xref: /freebsd/contrib/llvm-project/llvm/lib/CodeGen/ExpandLargeFpConvert.cpp (revision 9f23cbd6cae82fd77edfad7173432fa8dccd0a95) 
1 //===--- ExpandLargeFpConvert.cpp - Expand large fp convert----------------===//
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 
10 // This pass expands ‘fptoui .. to’, ‘fptosi .. to’, ‘uitofp .. to’,
11 // ‘sitofp .. to’ instructions with a bitwidth above a threshold into
12 // auto-generated functions. This is useful for targets like x86_64 that cannot
13 // lower fp convertions with more than 128 bits.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/Analysis/GlobalsModRef.h"
20 #include "llvm/CodeGen/Passes.h"
21 #include "llvm/CodeGen/TargetLowering.h"
22 #include "llvm/CodeGen/TargetPassConfig.h"
23 #include "llvm/CodeGen/TargetSubtargetInfo.h"
24 #include "llvm/IR/IRBuilder.h"
25 #include "llvm/IR/InstIterator.h"
26 #include "llvm/IR/PassManager.h"
27 #include "llvm/InitializePasses.h"
28 #include "llvm/Pass.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Target/TargetMachine.h"
31 
32 using namespace llvm;
33 
34 static cl::opt<unsigned>
35     ExpandFpConvertBits("expand-fp-convert-bits", cl::Hidden,
36                      cl::init(llvm::IntegerType::MAX_INT_BITS),
37                      cl::desc("fp convert instructions on integers with "
38                               "more than <N> bits are expanded."));
39 
40 /// Generate code to convert a fp number to integer, replacing FPToS(U)I with
41 /// the generated code. This currently generates code similarly to compiler-rt's
42 /// implementations.
43 ///
44 /// An example IR generated from compiler-rt/fixsfdi.c looks like below:
45 /// define dso_local i64 @foo(float noundef %a) local_unnamed_addr #0 {
46 /// entry:
47 ///   %0 = bitcast float %a to i32
48 ///   %conv.i = zext i32 %0 to i64
49 ///   %tobool.not = icmp sgt i32 %0, -1
50 ///   %conv = select i1 %tobool.not, i64 1, i64 -1
51 ///   %and = lshr i64 %conv.i, 23
52 ///   %shr = and i64 %and, 255
53 ///   %and2 = and i64 %conv.i, 8388607
54 ///   %or = or i64 %and2, 8388608
55 ///   %cmp = icmp ult i64 %shr, 127
56 ///   br i1 %cmp, label %cleanup, label %if.end
57 ///
58 /// if.end:                                           ; preds = %entry
59 ///   %sub = add nuw nsw i64 %shr, 4294967169
60 ///   %conv5 = and i64 %sub, 4294967232
61 ///   %cmp6.not = icmp eq i64 %conv5, 0
62 ///   br i1 %cmp6.not, label %if.end12, label %if.then8
63 ///
64 /// if.then8:                                         ; preds = %if.end
65 ///   %cond11 = select i1 %tobool.not, i64 9223372036854775807, i64 -9223372036854775808
66 ///   br label %cleanup
67 ///
68 /// if.end12:                                         ; preds = %if.end
69 ///   %cmp13 = icmp ult i64 %shr, 150
70 ///   br i1 %cmp13, label %if.then15, label %if.else
71 ///
72 /// if.then15:                                        ; preds = %if.end12
73 ///   %sub16 = sub nuw nsw i64 150, %shr
74 ///   %shr17 = lshr i64 %or, %sub16
75 ///   %mul = mul nsw i64 %shr17, %conv
76 ///   br label %cleanup
77 ///
78 /// if.else:                                          ; preds = %if.end12
79 ///   %sub18 = add nsw i64 %shr, -150
80 ///   %shl = shl i64 %or, %sub18
81 ///   %mul19 = mul nsw i64 %shl, %conv
82 ///   br label %cleanup
83 ///
84 /// cleanup:                                          ; preds = %entry, %if.else, %if.then15, %if.then8
85 ///   %retval.0 = phi i64 [ %cond11, %if.then8 ], [ %mul, %if.then15 ], [ %mul19, %if.else ], [ 0, %entry ]
86 ///   ret i64 %retval.0
87 /// }
88 ///
89 /// Replace fp to integer with generated code.
90 static void expandFPToI(Instruction *FPToI) {
91   IRBuilder<> Builder(FPToI);
92   auto *FloatVal = FPToI->getOperand(0);
93   IntegerType *IntTy = cast<IntegerType>(FPToI->getType());
94 
95   unsigned BitWidth = FPToI->getType()->getIntegerBitWidth();
96   unsigned FPMantissaWidth = FloatVal->getType()->getFPMantissaWidth() - 1;
97 
98   // FIXME: fp16's range is covered by i32. So `fptoi half` can convert
99   // to i32 first following a sext/zext to target integer type.
100   Value *A1 = nullptr;
101   if (FloatVal->getType()->isHalfTy()) {
102     if (FPToI->getOpcode() == Instruction::FPToUI) {
103       Value *A0 = Builder.CreateFPToUI(FloatVal, Builder.getIntNTy(32));
104       A1 = Builder.CreateZExt(A0, IntTy);
105     } else { // FPToSI
106       Value *A0 = Builder.CreateFPToSI(FloatVal, Builder.getIntNTy(32));
107       A1 = Builder.CreateSExt(A0, IntTy);
108     }
109     FPToI->replaceAllUsesWith(A1);
110     FPToI->dropAllReferences();
111     FPToI->eraseFromParent();
112     return;
113   }
114 
115   // fp80 conversion is implemented by fpext to fp128 first then do the
116   // conversion.
117   FPMantissaWidth = FPMantissaWidth == 63 ? 112 : FPMantissaWidth;
118   unsigned FloatWidth = PowerOf2Ceil(FPMantissaWidth);
119   unsigned ExponentWidth = FloatWidth - FPMantissaWidth - 1;
120   unsigned ExponentBias = (1 << (ExponentWidth - 1)) - 1;
121   Value *ImplicitBit = Builder.CreateShl(
122       Builder.getIntN(BitWidth, 1), Builder.getIntN(BitWidth, FPMantissaWidth));
123   Value *SignificandMask =
124       Builder.CreateSub(ImplicitBit, Builder.getIntN(BitWidth, 1));
125   Value *NegOne = Builder.CreateSExt(
126       ConstantInt::getSigned(Builder.getInt32Ty(), -1), IntTy);
127   Value *NegInf =
128       Builder.CreateShl(ConstantInt::getSigned(IntTy, 1),
129                         ConstantInt::getSigned(IntTy, BitWidth - 1));
130 
131   BasicBlock *Entry = Builder.GetInsertBlock();
132   Function *F = Entry->getParent();
133   Entry->setName(Twine(Entry->getName(), "fp-to-i-entry"));
134   BasicBlock *End =
135       Entry->splitBasicBlock(Builder.GetInsertPoint(), "fp-to-i-cleanup");
136   BasicBlock *IfEnd =
137       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-end", F, End);
138   BasicBlock *IfThen5 =
139       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-then5", F, End);
140   BasicBlock *IfEnd9 =
141       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-end9", F, End);
142   BasicBlock *IfThen12 =
143       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-then12", F, End);
144   BasicBlock *IfElse =
145       BasicBlock::Create(Builder.getContext(), "fp-to-i-if-else", F, End);
146 
147   Entry->getTerminator()->eraseFromParent();
148 
149   // entry:
150   Builder.SetInsertPoint(Entry);
151   Value *FloatVal0 = FloatVal;
152   // fp80 conversion is implemented by fpext to fp128 first then do the
153   // conversion.
154   if (FloatVal->getType()->isX86_FP80Ty())
155     FloatVal0 =
156         Builder.CreateFPExt(FloatVal, Type::getFP128Ty(Builder.getContext()));
157   Value *ARep0 =
158       Builder.CreateBitCast(FloatVal0, Builder.getIntNTy(FloatWidth));
159   Value *ARep = Builder.CreateZExt(ARep0, FPToI->getType());
160   Value *PosOrNeg = Builder.CreateICmpSGT(
161       ARep0, ConstantInt::getSigned(Builder.getIntNTy(FloatWidth), -1));
162   Value *Sign = Builder.CreateSelect(PosOrNeg, ConstantInt::getSigned(IntTy, 1),
163                                      ConstantInt::getSigned(IntTy, -1));
164   Value *And =
165       Builder.CreateLShr(ARep, Builder.getIntN(BitWidth, FPMantissaWidth));
166   Value *And2 = Builder.CreateAnd(
167       And, Builder.getIntN(BitWidth, (1 << ExponentWidth) - 1));
168   Value *Abs = Builder.CreateAnd(ARep, SignificandMask);
169   Value *Or = Builder.CreateOr(Abs, ImplicitBit);
170   Value *Cmp =
171       Builder.CreateICmpULT(And2, Builder.getIntN(BitWidth, ExponentBias));
172   Builder.CreateCondBr(Cmp, End, IfEnd);
173 
174   // if.end:
175   Builder.SetInsertPoint(IfEnd);
176   Value *Add1 = Builder.CreateAdd(
177       And2, ConstantInt::getSigned(IntTy, -int64_t(ExponentBias + BitWidth)));
178   Value *Cmp3 =
179       Builder.CreateICmpULT(Add1, ConstantInt::getSigned(IntTy, -BitWidth));
180   Builder.CreateCondBr(Cmp3, IfThen5, IfEnd9);
181 
182   // if.then5:
183   Builder.SetInsertPoint(IfThen5);
184   Value *PosInf = Builder.CreateXor(NegOne, NegInf);
185   Value *Cond8 = Builder.CreateSelect(PosOrNeg, PosInf, NegInf);
186   Builder.CreateBr(End);
187 
188   // if.end9:
189   Builder.SetInsertPoint(IfEnd9);
190   Value *Cmp10 = Builder.CreateICmpULT(
191       And2, Builder.getIntN(BitWidth, ExponentBias + FPMantissaWidth));
192   Builder.CreateCondBr(Cmp10, IfThen12, IfElse);
193 
194   // if.then12:
195   Builder.SetInsertPoint(IfThen12);
196   Value *Sub13 = Builder.CreateSub(
197       Builder.getIntN(BitWidth, ExponentBias + FPMantissaWidth), And2);
198   Value *Shr14 = Builder.CreateLShr(Or, Sub13);
199   Value *Mul = Builder.CreateMul(Shr14, Sign);
200   Builder.CreateBr(End);
201 
202   // if.else:
203   Builder.SetInsertPoint(IfElse);
204   Value *Sub15 = Builder.CreateAdd(
205       And2,
206       ConstantInt::getSigned(IntTy, -(ExponentBias + FPMantissaWidth)));
207   Value *Shl = Builder.CreateShl(Or, Sub15);
208   Value *Mul16 = Builder.CreateMul(Shl, Sign);
209   Builder.CreateBr(End);
210 
211   // cleanup:
212   Builder.SetInsertPoint(End, End->begin());
213   PHINode *Retval0 = Builder.CreatePHI(FPToI->getType(), 4);
214 
215   Retval0->addIncoming(Cond8, IfThen5);
216   Retval0->addIncoming(Mul, IfThen12);
217   Retval0->addIncoming(Mul16, IfElse);
218   Retval0->addIncoming(Builder.getIntN(BitWidth, 0), Entry);
219 
220   FPToI->replaceAllUsesWith(Retval0);
221   FPToI->dropAllReferences();
222   FPToI->eraseFromParent();
223 }
224 
225 /// Generate code to convert a fp number to integer, replacing S(U)IToFP with
226 /// the generated code. This currently generates code similarly to compiler-rt's
227 /// implementations. This implementation has an implicit assumption that integer
228 /// width is larger than fp.
229 ///
230 /// An example IR generated from compiler-rt/floatdisf.c looks like below:
231 /// define dso_local float @__floatdisf(i64 noundef %a) local_unnamed_addr #0 {
232 /// entry:
233 ///   %cmp = icmp eq i64 %a, 0
234 ///   br i1 %cmp, label %return, label %if.end
235 ///
236 /// if.end:                                           ; preds = %entry
237 ///   %shr = ashr i64 %a, 63
238 ///   %xor = xor i64 %shr, %a
239 ///   %sub = sub nsw i64 %xor, %shr
240 ///   %0 = tail call i64 @llvm.ctlz.i64(i64 %sub, i1 true), !range !5
241 ///   %cast = trunc i64 %0 to i32
242 ///   %sub1 = sub nuw nsw i32 64, %cast
243 ///   %sub2 = xor i32 %cast, 63
244 ///   %cmp3 = icmp ult i32 %cast, 40
245 ///   br i1 %cmp3, label %if.then4, label %if.else
246 ///
247 /// if.then4:                                         ; preds = %if.end
248 ///   switch i32 %sub1, label %sw.default [
249 ///     i32 25, label %sw.bb
250 ///     i32 26, label %sw.epilog
251 ///   ]
252 ///
253 /// sw.bb:                                            ; preds = %if.then4
254 ///   %shl = shl i64 %sub, 1
255 ///   br label %sw.epilog
256 ///
257 /// sw.default:                                       ; preds = %if.then4
258 ///   %sub5 = sub nsw i64 38, %0
259 ///   %sh_prom = and i64 %sub5, 4294967295
260 ///   %shr6 = lshr i64 %sub, %sh_prom
261 ///   %shr9 = lshr i64 274877906943, %0
262 ///   %and = and i64 %shr9, %sub
263 ///   %cmp10 = icmp ne i64 %and, 0
264 ///   %conv11 = zext i1 %cmp10 to i64
265 ///   %or = or i64 %shr6, %conv11
266 ///   br label %sw.epilog
267 ///
268 /// sw.epilog:                                        ; preds = %sw.default, %if.then4, %sw.bb
269 ///   %a.addr.0 = phi i64 [ %or, %sw.default ], [ %sub, %if.then4 ], [ %shl, %sw.bb ]
270 ///   %1 = lshr i64 %a.addr.0, 2
271 ///   %2 = and i64 %1, 1
272 ///   %or16 = or i64 %2, %a.addr.0
273 ///   %inc = add nsw i64 %or16, 1
274 ///   %3 = and i64 %inc, 67108864
275 ///   %tobool.not = icmp eq i64 %3, 0
276 ///   %spec.select.v = select i1 %tobool.not, i64 2, i64 3
277 ///   %spec.select = ashr i64 %inc, %spec.select.v
278 ///   %spec.select56 = select i1 %tobool.not, i32 %sub2, i32 %sub1
279 ///   br label %if.end26
280 ///
281 /// if.else:                                          ; preds = %if.end
282 ///   %sub23 = add nuw nsw i64 %0, 4294967256
283 ///   %sh_prom24 = and i64 %sub23, 4294967295
284 ///   %shl25 = shl i64 %sub, %sh_prom24
285 ///   br label %if.end26
286 ///
287 /// if.end26:                                         ; preds = %sw.epilog, %if.else
288 ///   %a.addr.1 = phi i64 [ %shl25, %if.else ], [ %spec.select, %sw.epilog ]
289 ///   %e.0 = phi i32 [ %sub2, %if.else ], [ %spec.select56, %sw.epilog ]
290 ///   %conv27 = trunc i64 %shr to i32
291 ///   %and28 = and i32 %conv27, -2147483648
292 ///   %add = shl nuw nsw i32 %e.0, 23
293 ///   %shl29 = add nuw nsw i32 %add, 1065353216
294 ///   %conv31 = trunc i64 %a.addr.1 to i32
295 ///   %and32 = and i32 %conv31, 8388607
296 ///   %or30 = or i32 %and32, %and28
297 ///   %or33 = or i32 %or30, %shl29
298 ///   %4 = bitcast i32 %or33 to float
299 ///   br label %return
300 ///
301 /// return:                                           ; preds = %entry, %if.end26
302 ///   %retval.0 = phi float [ %4, %if.end26 ], [ 0.000000e+00, %entry ]
303 ///   ret float %retval.0
304 /// }
305 ///
306 /// Replace integer to fp with generated code.
307 static void expandIToFP(Instruction *IToFP) {
308   IRBuilder<> Builder(IToFP);
309   auto *IntVal = IToFP->getOperand(0);
310   IntegerType *IntTy = cast<IntegerType>(IntVal->getType());
311 
312   unsigned BitWidth = IntVal->getType()->getIntegerBitWidth();
313   unsigned FPMantissaWidth = IToFP->getType()->getFPMantissaWidth() - 1;
314   // fp80 conversion is implemented by conversion tp fp128 first following
315   // a fptrunc to fp80.
316   FPMantissaWidth = FPMantissaWidth == 63 ? 112 : FPMantissaWidth;
317   // FIXME: As there is no related builtins added in compliler-rt,
318   // here currently utilized the fp32 <-> fp16 lib calls to implement.
319   FPMantissaWidth = FPMantissaWidth == 10 ? 23 : FPMantissaWidth;
320   unsigned FloatWidth = PowerOf2Ceil(FPMantissaWidth);
321   bool IsSigned = IToFP->getOpcode() == Instruction::SIToFP;
322 
323   assert(BitWidth > FloatWidth && "Unexpected conversion. expandIToFP() "
324                                   "assumes integer width is larger than fp.");
325 
326   Value *Temp1 =
327       Builder.CreateShl(Builder.getIntN(BitWidth, 1),
328                         Builder.getIntN(BitWidth, FPMantissaWidth + 3));
329 
330   BasicBlock *Entry = Builder.GetInsertBlock();
331   Function *F = Entry->getParent();
332   Entry->setName(Twine(Entry->getName(), "itofp-entry"));
333   BasicBlock *End =
334       Entry->splitBasicBlock(Builder.GetInsertPoint(), "itofp-return");
335   BasicBlock *IfEnd =
336       BasicBlock::Create(Builder.getContext(), "itofp-if-end", F, End);
337   BasicBlock *IfThen4 =
338       BasicBlock::Create(Builder.getContext(), "itofp-if-then4", F, End);
339   BasicBlock *SwBB =
340       BasicBlock::Create(Builder.getContext(), "itofp-sw-bb", F, End);
341   BasicBlock *SwDefault =
342       BasicBlock::Create(Builder.getContext(), "itofp-sw-default", F, End);
343   BasicBlock *SwEpilog =
344       BasicBlock::Create(Builder.getContext(), "itofp-sw-epilog", F, End);
345   BasicBlock *IfThen20 =
346       BasicBlock::Create(Builder.getContext(), "itofp-if-then20", F, End);
347   BasicBlock *IfElse =
348       BasicBlock::Create(Builder.getContext(), "itofp-if-else", F, End);
349   BasicBlock *IfEnd26 =
350       BasicBlock::Create(Builder.getContext(), "itofp-if-end26", F, End);
351 
352   Entry->getTerminator()->eraseFromParent();
353 
354   Function *CTLZ =
355       Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctlz, IntTy);
356   ConstantInt *True = Builder.getTrue();
357 
358   // entry:
359   Builder.SetInsertPoint(Entry);
360   Value *Cmp = Builder.CreateICmpEQ(IntVal, ConstantInt::getSigned(IntTy, 0));
361   Builder.CreateCondBr(Cmp, End, IfEnd);
362 
363   // if.end:
364   Builder.SetInsertPoint(IfEnd);
365   Value *Shr =
366       Builder.CreateAShr(IntVal, Builder.getIntN(BitWidth, BitWidth - 1));
367   Value *Xor = Builder.CreateXor(Shr, IntVal);
368   Value *Sub = Builder.CreateSub(Xor, Shr);
369   Value *Call = Builder.CreateCall(CTLZ, {IsSigned ? Sub : IntVal, True});
370   Value *Cast = Builder.CreateTrunc(Call, Builder.getInt32Ty());
371   int BitWidthNew = FloatWidth == 128 ? BitWidth : 32;
372   Value *Sub1 = Builder.CreateSub(Builder.getIntN(BitWidthNew, BitWidth),
373                                   FloatWidth == 128 ? Call : Cast);
374   Value *Sub2 = Builder.CreateSub(Builder.getIntN(BitWidthNew, BitWidth - 1),
375                                   FloatWidth == 128 ? Call : Cast);
376   Value *Cmp3 = Builder.CreateICmpSGT(
377       Sub2, Builder.getIntN(BitWidthNew, FPMantissaWidth + 1));
378   Builder.CreateCondBr(Cmp3, IfThen4, IfElse);
379 
380   // if.then4:
381   Builder.SetInsertPoint(IfThen4);
382   llvm::SwitchInst *SI = Builder.CreateSwitch(Sub1, SwDefault);
383   SI->addCase(Builder.getIntN(BitWidthNew, FPMantissaWidth + 2), SwBB);
384   SI->addCase(Builder.getIntN(BitWidthNew, FPMantissaWidth + 3), SwEpilog);
385 
386   // sw.bb:
387   Builder.SetInsertPoint(SwBB);
388   Value *Shl =
389       Builder.CreateShl(IsSigned ? Sub : IntVal, Builder.getIntN(BitWidth, 1));
390   Builder.CreateBr(SwEpilog);
391 
392   // sw.default:
393   Builder.SetInsertPoint(SwDefault);
394   Value *Sub5 = Builder.CreateSub(
395       Builder.getIntN(BitWidthNew, BitWidth - FPMantissaWidth - 3),
396       FloatWidth == 128 ? Call : Cast);
397   Value *ShProm = Builder.CreateZExt(Sub5, IntTy);
398   Value *Shr6 = Builder.CreateLShr(IsSigned ? Sub : IntVal,
399                                    FloatWidth == 128 ? Sub5 : ShProm);
400   Value *Sub8 =
401       Builder.CreateAdd(FloatWidth == 128 ? Call : Cast,
402                         Builder.getIntN(BitWidthNew, FPMantissaWidth + 3));
403   Value *ShProm9 = Builder.CreateZExt(Sub8, IntTy);
404   Value *Shr9 = Builder.CreateLShr(ConstantInt::getSigned(IntTy, -1),
405                                    FloatWidth == 128 ? Sub8 : ShProm9);
406   Value *And = Builder.CreateAnd(Shr9, IsSigned ? Sub : IntVal);
407   Value *Cmp10 = Builder.CreateICmpNE(And, Builder.getIntN(BitWidth, 0));
408   Value *Conv11 = Builder.CreateZExt(Cmp10, IntTy);
409   Value *Or = Builder.CreateOr(Shr6, Conv11);
410   Builder.CreateBr(SwEpilog);
411 
412   // sw.epilog:
413   Builder.SetInsertPoint(SwEpilog);
414   PHINode *AAddr0 = Builder.CreatePHI(IntTy, 3);
415   AAddr0->addIncoming(Or, SwDefault);
416   AAddr0->addIncoming(IsSigned ? Sub : IntVal, IfThen4);
417   AAddr0->addIncoming(Shl, SwBB);
418   Value *A0 = Builder.CreateTrunc(AAddr0, Builder.getInt32Ty());
419   Value *A1 = Builder.CreateLShr(A0, Builder.getIntN(32, 2));
420   Value *A2 = Builder.CreateAnd(A1, Builder.getIntN(32, 1));
421   Value *Conv16 = Builder.CreateZExt(A2, IntTy);
422   Value *Or17 = Builder.CreateOr(AAddr0, Conv16);
423   Value *Inc = Builder.CreateAdd(Or17, Builder.getIntN(BitWidth, 1));
424   Value *Shr18 = nullptr;
425   if (IsSigned)
426     Shr18 = Builder.CreateAShr(Inc, Builder.getIntN(BitWidth, 2));
427   else
428     Shr18 = Builder.CreateLShr(Inc, Builder.getIntN(BitWidth, 2));
429   Value *A3 = Builder.CreateAnd(Inc, Temp1, "a3");
430   Value *PosOrNeg = Builder.CreateICmpEQ(A3, Builder.getIntN(BitWidth, 0));
431   Value *ExtractT60 = Builder.CreateTrunc(Shr18, Builder.getIntNTy(FloatWidth));
432   Value *Extract63 = Builder.CreateLShr(Shr18, Builder.getIntN(BitWidth, 32));
433   Value *ExtractT64 = nullptr;
434   if (FloatWidth > 80)
435     ExtractT64 = Builder.CreateTrunc(Sub2, Builder.getInt64Ty());
436   else
437     ExtractT64 = Builder.CreateTrunc(Extract63, Builder.getInt32Ty());
438   Builder.CreateCondBr(PosOrNeg, IfEnd26, IfThen20);
439 
440   // if.then20
441   Builder.SetInsertPoint(IfThen20);
442   Value *Shr21 = nullptr;
443   if (IsSigned)
444     Shr21 = Builder.CreateAShr(Inc, Builder.getIntN(BitWidth, 3));
445   else
446     Shr21 = Builder.CreateLShr(Inc, Builder.getIntN(BitWidth, 3));
447   Value *ExtractT = Builder.CreateTrunc(Shr21, Builder.getIntNTy(FloatWidth));
448   Value *Extract = Builder.CreateLShr(Shr21, Builder.getIntN(BitWidth, 32));
449   Value *ExtractT62 = nullptr;
450   if (FloatWidth > 80)
451     ExtractT62 = Builder.CreateTrunc(Sub1, Builder.getIntNTy(64));
452   else
453     ExtractT62 = Builder.CreateTrunc(Extract, Builder.getIntNTy(32));
454   Builder.CreateBr(IfEnd26);
455 
456   // if.else:
457   Builder.SetInsertPoint(IfElse);
458   Value *Sub24 = Builder.CreateAdd(
459       FloatWidth == 128 ? Call : Cast,
460       ConstantInt::getSigned(Builder.getIntNTy(BitWidthNew),
461                              -(BitWidth - FPMantissaWidth - 1)));
462   Value *ShProm25 = Builder.CreateZExt(Sub24, IntTy);
463   Value *Shl26 = Builder.CreateShl(IsSigned ? Sub : IntVal,
464                                    FloatWidth == 128 ? Sub24 : ShProm25);
465   Value *ExtractT61 = Builder.CreateTrunc(Shl26, Builder.getIntNTy(FloatWidth));
466   Value *Extract65 = Builder.CreateLShr(Shl26, Builder.getIntN(BitWidth, 32));
467   Value *ExtractT66 = nullptr;
468   if (FloatWidth > 80)
469     ExtractT66 = Builder.CreateTrunc(Sub2, Builder.getIntNTy(64));
470   else
471     ExtractT66 = Builder.CreateTrunc(Extract65, Builder.getInt32Ty());
472   Builder.CreateBr(IfEnd26);
473 
474   // if.end26:
475   Builder.SetInsertPoint(IfEnd26);
476   PHINode *AAddr1Off0 = Builder.CreatePHI(Builder.getIntNTy(FloatWidth), 3);
477   AAddr1Off0->addIncoming(ExtractT, IfThen20);
478   AAddr1Off0->addIncoming(ExtractT60, SwEpilog);
479   AAddr1Off0->addIncoming(ExtractT61, IfElse);
480   PHINode *AAddr1Off32 = nullptr;
481   if (FloatWidth > 32) {
482     AAddr1Off32 =
483         Builder.CreatePHI(Builder.getIntNTy(FloatWidth > 80 ? 64 : 32), 3);
484     AAddr1Off32->addIncoming(ExtractT62, IfThen20);
485     AAddr1Off32->addIncoming(ExtractT64, SwEpilog);
486     AAddr1Off32->addIncoming(ExtractT66, IfElse);
487   }
488   PHINode *E0 = nullptr;
489   if (FloatWidth <= 80) {
490     E0 = Builder.CreatePHI(Builder.getIntNTy(BitWidthNew), 3);
491     E0->addIncoming(Sub1, IfThen20);
492     E0->addIncoming(Sub2, SwEpilog);
493     E0->addIncoming(Sub2, IfElse);
494   }
495   Value *And29 = nullptr;
496   if (FloatWidth > 80) {
497     Value *Temp2 = Builder.CreateShl(Builder.getIntN(BitWidth, 1),
498                                      Builder.getIntN(BitWidth, 63));
499     And29 = Builder.CreateAnd(Shr, Temp2, "and29");
500   } else {
501     Value *Conv28 = Builder.CreateTrunc(Shr, Builder.getIntNTy(32));
502     And29 = Builder.CreateAnd(
503         Conv28, ConstantInt::getSigned(Builder.getIntNTy(32), 0x80000000));
504   }
505   unsigned TempMod = FPMantissaWidth % 32;
506   Value *And34 = nullptr;
507   Value *Shl30 = nullptr;
508   if (FloatWidth > 80) {
509     TempMod += 32;
510     Value *Add = Builder.CreateShl(AAddr1Off32, Builder.getIntN(64, TempMod));
511     Shl30 = Builder.CreateAdd(
512         Add,
513         Builder.getIntN(64, ((1ull << (62ull - TempMod)) - 1ull) << TempMod));
514     And34 = Builder.CreateZExt(Shl30, Builder.getIntNTy(128));
515   } else {
516     Value *Add = Builder.CreateShl(E0, Builder.getIntN(32, TempMod));
517     Shl30 = Builder.CreateAdd(
518         Add, Builder.getIntN(32, ((1 << (30 - TempMod)) - 1) << TempMod));
519     And34 = Builder.CreateAnd(FloatWidth > 32 ? AAddr1Off32 : AAddr1Off0,
520                               Builder.getIntN(32, (1 << TempMod) - 1));
521   }
522   Value *Or35 = nullptr;
523   if (FloatWidth > 80) {
524     Value *And29Trunc = Builder.CreateTrunc(And29, Builder.getIntNTy(128));
525     Value *Or31 = Builder.CreateOr(And29Trunc, And34);
526     Value *Or34 = Builder.CreateShl(Or31, Builder.getIntN(128, 64));
527     Value *Temp3 = Builder.CreateShl(Builder.getIntN(128, 1),
528                                      Builder.getIntN(128, FPMantissaWidth));
529     Value *Temp4 = Builder.CreateSub(Temp3, Builder.getIntN(128, 1));
530     Value *A6 = Builder.CreateAnd(AAddr1Off0, Temp4);
531     Or35 = Builder.CreateOr(Or34, A6);
532   } else {
533     Value *Or31 = Builder.CreateOr(And34, And29);
534     Or35 = Builder.CreateOr(IsSigned ? Or31 : And34, Shl30);
535   }
536   Value *A4 = nullptr;
537   if (IToFP->getType()->isDoubleTy()) {
538     Value *ZExt1 = Builder.CreateZExt(Or35, Builder.getIntNTy(FloatWidth));
539     Value *Shl1 = Builder.CreateShl(ZExt1, Builder.getIntN(FloatWidth, 32));
540     Value *And1 =
541         Builder.CreateAnd(AAddr1Off0, Builder.getIntN(FloatWidth, 0xFFFFFFFF));
542     Value *Or1 = Builder.CreateOr(Shl1, And1);
543     A4 = Builder.CreateBitCast(Or1, IToFP->getType());
544   } else if (IToFP->getType()->isX86_FP80Ty()) {
545     Value *A40 =
546         Builder.CreateBitCast(Or35, Type::getFP128Ty(Builder.getContext()));
547     A4 = Builder.CreateFPTrunc(A40, IToFP->getType());
548   } else if (IToFP->getType()->isHalfTy()) {
549     // Deal with "half" situation. This is a workaround since we don't have
550     // floattihf.c currently as referring.
551     Value *A40 =
552         Builder.CreateBitCast(Or35, Type::getFloatTy(Builder.getContext()));
553     A4 = Builder.CreateFPTrunc(A40, IToFP->getType());
554   } else // float type
555     A4 = Builder.CreateBitCast(Or35, IToFP->getType());
556   Builder.CreateBr(End);
557 
558   // return:
559   Builder.SetInsertPoint(End, End->begin());
560   PHINode *Retval0 = Builder.CreatePHI(IToFP->getType(), 2);
561   Retval0->addIncoming(A4, IfEnd26);
562   Retval0->addIncoming(ConstantFP::getZero(IToFP->getType(), false), Entry);
563 
564   IToFP->replaceAllUsesWith(Retval0);
565   IToFP->dropAllReferences();
566   IToFP->eraseFromParent();
567 }
568 
569 static bool runImpl(Function &F, const TargetLowering &TLI) {
570   SmallVector<Instruction *, 4> Replace;
571   bool Modified = false;
572 
573   unsigned MaxLegalFpConvertBitWidth =
574       TLI.getMaxLargeFPConvertBitWidthSupported();
575   if (ExpandFpConvertBits != llvm::IntegerType::MAX_INT_BITS)
576     MaxLegalFpConvertBitWidth = ExpandFpConvertBits;
577 
578   if (MaxLegalFpConvertBitWidth >= llvm::IntegerType::MAX_INT_BITS)
579     return false;
580 
581   for (auto &I : instructions(F)) {
582     switch (I.getOpcode()) {
583     case Instruction::FPToUI:
584     case Instruction::FPToSI: {
585       // TODO: This pass doesn't handle vectors.
586       if (I.getOperand(0)->getType()->isVectorTy())
587         continue;
588 
589       auto *IntTy = dyn_cast<IntegerType>(I.getType());
590       if (IntTy->getIntegerBitWidth() <= MaxLegalFpConvertBitWidth)
591         continue;
592 
593       Replace.push_back(&I);
594       Modified = true;
595       break;
596     }
597     case Instruction::UIToFP:
598     case Instruction::SIToFP: {
599       // TODO: This pass doesn't handle vectors.
600       if (I.getOperand(0)->getType()->isVectorTy())
601         continue;
602 
603       auto *IntTy = dyn_cast<IntegerType>(I.getOperand(0)->getType());
604       if (IntTy->getIntegerBitWidth() <= MaxLegalFpConvertBitWidth)
605         continue;
606 
607       Replace.push_back(&I);
608       Modified = true;
609       break;
610     }
611     default:
612       break;
613     }
614   }
615 
616   if (Replace.empty())
617     return false;
618 
619   while (!Replace.empty()) {
620     Instruction *I = Replace.pop_back_val();
621     if (I->getOpcode() == Instruction::FPToUI ||
622         I->getOpcode() == Instruction::FPToSI) {
623       expandFPToI(I);
624     } else {
625       expandIToFP(I);
626     }
627   }
628 
629   return Modified;
630 }
631 
632 namespace {
633 class ExpandLargeFpConvertLegacyPass : public FunctionPass {
634 public:
635   static char ID;
636 
637   ExpandLargeFpConvertLegacyPass() : FunctionPass(ID) {
638     initializeExpandLargeFpConvertLegacyPassPass(
639         *PassRegistry::getPassRegistry());
640   }
641 
642   bool runOnFunction(Function &F) override {
643     auto *TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
644     auto *TLI = TM->getSubtargetImpl(F)->getTargetLowering();
645     return runImpl(F, *TLI);
646   }
647 
648   void getAnalysisUsage(AnalysisUsage &AU) const override {
649     AU.addRequired<TargetPassConfig>();
650     AU.addPreserved<AAResultsWrapperPass>();
651     AU.addPreserved<GlobalsAAWrapperPass>();
652   }
653 };
654 } // namespace
655 
656 char ExpandLargeFpConvertLegacyPass::ID = 0;
657 INITIALIZE_PASS_BEGIN(ExpandLargeFpConvertLegacyPass, "expand-large-fp-convert",
658                       "Expand large fp convert", false, false)
659 INITIALIZE_PASS_END(ExpandLargeFpConvertLegacyPass, "expand-large-fp-convert",
660                     "Expand large fp convert", false, false)
661 
662 FunctionPass *llvm::createExpandLargeFpConvertPass() {
663   return new ExpandLargeFpConvertLegacyPass();
664 }
665