCallSite(F, Call))
2198     return true;
2199 
2200   // Next check if it is an intrinsic we know about.
2201   // FIXME: Lift this into part of the InstVisitor.
2202   if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&Call)) {
2203     switch (II->getIntrinsicID()) {
2204     default:
2205       if (!Call.onlyReadsMemory() && !isAssumeLikeIntrinsic(II))
2206         disableLoadElimination();
2207       return Base::visitCallBase(Call);
2208 
2209     case Intrinsic::load_relative:
2210       onLoadRelativeIntrinsic();
2211       return false;
2212 
2213     case Intrinsic::memset:
2214     case Intrinsic::memcpy:
2215     case Intrinsic::memmove:
2216       disableLoadElimination();
2217       // SROA can usually chew through these intrinsics, but they aren't free.
2218       return false;
2219     case Intrinsic::icall_branch_funnel:
2220     case Intrinsic::localescape:
2221       HasUninlineableIntrinsic = true;
2222       return false;
2223     case Intrinsic::vastart:
2224       InitsVargArgs = true;
2225       return false;
2226     case Intrinsic::launder_invariant_group:
2227     case Intrinsic::strip_invariant_group:
2228       if (auto *SROAArg = getSROAArgForValueOrNull(II->getOperand(0)))
2229         SROAArgValues[II] = SROAArg;
2230       return true;
2231     case Intrinsic::is_constant:
2232       return simplifyIntrinsicCallIsConstant(Call);
2233     case Intrinsic::objectsize:
2234       return simplifyIntrinsicCallObjectSize(Call);
2235     }
2236   }
2237 
2238   if (F == Call.getFunction()) {
2239     // This flag will fully abort the analysis, so don't bother with anything
2240     // else.
2241     IsRecursiveCall = true;
2242     if (!AllowRecursiveCall)
2243       return false;
2244   }
2245 
2246   if (TTI.isLoweredToCall(F)) {
2247     onLoweredCall(F, Call, IsIndirectCall);
2248   }
2249 
2250   if (!(Call.onlyReadsMemory() || (IsIndirectCall && F->onlyReadsMemory())))
2251     disableLoadElimination();
2252   return Base::visitCallBase(Call);
2253 }
2254 
2255 bool CallAnalyzer::visitReturnInst(ReturnInst &RI) {
2256   // At least one return instruction will be free after inlining.
2257   bool Free = !HasReturn;
2258   HasReturn = true;
2259   return Free;
2260 }
2261 
2262 bool CallAnalyzer::visitBranchInst(BranchInst &BI) {
2263   // We model unconditional branches as essentially free -- they really
2264   // shouldn't exist at all, but handling them makes the behavior of the
2265   // inliner more regular and predictable. Interestingly, conditional branches
2266   // which will fold away are also free.
2267   return BI.isUnconditional() || isa<ConstantInt>(BI.getCondition()) ||
2268          isa_and_nonnull<ConstantInt>(
2269              SimplifiedValues.lookup(BI.getCondition()));
2270 }
2271 
2272 bool CallAnalyzer::visitSelectInst(SelectInst &SI) {
2273   bool CheckSROA = SI.getType()->isPointerTy();
2274   Value *TrueVal = SI.getTrueValue();
2275   Value *FalseVal = SI.getFalseValue();
2276 
2277   Constant *TrueC = dyn_cast<Constant>(TrueVal);
2278   if (!TrueC)
2279     TrueC = SimplifiedValues.lookup(TrueVal);
2280   Constant *FalseC = dyn_cast<Constant>(FalseVal);
2281   if (!FalseC)
2282     FalseC = SimplifiedValues.lookup(FalseVal);
2283   Constant *CondC =
2284       dyn_cast_or_null<Constant>(SimplifiedValues.lookup(SI.getCondition()));
2285 
2286   if (!CondC) {
2287     // Select C, X, X => X
2288     if (TrueC == FalseC && TrueC) {
2289       SimplifiedValues[&SI] = TrueC;
2290       return true;
2291     }
2292 
2293     if (!CheckSROA)
2294       return Base::visitSelectInst(SI);
2295 
2296     std::pair<Value *, APInt> TrueBaseAndOffset =
2297         ConstantOffsetPtrs.lookup(TrueVal);
2298     std::pair<Value *, APInt> FalseBaseAndOffset =
2299         ConstantOffsetPtrs.lookup(FalseVal);
2300     if (TrueBaseAndOffset == FalseBaseAndOffset && TrueBaseAndOffset.first) {
2301       ConstantOffsetPtrs[&SI] = TrueBaseAndOffset;
2302 
2303       if (auto *SROAArg = getSROAArgForValueOrNull(TrueVal))
2304         SROAArgValues[&SI] = SROAArg;
2305       return true;
2306     }
2307 
2308     return Base::visitSelectInst(SI);
2309   }
2310 
2311   // Select condition is a constant.
2312   Value *SelectedV = CondC->isAllOnesValue()  ? TrueVal
2313                      : (CondC->isNullValue()) ? FalseVal
2314                                               : nullptr;
2315   if (!SelectedV) {
2316     // Condition is a vector constant that is not all 1s or all 0s.  If all
2317     // operands are constants, ConstantExpr::getSelect() can handle the cases
2318     // such as select vectors.
2319     if (TrueC && FalseC) {
2320       if (auto *C = ConstantExpr::getSelect(CondC, TrueC, FalseC)) {
2321         SimplifiedValues[&SI] = C;
2322         return true;
2323       }
2324     }
2325     return Base::visitSelectInst(SI);
2326   }
2327 
2328   // Condition is either all 1s or all 0s. SI can be simplified.
2329   if (Constant *SelectedC = dyn_cast<Constant>(SelectedV)) {
2330     SimplifiedValues[&SI] = SelectedC;
2331     return true;
2332   }
2333 
2334   if (!CheckSROA)
2335     return true;
2336 
2337   std::pair<Value *, APInt> BaseAndOffset =
2338       ConstantOffsetPtrs.lookup(SelectedV);
2339   if (BaseAndOffset.first) {
2340     ConstantOffsetPtrs[&SI] = BaseAndOffset;
2341 
2342     if (auto *SROAArg = getSROAArgForValueOrNull(SelectedV))
2343       SROAArgValues[&SI] = SROAArg;
2344   }
2345 
2346   return true;
2347 }
2348 
2349 bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
2350   // We model unconditional switches as free, see the comments on handling
2351   // branches.
2352   if (isa<ConstantInt>(SI.getCondition()))
2353     return true;
2354   if (Value *V = SimplifiedValues.lookup(SI.getCondition()))
2355     if (isa<ConstantInt>(V))
2356       return true;
2357 
2358   // Assume the most general case where the switch is lowered into
2359   // either a jump table, bit test, or a balanced binary tree consisting of
2360   // case clusters without merging adjacent clusters with the same
2361   // destination. We do not consider the switches that are lowered with a mix
2362   // of jump table/bit test/binary search tree. The cost of the switch is
2363   // proportional to the size of the tree or the size of jump table range.
2364   //
2365   // NB: We convert large switches which are just used to initialize large phi
2366   // nodes to lookup tables instead in simplifycfg, so this shouldn't prevent
2367   // inlining those. It will prevent inlining in cases where the optimization
2368   // does not (yet) fire.
2369 
2370   unsigned JumpTableSize = 0;
2371   BlockFrequencyInfo *BFI = GetBFI ? &(GetBFI(F)) : nullptr;
2372   unsigned NumCaseCluster =
2373       TTI.getEstimatedNumberOfCaseClusters(SI, JumpTableSize, PSI, BFI);
2374 
2375   onFinalizeSwitch(JumpTableSize, NumCaseCluster);
2376   return false;
2377 }
2378 
2379 bool CallAnalyzer::visitIndirectBrInst(IndirectBrInst &IBI) {
2380   // We never want to inline functions that contain an indirectbr.  This is
2381   // incorrect because all the blockaddress's (in static global initializers
2382   // for example) would be referring to the original function, and this
2383   // indirect jump would jump from the inlined copy of the function into the
2384   // original function which is extremely undefined behavior.
2385   // FIXME: This logic isn't really right; we can safely inline functions with
2386   // indirectbr's as long as no other function or global references the
2387   // blockaddress of a block within the current function.
2388   HasIndirectBr = true;
2389   return false;
2390 }
2391 
2392 bool CallAnalyzer::visitResumeInst(ResumeInst &RI) {
2393   // FIXME: It's not clear that a single instruction is an accurate model for
2394   // the inline cost of a resume instruction.
2395   return false;
2396 }
2397 
2398 bool CallAnalyzer::visitCleanupReturnInst(CleanupReturnInst &CRI) {
2399   // FIXME: It's not clear that a single instruction is an accurate model for
2400   // the inline cost of a cleanupret instruction.
2401   return false;
2402 }
2403 
2404 bool CallAnalyzer::visitCatchReturnInst(CatchReturnInst &CRI) {
2405   // FIXME: It's not clear that a single instruction is an accurate model for
2406   // the inline cost of a catchret instruction.
2407   return false;
2408 }
2409 
2410 bool CallAnalyzer::visitUnreachableInst(UnreachableInst &I) {
2411   // FIXME: It might be reasonably to discount the cost of instructions leading
2412   // to unreachable as they have the lowest possible impact on both runtime and
2413   // code size.
2414   return true; // No actual code is needed for unreachable.
2415 }
2416 
2417 bool CallAnalyzer::visitInstruction(Instruction &I) {
2418   // Some instructions are free. All of the free intrinsics can also be
2419   // handled by SROA, etc.
2420   if (TTI.getInstructionCost(&I, TargetTransformInfo::TCK_SizeAndLatency) ==
2421       TargetTransformInfo::TCC_Free)
2422     return true;
2423 
2424   // We found something we don't understand or can't handle. Mark any SROA-able
2425   // values in the operand list as no longer viable.
2426   for (const Use &Op : I.operands())
2427     disableSROA(Op);
2428 
2429   return false;
2430 }
2431 
2432 /// Analyze a basic block for its contribution to the inline cost.
2433 ///
2434 /// This method walks the analyzer over every instruction in the given basic
2435 /// block and accounts for their cost during inlining at this callsite. It
2436 /// aborts early if the threshold has been exceeded or an impossible to inline
2437 /// construct has been detected. It returns false if inlining is no longer
2438 /// viable, and true if inlining remains viable.
2439 InlineResult
2440 CallAnalyzer::analyzeBlock(BasicBlock *BB,
2441                            SmallPtrSetImpl<const Value *> &EphValues) {
2442   for (Instruction &I : *BB) {
2443     // FIXME: Currently, the number of instructions in a function regardless of
2444     // our ability to simplify them during inline to constants or dead code,
2445     // are actually used by the vector bonus heuristic. As long as that's true,
2446     // we have to special case debug intrinsics here to prevent differences in
2447     // inlining due to debug symbols. Eventually, the number of unsimplified
2448     // instructions shouldn't factor into the cost computation, but until then,
2449     // hack around it here.
2450     // Similarly, skip pseudo-probes.
2451     if (I.isDebugOrPseudoInst())
2452       continue;
2453 
2454     // Skip ephemeral values.
2455     if (EphValues.count(&I))
2456       continue;
2457 
2458     ++NumInstructions;
2459     if (isa<ExtractElementInst>(I) || I.getType()->isVectorTy())
2460       ++NumVectorInstructions;
2461 
2462     // If the instruction simplified to a constant, there is no cost to this
2463     // instruction. Visit the instructions using our InstVisitor to account for
2464     // all of the per-instruction logic. The visit tree returns true if we
2465     // consumed the instruction in any way, and false if the instruction's base
2466     // cost should count against inlining.
2467     onInstructionAnalysisStart(&I);
2468 
2469     if (Base::visit(&I))
2470       ++NumInstructionsSimplified;
2471     else
2472       onMissedSimplification();
2473 
2474     onInstructionAnalysisFinish(&I);
2475     using namespace ore;
2476     // If the visit this instruction detected an uninlinable pattern, abort.
2477     InlineResult IR = InlineResult::success();
2478     if (IsRecursiveCall && !AllowRecursiveCall)
2479       IR = InlineResult::failure("recursive");
2480     else if (ExposesReturnsTwice)
2481       IR = InlineResult::failure("exposes returns twice");
2482     else if (HasDynamicAlloca)
2483       IR = InlineResult::failure("dynamic alloca");
2484     else if (HasIndirectBr)
2485       IR = InlineResult::failure("indirect branch");
2486     else if (HasUninlineableIntrinsic)
2487       IR = InlineResult::failure("uninlinable intrinsic");
2488     else if (InitsVargArgs)
2489       IR = InlineResult::failure("varargs");
2490     if (!IR.isSuccess()) {
2491       if (ORE)
2492         ORE->emit([&]() {
2493           return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline",
2494                                           &CandidateCall)
2495                  << NV("Callee", &F) << " has uninlinable pattern ("
2496                  << NV("InlineResult", IR.getFailureReason())
2497                  << ") and cost is not fully computed";
2498         });
2499       return IR;
2500     }
2501 
2502     // If the caller is a recursive function then we don't want to inline
2503     // functions which allocate a lot of stack space because it would increase
2504     // the caller stack usage dramatically.
2505     if (IsCallerRecursive && AllocatedSize > RecurStackSizeThreshold) {
2506       auto IR =
2507           InlineResult::failure("recursive and allocates too much stack space");
2508       if (ORE)
2509         ORE->emit([&]() {
2510           return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline",
2511                                           &CandidateCall)
2512                  << NV("Callee", &F) << " is "
2513                  << NV("InlineResult", IR.getFailureReason())
2514                  << ". Cost is not fully computed";
2515         });
2516       return IR;
2517     }
2518 
2519     if (shouldStop())
2520       return InlineResult::failure(
2521           "Call site analysis is not favorable to inlining.");
2522   }
2523 
2524   return InlineResult::success();
2525 }
2526 
2527 /// Compute the base pointer and cumulative constant offsets for V.
2528 ///
2529 /// This strips all constant offsets off of V, leaving it the base pointer, and
2530 /// accumulates the total constant offset applied in the returned constant. It
2531 /// returns 0 if V is not a pointer, and returns the constant '0' if there are
2532 /// no constant offsets applied.
2533 ConstantInt *CallAnalyzer::stripAndComputeInBoundsConstantOffsets(Value *&V) {
2534   if (!V->getType()->isPointerTy())
2535     return nullptr;
2536 
2537   unsigned AS = V->getType()->getPointerAddressSpace();
2538   unsigned IntPtrWidth = DL.getIndexSizeInBits(AS);
2539   APInt Offset = APInt::getZero(IntPtrWidth);
2540 
2541   // Even though we don't look through PHI nodes, we could be called on an
2542   // instruction in an unreachable block, which may be on a cycle.
2543   SmallPtrSet<Value *, 4> Visited;
2544   Visited.insert(V);
2545   do {
2546     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
2547       if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset))
2548         return nullptr;
2549       V = GEP->getPointerOperand();
2550     } else if (Operator::getOpcode(V) == Instruction::BitCast) {
2551       V = cast<Operator>(V)->getOperand(0);
2552     } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
2553       if (GA->isInterposable())
2554         break;
2555       V = GA->getAliasee();
2556     } else {
2557       break;
2558     }
2559     assert(V->getType()->isPointerTy() && "Unexpected operand type!");
2560   } while (Visited.insert(V).second);
2561 
2562   Type *IdxPtrTy = DL.getIndexType(V->getType());
2563   return cast<ConstantInt>(ConstantInt::get(IdxPtrTy, Offset));
2564 }
2565 
2566 /// Find dead blocks due to deleted CFG edges during inlining.
2567 ///
2568 /// If we know the successor of the current block, \p CurrBB, has to be \p
2569 /// NextBB, the other successors of \p CurrBB are dead if these successors have
2570 /// no live incoming CFG edges.  If one block is found to be dead, we can
2571 /// continue growing the dead block list by checking the successors of the dead
2572 /// blocks to see if all their incoming edges are dead or not.
2573 void CallAnalyzer::findDeadBlocks(BasicBlock *CurrBB, BasicBlock *NextBB) {
2574   auto IsEdgeDead = [&](BasicBlock *Pred, BasicBlock *Succ) {
2575     // A CFG edge is dead if the predecessor is dead or the predecessor has a
2576     // known successor which is not the one under exam.
2577     return (DeadBlocks.count(Pred) ||
2578             (KnownSuccessors[Pred] && KnownSuccessors[Pred] != Succ));
2579   };
2580 
2581   auto IsNewlyDead = [&](BasicBlock *BB) {
2582     // If all the edges to a block are dead, the block is also dead.
2583     return (!DeadBlocks.count(BB) &&
2584             llvm::all_of(predecessors(BB),
2585                          [&](BasicBlock *P) { return IsEdgeDead(P, BB); }));
2586   };
2587 
2588   for (BasicBlock *Succ : successors(CurrBB)) {
2589     if (Succ == NextBB || !IsNewlyDead(Succ))
2590       continue;
2591     SmallVector<BasicBlock *, 4> NewDead;
2592     NewDead.push_back(Succ);
2593     while (!NewDead.empty()) {
2594       BasicBlock *Dead = NewDead.pop_back_val();
2595       if (DeadBlocks.insert(Dead).second)
2596         // Continue growing the dead block lists.
2597         for (BasicBlock *S : successors(Dead))
2598           if (IsNewlyDead(S))
2599             NewDead.push_back(S);
2600     }
2601   }
2602 }
2603 
2604 /// Analyze a call site for potential inlining.
2605 ///
2606 /// Returns true if inlining this call is viable, and false if it is not
2607 /// viable. It computes the cost and adjusts the threshold based on numerous
2608 /// factors and heuristics. If this method returns false but the computed cost
2609 /// is below the computed threshold, then inlining was forcibly disabled by
2610 /// some artifact of the routine.
2611 InlineResult CallAnalyzer::analyze() {
2612   ++NumCallsAnalyzed;
2613 
2614   auto Result = onAnalysisStart();
2615   if (!Result.isSuccess())
2616     return Result;
2617 
2618   if (F.empty())
2619     return InlineResult::success();
2620 
2621   Function *Caller = CandidateCall.getFunction();
2622   // Check if the caller function is recursive itself.
2623   for (User *U : Caller->users()) {
2624     CallBase *Call = dyn_cast<CallBase>(U);
2625     if (Call && Call->getFunction() == Caller) {
2626       IsCallerRecursive = true;
2627       break;
2628     }
2629   }
2630 
2631   // Populate our simplified values by mapping from function arguments to call
2632   // arguments with known important simplifications.
2633   auto CAI = CandidateCall.arg_begin();
2634   for (Argument &FAI : F.args()) {
2635     assert(CAI != CandidateCall.arg_end());
2636     if (Constant *C = dyn_cast<Constant>(CAI))
2637       SimplifiedValues[&FAI] = C;
2638 
2639     Value *PtrArg = *CAI;
2640     if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) {
2641       ConstantOffsetPtrs[&FAI] = std::make_pair(PtrArg, C->getValue());
2642 
2643       // We can SROA any pointer arguments derived from alloca instructions.
2644       if (auto *SROAArg = dyn_cast<AllocaInst>(PtrArg)) {
2645         SROAArgValues[&FAI] = SROAArg;
2646         onInitializeSROAArg(SROAArg);
2647         EnabledSROAAllocas.insert(SROAArg);
2648       }
2649     }
2650     ++CAI;
2651   }
2652   NumConstantArgs = SimplifiedValues.size();
2653   NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
2654   NumAllocaArgs = SROAArgValues.size();
2655 
2656   // FIXME: If a caller has multiple calls to a callee, we end up recomputing
2657   // the ephemeral values multiple times (and they're completely determined by
2658   // the callee, so this is purely duplicate work).
2659   SmallPtrSet<const Value *, 32> EphValues;
2660   CodeMetrics::collectEphemeralValues(&F, &GetAssumptionCache(F), EphValues);
2661 
2662   // The worklist of live basic blocks in the callee *after* inlining. We avoid
2663   // adding basic blocks of the callee which can be proven to be dead for this
2664   // particular call site in order to get more accurate cost estimates. This
2665   // requires a somewhat heavyweight iteration pattern: we need to walk the
2666   // basic blocks in a breadth-first order as we insert live successors. To
2667   // accomplish this, prioritizing for small iterations because we exit after
2668   // crossing our threshold, we use a small-size optimized SetVector.
2669   typedef SetVector<BasicBlock *, SmallVector<BasicBlock *, 16>,
2670                     SmallPtrSet<BasicBlock *, 16>>
2671       BBSetVector;
2672   BBSetVector BBWorklist;
2673   BBWorklist.insert(&F.getEntryBlock());
2674 
2675   // Note that we *must not* cache the size, this loop grows the worklist.
2676   for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
2677     if (shouldStop())
2678       break;
2679 
2680     BasicBlock *BB = BBWorklist[Idx];
2681     if (BB->empty())
2682       continue;
2683 
2684     onBlockStart(BB);
2685 
2686     // Disallow inlining a blockaddress with uses other than strictly callbr.
2687     // A blockaddress only has defined behavior for an indirect branch in the
2688     // same function, and we do not currently support inlining indirect
2689     // branches.  But, the inliner may not see an indirect branch that ends up
2690     // being dead code at a particular call site. If the blockaddress escapes
2691     // the function, e.g., via a global variable, inlining may lead to an
2692     // invalid cross-function reference.
2693     // FIXME: pr/39560: continue relaxing this overt restriction.
2694     if (BB->hasAddressTaken())
2695       for (User *U : BlockAddress::get(&*BB)->users())
2696         if (!isa<CallBrInst>(*U))
2697           return InlineResult::failure("blockaddress used outside of callbr");
2698 
2699     // Analyze the cost of this block. If we blow through the threshold, this
2700     // returns false, and we can bail on out.
2701     InlineResult IR = analyzeBlock(BB, EphValues);
2702     if (!IR.isSuccess())
2703       return IR;
2704 
2705     Instruction *TI = BB->getTerminator();
2706 
2707     // Add in the live successors by first checking whether we have terminator
2708     // that may be simplified based on the values simplified by this call.
2709     if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
2710       if (BI->isConditional()) {
2711         Value *Cond = BI->getCondition();
2712         if (ConstantInt *SimpleCond =
2713                 dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
2714           BasicBlock *NextBB = BI->getSuccessor(SimpleCond->isZero() ? 1 : 0);
2715           BBWorklist.insert(NextBB);
2716           KnownSuccessors[BB] = NextBB;
2717           findDeadBlocks(BB, NextBB);
2718           continue;
2719         }
2720       }
2721     } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
2722       Value *Cond = SI->getCondition();
2723       if (ConstantInt *SimpleCond =
2724               dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
2725         BasicBlock *NextBB = SI->findCaseValue(SimpleCond)->getCaseSuccessor();
2726         BBWorklist.insert(NextBB);
2727         KnownSuccessors[BB] = NextBB;
2728         findDeadBlocks(BB, NextBB);
2729         continue;
2730       }
2731     }
2732 
2733     // If we're unable to select a particular successor, just count all of
2734     // them.
2735     for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize;
2736          ++TIdx)
2737       BBWorklist.insert(TI->getSuccessor(TIdx));
2738 
2739     onBlockAnalyzed(BB);
2740   }
2741 
2742   // If this is a noduplicate call, we can still inline as long as
2743   // inlining this would cause the removal of the caller (so the instruction
2744   // is not actually duplicated, just moved).
2745   if (!isSoleCallToLocalFunction(CandidateCall, F) && ContainsNoDuplicateCall)
2746     return InlineResult::failure("noduplicate");
2747 
2748   // If the callee's stack size exceeds the user-specified threshold,
2749   // do not let it be inlined.
2750   // The command line option overrides a limit set in the function attributes.
2751   size_t FinalStackSizeThreshold = StackSizeThreshold;
2752   if (!StackSizeThreshold.getNumOccurrences())
2753     if (std::optional<int> AttrMaxStackSize = getStringFnAttrAsInt(
2754             Caller, InlineConstants::MaxInlineStackSizeAttributeName))
2755       FinalStackSizeThreshold = *AttrMaxStackSize;
2756   if (AllocatedSize > FinalStackSizeThreshold)
2757     return InlineResult::failure("stacksize");
2758 
2759   return finalizeAnalysis();
2760 }
2761 
2762 void InlineCostCallAnalyzer::print(raw_ostream &OS) {
2763 #define DEBUG_PRINT_STAT(x) OS << "      " #x ": " << x << "\n"
2764   if (PrintInstructionComments)
2765     F.print(OS, &Writer);
2766   DEBUG_PRINT_STAT(NumConstantArgs);
2767   DEBUG_PRINT_STAT(NumConstantOffsetPtrArgs);
2768   DEBUG_PRINT_STAT(NumAllocaArgs);
2769   DEBUG_PRINT_STAT(NumConstantPtrCmps);
2770   DEBUG_PRINT_STAT(NumConstantPtrDiffs);
2771   DEBUG_PRINT_STAT(NumInstructionsSimplified);
2772   DEBUG_PRINT_STAT(NumInstructions);
2773   DEBUG_PRINT_STAT(SROACostSavings);
2774   DEBUG_PRINT_STAT(SROACostSavingsLost);
2775   DEBUG_PRINT_STAT(LoadEliminationCost);
2776   DEBUG_PRINT_STAT(ContainsNoDuplicateCall);
2777   DEBUG_PRINT_STAT(Cost);
2778   DEBUG_PRINT_STAT(Threshold);
2779 #undef DEBUG_PRINT_STAT
2780 }
2781 
2782 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
2783 /// Dump stats about this call's analysis.
2784 LLVM_DUMP_METHOD void InlineCostCallAnalyzer::dump() { print(dbgs()); }
2785 #endif
2786 
2787 /// Test that there are no attribute conflicts between Caller and Callee
2788 ///        that prevent inlining.
2789 static bool functionsHaveCompatibleAttributes(
2790     Function *Caller, Function *Callee, TargetTransformInfo &TTI,
2791     function_ref<const TargetLibraryInfo &(Function &)> &GetTLI) {
2792   // Note that CalleeTLI must be a copy not a reference. The legacy pass manager
2793   // caches the most recently created TLI in the TargetLibraryInfoWrapperPass
2794   // object, and always returns the same object (which is overwritten on each
2795   // GetTLI call). Therefore we copy the first result.
2796   auto CalleeTLI = GetTLI(*Callee);
2797   return (IgnoreTTIInlineCompatible ||
2798           TTI.areInlineCompatible(Caller, Callee)) &&
2799          GetTLI(*Caller).areInlineCompatible(CalleeTLI,
2800                                              InlineCallerSupersetNoBuiltin) &&
2801          AttributeFuncs::areInlineCompatible(*Caller, *Callee);
2802 }
2803 
2804 int llvm::getCallsiteCost(const CallBase &Call, const DataLayout &DL) {
2805   int64_t Cost = 0;
2806   for (unsigned I = 0, E = Call.arg_size(); I != E; ++I) {
2807     if (Call.isByValArgument(I)) {
2808       // We approximate the number of loads and stores needed by dividing the
2809       // size of the byval type by the target's pointer size.
2810       PointerType *PTy = cast<PointerType>(Call.getArgOperand(I)->getType());
2811       unsigned TypeSize = DL.getTypeSizeInBits(Call.getParamByValType(I));
2812       unsigned AS = PTy->getAddressSpace();
2813       unsigned PointerSize = DL.getPointerSizeInBits(AS);
2814       // Ceiling division.
2815       unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize;
2816 
2817       // If it generates more than 8 stores it is likely to be expanded as an
2818       // inline memcpy so we take that as an upper bound. Otherwise we assume
2819       // one load and one store per word copied.
2820       // FIXME: The maxStoresPerMemcpy setting from the target should be used
2821       // here instead of a magic number of 8, but it's not available via
2822       // DataLayout.
2823       NumStores = std::min(NumStores, 8U);
2824 
2825       Cost += 2 * NumStores * InstrCost;
2826     } else {
2827       // For non-byval arguments subtract off one instruction per call
2828       // argument.
2829       Cost += InstrCost;
2830     }
2831   }
2832   // The call instruction also disappears after inlining.
2833   Cost += InstrCost;
2834   Cost += CallPenalty;
2835   return std::min<int64_t>(Cost, INT_MAX);
2836 }
2837 
2838 InlineCost llvm::getInlineCost(
2839     CallBase &Call, const InlineParams &Params, TargetTransformInfo &CalleeTTI,
2840     function_ref<AssumptionCache &(Function &)> GetAssumptionCache,
2841     function_ref<const TargetLibraryInfo &(Function &)> GetTLI,
2842     function_ref<BlockFrequencyInfo &(Function &)> GetBFI,
2843     ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE) {
2844   return getInlineCost(Call, Call.getCalledFunction(), Params, CalleeTTI,
2845                        GetAssumptionCache, GetTLI, GetBFI, PSI, ORE);
2846 }
2847 
2848 std::optional<int> llvm::getInliningCostEstimate(
2849     CallBase &Call, TargetTransformInfo &CalleeTTI,
2850     function_ref<AssumptionCache &(Function &)> GetAssumptionCache,
2851     function_ref<BlockFrequencyInfo &(Function &)> GetBFI,
2852     ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE) {
2853   const InlineParams Params = {/* DefaultThreshold*/ 0,
2854                                /*HintThreshold*/ {},
2855                                /*ColdThreshold*/ {},
2856                                /*OptSizeThreshold*/ {},
2857                                /*OptMinSizeThreshold*/ {},
2858                                /*HotCallSiteThreshold*/ {},
2859                                /*LocallyHotCallSiteThreshold*/ {},
2860                                /*ColdCallSiteThreshold*/ {},
2861                                /*ComputeFullInlineCost*/ true,
2862                                /*EnableDeferral*/ true};
2863 
2864   InlineCostCallAnalyzer CA(*Call.getCalledFunction(), Call, Params, CalleeTTI,
2865                             GetAssumptionCache, GetBFI, PSI, ORE, true,
2866                             /*IgnoreThreshold*/ true);
2867   auto R = CA.analyze();
2868   if (!R.isSuccess())
2869     return std::nullopt;
2870   return CA.getCost();
2871 }
2872 
2873 std::optional<InlineCostFeatures> llvm::getInliningCostFeatures(
2874     CallBase &Call, TargetTransformInfo &CalleeTTI,
2875     function_ref<AssumptionCache &(Function &)> GetAssumptionCache,
2876     function_ref<BlockFrequencyInfo &(Function &)> GetBFI,
2877     ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE) {
2878   InlineCostFeaturesAnalyzer CFA(CalleeTTI, GetAssumptionCache, GetBFI, PSI,
2879                                  ORE, *Call.getCalledFunction(), Call);
2880   auto R = CFA.analyze();
2881   if (!R.isSuccess())
2882     return std::nullopt;
2883   return CFA.features();
2884 }
2885 
2886 std::optional<InlineResult> llvm::getAttributeBasedInliningDecision(
2887     CallBase &Call, Function *Callee, TargetTransformInfo &CalleeTTI,
2888     function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
2889 
2890   // Cannot inline indirect calls.
2891   if (!Callee)
2892     return InlineResult::failure("indirect call");
2893 
2894   // When callee coroutine function is inlined into caller coroutine function
2895   // before coro-split pass,
2896   // coro-early pass can not handle this quiet well.
2897   // So we won't inline the coroutine function if it have not been unsplited
2898   if (Callee->isPresplitCoroutine())
2899     return InlineResult::failure("unsplited coroutine call");
2900 
2901   // Never inline calls with byval arguments that does not have the alloca
2902   // address space. Since byval arguments can be replaced with a copy to an
2903   // alloca, the inlined code would need to be adjusted to handle that the
2904   // argument is in the alloca address space (so it is a little bit complicated
2905   // to solve).
2906   unsigned AllocaAS = Callee->getParent()->getDataLayout().getAllocaAddrSpace();
2907   for (unsigned I = 0, E = Call.arg_size(); I != E; ++I)
2908     if (Call.isByValArgument(I)) {
2909       PointerType *PTy = cast<PointerType>(Call.getArgOperand(I)->getType());
2910       if (PTy->getAddressSpace() != AllocaAS)
2911         return InlineResult::failure("byval arguments without alloca"
2912                                      " address space");
2913     }
2914 
2915   // Calls to functions with always-inline attributes should be inlined
2916   // whenever possible.
2917   if (Call.hasFnAttr(Attribute::AlwaysInline)) {
2918     if (Call.getAttributes().hasFnAttr(Attribute::NoInline))
2919       return InlineResult::failure("noinline call site attribute");
2920 
2921     auto IsViable = isInlineViable(*Callee);
2922     if (IsViable.isSuccess())
2923       return InlineResult::success();
2924     return InlineResult::failure(IsViable.getFailureReason());
2925   }
2926 
2927   // Never inline functions with conflicting attributes (unless callee has
2928   // always-inline attribute).
2929   Function *Caller = Call.getCaller();
2930   if (!functionsHaveCompatibleAttributes(Caller, Callee, CalleeTTI, GetTLI))
2931     return InlineResult::failure("conflicting attributes");
2932 
2933   // Don't inline this call if the caller has the optnone attribute.
2934   if (Caller->hasOptNone())
2935     return InlineResult::failure("optnone attribute");
2936 
2937   // Don't inline a function that treats null pointer as valid into a caller
2938   // that does not have this attribute.
2939   if (!Caller->nullPointerIsDefined() && Callee->nullPointerIsDefined())
2940     return InlineResult::failure("nullptr definitions incompatible");
2941 
2942   // Don't inline functions which can be interposed at link-time.
2943   if (Callee->isInterposable())
2944     return InlineResult::failure("interposable");
2945 
2946   // Don't inline functions marked noinline.
2947   if (Callee->hasFnAttribute(Attribute::NoInline))
2948     return InlineResult::failure("noinline function attribute");
2949 
2950   // Don't inline call sites marked noinline.
2951   if (Call.isNoInline())
2952     return InlineResult::failure("noinline call site attribute");
2953 
2954   return std::nullopt;
2955 }
2956 
2957 InlineCost llvm::getInlineCost(
2958     CallBase &Call, Function *Callee, const InlineParams &Params,
2959     TargetTransformInfo &CalleeTTI,
2960     function_ref<AssumptionCache &(Function &)> GetAssumptionCache,
2961     function_ref<const TargetLibraryInfo &(Function &)> GetTLI,
2962     function_ref<BlockFrequencyInfo &(Function &)> GetBFI,
2963     ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE) {
2964 
2965   auto UserDecision =
2966       llvm::getAttributeBasedInliningDecision(Call, Callee, CalleeTTI, GetTLI);
2967 
2968   if (UserDecision) {
2969     if (UserDecision->isSuccess())
2970       return llvm::InlineCost::getAlways("always inline attribute");
2971     return llvm::InlineCost::getNever(UserDecision->getFailureReason());
2972   }
2973 
2974   LLVM_DEBUG(llvm::dbgs() << "      Analyzing call of " << Callee->getName()
2975                           << "... (caller:" << Call.getCaller()->getName()
2976                           << ")\n");
2977 
2978   InlineCostCallAnalyzer CA(*Callee, Call, Params, CalleeTTI,
2979                             GetAssumptionCache, GetBFI, PSI, ORE);
2980   InlineResult ShouldInline = CA.analyze();
2981 
2982   LLVM_DEBUG(CA.dump());
2983 
2984   // Always make cost benefit based decision explicit.
2985   // We use always/never here since threshold is not meaningful,
2986   // as it's not what drives cost-benefit analysis.
2987   if (CA.wasDecidedByCostBenefit()) {
2988     if (ShouldInline.isSuccess())
2989       return InlineCost::getAlways("benefit over cost",
2990                                    CA.getCostBenefitPair());
2991     else
2992       return InlineCost::getNever("cost over benefit", CA.getCostBenefitPair());
2993   }
2994 
2995   if (CA.wasDecidedByCostThreshold())
2996     return InlineCost::get(CA.getCost(), CA.getThreshold(),
2997                            CA.getStaticBonusApplied());
2998 
2999   // No details on how the decision was made, simply return always or never.
3000   return ShouldInline.isSuccess()
3001              ? InlineCost::getAlways("empty function")
3002              : InlineCost::getNever(ShouldInline.getFailureReason());
3003 }
3004 
3005 InlineResult llvm::isInlineViable(Function &F) {
3006   bool ReturnsTwice = F.hasFnAttribute(Attribute::ReturnsTwice);
3007   for (BasicBlock &BB : F) {
3008     // Disallow inlining of functions which contain indirect branches.
3009     if (isa<IndirectBrInst>(BB.getTerminator()))
3010       return InlineResult::failure("contains indirect branches");
3011 
3012     // Disallow inlining of blockaddresses which are used by non-callbr
3013     // instructions.
3014     if (BB.hasAddressTaken())
3015       for (User *U : BlockAddress::get(&BB)->users())
3016         if (!isa<CallBrInst>(*U))
3017           return InlineResult::failure("blockaddress used outside of callbr");
3018 
3019     for (auto &II : BB) {
3020       CallBase *Call = dyn_cast<CallBase>(&II);
3021       if (!Call)
3022         continue;
3023 
3024       // Disallow recursive calls.
3025       Function *Callee = Call->getCalledFunction();
3026       if (&F == Callee)
3027         return InlineResult::failure("recursive call");
3028 
3029       // Disallow calls which expose returns-twice to a function not previously
3030       // attributed as such.
3031       if (!ReturnsTwice && isa<CallInst>(Call) &&
3032           cast<CallInst>(Call)->canReturnTwice())
3033         return InlineResult::failure("exposes returns-twice attribute");
3034 
3035       if (Callee)
3036         switch (Callee->getIntrinsicID()) {
3037         default:
3038           break;
3039         case llvm::Intrinsic::icall_branch_funnel:
3040           // Disallow inlining of @llvm.icall.branch.funnel because current
3041           // backend can't separate call targets from call arguments.
3042           return InlineResult::failure(
3043               "disallowed inlining of @llvm.icall.branch.funnel");
3044         case llvm::Intrinsic::localescape:
3045           // Disallow inlining functions that call @llvm.localescape. Doing this
3046           // correctly would require major changes to the inliner.
3047           return InlineResult::failure(
3048               "disallowed inlining of @llvm.localescape");
3049         case llvm::Intrinsic::vastart:
3050           // Disallow inlining of functions that initialize VarArgs with
3051           // va_start.
3052           return InlineResult::failure(
3053               "contains VarArgs initialized with va_start");
3054         }
3055     }
3056   }
3057 
3058   return InlineResult::success();
3059 }
3060 
3061 // APIs to create InlineParams based on command line flags and/or other
3062 // parameters.
3063 
3064 InlineParams llvm::getInlineParams(int Threshold) {
3065   InlineParams Params;
3066 
3067   // This field is the threshold to use for a callee by default. This is
3068   // derived from one or more of:
3069   //  * optimization or size-optimization levels,
3070   //  * a value passed to createFunctionInliningPass function, or
3071   //  * the -inline-threshold flag.
3072   //  If the -inline-threshold flag is explicitly specified, that is used
3073   //  irrespective of anything else.
3074   if (InlineThreshold.getNumOccurrences() > 0)
3075     Params.DefaultThreshold = InlineThreshold;
3076   else
3077     Params.DefaultThreshold = Threshold;
3078 
3079   // Set the HintThreshold knob from the -inlinehint-threshold.
3080   Params.HintThreshold = HintThreshold;
3081 
3082   // Set the HotCallSiteThreshold knob from the -hot-callsite-threshold.
3083   Params.HotCallSiteThreshold = HotCallSiteThreshold;
3084 
3085   // If the -locally-hot-callsite-threshold is explicitly specified, use it to
3086   // populate LocallyHotCallSiteThreshold. Later, we populate
3087   // Params.LocallyHotCallSiteThreshold from -locally-hot-callsite-threshold if
3088   // we know that optimization level is O3 (in the getInlineParams variant that
3089   // takes the opt and size levels).
3090   // FIXME: Remove this check (and make the assignment unconditional) after
3091   // addressing size regression issues at O2.
3092   if (LocallyHotCallSiteThreshold.getNumOccurrences() > 0)
3093     Params.LocallyHotCallSiteThreshold = LocallyHotCallSiteThreshold;
3094 
3095   // Set the ColdCallSiteThreshold knob from the
3096   // -inline-cold-callsite-threshold.
3097   Params.ColdCallSiteThreshold = ColdCallSiteThreshold;
3098 
3099   // Set the OptMinSizeThreshold and OptSizeThreshold params only if the
3100   // -inlinehint-threshold commandline option is not explicitly given. If that
3101   // option is present, then its value applies even for callees with size and
3102   // minsize attributes.
3103   // If the -inline-threshold is not specified, set the ColdThreshold from the
3104   // -inlinecold-threshold even if it is not explicitly passed. If
3105   // -inline-threshold is specified, then -inlinecold-threshold needs to be
3106   // explicitly specified to set the ColdThreshold knob
3107   if (InlineThreshold.getNumOccurrences() == 0) {
3108     Params.OptMinSizeThreshold = InlineConstants::OptMinSizeThreshold;
3109     Params.OptSizeThreshold = InlineConstants::OptSizeThreshold;
3110     Params.ColdThreshold = ColdThreshold;
3111   } else if (ColdThreshold.getNumOccurrences() > 0) {
3112     Params.ColdThreshold = ColdThreshold;
3113   }
3114   return Params;
3115 }
3116 
3117 InlineParams llvm::getInlineParams() {
3118   return getInlineParams(DefaultThreshold);
3119 }
3120 
3121 // Compute the default threshold for inlining based on the opt level and the
3122 // size opt level.
3123 static int computeThresholdFromOptLevels(unsigned OptLevel,
3124                                          unsigned SizeOptLevel) {
3125   if (OptLevel > 2)
3126     return InlineConstants::OptAggressiveThreshold;
3127   if (SizeOptLevel == 1) // -Os
3128     return InlineConstants::OptSizeThreshold;
3129   if (SizeOptLevel == 2) // -Oz
3130     return InlineConstants::OptMinSizeThreshold;
3131   return DefaultThreshold;
3132 }
3133 
3134 InlineParams llvm::getInlineParams(unsigned OptLevel, unsigned SizeOptLevel) {
3135   auto Params =
3136       getInlineParams(computeThresholdFromOptLevels(OptLevel, SizeOptLevel));
3137   // At O3, use the value of -locally-hot-callsite-threshold option to populate
3138   // Params.LocallyHotCallSiteThreshold. Below O3, this flag has effect only
3139   // when it is specified explicitly.
3140   if (OptLevel > 2)
3141     Params.LocallyHotCallSiteThreshold = LocallyHotCallSiteThreshold;
3142   return Params;
3143 }
3144 
3145 PreservedAnalyses
3146 InlineCostAnnotationPrinterPass::run(Function &F,
3147                                      FunctionAnalysisManager &FAM) {
3148   PrintInstructionComments = true;
3149   std::function<AssumptionCache &(Function &)> GetAssumptionCache =
3150       [&](Function &F) -> AssumptionCache & {
3151     return FAM.getResult<AssumptionAnalysis>(F);
3152   };
3153   Module *M = F.getParent();
3154   ProfileSummaryInfo PSI(*M);
3155   DataLayout DL(M);
3156   TargetTransformInfo TTI(DL);
3157   // FIXME: Redesign the usage of InlineParams to expand the scope of this pass.
3158   // In the current implementation, the type of InlineParams doesn't matter as
3159   // the pass serves only for verification of inliner's decisions.
3160   // We can add a flag which determines InlineParams for this run. Right now,
3161   // the default InlineParams are used.
3162   const InlineParams Params = llvm::getInlineParams();
3163   for (BasicBlock &BB : F) {
3164     for (Instruction &I : BB) {
3165       if (CallInst *CI = dyn_cast<CallInst>(&I)) {
3166         Function *CalledFunction = CI->getCalledFunction();
3167         if (!CalledFunction || CalledFunction->isDeclaration())
3168           continue;
3169         OptimizationRemarkEmitter ORE(CalledFunction);
3170         InlineCostCallAnalyzer ICCA(*CalledFunction, *CI, Params, TTI,
3171                                     GetAssumptionCache, nullptr, &PSI, &ORE);
3172         ICCA.analyze();
3173         OS << "      Analyzing call of " << CalledFunction->getName()
3174            << "... (caller:" << CI->getCaller()->getName() << ")\n";
3175         ICCA.print(OS);
3176         OS << "\n";
3177       }
3178     }
3179   }
3180   return PreservedAnalyses::all();
3181 }
3182