1 //===-- Lint.cpp - Check for common errors in LLVM IR ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass statically checks for common and easily-identified constructs
11 // which produce undefined or likely unintended behavior in LLVM IR.
13 // It is not a guarantee of correctness, in two ways. First, it isn't
14 // comprehensive. There are checks which could be done statically which are
15 // not yet implemented. Some of these are indicated by TODO comments, but
16 // those aren't comprehensive either. Second, many conditions cannot be
17 // checked statically. This pass does no dynamic instrumentation, so it
18 // can't check for all possible problems.
20 // Another limitation is that it assumes all code will be executed. A store
21 // through a null pointer in a basic block which is never reached is harmless,
22 // but this pass will warn about it anyway. This is the main reason why most
23 // of these checks live here instead of in the Verifier pass.
25 // Optimization passes may make conditions that this pass checks for more or
26 // less obvious. If an optimization pass appears to be introducing a warning,
27 // it may be that the optimization pass is merely exposing an existing
28 // condition in the code.
30 // This code may be run before instcombine. In many cases, instcombine checks
31 // for the same kinds of things and turns instructions with undefined behavior
32 // into unreachable (or equivalent). Because of this, this pass makes some
33 // effort to look through bitcasts and so on.
35 //===----------------------------------------------------------------------===//
37 #include "llvm/Analysis/Passes.h"
38 #include "llvm/Analysis/AliasAnalysis.h"
39 #include "llvm/Analysis/InstructionSimplify.h"
40 #include "llvm/Analysis/ConstantFolding.h"
41 #include "llvm/Analysis/Dominators.h"
42 #include "llvm/Analysis/Lint.h"
43 #include "llvm/Analysis/Loads.h"
44 #include "llvm/Analysis/ValueTracking.h"
45 #include "llvm/Assembly/Writer.h"
46 #include "llvm/Target/TargetData.h"
47 #include "llvm/Pass.h"
48 #include "llvm/PassManager.h"
49 #include "llvm/IntrinsicInst.h"
50 #include "llvm/Function.h"
51 #include "llvm/Support/CallSite.h"
52 #include "llvm/Support/Debug.h"
53 #include "llvm/Support/InstVisitor.h"
54 #include "llvm/Support/raw_ostream.h"
55 #include "llvm/ADT/STLExtras.h"
60 static unsigned Read = 1;
61 static unsigned Write = 2;
62 static unsigned Callee = 4;
63 static unsigned Branchee = 8;
66 class Lint : public FunctionPass, public InstVisitor<Lint> {
67 friend class InstVisitor<Lint>;
69 void visitFunction(Function &F);
71 void visitCallSite(CallSite CS);
72 void visitMemoryReference(Instruction &I, Value *Ptr,
73 unsigned Size, unsigned Align,
74 const Type *Ty, unsigned Flags);
76 void visitCallInst(CallInst &I);
77 void visitInvokeInst(InvokeInst &I);
78 void visitReturnInst(ReturnInst &I);
79 void visitLoadInst(LoadInst &I);
80 void visitStoreInst(StoreInst &I);
81 void visitXor(BinaryOperator &I);
82 void visitSub(BinaryOperator &I);
83 void visitLShr(BinaryOperator &I);
84 void visitAShr(BinaryOperator &I);
85 void visitShl(BinaryOperator &I);
86 void visitSDiv(BinaryOperator &I);
87 void visitUDiv(BinaryOperator &I);
88 void visitSRem(BinaryOperator &I);
89 void visitURem(BinaryOperator &I);
90 void visitAllocaInst(AllocaInst &I);
91 void visitVAArgInst(VAArgInst &I);
92 void visitIndirectBrInst(IndirectBrInst &I);
93 void visitExtractElementInst(ExtractElementInst &I);
94 void visitInsertElementInst(InsertElementInst &I);
95 void visitUnreachableInst(UnreachableInst &I);
97 Value *findValue(Value *V, bool OffsetOk) const;
98 Value *findValueImpl(Value *V, bool OffsetOk,
99 SmallPtrSet<Value *, 4> &Visited) const;
107 std::string Messages;
108 raw_string_ostream MessagesStr;
110 static char ID; // Pass identification, replacement for typeid
111 Lint() : FunctionPass(ID), MessagesStr(Messages) {}
113 virtual bool runOnFunction(Function &F);
115 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
116 AU.setPreservesAll();
117 AU.addRequired<AliasAnalysis>();
118 AU.addRequired<DominatorTree>();
120 virtual void print(raw_ostream &O, const Module *M) const {}
122 void WriteValue(const Value *V) {
124 if (isa<Instruction>(V)) {
125 MessagesStr << *V << '\n';
127 WriteAsOperand(MessagesStr, V, true, Mod);
132 void WriteType(const Type *T) {
135 WriteTypeSymbolic(MessagesStr, T, Mod);
138 // CheckFailed - A check failed, so print out the condition and the message
139 // that failed. This provides a nice place to put a breakpoint if you want
140 // to see why something is not correct.
141 void CheckFailed(const Twine &Message,
142 const Value *V1 = 0, const Value *V2 = 0,
143 const Value *V3 = 0, const Value *V4 = 0) {
144 MessagesStr << Message.str() << "\n";
151 void CheckFailed(const Twine &Message, const Value *V1,
152 const Type *T2, const Value *V3 = 0) {
153 MessagesStr << Message.str() << "\n";
159 void CheckFailed(const Twine &Message, const Type *T1,
160 const Type *T2 = 0, const Type *T3 = 0) {
161 MessagesStr << Message.str() << "\n";
170 INITIALIZE_PASS(Lint, "lint", "Statically lint-checks LLVM IR", false, true);
172 // Assert - We know that cond should be true, if not print an error message.
173 #define Assert(C, M) \
174 do { if (!(C)) { CheckFailed(M); return; } } while (0)
175 #define Assert1(C, M, V1) \
176 do { if (!(C)) { CheckFailed(M, V1); return; } } while (0)
177 #define Assert2(C, M, V1, V2) \
178 do { if (!(C)) { CheckFailed(M, V1, V2); return; } } while (0)
179 #define Assert3(C, M, V1, V2, V3) \
180 do { if (!(C)) { CheckFailed(M, V1, V2, V3); return; } } while (0)
181 #define Assert4(C, M, V1, V2, V3, V4) \
182 do { if (!(C)) { CheckFailed(M, V1, V2, V3, V4); return; } } while (0)
184 // Lint::run - This is the main Analysis entry point for a
187 bool Lint::runOnFunction(Function &F) {
189 AA = &getAnalysis<AliasAnalysis>();
190 DT = &getAnalysis<DominatorTree>();
191 TD = getAnalysisIfAvailable<TargetData>();
193 dbgs() << MessagesStr.str();
198 void Lint::visitFunction(Function &F) {
199 // This isn't undefined behavior, it's just a little unusual, and it's a
200 // fairly common mistake to neglect to name a function.
201 Assert1(F.hasName() || F.hasLocalLinkage(),
202 "Unusual: Unnamed function with non-local linkage", &F);
204 // TODO: Check for irreducible control flow.
207 void Lint::visitCallSite(CallSite CS) {
208 Instruction &I = *CS.getInstruction();
209 Value *Callee = CS.getCalledValue();
211 visitMemoryReference(I, Callee, ~0u, 0, 0, MemRef::Callee);
213 if (Function *F = dyn_cast<Function>(findValue(Callee, /*OffsetOk=*/false))) {
214 Assert1(CS.getCallingConv() == F->getCallingConv(),
215 "Undefined behavior: Caller and callee calling convention differ",
218 const FunctionType *FT = F->getFunctionType();
219 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
221 Assert1(FT->isVarArg() ?
222 FT->getNumParams() <= NumActualArgs :
223 FT->getNumParams() == NumActualArgs,
224 "Undefined behavior: Call argument count mismatches callee "
225 "argument count", &I);
227 Assert1(FT->getReturnType() == I.getType(),
228 "Undefined behavior: Call return type mismatches "
229 "callee return type", &I);
231 // Check argument types (in case the callee was casted) and attributes.
232 // TODO: Verify that caller and callee attributes are compatible.
233 Function::arg_iterator PI = F->arg_begin(), PE = F->arg_end();
234 CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
235 for (; AI != AE; ++AI) {
238 Argument *Formal = PI++;
239 Assert1(Formal->getType() == Actual->getType(),
240 "Undefined behavior: Call argument type mismatches "
241 "callee parameter type", &I);
243 // Check that noalias arguments don't alias other arguments. The
244 // AliasAnalysis API isn't expressive enough for what we really want
245 // to do. Known partial overlap is not distinguished from the case
246 // where nothing is known.
247 if (Formal->hasNoAliasAttr() && Actual->getType()->isPointerTy())
248 for (CallSite::arg_iterator BI = CS.arg_begin(); BI != AE; ++BI) {
249 Assert1(AI == BI || AA->alias(*AI, *BI) != AliasAnalysis::MustAlias,
250 "Unusual: noalias argument aliases another argument", &I);
253 // Check that an sret argument points to valid memory.
254 if (Formal->hasStructRetAttr() && Actual->getType()->isPointerTy()) {
256 cast<PointerType>(Formal->getType())->getElementType();
257 visitMemoryReference(I, Actual, AA->getTypeStoreSize(Ty),
258 TD ? TD->getABITypeAlignment(Ty) : 0,
259 Ty, MemRef::Read | MemRef::Write);
265 if (CS.isCall() && cast<CallInst>(CS.getInstruction())->isTailCall())
266 for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
268 Value *Obj = findValue(*AI, /*OffsetOk=*/true);
269 Assert1(!isa<AllocaInst>(Obj),
270 "Undefined behavior: Call with \"tail\" keyword references "
275 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I))
276 switch (II->getIntrinsicID()) {
279 // TODO: Check more intrinsics
281 case Intrinsic::memcpy: {
282 MemCpyInst *MCI = cast<MemCpyInst>(&I);
283 // TODO: If the size is known, use it.
284 visitMemoryReference(I, MCI->getDest(), ~0u, MCI->getAlignment(), 0,
286 visitMemoryReference(I, MCI->getSource(), ~0u, MCI->getAlignment(), 0,
289 // Check that the memcpy arguments don't overlap. The AliasAnalysis API
290 // isn't expressive enough for what we really want to do. Known partial
291 // overlap is not distinguished from the case where nothing is known.
293 if (const ConstantInt *Len =
294 dyn_cast<ConstantInt>(findValue(MCI->getLength(),
295 /*OffsetOk=*/false)))
296 if (Len->getValue().isIntN(32))
297 Size = Len->getValue().getZExtValue();
298 Assert1(AA->alias(MCI->getSource(), Size, MCI->getDest(), Size) !=
299 AliasAnalysis::MustAlias,
300 "Undefined behavior: memcpy source and destination overlap", &I);
303 case Intrinsic::memmove: {
304 MemMoveInst *MMI = cast<MemMoveInst>(&I);
305 // TODO: If the size is known, use it.
306 visitMemoryReference(I, MMI->getDest(), ~0u, MMI->getAlignment(), 0,
308 visitMemoryReference(I, MMI->getSource(), ~0u, MMI->getAlignment(), 0,
312 case Intrinsic::memset: {
313 MemSetInst *MSI = cast<MemSetInst>(&I);
314 // TODO: If the size is known, use it.
315 visitMemoryReference(I, MSI->getDest(), ~0u, MSI->getAlignment(), 0,
320 case Intrinsic::vastart:
321 Assert1(I.getParent()->getParent()->isVarArg(),
322 "Undefined behavior: va_start called in a non-varargs function",
325 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
326 MemRef::Read | MemRef::Write);
328 case Intrinsic::vacopy:
329 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0, MemRef::Write);
330 visitMemoryReference(I, CS.getArgument(1), ~0u, 0, 0, MemRef::Read);
332 case Intrinsic::vaend:
333 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
334 MemRef::Read | MemRef::Write);
337 case Intrinsic::stackrestore:
338 // Stackrestore doesn't read or write memory, but it sets the
339 // stack pointer, which the compiler may read from or write to
340 // at any time, so check it for both readability and writeability.
341 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
342 MemRef::Read | MemRef::Write);
347 void Lint::visitCallInst(CallInst &I) {
348 return visitCallSite(&I);
351 void Lint::visitInvokeInst(InvokeInst &I) {
352 return visitCallSite(&I);
355 void Lint::visitReturnInst(ReturnInst &I) {
356 Function *F = I.getParent()->getParent();
357 Assert1(!F->doesNotReturn(),
358 "Unusual: Return statement in function with noreturn attribute",
361 if (Value *V = I.getReturnValue()) {
362 Value *Obj = findValue(V, /*OffsetOk=*/true);
363 Assert1(!isa<AllocaInst>(Obj),
364 "Unusual: Returning alloca value", &I);
368 // TODO: Check that the reference is in bounds.
369 // TODO: Check readnone/readonly function attributes.
370 void Lint::visitMemoryReference(Instruction &I,
371 Value *Ptr, unsigned Size, unsigned Align,
372 const Type *Ty, unsigned Flags) {
373 // If no memory is being referenced, it doesn't matter if the pointer
378 Value *UnderlyingObject = findValue(Ptr, /*OffsetOk=*/true);
379 Assert1(!isa<ConstantPointerNull>(UnderlyingObject),
380 "Undefined behavior: Null pointer dereference", &I);
381 Assert1(!isa<UndefValue>(UnderlyingObject),
382 "Undefined behavior: Undef pointer dereference", &I);
383 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
384 !cast<ConstantInt>(UnderlyingObject)->isAllOnesValue(),
385 "Unusual: All-ones pointer dereference", &I);
386 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
387 !cast<ConstantInt>(UnderlyingObject)->isOne(),
388 "Unusual: Address one pointer dereference", &I);
390 if (Flags & MemRef::Write) {
391 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(UnderlyingObject))
392 Assert1(!GV->isConstant(),
393 "Undefined behavior: Write to read-only memory", &I);
394 Assert1(!isa<Function>(UnderlyingObject) &&
395 !isa<BlockAddress>(UnderlyingObject),
396 "Undefined behavior: Write to text section", &I);
398 if (Flags & MemRef::Read) {
399 Assert1(!isa<Function>(UnderlyingObject),
400 "Unusual: Load from function body", &I);
401 Assert1(!isa<BlockAddress>(UnderlyingObject),
402 "Undefined behavior: Load from block address", &I);
404 if (Flags & MemRef::Callee) {
405 Assert1(!isa<BlockAddress>(UnderlyingObject),
406 "Undefined behavior: Call to block address", &I);
408 if (Flags & MemRef::Branchee) {
409 Assert1(!isa<Constant>(UnderlyingObject) ||
410 isa<BlockAddress>(UnderlyingObject),
411 "Undefined behavior: Branch to non-blockaddress", &I);
415 if (Align == 0 && Ty) Align = TD->getABITypeAlignment(Ty);
418 unsigned BitWidth = TD->getTypeSizeInBits(Ptr->getType());
419 APInt Mask = APInt::getAllOnesValue(BitWidth),
420 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
421 ComputeMaskedBits(Ptr, Mask, KnownZero, KnownOne, TD);
422 Assert1(!(KnownOne & APInt::getLowBitsSet(BitWidth, Log2_32(Align))),
423 "Undefined behavior: Memory reference address is misaligned", &I);
428 void Lint::visitLoadInst(LoadInst &I) {
429 visitMemoryReference(I, I.getPointerOperand(),
430 AA->getTypeStoreSize(I.getType()), I.getAlignment(),
431 I.getType(), MemRef::Read);
434 void Lint::visitStoreInst(StoreInst &I) {
435 visitMemoryReference(I, I.getPointerOperand(),
436 AA->getTypeStoreSize(I.getOperand(0)->getType()),
438 I.getOperand(0)->getType(), MemRef::Write);
441 void Lint::visitXor(BinaryOperator &I) {
442 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
443 !isa<UndefValue>(I.getOperand(1)),
444 "Undefined result: xor(undef, undef)", &I);
447 void Lint::visitSub(BinaryOperator &I) {
448 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
449 !isa<UndefValue>(I.getOperand(1)),
450 "Undefined result: sub(undef, undef)", &I);
453 void Lint::visitLShr(BinaryOperator &I) {
454 if (ConstantInt *CI =
455 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
456 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
457 "Undefined result: Shift count out of range", &I);
460 void Lint::visitAShr(BinaryOperator &I) {
461 if (ConstantInt *CI =
462 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
463 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
464 "Undefined result: Shift count out of range", &I);
467 void Lint::visitShl(BinaryOperator &I) {
468 if (ConstantInt *CI =
469 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
470 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
471 "Undefined result: Shift count out of range", &I);
474 static bool isZero(Value *V, TargetData *TD) {
475 // Assume undef could be zero.
476 if (isa<UndefValue>(V)) return true;
478 unsigned BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
479 APInt Mask = APInt::getAllOnesValue(BitWidth),
480 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
481 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD);
482 return KnownZero.isAllOnesValue();
485 void Lint::visitSDiv(BinaryOperator &I) {
486 Assert1(!isZero(I.getOperand(1), TD),
487 "Undefined behavior: Division by zero", &I);
490 void Lint::visitUDiv(BinaryOperator &I) {
491 Assert1(!isZero(I.getOperand(1), TD),
492 "Undefined behavior: Division by zero", &I);
495 void Lint::visitSRem(BinaryOperator &I) {
496 Assert1(!isZero(I.getOperand(1), TD),
497 "Undefined behavior: Division by zero", &I);
500 void Lint::visitURem(BinaryOperator &I) {
501 Assert1(!isZero(I.getOperand(1), TD),
502 "Undefined behavior: Division by zero", &I);
505 void Lint::visitAllocaInst(AllocaInst &I) {
506 if (isa<ConstantInt>(I.getArraySize()))
507 // This isn't undefined behavior, it's just an obvious pessimization.
508 Assert1(&I.getParent()->getParent()->getEntryBlock() == I.getParent(),
509 "Pessimization: Static alloca outside of entry block", &I);
511 // TODO: Check for an unusual size (MSB set?)
514 void Lint::visitVAArgInst(VAArgInst &I) {
515 visitMemoryReference(I, I.getOperand(0), ~0u, 0, 0,
516 MemRef::Read | MemRef::Write);
519 void Lint::visitIndirectBrInst(IndirectBrInst &I) {
520 visitMemoryReference(I, I.getAddress(), ~0u, 0, 0, MemRef::Branchee);
522 Assert1(I.getNumDestinations() != 0,
523 "Undefined behavior: indirectbr with no destinations", &I);
526 void Lint::visitExtractElementInst(ExtractElementInst &I) {
527 if (ConstantInt *CI =
528 dyn_cast<ConstantInt>(findValue(I.getIndexOperand(),
529 /*OffsetOk=*/false)))
530 Assert1(CI->getValue().ult(I.getVectorOperandType()->getNumElements()),
531 "Undefined result: extractelement index out of range", &I);
534 void Lint::visitInsertElementInst(InsertElementInst &I) {
535 if (ConstantInt *CI =
536 dyn_cast<ConstantInt>(findValue(I.getOperand(2),
537 /*OffsetOk=*/false)))
538 Assert1(CI->getValue().ult(I.getType()->getNumElements()),
539 "Undefined result: insertelement index out of range", &I);
542 void Lint::visitUnreachableInst(UnreachableInst &I) {
543 // This isn't undefined behavior, it's merely suspicious.
544 Assert1(&I == I.getParent()->begin() ||
545 prior(BasicBlock::iterator(&I))->mayHaveSideEffects(),
546 "Unusual: unreachable immediately preceded by instruction without "
550 /// findValue - Look through bitcasts and simple memory reference patterns
551 /// to identify an equivalent, but more informative, value. If OffsetOk
552 /// is true, look through getelementptrs with non-zero offsets too.
554 /// Most analysis passes don't require this logic, because instcombine
555 /// will simplify most of these kinds of things away. But it's a goal of
556 /// this Lint pass to be useful even on non-optimized IR.
557 Value *Lint::findValue(Value *V, bool OffsetOk) const {
558 SmallPtrSet<Value *, 4> Visited;
559 return findValueImpl(V, OffsetOk, Visited);
562 /// findValueImpl - Implementation helper for findValue.
563 Value *Lint::findValueImpl(Value *V, bool OffsetOk,
564 SmallPtrSet<Value *, 4> &Visited) const {
565 // Detect self-referential values.
566 if (!Visited.insert(V))
567 return UndefValue::get(V->getType());
569 // TODO: Look through sext or zext cast, when the result is known to
570 // be interpreted as signed or unsigned, respectively.
571 // TODO: Look through eliminable cast pairs.
572 // TODO: Look through calls with unique return values.
573 // TODO: Look through vector insert/extract/shuffle.
574 V = OffsetOk ? V->getUnderlyingObject() : V->stripPointerCasts();
575 if (LoadInst *L = dyn_cast<LoadInst>(V)) {
576 BasicBlock::iterator BBI = L;
577 BasicBlock *BB = L->getParent();
578 SmallPtrSet<BasicBlock *, 4> VisitedBlocks;
580 if (!VisitedBlocks.insert(BB)) break;
581 if (Value *U = FindAvailableLoadedValue(L->getPointerOperand(),
583 return findValueImpl(U, OffsetOk, Visited);
584 if (BBI != BB->begin()) break;
585 BB = BB->getUniquePredecessor();
589 } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
590 if (Value *W = PN->hasConstantValue(DT))
591 return findValueImpl(W, OffsetOk, Visited);
592 } else if (CastInst *CI = dyn_cast<CastInst>(V)) {
593 if (CI->isNoopCast(TD ? TD->getIntPtrType(V->getContext()) :
594 Type::getInt64Ty(V->getContext())))
595 return findValueImpl(CI->getOperand(0), OffsetOk, Visited);
596 } else if (ExtractValueInst *Ex = dyn_cast<ExtractValueInst>(V)) {
597 if (Value *W = FindInsertedValue(Ex->getAggregateOperand(),
601 return findValueImpl(W, OffsetOk, Visited);
602 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
603 // Same as above, but for ConstantExpr instead of Instruction.
604 if (Instruction::isCast(CE->getOpcode())) {
605 if (CastInst::isNoopCast(Instruction::CastOps(CE->getOpcode()),
606 CE->getOperand(0)->getType(),
608 TD ? TD->getIntPtrType(V->getContext()) :
609 Type::getInt64Ty(V->getContext())))
610 return findValueImpl(CE->getOperand(0), OffsetOk, Visited);
611 } else if (CE->getOpcode() == Instruction::ExtractValue) {
612 const SmallVector<unsigned, 4> &Indices = CE->getIndices();
613 if (Value *W = FindInsertedValue(CE->getOperand(0),
617 return findValueImpl(W, OffsetOk, Visited);
621 // As a last resort, try SimplifyInstruction or constant folding.
622 if (Instruction *Inst = dyn_cast<Instruction>(V)) {
623 if (Value *W = SimplifyInstruction(Inst, TD))
625 return findValueImpl(W, OffsetOk, Visited);
626 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
627 if (Value *W = ConstantFoldConstantExpression(CE, TD))
629 return findValueImpl(W, OffsetOk, Visited);
635 //===----------------------------------------------------------------------===//
636 // Implement the public interfaces to this file...
637 //===----------------------------------------------------------------------===//
639 FunctionPass *llvm::createLintPass() {
643 /// lintFunction - Check a function for errors, printing messages on stderr.
645 void llvm::lintFunction(const Function &f) {
646 Function &F = const_cast<Function&>(f);
647 assert(!F.isDeclaration() && "Cannot lint external functions");
649 FunctionPassManager FPM(F.getParent());
650 Lint *V = new Lint();
655 /// lintModule - Check a module for errors, printing messages on stderr.
657 void llvm::lintModule(const Module &M) {
659 Lint *V = new Lint();
661 PM.run(const_cast<Module&>(M));