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/Support/Casting.h"
38 #include "llvm/Support/CommandLine.h"
39 #include "llvm/Support/ErrorHandling.h"
40 #include "llvm/Support/FileSystem.h"
41 #include "llvm/Support/ManagedStatic.h"
42 #include "llvm/Support/PrettyStackTrace.h"
43 #include "llvm/Support/ToolOutputFile.h"
44 #include "llvm/Support/raw_ostream.h"
45 #include <algorithm>
46 #include <cassert>
47 #include <cstddef>
48 #include <cstdint>
49 #include <memory>
50 #include <string>
51 #include <system_error>
52 #include <vector>
53 
54 namespace llvm {
55 
56 static cl::opt<unsigned> SeedCL("seed",
57   cl::desc("Seed used for randomness"), cl::init(0));
58 
59 static cl::opt<unsigned> SizeCL("size",
60   cl::desc("The estimated size of the generated function (# of instrs)"),
61   cl::init(100));
62 
63 static cl::opt<std::string>
64 OutputFilename("o", cl::desc("Override output filename"),
65                cl::value_desc("filename"));
66 
67 static LLVMContext Context;
68 
69 namespace cl {
70 
71 template <> class parser<Type*> final : public basic_parser<Type*> {
72 public:
73   parser(Option &O) : basic_parser(O) {}
74 
75   // Parse options as IR types. Return true on error.
76   bool parse(Option &O, StringRef, StringRef Arg, Type *&Value) {
77     if      (Arg == "half")      Value = Type::getHalfTy(Context);
78     else if (Arg == "fp128")     Value = Type::getFP128Ty(Context);
79     else if (Arg == "x86_fp80")  Value = Type::getX86_FP80Ty(Context);
80     else if (Arg == "ppc_fp128") Value = Type::getPPC_FP128Ty(Context);
81     else if (Arg == "x86_mmx")   Value = Type::getX86_MMXTy(Context);
82     else if (Arg.startswith("i")) {
83       unsigned N = 0;
84       Arg.drop_front().getAsInteger(10, N);
85       if (N > 0)
86         Value = Type::getIntNTy(Context, N);
87     }
88 
89     if (!Value)
90       return O.error("Invalid IR scalar type: '" + Arg + "'!");
91     return false;
92   }
93 
94   StringRef getValueName() const override { return "IR scalar type"; }
95 };
96 
97 } // end namespace cl
98 
99 static cl::list<Type*> AdditionalScalarTypes("types", cl::CommaSeparated,
100   cl::desc("Additional IR scalar types "
101            "(always includes i1, i8, i16, i32, i64, float and double)"));
102 
103 namespace {
104 
105 /// A utility class to provide a pseudo-random number generator which is
106 /// the same across all platforms. This is somewhat close to the libc
107 /// implementation. Note: This is not a cryptographically secure pseudorandom
108 /// number generator.
109 class Random {
110 public:
111   /// C'tor
112   Random(unsigned _seed):Seed(_seed) {}
113 
114   /// Return a random integer, up to a
115   /// maximum of 2**19 - 1.
116   uint32_t Rand() {
117     uint32_t Val = Seed + 0x000b07a1;
118     Seed = (Val * 0x3c7c0ac1);
119     // Only lowest 19 bits are random-ish.
120     return Seed & 0x7ffff;
121   }
122 
123   /// Return a random 64 bit integer.
124   uint64_t Rand64() {
125     uint64_t Val = Rand() & 0xffff;
126     Val |= uint64_t(Rand() & 0xffff) << 16;
127     Val |= uint64_t(Rand() & 0xffff) << 32;
128     Val |= uint64_t(Rand() & 0xffff) << 48;
129     return Val;
130   }
131 
132   /// Rand operator for STL algorithms.
133   ptrdiff_t operator()(ptrdiff_t y) {
134     return  Rand64() % y;
135   }
136 
137   /// Make this like a C++11 random device
138   using result_type = uint32_t ;
139 
140   static constexpr result_type min() { return 0; }
141   static constexpr result_type max() { return 0x7ffff; }
142 
143   uint32_t operator()() {
144     uint32_t Val = Rand();
145     assert(Val <= max() && "Random value out of range");
146     return Val;
147   }
148 
149 private:
150   unsigned Seed;
151 };
152 
153 /// Generate an empty function with a default argument list.
154 Function *GenEmptyFunction(Module *M) {
155   // Define a few arguments
156   LLVMContext &Context = M->getContext();
157   Type* ArgsTy[] = {
158     Type::getInt8PtrTy(Context),
159     Type::getInt32PtrTy(Context),
160     Type::getInt64PtrTy(Context),
161     Type::getInt32Ty(Context),
162     Type::getInt64Ty(Context),
163     Type::getInt8Ty(Context)
164   };
165 
166   auto *FuncTy = FunctionType::get(Type::getVoidTy(Context), ArgsTy, false);
167   // Pick a unique name to describe the input parameters
168   Twine Name = "autogen_SD" + Twine{SeedCL};
169   auto *Func = Function::Create(FuncTy, GlobalValue::ExternalLinkage, Name, M);
170   Func->setCallingConv(CallingConv::C);
171   return Func;
172 }
173 
174 /// A base class, implementing utilities needed for
175 /// modifying and adding new random instructions.
176 struct Modifier {
177   /// Used to store the randomly generated values.
178   using PieceTable = std::vector<Value *>;
179 
180 public:
181   /// C'tor
182   Modifier(BasicBlock *Block, PieceTable *PT, Random *R)
183       : BB(Block), PT(PT), Ran(R), Context(BB->getContext()) {}
184 
185   /// virtual D'tor to silence warnings.
186   virtual ~Modifier() = default;
187 
188   /// Add a new instruction.
189   virtual void Act() = 0;
190 
191   /// Add N new instructions,
192   virtual void ActN(unsigned n) {
193     for (unsigned i=0; i<n; ++i)
194       Act();
195   }
196 
197 protected:
198   /// Return a random integer.
199   uint32_t getRandom() {
200     return Ran->Rand();
201   }
202 
203   /// Return a random value from the list of known values.
204   Value *getRandomVal() {
205     assert(PT->size());
206     return PT->at(getRandom() % PT->size());
207   }
208 
209   Constant *getRandomConstant(Type *Tp) {
210     if (Tp->isIntegerTy()) {
211       if (getRandom() & 1)
212         return ConstantInt::getAllOnesValue(Tp);
213       return ConstantInt::getNullValue(Tp);
214     } else if (Tp->isFloatingPointTy()) {
215       if (getRandom() & 1)
216         return ConstantFP::getAllOnesValue(Tp);
217       return ConstantFP::getNullValue(Tp);
218     }
219     return UndefValue::get(Tp);
220   }
221 
222   /// Return a random value with a known type.
223   Value *getRandomValue(Type *Tp) {
224     unsigned index = getRandom();
225     for (unsigned i=0; i<PT->size(); ++i) {
226       Value *V = PT->at((index + i) % PT->size());
227       if (V->getType() == Tp)
228         return V;
229     }
230 
231     // If the requested type was not found, generate a constant value.
232     if (Tp->isIntegerTy()) {
233       if (getRandom() & 1)
234         return ConstantInt::getAllOnesValue(Tp);
235       return ConstantInt::getNullValue(Tp);
236     } else if (Tp->isFloatingPointTy()) {
237       if (getRandom() & 1)
238         return ConstantFP::getAllOnesValue(Tp);
239       return ConstantFP::getNullValue(Tp);
240     } else if (Tp->isVectorTy()) {
241       VectorType *VTp = cast<VectorType>(Tp);
242 
243       std::vector<Constant*> TempValues;
244       TempValues.reserve(VTp->getNumElements());
245       for (unsigned i = 0; i < VTp->getNumElements(); ++i)
246         TempValues.push_back(getRandomConstant(VTp->getScalarType()));
247 
248       ArrayRef<Constant*> VectorValue(TempValues);
249       return ConstantVector::get(VectorValue);
250     }
251 
252     return UndefValue::get(Tp);
253   }
254 
255   /// Return a random value of any pointer type.
256   Value *getRandomPointerValue() {
257     unsigned index = getRandom();
258     for (unsigned i=0; i<PT->size(); ++i) {
259       Value *V = PT->at((index + i) % PT->size());
260       if (V->getType()->isPointerTy())
261         return V;
262     }
263     return UndefValue::get(pickPointerType());
264   }
265 
266   /// Return a random value of any vector type.
267   Value *getRandomVectorValue() {
268     unsigned index = getRandom();
269     for (unsigned i=0; i<PT->size(); ++i) {
270       Value *V = PT->at((index + i) % PT->size());
271       if (V->getType()->isVectorTy())
272         return V;
273     }
274     return UndefValue::get(pickVectorType());
275   }
276 
277   /// Pick a random type.
278   Type *pickType() {
279     return (getRandom() & 1) ? pickVectorType() : pickScalarType();
280   }
281 
282   /// Pick a random pointer type.
283   Type *pickPointerType() {
284     Type *Ty = pickType();
285     return PointerType::get(Ty, 0);
286   }
287 
288   /// Pick a random vector type.
289   Type *pickVectorType(unsigned len = (unsigned)-1) {
290     // Pick a random vector width in the range 2**0 to 2**4.
291     // by adding two randoms we are generating a normal-like distribution
292     // around 2**3.
293     unsigned width = 1<<((getRandom() % 3) + (getRandom() % 3));
294     Type *Ty;
295 
296     // Vectors of x86mmx are illegal; keep trying till we get something else.
297     do {
298       Ty = pickScalarType();
299     } while (Ty->isX86_MMXTy());
300 
301     if (len != (unsigned)-1)
302       width = len;
303     return FixedVectorType::get(Ty, width);
304   }
305 
306   /// Pick a random scalar type.
307   Type *pickScalarType() {
308     static std::vector<Type*> ScalarTypes;
309     if (ScalarTypes.empty()) {
310       ScalarTypes.assign({
311         Type::getInt1Ty(Context),
312         Type::getInt8Ty(Context),
313         Type::getInt16Ty(Context),
314         Type::getInt32Ty(Context),
315         Type::getInt64Ty(Context),
316         Type::getFloatTy(Context),
317         Type::getDoubleTy(Context)
318       });
319       ScalarTypes.insert(ScalarTypes.end(),
320         AdditionalScalarTypes.begin(), AdditionalScalarTypes.end());
321     }
322 
323     return ScalarTypes[getRandom() % ScalarTypes.size()];
324   }
325 
326   /// Basic block to populate
327   BasicBlock *BB;
328 
329   /// Value table
330   PieceTable *PT;
331 
332   /// Random number generator
333   Random *Ran;
334 
335   /// Context
336   LLVMContext &Context;
337 };
338 
339 struct LoadModifier: public Modifier {
340   LoadModifier(BasicBlock *BB, PieceTable *PT, Random *R)
341       : Modifier(BB, PT, R) {}
342 
343   void Act() override {
344     // Try to use predefined pointers. If non-exist, use undef pointer value;
345     Value *Ptr = getRandomPointerValue();
346     PointerType *Tp = cast<PointerType>(Ptr->getType());
347     Value *V = new LoadInst(Tp->getElementType(), Ptr, "L",
348                             BB->getTerminator());
349     PT->push_back(V);
350   }
351 };
352 
353 struct StoreModifier: public Modifier {
354   StoreModifier(BasicBlock *BB, PieceTable *PT, Random *R)
355       : Modifier(BB, PT, R) {}
356 
357   void Act() override {
358     // Try to use predefined pointers. If non-exist, use undef pointer value;
359     Value *Ptr = getRandomPointerValue();
360     PointerType *Tp = cast<PointerType>(Ptr->getType());
361     Value *Val = getRandomValue(Tp->getElementType());
362     Type  *ValTy = Val->getType();
363 
364     // Do not store vectors of i1s because they are unsupported
365     // by the codegen.
366     if (ValTy->isVectorTy() && ValTy->getScalarSizeInBits() == 1)
367       return;
368 
369     new StoreInst(Val, Ptr, BB->getTerminator());
370   }
371 };
372 
373 struct BinModifier: public Modifier {
374   BinModifier(BasicBlock *BB, PieceTable *PT, Random *R)
375       : Modifier(BB, PT, R) {}
376 
377   void Act() override {
378     Value *Val0 = getRandomVal();
379     Value *Val1 = getRandomValue(Val0->getType());
380 
381     // Don't handle pointer types.
382     if (Val0->getType()->isPointerTy() ||
383         Val1->getType()->isPointerTy())
384       return;
385 
386     // Don't handle i1 types.
387     if (Val0->getType()->getScalarSizeInBits() == 1)
388       return;
389 
390     bool isFloat = Val0->getType()->getScalarType()->isFloatingPointTy();
391     Instruction* Term = BB->getTerminator();
392     unsigned R = getRandom() % (isFloat ? 7 : 13);
393     Instruction::BinaryOps Op;
394 
395     switch (R) {
396     default: llvm_unreachable("Invalid BinOp");
397     case 0:{Op = (isFloat?Instruction::FAdd : Instruction::Add); break; }
398     case 1:{Op = (isFloat?Instruction::FSub : Instruction::Sub); break; }
399     case 2:{Op = (isFloat?Instruction::FMul : Instruction::Mul); break; }
400     case 3:{Op = (isFloat?Instruction::FDiv : Instruction::SDiv); break; }
401     case 4:{Op = (isFloat?Instruction::FDiv : Instruction::UDiv); break; }
402     case 5:{Op = (isFloat?Instruction::FRem : Instruction::SRem); break; }
403     case 6:{Op = (isFloat?Instruction::FRem : Instruction::URem); break; }
404     case 7: {Op = Instruction::Shl;  break; }
405     case 8: {Op = Instruction::LShr; break; }
406     case 9: {Op = Instruction::AShr; break; }
407     case 10:{Op = Instruction::And;  break; }
408     case 11:{Op = Instruction::Or;   break; }
409     case 12:{Op = Instruction::Xor;  break; }
410     }
411 
412     PT->push_back(BinaryOperator::Create(Op, Val0, Val1, "B", Term));
413   }
414 };
415 
416 /// Generate constant values.
417 struct ConstModifier: public Modifier {
418   ConstModifier(BasicBlock *BB, PieceTable *PT, Random *R)
419       : Modifier(BB, PT, R) {}
420 
421   void Act() override {
422     Type *Ty = pickType();
423 
424     if (Ty->isVectorTy()) {
425       switch (getRandom() % 2) {
426       case 0: if (Ty->isIntOrIntVectorTy())
427                 return PT->push_back(ConstantVector::getAllOnesValue(Ty));
428               break;
429       case 1: if (Ty->isIntOrIntVectorTy())
430                 return PT->push_back(ConstantVector::getNullValue(Ty));
431       }
432     }
433 
434     if (Ty->isFloatingPointTy()) {
435       // Generate 128 random bits, the size of the (currently)
436       // largest floating-point types.
437       uint64_t RandomBits[2];
438       for (unsigned i = 0; i < 2; ++i)
439         RandomBits[i] = Ran->Rand64();
440 
441       APInt RandomInt(Ty->getPrimitiveSizeInBits(), makeArrayRef(RandomBits));
442       APFloat RandomFloat(Ty->getFltSemantics(), RandomInt);
443 
444       if (getRandom() & 1)
445         return PT->push_back(ConstantFP::getNullValue(Ty));
446       return PT->push_back(ConstantFP::get(Ty->getContext(), RandomFloat));
447     }
448 
449     if (Ty->isIntegerTy()) {
450       switch (getRandom() % 7) {
451       case 0:
452         return PT->push_back(ConstantInt::get(
453             Ty, APInt::getAllOnesValue(Ty->getPrimitiveSizeInBits())));
454       case 1:
455         return PT->push_back(ConstantInt::get(
456             Ty, APInt::getNullValue(Ty->getPrimitiveSizeInBits())));
457       case 2:
458       case 3:
459       case 4:
460       case 5:
461       case 6:
462         PT->push_back(ConstantInt::get(Ty, getRandom()));
463       }
464     }
465   }
466 };
467 
468 struct AllocaModifier: public Modifier {
469   AllocaModifier(BasicBlock *BB, PieceTable *PT, Random *R)
470       : Modifier(BB, PT, R) {}
471 
472   void Act() override {
473     Type *Tp = pickType();
474     const DataLayout &DL = BB->getModule()->getDataLayout();
475     PT->push_back(new AllocaInst(Tp, DL.getAllocaAddrSpace(),
476                                  "A", BB->getFirstNonPHI()));
477   }
478 };
479 
480 struct ExtractElementModifier: public Modifier {
481   ExtractElementModifier(BasicBlock *BB, PieceTable *PT, Random *R)
482       : Modifier(BB, PT, R) {}
483 
484   void Act() override {
485     Value *Val0 = getRandomVectorValue();
486     Value *V = ExtractElementInst::Create(Val0,
487              ConstantInt::get(Type::getInt32Ty(BB->getContext()),
488              getRandom() % cast<VectorType>(Val0->getType())->getNumElements()),
489              "E", BB->getTerminator());
490     return PT->push_back(V);
491   }
492 };
493 
494 struct ShuffModifier: public Modifier {
495   ShuffModifier(BasicBlock *BB, PieceTable *PT, Random *R)
496       : Modifier(BB, PT, R) {}
497 
498   void Act() override {
499     Value *Val0 = getRandomVectorValue();
500     Value *Val1 = getRandomValue(Val0->getType());
501 
502     unsigned Width = cast<VectorType>(Val0->getType())->getNumElements();
503     std::vector<Constant*> Idxs;
504 
505     Type *I32 = Type::getInt32Ty(BB->getContext());
506     for (unsigned i=0; i<Width; ++i) {
507       Constant *CI = ConstantInt::get(I32, getRandom() % (Width*2));
508       // Pick some undef values.
509       if (!(getRandom() % 5))
510         CI = UndefValue::get(I32);
511       Idxs.push_back(CI);
512     }
513 
514     Constant *Mask = ConstantVector::get(Idxs);
515 
516     Value *V = new ShuffleVectorInst(Val0, Val1, Mask, "Shuff",
517                                      BB->getTerminator());
518     PT->push_back(V);
519   }
520 };
521 
522 struct InsertElementModifier: public Modifier {
523   InsertElementModifier(BasicBlock *BB, PieceTable *PT, Random *R)
524       : Modifier(BB, PT, R) {}
525 
526   void Act() override {
527     Value *Val0 = getRandomVectorValue();
528     Value *Val1 = getRandomValue(Val0->getType()->getScalarType());
529 
530     Value *V = InsertElementInst::Create(Val0, Val1,
531               ConstantInt::get(Type::getInt32Ty(BB->getContext()),
532               getRandom() % cast<VectorType>(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       VectorType *VecTy = cast<VectorType>(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   std::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   // Init LLVM, call llvm_shutdown() on exit, parse args, etc.
737   PrettyStackTraceProgram X(argc, argv);
738   cl::ParseCommandLineOptions(argc, argv, "llvm codegen stress-tester\n");
739   llvm_shutdown_obj Y;
740 
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