xref: /freebsd/contrib/llvm-project/llvm/tools/llvm-stress/llvm-stress.cpp (revision 035dd78d30ba28a3dc15c05ec85ad10127165677) 
1 //===- llvm-stress.cpp - Generate random LL files to stress-test LLVM -----===//
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 program is a utility that generates random .ll files to stress-test
10 // different components in LLVM.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ADT/APFloat.h"
15 #include "llvm/ADT/APInt.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ADT/Twine.h"
20 #include "llvm/IR/BasicBlock.h"
21 #include "llvm/IR/CallingConv.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/DerivedTypes.h"
25 #include "llvm/IR/Function.h"
26 #include "llvm/IR/GlobalValue.h"
27 #include "llvm/IR/IRPrintingPasses.h"
28 #include "llvm/IR/InstrTypes.h"
29 #include "llvm/IR/Instruction.h"
30 #include "llvm/IR/Instructions.h"
31 #include "llvm/IR/LLVMContext.h"
32 #include "llvm/IR/LegacyPassManager.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/Type.h"
35 #include "llvm/IR/Value.h"
36 #include "llvm/IR/Verifier.h"
37 #include "llvm/Pass.h"
38 #include "llvm/Support/Casting.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/ErrorHandling.h"
41 #include "llvm/Support/FileSystem.h"
42 #include "llvm/Support/InitLLVM.h"
43 #include "llvm/Support/ToolOutputFile.h"
44 #include "llvm/Support/WithColor.h"
45 #include "llvm/Support/raw_ostream.h"
46 #include <algorithm>
47 #include <cassert>
48 #include <cstddef>
49 #include <cstdint>
50 #include <memory>
51 #include <string>
52 #include <system_error>
53 #include <vector>
54 
55 namespace llvm {
56 
57 static cl::OptionCategory StressCategory("Stress Options");
58 
59 static cl::opt<unsigned> SeedCL("seed", cl::desc("Seed used for randomness"),
60                                 cl::init(0), cl::cat(StressCategory));
61 
62 static cl::opt<unsigned> SizeCL(
63     "size",
64     cl::desc("The estimated size of the generated function (# of instrs)"),
65     cl::init(100), cl::cat(StressCategory));
66 
67 static cl::opt<std::string> OutputFilename("o",
68                                            cl::desc("Override output filename"),
69                                            cl::value_desc("filename"),
70                                            cl::cat(StressCategory));
71 
72 static cl::list<StringRef> AdditionalScalarTypes(
73     "types", cl::CommaSeparated,
74     cl::desc("Additional IR scalar types "
75              "(always includes i1, i8, i16, i32, i64, float and double)"));
76 
77 namespace {
78 
79 /// A utility class to provide a pseudo-random number generator which is
80 /// the same across all platforms. This is somewhat close to the libc
81 /// implementation. Note: This is not a cryptographically secure pseudorandom
82 /// number generator.
83 class Random {
84 public:
85   /// C'tor
86   Random(unsigned _seed):Seed(_seed) {}
87 
88   /// Return a random integer, up to a
89   /// maximum of 2**19 - 1.
90   uint32_t Rand() {
91     uint32_t Val = Seed + 0x000b07a1;
92     Seed = (Val * 0x3c7c0ac1);
93     // Only lowest 19 bits are random-ish.
94     return Seed & 0x7ffff;
95   }
96 
97   /// Return a random 64 bit integer.
98   uint64_t Rand64() {
99     uint64_t Val = Rand() & 0xffff;
100     Val |= uint64_t(Rand() & 0xffff) << 16;
101     Val |= uint64_t(Rand() & 0xffff) << 32;
102     Val |= uint64_t(Rand() & 0xffff) << 48;
103     return Val;
104   }
105 
106   /// Rand operator for STL algorithms.
107   ptrdiff_t operator()(ptrdiff_t y) {
108     return  Rand64() % y;
109   }
110 
111   /// Make this like a C++11 random device
112   using result_type = uint32_t ;
113 
114   static constexpr result_type min() { return 0; }
115   static constexpr result_type max() { return 0x7ffff; }
116 
117   uint32_t operator()() {
118     uint32_t Val = Rand();
119     assert(Val <= max() && "Random value out of range");
120     return Val;
121   }
122 
123 private:
124   unsigned Seed;
125 };
126 
127 /// Generate an empty function with a default argument list.
128 Function *GenEmptyFunction(Module *M) {
129   // Define a few arguments
130   LLVMContext &Context = M->getContext();
131   Type* ArgsTy[] = {
132     Type::getInt8PtrTy(Context),
133     Type::getInt32PtrTy(Context),
134     Type::getInt64PtrTy(Context),
135     Type::getInt32Ty(Context),
136     Type::getInt64Ty(Context),
137     Type::getInt8Ty(Context)
138   };
139 
140   auto *FuncTy = FunctionType::get(Type::getVoidTy(Context), ArgsTy, false);
141   // Pick a unique name to describe the input parameters
142   Twine Name = "autogen_SD" + Twine{SeedCL};
143   auto *Func = Function::Create(FuncTy, GlobalValue::ExternalLinkage, Name, M);
144   Func->setCallingConv(CallingConv::C);
145   return Func;
146 }
147 
148 /// A base class, implementing utilities needed for
149 /// modifying and adding new random instructions.
150 struct Modifier {
151   /// Used to store the randomly generated values.
152   using PieceTable = std::vector<Value *>;
153 
154 public:
155   /// C'tor
156   Modifier(BasicBlock *Block, PieceTable *PT, Random *R)
157       : BB(Block), PT(PT), Ran(R), Context(BB->getContext()) {
158     ScalarTypes.assign({Type::getInt1Ty(Context), Type::getInt8Ty(Context),
159                         Type::getInt16Ty(Context), Type::getInt32Ty(Context),
160                         Type::getInt64Ty(Context), Type::getFloatTy(Context),
161                         Type::getDoubleTy(Context)});
162 
163     for (auto &Arg : AdditionalScalarTypes) {
164       Type *Ty = nullptr;
165       if (Arg == "half")
166         Ty = Type::getHalfTy(Context);
167       else if (Arg == "fp128")
168         Ty = Type::getFP128Ty(Context);
169       else if (Arg == "x86_fp80")
170         Ty = Type::getX86_FP80Ty(Context);
171       else if (Arg == "ppc_fp128")
172         Ty = Type::getPPC_FP128Ty(Context);
173       else if (Arg == "x86_mmx")
174         Ty = Type::getX86_MMXTy(Context);
175       else if (Arg.startswith("i")) {
176         unsigned N = 0;
177         Arg.drop_front().getAsInteger(10, N);
178         if (N > 0)
179           Ty = Type::getIntNTy(Context, N);
180       }
181       if (!Ty) {
182         errs() << "Invalid IR scalar type: '" << Arg << "'!\n";
183         exit(1);
184       }
185 
186       ScalarTypes.push_back(Ty);
187     }
188   }
189 
190   /// virtual D'tor to silence warnings.
191   virtual ~Modifier() = default;
192 
193   /// Add a new instruction.
194   virtual void Act() = 0;
195 
196   /// Add N new instructions,
197   virtual void ActN(unsigned n) {
198     for (unsigned i=0; i<n; ++i)
199       Act();
200   }
201 
202 protected:
203   /// Return a random integer.
204   uint32_t getRandom() {
205     return Ran->Rand();
206   }
207 
208   /// Return a random value from the list of known values.
209   Value *getRandomVal() {
210     assert(PT->size());
211     return PT->at(getRandom() % PT->size());
212   }
213 
214   Constant *getRandomConstant(Type *Tp) {
215     if (Tp->isIntegerTy()) {
216       if (getRandom() & 1)
217         return ConstantInt::getAllOnesValue(Tp);
218       return ConstantInt::getNullValue(Tp);
219     } else if (Tp->isFloatingPointTy()) {
220       if (getRandom() & 1)
221         return ConstantFP::getAllOnesValue(Tp);
222       return ConstantFP::getNullValue(Tp);
223     }
224     return UndefValue::get(Tp);
225   }
226 
227   /// Return a random value with a known type.
228   Value *getRandomValue(Type *Tp) {
229     unsigned index = getRandom();
230     for (unsigned i=0; i<PT->size(); ++i) {
231       Value *V = PT->at((index + i) % PT->size());
232       if (V->getType() == Tp)
233         return V;
234     }
235 
236     // If the requested type was not found, generate a constant value.
237     if (Tp->isIntegerTy()) {
238       if (getRandom() & 1)
239         return ConstantInt::getAllOnesValue(Tp);
240       return ConstantInt::getNullValue(Tp);
241     } else if (Tp->isFloatingPointTy()) {
242       if (getRandom() & 1)
243         return ConstantFP::getAllOnesValue(Tp);
244       return ConstantFP::getNullValue(Tp);
245     } else if (Tp->isVectorTy()) {
246       auto *VTp = cast<FixedVectorType>(Tp);
247 
248       std::vector<Constant*> TempValues;
249       TempValues.reserve(VTp->getNumElements());
250       for (unsigned i = 0; i < VTp->getNumElements(); ++i)
251         TempValues.push_back(getRandomConstant(VTp->getScalarType()));
252 
253       ArrayRef<Constant*> VectorValue(TempValues);
254       return ConstantVector::get(VectorValue);
255     }
256 
257     return UndefValue::get(Tp);
258   }
259 
260   /// Return a random value of any pointer type.
261   Value *getRandomPointerValue() {
262     unsigned index = getRandom();
263     for (unsigned i=0; i<PT->size(); ++i) {
264       Value *V = PT->at((index + i) % PT->size());
265       if (V->getType()->isPointerTy())
266         return V;
267     }
268     return UndefValue::get(pickPointerType());
269   }
270 
271   /// Return a random value of any vector type.
272   Value *getRandomVectorValue() {
273     unsigned index = getRandom();
274     for (unsigned i=0; i<PT->size(); ++i) {
275       Value *V = PT->at((index + i) % PT->size());
276       if (V->getType()->isVectorTy())
277         return V;
278     }
279     return UndefValue::get(pickVectorType());
280   }
281 
282   /// Pick a random type.
283   Type *pickType() {
284     return (getRandom() & 1) ? pickVectorType() : pickScalarType();
285   }
286 
287   /// Pick a random pointer type.
288   Type *pickPointerType() {
289     Type *Ty = pickType();
290     return PointerType::get(Ty, 0);
291   }
292 
293   /// Pick a random vector type.
294   Type *pickVectorType(unsigned len = (unsigned)-1) {
295     // Pick a random vector width in the range 2**0 to 2**4.
296     // by adding two randoms we are generating a normal-like distribution
297     // around 2**3.
298     unsigned width = 1<<((getRandom() % 3) + (getRandom() % 3));
299     Type *Ty;
300 
301     // Vectors of x86mmx are illegal; keep trying till we get something else.
302     do {
303       Ty = pickScalarType();
304     } while (Ty->isX86_MMXTy());
305 
306     if (len != (unsigned)-1)
307       width = len;
308     return FixedVectorType::get(Ty, width);
309   }
310 
311   /// Pick a random scalar type.
312   Type *pickScalarType() {
313     return ScalarTypes[getRandom() % ScalarTypes.size()];
314   }
315 
316   /// Basic block to populate
317   BasicBlock *BB;
318 
319   /// Value table
320   PieceTable *PT;
321 
322   /// Random number generator
323   Random *Ran;
324 
325   /// Context
326   LLVMContext &Context;
327 
328   std::vector<Type *> ScalarTypes;
329 };
330 
331 struct LoadModifier: public Modifier {
332   LoadModifier(BasicBlock *BB, PieceTable *PT, Random *R)
333       : Modifier(BB, PT, R) {}
334 
335   void Act() override {
336     // Try to use predefined pointers. If non-exist, use undef pointer value;
337     Value *Ptr = getRandomPointerValue();
338     Type *Ty = Ptr->getType()->isOpaquePointerTy()
339                    ? pickType()
340                    : Ptr->getType()->getNonOpaquePointerElementType();
341     Value *V = new LoadInst(Ty, Ptr, "L", BB->getTerminator());
342     PT->push_back(V);
343   }
344 };
345 
346 struct StoreModifier: public Modifier {
347   StoreModifier(BasicBlock *BB, PieceTable *PT, Random *R)
348       : Modifier(BB, PT, R) {}
349 
350   void Act() override {
351     // Try to use predefined pointers. If non-exist, use undef pointer value;
352     Value *Ptr = getRandomPointerValue();
353     Type *ValTy = Ptr->getType()->isOpaquePointerTy()
354                       ? pickType()
355                       : Ptr->getType()->getNonOpaquePointerElementType();
356 
357     // Do not store vectors of i1s because they are unsupported
358     // by the codegen.
359     if (ValTy->isVectorTy() && ValTy->getScalarSizeInBits() == 1)
360       return;
361 
362     Value *Val = getRandomValue(ValTy);
363     new StoreInst(Val, Ptr, BB->getTerminator());
364   }
365 };
366 
367 struct BinModifier: public Modifier {
368   BinModifier(BasicBlock *BB, PieceTable *PT, Random *R)
369       : Modifier(BB, PT, R) {}
370 
371   void Act() override {
372     Value *Val0 = getRandomVal();
373     Value *Val1 = getRandomValue(Val0->getType());
374 
375     // Don't handle pointer types.
376     if (Val0->getType()->isPointerTy() ||
377         Val1->getType()->isPointerTy())
378       return;
379 
380     // Don't handle i1 types.
381     if (Val0->getType()->getScalarSizeInBits() == 1)
382       return;
383 
384     bool isFloat = Val0->getType()->getScalarType()->isFloatingPointTy();
385     Instruction* Term = BB->getTerminator();
386     unsigned R = getRandom() % (isFloat ? 7 : 13);
387     Instruction::BinaryOps Op;
388 
389     switch (R) {
390     default: llvm_unreachable("Invalid BinOp");
391     case 0:{Op = (isFloat?Instruction::FAdd : Instruction::Add); break; }
392     case 1:{Op = (isFloat?Instruction::FSub : Instruction::Sub); break; }
393     case 2:{Op = (isFloat?Instruction::FMul : Instruction::Mul); break; }
394     case 3:{Op = (isFloat?Instruction::FDiv : Instruction::SDiv); break; }
395     case 4:{Op = (isFloat?Instruction::FDiv : Instruction::UDiv); break; }
396     case 5:{Op = (isFloat?Instruction::FRem : Instruction::SRem); break; }
397     case 6:{Op = (isFloat?Instruction::FRem : Instruction::URem); break; }
398     case 7: {Op = Instruction::Shl;  break; }
399     case 8: {Op = Instruction::LShr; break; }
400     case 9: {Op = Instruction::AShr; break; }
401     case 10:{Op = Instruction::And;  break; }
402     case 11:{Op = Instruction::Or;   break; }
403     case 12:{Op = Instruction::Xor;  break; }
404     }
405 
406     PT->push_back(BinaryOperator::Create(Op, Val0, Val1, "B", Term));
407   }
408 };
409 
410 /// Generate constant values.
411 struct ConstModifier: public Modifier {
412   ConstModifier(BasicBlock *BB, PieceTable *PT, Random *R)
413       : Modifier(BB, PT, R) {}
414 
415   void Act() override {
416     Type *Ty = pickType();
417 
418     if (Ty->isVectorTy()) {
419       switch (getRandom() % 2) {
420       case 0: if (Ty->isIntOrIntVectorTy())
421                 return PT->push_back(ConstantVector::getAllOnesValue(Ty));
422               break;
423       case 1: if (Ty->isIntOrIntVectorTy())
424                 return PT->push_back(ConstantVector::getNullValue(Ty));
425       }
426     }
427 
428     if (Ty->isFloatingPointTy()) {
429       // Generate 128 random bits, the size of the (currently)
430       // largest floating-point types.
431       uint64_t RandomBits[2];
432       for (unsigned i = 0; i < 2; ++i)
433         RandomBits[i] = Ran->Rand64();
434 
435       APInt RandomInt(Ty->getPrimitiveSizeInBits(), makeArrayRef(RandomBits));
436       APFloat RandomFloat(Ty->getFltSemantics(), RandomInt);
437 
438       if (getRandom() & 1)
439         return PT->push_back(ConstantFP::getNullValue(Ty));
440       return PT->push_back(ConstantFP::get(Ty->getContext(), RandomFloat));
441     }
442 
443     if (Ty->isIntegerTy()) {
444       switch (getRandom() % 7) {
445       case 0:
446         return PT->push_back(ConstantInt::get(
447             Ty, APInt::getAllOnes(Ty->getPrimitiveSizeInBits())));
448       case 1:
449         return PT->push_back(
450             ConstantInt::get(Ty, APInt::getZero(Ty->getPrimitiveSizeInBits())));
451       case 2:
452       case 3:
453       case 4:
454       case 5:
455       case 6:
456         PT->push_back(ConstantInt::get(Ty, getRandom()));
457       }
458     }
459   }
460 };
461 
462 struct AllocaModifier: public Modifier {
463   AllocaModifier(BasicBlock *BB, PieceTable *PT, Random *R)
464       : Modifier(BB, PT, R) {}
465 
466   void Act() override {
467     Type *Tp = pickType();
468     const DataLayout &DL = BB->getModule()->getDataLayout();
469     PT->push_back(new AllocaInst(Tp, DL.getAllocaAddrSpace(),
470                                  "A", BB->getFirstNonPHI()));
471   }
472 };
473 
474 struct ExtractElementModifier: public Modifier {
475   ExtractElementModifier(BasicBlock *BB, PieceTable *PT, Random *R)
476       : Modifier(BB, PT, R) {}
477 
478   void Act() override {
479     Value *Val0 = getRandomVectorValue();
480     Value *V = ExtractElementInst::Create(
481         Val0,
482         ConstantInt::get(
483             Type::getInt32Ty(BB->getContext()),
484             getRandom() %
485                 cast<FixedVectorType>(Val0->getType())->getNumElements()),
486         "E", BB->getTerminator());
487     return PT->push_back(V);
488   }
489 };
490 
491 struct ShuffModifier: public Modifier {
492   ShuffModifier(BasicBlock *BB, PieceTable *PT, Random *R)
493       : Modifier(BB, PT, R) {}
494 
495   void Act() override {
496     Value *Val0 = getRandomVectorValue();
497     Value *Val1 = getRandomValue(Val0->getType());
498 
499     unsigned Width = cast<FixedVectorType>(Val0->getType())->getNumElements();
500     std::vector<Constant*> Idxs;
501 
502     Type *I32 = Type::getInt32Ty(BB->getContext());
503     for (unsigned i=0; i<Width; ++i) {
504       Constant *CI = ConstantInt::get(I32, getRandom() % (Width*2));
505       // Pick some undef values.
506       if (!(getRandom() % 5))
507         CI = UndefValue::get(I32);
508       Idxs.push_back(CI);
509     }
510 
511     Constant *Mask = ConstantVector::get(Idxs);
512 
513     Value *V = new ShuffleVectorInst(Val0, Val1, Mask, "Shuff",
514                                      BB->getTerminator());
515     PT->push_back(V);
516   }
517 };
518 
519 struct InsertElementModifier: public Modifier {
520   InsertElementModifier(BasicBlock *BB, PieceTable *PT, Random *R)
521       : Modifier(BB, PT, R) {}
522 
523   void Act() override {
524     Value *Val0 = getRandomVectorValue();
525     Value *Val1 = getRandomValue(Val0->getType()->getScalarType());
526 
527     Value *V = InsertElementInst::Create(
528         Val0, Val1,
529         ConstantInt::get(
530             Type::getInt32Ty(BB->getContext()),
531             getRandom() %
532                 cast<FixedVectorType>(Val0->getType())->getNumElements()),
533         "I", BB->getTerminator());
534     return PT->push_back(V);
535   }
536 };
537 
538 struct CastModifier: public Modifier {
539   CastModifier(BasicBlock *BB, PieceTable *PT, Random *R)
540       : Modifier(BB, PT, R) {}
541 
542   void Act() override {
543     Value *V = getRandomVal();
544     Type *VTy = V->getType();
545     Type *DestTy = pickScalarType();
546 
547     // Handle vector casts vectors.
548     if (VTy->isVectorTy()) {
549       auto *VecTy = cast<FixedVectorType>(VTy);
550       DestTy = pickVectorType(VecTy->getNumElements());
551     }
552 
553     // no need to cast.
554     if (VTy == DestTy) return;
555 
556     // Pointers:
557     if (VTy->isPointerTy()) {
558       if (!DestTy->isPointerTy())
559         DestTy = PointerType::get(DestTy, 0);
560       return PT->push_back(
561         new BitCastInst(V, DestTy, "PC", BB->getTerminator()));
562     }
563 
564     unsigned VSize = VTy->getScalarType()->getPrimitiveSizeInBits();
565     unsigned DestSize = DestTy->getScalarType()->getPrimitiveSizeInBits();
566 
567     // Generate lots of bitcasts.
568     if ((getRandom() & 1) && VSize == DestSize) {
569       return PT->push_back(
570         new BitCastInst(V, DestTy, "BC", BB->getTerminator()));
571     }
572 
573     // Both types are integers:
574     if (VTy->isIntOrIntVectorTy() && DestTy->isIntOrIntVectorTy()) {
575       if (VSize > DestSize) {
576         return PT->push_back(
577           new TruncInst(V, DestTy, "Tr", BB->getTerminator()));
578       } else {
579         assert(VSize < DestSize && "Different int types with the same size?");
580         if (getRandom() & 1)
581           return PT->push_back(
582             new ZExtInst(V, DestTy, "ZE", BB->getTerminator()));
583         return PT->push_back(new SExtInst(V, DestTy, "Se", BB->getTerminator()));
584       }
585     }
586 
587     // Fp to int.
588     if (VTy->isFPOrFPVectorTy() && DestTy->isIntOrIntVectorTy()) {
589       if (getRandom() & 1)
590         return PT->push_back(
591           new FPToSIInst(V, DestTy, "FC", BB->getTerminator()));
592       return PT->push_back(new FPToUIInst(V, DestTy, "FC", BB->getTerminator()));
593     }
594 
595     // Int to fp.
596     if (VTy->isIntOrIntVectorTy() && DestTy->isFPOrFPVectorTy()) {
597       if (getRandom() & 1)
598         return PT->push_back(
599           new SIToFPInst(V, DestTy, "FC", BB->getTerminator()));
600       return PT->push_back(new UIToFPInst(V, DestTy, "FC", BB->getTerminator()));
601     }
602 
603     // Both floats.
604     if (VTy->isFPOrFPVectorTy() && DestTy->isFPOrFPVectorTy()) {
605       if (VSize > DestSize) {
606         return PT->push_back(
607           new FPTruncInst(V, DestTy, "Tr", BB->getTerminator()));
608       } else if (VSize < DestSize) {
609         return PT->push_back(
610           new FPExtInst(V, DestTy, "ZE", BB->getTerminator()));
611       }
612       // If VSize == DestSize, then the two types must be fp128 and ppc_fp128,
613       // for which there is no defined conversion. So do nothing.
614     }
615   }
616 };
617 
618 struct SelectModifier: public Modifier {
619   SelectModifier(BasicBlock *BB, PieceTable *PT, Random *R)
620       : Modifier(BB, PT, R) {}
621 
622   void Act() override {
623     // Try a bunch of different select configuration until a valid one is found.
624     Value *Val0 = getRandomVal();
625     Value *Val1 = getRandomValue(Val0->getType());
626 
627     Type *CondTy = Type::getInt1Ty(Context);
628 
629     // If the value type is a vector, and we allow vector select, then in 50%
630     // of the cases generate a vector select.
631     if (isa<FixedVectorType>(Val0->getType()) && (getRandom() & 1)) {
632       unsigned NumElem =
633           cast<FixedVectorType>(Val0->getType())->getNumElements();
634       CondTy = FixedVectorType::get(CondTy, NumElem);
635     }
636 
637     Value *Cond = getRandomValue(CondTy);
638     Value *V = SelectInst::Create(Cond, Val0, Val1, "Sl", BB->getTerminator());
639     return PT->push_back(V);
640   }
641 };
642 
643 struct CmpModifier: public Modifier {
644   CmpModifier(BasicBlock *BB, PieceTable *PT, Random *R)
645       : Modifier(BB, PT, R) {}
646 
647   void Act() override {
648     Value *Val0 = getRandomVal();
649     Value *Val1 = getRandomValue(Val0->getType());
650 
651     if (Val0->getType()->isPointerTy()) return;
652     bool fp = Val0->getType()->getScalarType()->isFloatingPointTy();
653 
654     int op;
655     if (fp) {
656       op = getRandom() %
657       (CmpInst::LAST_FCMP_PREDICATE - CmpInst::FIRST_FCMP_PREDICATE) +
658        CmpInst::FIRST_FCMP_PREDICATE;
659     } else {
660       op = getRandom() %
661       (CmpInst::LAST_ICMP_PREDICATE - CmpInst::FIRST_ICMP_PREDICATE) +
662        CmpInst::FIRST_ICMP_PREDICATE;
663     }
664 
665     Value *V = CmpInst::Create(fp ? Instruction::FCmp : Instruction::ICmp,
666                                (CmpInst::Predicate)op, Val0, Val1, "Cmp",
667                                BB->getTerminator());
668     return PT->push_back(V);
669   }
670 };
671 
672 } // end anonymous namespace
673 
674 static void FillFunction(Function *F, Random &R) {
675   // Create a legal entry block.
676   BasicBlock *BB = BasicBlock::Create(F->getContext(), "BB", F);
677   ReturnInst::Create(F->getContext(), BB);
678 
679   // Create the value table.
680   Modifier::PieceTable PT;
681 
682   // Consider arguments as legal values.
683   for (auto &arg : F->args())
684     PT.push_back(&arg);
685 
686   // List of modifiers which add new random instructions.
687   std::vector<std::unique_ptr<Modifier>> Modifiers;
688   Modifiers.emplace_back(new LoadModifier(BB, &PT, &R));
689   Modifiers.emplace_back(new StoreModifier(BB, &PT, &R));
690   auto SM = Modifiers.back().get();
691   Modifiers.emplace_back(new ExtractElementModifier(BB, &PT, &R));
692   Modifiers.emplace_back(new ShuffModifier(BB, &PT, &R));
693   Modifiers.emplace_back(new InsertElementModifier(BB, &PT, &R));
694   Modifiers.emplace_back(new BinModifier(BB, &PT, &R));
695   Modifiers.emplace_back(new CastModifier(BB, &PT, &R));
696   Modifiers.emplace_back(new SelectModifier(BB, &PT, &R));
697   Modifiers.emplace_back(new CmpModifier(BB, &PT, &R));
698 
699   // Generate the random instructions
700   AllocaModifier{BB, &PT, &R}.ActN(5); // Throw in a few allocas
701   ConstModifier{BB, &PT, &R}.ActN(40); // Throw in a few constants
702 
703   for (unsigned i = 0; i < SizeCL / Modifiers.size(); ++i)
704     for (auto &Mod : Modifiers)
705       Mod->Act();
706 
707   SM->ActN(5); // Throw in a few stores.
708 }
709 
710 static void IntroduceControlFlow(Function *F, Random &R) {
711   std::vector<Instruction*> BoolInst;
712   for (auto &Instr : F->front()) {
713     if (Instr.getType() == IntegerType::getInt1Ty(F->getContext()))
714       BoolInst.push_back(&Instr);
715   }
716 
717   llvm::shuffle(BoolInst.begin(), BoolInst.end(), R);
718 
719   for (auto *Instr : BoolInst) {
720     BasicBlock *Curr = Instr->getParent();
721     BasicBlock::iterator Loc = Instr->getIterator();
722     BasicBlock *Next = Curr->splitBasicBlock(Loc, "CF");
723     Instr->moveBefore(Curr->getTerminator());
724     if (Curr != &F->getEntryBlock()) {
725       BranchInst::Create(Curr, Next, Instr, Curr->getTerminator());
726       Curr->getTerminator()->eraseFromParent();
727     }
728   }
729 }
730 
731 } // end namespace llvm
732 
733 int main(int argc, char **argv) {
734   using namespace llvm;
735 
736   InitLLVM X(argc, argv);
737   cl::HideUnrelatedOptions({&StressCategory, &getColorCategory()});
738   cl::ParseCommandLineOptions(argc, argv, "llvm codegen stress-tester\n");
739 
740   LLVMContext Context;
741   auto M = std::make_unique<Module>("/tmp/autogen.bc", Context);
742   Function *F = GenEmptyFunction(M.get());
743 
744   // Pick an initial seed value
745   Random R(SeedCL);
746   // Generate lots of random instructions inside a single basic block.
747   FillFunction(F, R);
748   // Break the basic block into many loops.
749   IntroduceControlFlow(F, R);
750 
751   // Figure out what stream we are supposed to write to...
752   std::unique_ptr<ToolOutputFile> Out;
753   // Default to standard output.
754   if (OutputFilename.empty())
755     OutputFilename = "-";
756 
757   std::error_code EC;
758   Out.reset(new ToolOutputFile(OutputFilename, EC, sys::fs::OF_None));
759   if (EC) {
760     errs() << EC.message() << '\n';
761     return 1;
762   }
763 
764   legacy::PassManager Passes;
765   Passes.add(createVerifierPass());
766   Passes.add(createPrintModulePass(Out->os()));
767   Passes.run(*M.get());
768   Out->keep();
769 
770   return 0;
771 }
772