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 // CheckFailed - A check failed, so print out the condition and the message
133 // that failed. This provides a nice place to put a breakpoint if you want
134 // to see why something is not correct.
135 void CheckFailed(const Twine &Message,
136 const Value *V1 = 0, const Value *V2 = 0,
137 const Value *V3 = 0, const Value *V4 = 0) {
138 MessagesStr << Message.str() << "\n";
148 INITIALIZE_PASS_BEGIN(Lint, "lint", "Statically lint-checks LLVM IR",
150 INITIALIZE_PASS_DEPENDENCY(DominatorTree)
151 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
152 INITIALIZE_PASS_END(Lint, "lint", "Statically lint-checks LLVM IR",
155 // Assert - We know that cond should be true, if not print an error message.
156 #define Assert(C, M) \
157 do { if (!(C)) { CheckFailed(M); return; } } while (0)
158 #define Assert1(C, M, V1) \
159 do { if (!(C)) { CheckFailed(M, V1); return; } } while (0)
160 #define Assert2(C, M, V1, V2) \
161 do { if (!(C)) { CheckFailed(M, V1, V2); return; } } while (0)
162 #define Assert3(C, M, V1, V2, V3) \
163 do { if (!(C)) { CheckFailed(M, V1, V2, V3); return; } } while (0)
164 #define Assert4(C, M, V1, V2, V3, V4) \
165 do { if (!(C)) { CheckFailed(M, V1, V2, V3, V4); return; } } while (0)
167 // Lint::run - This is the main Analysis entry point for a
170 bool Lint::runOnFunction(Function &F) {
172 AA = &getAnalysis<AliasAnalysis>();
173 DT = &getAnalysis<DominatorTree>();
174 TD = getAnalysisIfAvailable<TargetData>();
176 dbgs() << MessagesStr.str();
181 void Lint::visitFunction(Function &F) {
182 // This isn't undefined behavior, it's just a little unusual, and it's a
183 // fairly common mistake to neglect to name a function.
184 Assert1(F.hasName() || F.hasLocalLinkage(),
185 "Unusual: Unnamed function with non-local linkage", &F);
187 // TODO: Check for irreducible control flow.
190 void Lint::visitCallSite(CallSite CS) {
191 Instruction &I = *CS.getInstruction();
192 Value *Callee = CS.getCalledValue();
194 visitMemoryReference(I, Callee, ~0u, 0, 0, MemRef::Callee);
196 if (Function *F = dyn_cast<Function>(findValue(Callee, /*OffsetOk=*/false))) {
197 Assert1(CS.getCallingConv() == F->getCallingConv(),
198 "Undefined behavior: Caller and callee calling convention differ",
201 const FunctionType *FT = F->getFunctionType();
202 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
204 Assert1(FT->isVarArg() ?
205 FT->getNumParams() <= NumActualArgs :
206 FT->getNumParams() == NumActualArgs,
207 "Undefined behavior: Call argument count mismatches callee "
208 "argument count", &I);
210 Assert1(FT->getReturnType() == I.getType(),
211 "Undefined behavior: Call return type mismatches "
212 "callee return type", &I);
214 // Check argument types (in case the callee was casted) and attributes.
215 // TODO: Verify that caller and callee attributes are compatible.
216 Function::arg_iterator PI = F->arg_begin(), PE = F->arg_end();
217 CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
218 for (; AI != AE; ++AI) {
221 Argument *Formal = PI++;
222 Assert1(Formal->getType() == Actual->getType(),
223 "Undefined behavior: Call argument type mismatches "
224 "callee parameter type", &I);
226 // Check that noalias arguments don't alias other arguments. The
227 // AliasAnalysis API isn't expressive enough for what we really want
228 // to do. Known partial overlap is not distinguished from the case
229 // where nothing is known.
230 if (Formal->hasNoAliasAttr() && Actual->getType()->isPointerTy())
231 for (CallSite::arg_iterator BI = CS.arg_begin(); BI != AE; ++BI) {
232 Assert1(AI == BI || AA->alias(*AI, *BI) != AliasAnalysis::MustAlias,
233 "Unusual: noalias argument aliases another argument", &I);
236 // Check that an sret argument points to valid memory.
237 if (Formal->hasStructRetAttr() && Actual->getType()->isPointerTy()) {
239 cast<PointerType>(Formal->getType())->getElementType();
240 visitMemoryReference(I, Actual, AA->getTypeStoreSize(Ty),
241 TD ? TD->getABITypeAlignment(Ty) : 0,
242 Ty, MemRef::Read | MemRef::Write);
248 if (CS.isCall() && cast<CallInst>(CS.getInstruction())->isTailCall())
249 for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
251 Value *Obj = findValue(*AI, /*OffsetOk=*/true);
252 Assert1(!isa<AllocaInst>(Obj),
253 "Undefined behavior: Call with \"tail\" keyword references "
258 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I))
259 switch (II->getIntrinsicID()) {
262 // TODO: Check more intrinsics
264 case Intrinsic::memcpy: {
265 MemCpyInst *MCI = cast<MemCpyInst>(&I);
266 // TODO: If the size is known, use it.
267 visitMemoryReference(I, MCI->getDest(), ~0u, MCI->getAlignment(), 0,
269 visitMemoryReference(I, MCI->getSource(), ~0u, MCI->getAlignment(), 0,
272 // Check that the memcpy arguments don't overlap. The AliasAnalysis API
273 // isn't expressive enough for what we really want to do. Known partial
274 // overlap is not distinguished from the case where nothing is known.
276 if (const ConstantInt *Len =
277 dyn_cast<ConstantInt>(findValue(MCI->getLength(),
278 /*OffsetOk=*/false)))
279 if (Len->getValue().isIntN(32))
280 Size = Len->getValue().getZExtValue();
281 Assert1(AA->alias(MCI->getSource(), Size, MCI->getDest(), Size) !=
282 AliasAnalysis::MustAlias,
283 "Undefined behavior: memcpy source and destination overlap", &I);
286 case Intrinsic::memmove: {
287 MemMoveInst *MMI = cast<MemMoveInst>(&I);
288 // TODO: If the size is known, use it.
289 visitMemoryReference(I, MMI->getDest(), ~0u, MMI->getAlignment(), 0,
291 visitMemoryReference(I, MMI->getSource(), ~0u, MMI->getAlignment(), 0,
295 case Intrinsic::memset: {
296 MemSetInst *MSI = cast<MemSetInst>(&I);
297 // TODO: If the size is known, use it.
298 visitMemoryReference(I, MSI->getDest(), ~0u, MSI->getAlignment(), 0,
303 case Intrinsic::vastart:
304 Assert1(I.getParent()->getParent()->isVarArg(),
305 "Undefined behavior: va_start called in a non-varargs function",
308 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
309 MemRef::Read | MemRef::Write);
311 case Intrinsic::vacopy:
312 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0, MemRef::Write);
313 visitMemoryReference(I, CS.getArgument(1), ~0u, 0, 0, MemRef::Read);
315 case Intrinsic::vaend:
316 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
317 MemRef::Read | MemRef::Write);
320 case Intrinsic::stackrestore:
321 // Stackrestore doesn't read or write memory, but it sets the
322 // stack pointer, which the compiler may read from or write to
323 // at any time, so check it for both readability and writeability.
324 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
325 MemRef::Read | MemRef::Write);
330 void Lint::visitCallInst(CallInst &I) {
331 return visitCallSite(&I);
334 void Lint::visitInvokeInst(InvokeInst &I) {
335 return visitCallSite(&I);
338 void Lint::visitReturnInst(ReturnInst &I) {
339 Function *F = I.getParent()->getParent();
340 Assert1(!F->doesNotReturn(),
341 "Unusual: Return statement in function with noreturn attribute",
344 if (Value *V = I.getReturnValue()) {
345 Value *Obj = findValue(V, /*OffsetOk=*/true);
346 Assert1(!isa<AllocaInst>(Obj),
347 "Unusual: Returning alloca value", &I);
351 // TODO: Check that the reference is in bounds.
352 // TODO: Check readnone/readonly function attributes.
353 void Lint::visitMemoryReference(Instruction &I,
354 Value *Ptr, unsigned Size, unsigned Align,
355 const Type *Ty, unsigned Flags) {
356 // If no memory is being referenced, it doesn't matter if the pointer
361 Value *UnderlyingObject = findValue(Ptr, /*OffsetOk=*/true);
362 Assert1(!isa<ConstantPointerNull>(UnderlyingObject),
363 "Undefined behavior: Null pointer dereference", &I);
364 Assert1(!isa<UndefValue>(UnderlyingObject),
365 "Undefined behavior: Undef pointer dereference", &I);
366 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
367 !cast<ConstantInt>(UnderlyingObject)->isAllOnesValue(),
368 "Unusual: All-ones pointer dereference", &I);
369 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
370 !cast<ConstantInt>(UnderlyingObject)->isOne(),
371 "Unusual: Address one pointer dereference", &I);
373 if (Flags & MemRef::Write) {
374 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(UnderlyingObject))
375 Assert1(!GV->isConstant(),
376 "Undefined behavior: Write to read-only memory", &I);
377 Assert1(!isa<Function>(UnderlyingObject) &&
378 !isa<BlockAddress>(UnderlyingObject),
379 "Undefined behavior: Write to text section", &I);
381 if (Flags & MemRef::Read) {
382 Assert1(!isa<Function>(UnderlyingObject),
383 "Unusual: Load from function body", &I);
384 Assert1(!isa<BlockAddress>(UnderlyingObject),
385 "Undefined behavior: Load from block address", &I);
387 if (Flags & MemRef::Callee) {
388 Assert1(!isa<BlockAddress>(UnderlyingObject),
389 "Undefined behavior: Call to block address", &I);
391 if (Flags & MemRef::Branchee) {
392 Assert1(!isa<Constant>(UnderlyingObject) ||
393 isa<BlockAddress>(UnderlyingObject),
394 "Undefined behavior: Branch to non-blockaddress", &I);
398 if (Align == 0 && Ty) Align = TD->getABITypeAlignment(Ty);
401 unsigned BitWidth = TD->getTypeSizeInBits(Ptr->getType());
402 APInt Mask = APInt::getAllOnesValue(BitWidth),
403 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
404 ComputeMaskedBits(Ptr, Mask, KnownZero, KnownOne, TD);
405 Assert1(!(KnownOne & APInt::getLowBitsSet(BitWidth, Log2_32(Align))),
406 "Undefined behavior: Memory reference address is misaligned", &I);
411 void Lint::visitLoadInst(LoadInst &I) {
412 visitMemoryReference(I, I.getPointerOperand(),
413 AA->getTypeStoreSize(I.getType()), I.getAlignment(),
414 I.getType(), MemRef::Read);
417 void Lint::visitStoreInst(StoreInst &I) {
418 visitMemoryReference(I, I.getPointerOperand(),
419 AA->getTypeStoreSize(I.getOperand(0)->getType()),
421 I.getOperand(0)->getType(), MemRef::Write);
424 void Lint::visitXor(BinaryOperator &I) {
425 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
426 !isa<UndefValue>(I.getOperand(1)),
427 "Undefined result: xor(undef, undef)", &I);
430 void Lint::visitSub(BinaryOperator &I) {
431 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
432 !isa<UndefValue>(I.getOperand(1)),
433 "Undefined result: sub(undef, undef)", &I);
436 void Lint::visitLShr(BinaryOperator &I) {
437 if (ConstantInt *CI =
438 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
439 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
440 "Undefined result: Shift count out of range", &I);
443 void Lint::visitAShr(BinaryOperator &I) {
444 if (ConstantInt *CI =
445 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
446 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
447 "Undefined result: Shift count out of range", &I);
450 void Lint::visitShl(BinaryOperator &I) {
451 if (ConstantInt *CI =
452 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
453 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
454 "Undefined result: Shift count out of range", &I);
457 static bool isZero(Value *V, TargetData *TD) {
458 // Assume undef could be zero.
459 if (isa<UndefValue>(V)) return true;
461 unsigned BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
462 APInt Mask = APInt::getAllOnesValue(BitWidth),
463 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
464 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD);
465 return KnownZero.isAllOnesValue();
468 void Lint::visitSDiv(BinaryOperator &I) {
469 Assert1(!isZero(I.getOperand(1), TD),
470 "Undefined behavior: Division by zero", &I);
473 void Lint::visitUDiv(BinaryOperator &I) {
474 Assert1(!isZero(I.getOperand(1), TD),
475 "Undefined behavior: Division by zero", &I);
478 void Lint::visitSRem(BinaryOperator &I) {
479 Assert1(!isZero(I.getOperand(1), TD),
480 "Undefined behavior: Division by zero", &I);
483 void Lint::visitURem(BinaryOperator &I) {
484 Assert1(!isZero(I.getOperand(1), TD),
485 "Undefined behavior: Division by zero", &I);
488 void Lint::visitAllocaInst(AllocaInst &I) {
489 if (isa<ConstantInt>(I.getArraySize()))
490 // This isn't undefined behavior, it's just an obvious pessimization.
491 Assert1(&I.getParent()->getParent()->getEntryBlock() == I.getParent(),
492 "Pessimization: Static alloca outside of entry block", &I);
494 // TODO: Check for an unusual size (MSB set?)
497 void Lint::visitVAArgInst(VAArgInst &I) {
498 visitMemoryReference(I, I.getOperand(0), ~0u, 0, 0,
499 MemRef::Read | MemRef::Write);
502 void Lint::visitIndirectBrInst(IndirectBrInst &I) {
503 visitMemoryReference(I, I.getAddress(), ~0u, 0, 0, MemRef::Branchee);
505 Assert1(I.getNumDestinations() != 0,
506 "Undefined behavior: indirectbr with no destinations", &I);
509 void Lint::visitExtractElementInst(ExtractElementInst &I) {
510 if (ConstantInt *CI =
511 dyn_cast<ConstantInt>(findValue(I.getIndexOperand(),
512 /*OffsetOk=*/false)))
513 Assert1(CI->getValue().ult(I.getVectorOperandType()->getNumElements()),
514 "Undefined result: extractelement index out of range", &I);
517 void Lint::visitInsertElementInst(InsertElementInst &I) {
518 if (ConstantInt *CI =
519 dyn_cast<ConstantInt>(findValue(I.getOperand(2),
520 /*OffsetOk=*/false)))
521 Assert1(CI->getValue().ult(I.getType()->getNumElements()),
522 "Undefined result: insertelement index out of range", &I);
525 void Lint::visitUnreachableInst(UnreachableInst &I) {
526 // This isn't undefined behavior, it's merely suspicious.
527 Assert1(&I == I.getParent()->begin() ||
528 prior(BasicBlock::iterator(&I))->mayHaveSideEffects(),
529 "Unusual: unreachable immediately preceded by instruction without "
533 /// findValue - Look through bitcasts and simple memory reference patterns
534 /// to identify an equivalent, but more informative, value. If OffsetOk
535 /// is true, look through getelementptrs with non-zero offsets too.
537 /// Most analysis passes don't require this logic, because instcombine
538 /// will simplify most of these kinds of things away. But it's a goal of
539 /// this Lint pass to be useful even on non-optimized IR.
540 Value *Lint::findValue(Value *V, bool OffsetOk) const {
541 SmallPtrSet<Value *, 4> Visited;
542 return findValueImpl(V, OffsetOk, Visited);
545 /// findValueImpl - Implementation helper for findValue.
546 Value *Lint::findValueImpl(Value *V, bool OffsetOk,
547 SmallPtrSet<Value *, 4> &Visited) const {
548 // Detect self-referential values.
549 if (!Visited.insert(V))
550 return UndefValue::get(V->getType());
552 // TODO: Look through sext or zext cast, when the result is known to
553 // be interpreted as signed or unsigned, respectively.
554 // TODO: Look through eliminable cast pairs.
555 // TODO: Look through calls with unique return values.
556 // TODO: Look through vector insert/extract/shuffle.
557 V = OffsetOk ? V->getUnderlyingObject() : V->stripPointerCasts();
558 if (LoadInst *L = dyn_cast<LoadInst>(V)) {
559 BasicBlock::iterator BBI = L;
560 BasicBlock *BB = L->getParent();
561 SmallPtrSet<BasicBlock *, 4> VisitedBlocks;
563 if (!VisitedBlocks.insert(BB)) break;
564 if (Value *U = FindAvailableLoadedValue(L->getPointerOperand(),
566 return findValueImpl(U, OffsetOk, Visited);
567 if (BBI != BB->begin()) break;
568 BB = BB->getUniquePredecessor();
572 } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
573 if (Value *W = PN->hasConstantValue(DT))
574 return findValueImpl(W, OffsetOk, Visited);
575 } else if (CastInst *CI = dyn_cast<CastInst>(V)) {
576 if (CI->isNoopCast(TD ? TD->getIntPtrType(V->getContext()) :
577 Type::getInt64Ty(V->getContext())))
578 return findValueImpl(CI->getOperand(0), OffsetOk, Visited);
579 } else if (ExtractValueInst *Ex = dyn_cast<ExtractValueInst>(V)) {
580 if (Value *W = FindInsertedValue(Ex->getAggregateOperand(),
584 return findValueImpl(W, OffsetOk, Visited);
585 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
586 // Same as above, but for ConstantExpr instead of Instruction.
587 if (Instruction::isCast(CE->getOpcode())) {
588 if (CastInst::isNoopCast(Instruction::CastOps(CE->getOpcode()),
589 CE->getOperand(0)->getType(),
591 TD ? TD->getIntPtrType(V->getContext()) :
592 Type::getInt64Ty(V->getContext())))
593 return findValueImpl(CE->getOperand(0), OffsetOk, Visited);
594 } else if (CE->getOpcode() == Instruction::ExtractValue) {
595 const SmallVector<unsigned, 4> &Indices = CE->getIndices();
596 if (Value *W = FindInsertedValue(CE->getOperand(0),
600 return findValueImpl(W, OffsetOk, Visited);
604 // As a last resort, try SimplifyInstruction or constant folding.
605 if (Instruction *Inst = dyn_cast<Instruction>(V)) {
606 if (Value *W = SimplifyInstruction(Inst, TD))
608 return findValueImpl(W, OffsetOk, Visited);
609 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
610 if (Value *W = ConstantFoldConstantExpression(CE, TD))
612 return findValueImpl(W, OffsetOk, Visited);
618 //===----------------------------------------------------------------------===//
619 // Implement the public interfaces to this file...
620 //===----------------------------------------------------------------------===//
622 FunctionPass *llvm::createLintPass() {
626 /// lintFunction - Check a function for errors, printing messages on stderr.
628 void llvm::lintFunction(const Function &f) {
629 Function &F = const_cast<Function&>(f);
630 assert(!F.isDeclaration() && "Cannot lint external functions");
632 FunctionPassManager FPM(F.getParent());
633 Lint *V = new Lint();
638 /// lintModule - Check a module for errors, printing messages on stderr.
640 void llvm::lintModule(const Module &M) {
642 Lint *V = new Lint();
644 PM.run(const_cast<Module&>(M));