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 uint64_t 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) {
112 initializeLintPass(*PassRegistry::getPassRegistry());
115 virtual bool runOnFunction(Function &F);
117 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
118 AU.setPreservesAll();
119 AU.addRequired<AliasAnalysis>();
120 AU.addRequired<DominatorTree>();
122 virtual void print(raw_ostream &O, const Module *M) const {}
124 void WriteValue(const Value *V) {
126 if (isa<Instruction>(V)) {
127 MessagesStr << *V << '\n';
129 WriteAsOperand(MessagesStr, V, true, Mod);
134 // CheckFailed - A check failed, so print out the condition and the message
135 // that failed. This provides a nice place to put a breakpoint if you want
136 // to see why something is not correct.
137 void CheckFailed(const Twine &Message,
138 const Value *V1 = 0, const Value *V2 = 0,
139 const Value *V3 = 0, const Value *V4 = 0) {
140 MessagesStr << Message.str() << "\n";
150 INITIALIZE_PASS_BEGIN(Lint, "lint", "Statically lint-checks LLVM IR",
152 INITIALIZE_PASS_DEPENDENCY(DominatorTree)
153 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
154 INITIALIZE_PASS_END(Lint, "lint", "Statically lint-checks LLVM IR",
157 // Assert - We know that cond should be true, if not print an error message.
158 #define Assert(C, M) \
159 do { if (!(C)) { CheckFailed(M); return; } } while (0)
160 #define Assert1(C, M, V1) \
161 do { if (!(C)) { CheckFailed(M, V1); return; } } while (0)
162 #define Assert2(C, M, V1, V2) \
163 do { if (!(C)) { CheckFailed(M, V1, V2); return; } } while (0)
164 #define Assert3(C, M, V1, V2, V3) \
165 do { if (!(C)) { CheckFailed(M, V1, V2, V3); return; } } while (0)
166 #define Assert4(C, M, V1, V2, V3, V4) \
167 do { if (!(C)) { CheckFailed(M, V1, V2, V3, V4); return; } } while (0)
169 // Lint::run - This is the main Analysis entry point for a
172 bool Lint::runOnFunction(Function &F) {
174 AA = &getAnalysis<AliasAnalysis>();
175 DT = &getAnalysis<DominatorTree>();
176 TD = getAnalysisIfAvailable<TargetData>();
178 dbgs() << MessagesStr.str();
183 void Lint::visitFunction(Function &F) {
184 // This isn't undefined behavior, it's just a little unusual, and it's a
185 // fairly common mistake to neglect to name a function.
186 Assert1(F.hasName() || F.hasLocalLinkage(),
187 "Unusual: Unnamed function with non-local linkage", &F);
189 // TODO: Check for irreducible control flow.
192 void Lint::visitCallSite(CallSite CS) {
193 Instruction &I = *CS.getInstruction();
194 Value *Callee = CS.getCalledValue();
196 visitMemoryReference(I, Callee, AliasAnalysis::UnknownSize,
197 0, 0, MemRef::Callee);
199 if (Function *F = dyn_cast<Function>(findValue(Callee, /*OffsetOk=*/false))) {
200 Assert1(CS.getCallingConv() == F->getCallingConv(),
201 "Undefined behavior: Caller and callee calling convention differ",
204 const FunctionType *FT = F->getFunctionType();
205 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
207 Assert1(FT->isVarArg() ?
208 FT->getNumParams() <= NumActualArgs :
209 FT->getNumParams() == NumActualArgs,
210 "Undefined behavior: Call argument count mismatches callee "
211 "argument count", &I);
213 Assert1(FT->getReturnType() == I.getType(),
214 "Undefined behavior: Call return type mismatches "
215 "callee return type", &I);
217 // Check argument types (in case the callee was casted) and attributes.
218 // TODO: Verify that caller and callee attributes are compatible.
219 Function::arg_iterator PI = F->arg_begin(), PE = F->arg_end();
220 CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
221 for (; AI != AE; ++AI) {
224 Argument *Formal = PI++;
225 Assert1(Formal->getType() == Actual->getType(),
226 "Undefined behavior: Call argument type mismatches "
227 "callee parameter type", &I);
229 // Check that noalias arguments don't alias other arguments. The
230 // AliasAnalysis API isn't expressive enough for what we really want
231 // to do. Known partial overlap is not distinguished from the case
232 // where nothing is known.
233 if (Formal->hasNoAliasAttr() && Actual->getType()->isPointerTy())
234 for (CallSite::arg_iterator BI = CS.arg_begin(); BI != AE; ++BI)
236 !(*BI)->getType()->isPointerTy() ||
237 AA->alias(*AI, *BI) != AliasAnalysis::MustAlias,
238 "Unusual: noalias argument aliases another argument", &I);
240 // Check that an sret argument points to valid memory.
241 if (Formal->hasStructRetAttr() && Actual->getType()->isPointerTy()) {
243 cast<PointerType>(Formal->getType())->getElementType();
244 visitMemoryReference(I, Actual, AA->getTypeStoreSize(Ty),
245 TD ? TD->getABITypeAlignment(Ty) : 0,
246 Ty, MemRef::Read | MemRef::Write);
252 if (CS.isCall() && cast<CallInst>(CS.getInstruction())->isTailCall())
253 for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
255 Value *Obj = findValue(*AI, /*OffsetOk=*/true);
256 Assert1(!isa<AllocaInst>(Obj),
257 "Undefined behavior: Call with \"tail\" keyword references "
262 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I))
263 switch (II->getIntrinsicID()) {
266 // TODO: Check more intrinsics
268 case Intrinsic::memcpy: {
269 MemCpyInst *MCI = cast<MemCpyInst>(&I);
270 // TODO: If the size is known, use it.
271 visitMemoryReference(I, MCI->getDest(), AliasAnalysis::UnknownSize,
272 MCI->getAlignment(), 0,
274 visitMemoryReference(I, MCI->getSource(), AliasAnalysis::UnknownSize,
275 MCI->getAlignment(), 0,
278 // Check that the memcpy arguments don't overlap. The AliasAnalysis API
279 // isn't expressive enough for what we really want to do. Known partial
280 // overlap is not distinguished from the case where nothing is known.
282 if (const ConstantInt *Len =
283 dyn_cast<ConstantInt>(findValue(MCI->getLength(),
284 /*OffsetOk=*/false)))
285 if (Len->getValue().isIntN(32))
286 Size = Len->getValue().getZExtValue();
287 Assert1(AA->alias(MCI->getSource(), Size, MCI->getDest(), Size) !=
288 AliasAnalysis::MustAlias,
289 "Undefined behavior: memcpy source and destination overlap", &I);
292 case Intrinsic::memmove: {
293 MemMoveInst *MMI = cast<MemMoveInst>(&I);
294 // TODO: If the size is known, use it.
295 visitMemoryReference(I, MMI->getDest(), AliasAnalysis::UnknownSize,
296 MMI->getAlignment(), 0,
298 visitMemoryReference(I, MMI->getSource(), AliasAnalysis::UnknownSize,
299 MMI->getAlignment(), 0,
303 case Intrinsic::memset: {
304 MemSetInst *MSI = cast<MemSetInst>(&I);
305 // TODO: If the size is known, use it.
306 visitMemoryReference(I, MSI->getDest(), AliasAnalysis::UnknownSize,
307 MSI->getAlignment(), 0,
312 case Intrinsic::vastart:
313 Assert1(I.getParent()->getParent()->isVarArg(),
314 "Undefined behavior: va_start called in a non-varargs function",
317 visitMemoryReference(I, CS.getArgument(0), AliasAnalysis::UnknownSize,
318 0, 0, MemRef::Read | MemRef::Write);
320 case Intrinsic::vacopy:
321 visitMemoryReference(I, CS.getArgument(0), AliasAnalysis::UnknownSize,
322 0, 0, MemRef::Write);
323 visitMemoryReference(I, CS.getArgument(1), AliasAnalysis::UnknownSize,
326 case Intrinsic::vaend:
327 visitMemoryReference(I, CS.getArgument(0), AliasAnalysis::UnknownSize,
328 0, 0, MemRef::Read | MemRef::Write);
331 case Intrinsic::stackrestore:
332 // Stackrestore doesn't read or write memory, but it sets the
333 // stack pointer, which the compiler may read from or write to
334 // at any time, so check it for both readability and writeability.
335 visitMemoryReference(I, CS.getArgument(0), AliasAnalysis::UnknownSize,
336 0, 0, MemRef::Read | MemRef::Write);
341 void Lint::visitCallInst(CallInst &I) {
342 return visitCallSite(&I);
345 void Lint::visitInvokeInst(InvokeInst &I) {
346 return visitCallSite(&I);
349 void Lint::visitReturnInst(ReturnInst &I) {
350 Function *F = I.getParent()->getParent();
351 Assert1(!F->doesNotReturn(),
352 "Unusual: Return statement in function with noreturn attribute",
355 if (Value *V = I.getReturnValue()) {
356 Value *Obj = findValue(V, /*OffsetOk=*/true);
357 Assert1(!isa<AllocaInst>(Obj),
358 "Unusual: Returning alloca value", &I);
362 // TODO: Check that the reference is in bounds.
363 // TODO: Check readnone/readonly function attributes.
364 void Lint::visitMemoryReference(Instruction &I,
365 Value *Ptr, uint64_t Size, unsigned Align,
366 const Type *Ty, unsigned Flags) {
367 // If no memory is being referenced, it doesn't matter if the pointer
372 Value *UnderlyingObject = findValue(Ptr, /*OffsetOk=*/true);
373 Assert1(!isa<ConstantPointerNull>(UnderlyingObject),
374 "Undefined behavior: Null pointer dereference", &I);
375 Assert1(!isa<UndefValue>(UnderlyingObject),
376 "Undefined behavior: Undef pointer dereference", &I);
377 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
378 !cast<ConstantInt>(UnderlyingObject)->isAllOnesValue(),
379 "Unusual: All-ones pointer dereference", &I);
380 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
381 !cast<ConstantInt>(UnderlyingObject)->isOne(),
382 "Unusual: Address one pointer dereference", &I);
384 if (Flags & MemRef::Write) {
385 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(UnderlyingObject))
386 Assert1(!GV->isConstant(),
387 "Undefined behavior: Write to read-only memory", &I);
388 Assert1(!isa<Function>(UnderlyingObject) &&
389 !isa<BlockAddress>(UnderlyingObject),
390 "Undefined behavior: Write to text section", &I);
392 if (Flags & MemRef::Read) {
393 Assert1(!isa<Function>(UnderlyingObject),
394 "Unusual: Load from function body", &I);
395 Assert1(!isa<BlockAddress>(UnderlyingObject),
396 "Undefined behavior: Load from block address", &I);
398 if (Flags & MemRef::Callee) {
399 Assert1(!isa<BlockAddress>(UnderlyingObject),
400 "Undefined behavior: Call to block address", &I);
402 if (Flags & MemRef::Branchee) {
403 Assert1(!isa<Constant>(UnderlyingObject) ||
404 isa<BlockAddress>(UnderlyingObject),
405 "Undefined behavior: Branch to non-blockaddress", &I);
409 if (Align == 0 && Ty) Align = TD->getABITypeAlignment(Ty);
412 unsigned BitWidth = TD->getTypeSizeInBits(Ptr->getType());
413 APInt Mask = APInt::getAllOnesValue(BitWidth),
414 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
415 ComputeMaskedBits(Ptr, Mask, KnownZero, KnownOne, TD);
416 Assert1(!(KnownOne & APInt::getLowBitsSet(BitWidth, Log2_32(Align))),
417 "Undefined behavior: Memory reference address is misaligned", &I);
422 void Lint::visitLoadInst(LoadInst &I) {
423 visitMemoryReference(I, I.getPointerOperand(),
424 AA->getTypeStoreSize(I.getType()), I.getAlignment(),
425 I.getType(), MemRef::Read);
428 void Lint::visitStoreInst(StoreInst &I) {
429 visitMemoryReference(I, I.getPointerOperand(),
430 AA->getTypeStoreSize(I.getOperand(0)->getType()),
432 I.getOperand(0)->getType(), MemRef::Write);
435 void Lint::visitXor(BinaryOperator &I) {
436 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
437 !isa<UndefValue>(I.getOperand(1)),
438 "Undefined result: xor(undef, undef)", &I);
441 void Lint::visitSub(BinaryOperator &I) {
442 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
443 !isa<UndefValue>(I.getOperand(1)),
444 "Undefined result: sub(undef, undef)", &I);
447 void Lint::visitLShr(BinaryOperator &I) {
448 if (ConstantInt *CI =
449 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
450 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
451 "Undefined result: Shift count out of range", &I);
454 void Lint::visitAShr(BinaryOperator &I) {
455 if (ConstantInt *CI =
456 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
457 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
458 "Undefined result: Shift count out of range", &I);
461 void Lint::visitShl(BinaryOperator &I) {
462 if (ConstantInt *CI =
463 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
464 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
465 "Undefined result: Shift count out of range", &I);
468 static bool isZero(Value *V, TargetData *TD) {
469 // Assume undef could be zero.
470 if (isa<UndefValue>(V)) return true;
472 unsigned BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
473 APInt Mask = APInt::getAllOnesValue(BitWidth),
474 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
475 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD);
476 return KnownZero.isAllOnesValue();
479 void Lint::visitSDiv(BinaryOperator &I) {
480 Assert1(!isZero(I.getOperand(1), TD),
481 "Undefined behavior: Division by zero", &I);
484 void Lint::visitUDiv(BinaryOperator &I) {
485 Assert1(!isZero(I.getOperand(1), TD),
486 "Undefined behavior: Division by zero", &I);
489 void Lint::visitSRem(BinaryOperator &I) {
490 Assert1(!isZero(I.getOperand(1), TD),
491 "Undefined behavior: Division by zero", &I);
494 void Lint::visitURem(BinaryOperator &I) {
495 Assert1(!isZero(I.getOperand(1), TD),
496 "Undefined behavior: Division by zero", &I);
499 void Lint::visitAllocaInst(AllocaInst &I) {
500 if (isa<ConstantInt>(I.getArraySize()))
501 // This isn't undefined behavior, it's just an obvious pessimization.
502 Assert1(&I.getParent()->getParent()->getEntryBlock() == I.getParent(),
503 "Pessimization: Static alloca outside of entry block", &I);
505 // TODO: Check for an unusual size (MSB set?)
508 void Lint::visitVAArgInst(VAArgInst &I) {
509 visitMemoryReference(I, I.getOperand(0), AliasAnalysis::UnknownSize, 0, 0,
510 MemRef::Read | MemRef::Write);
513 void Lint::visitIndirectBrInst(IndirectBrInst &I) {
514 visitMemoryReference(I, I.getAddress(), AliasAnalysis::UnknownSize, 0, 0,
517 Assert1(I.getNumDestinations() != 0,
518 "Undefined behavior: indirectbr with no destinations", &I);
521 void Lint::visitExtractElementInst(ExtractElementInst &I) {
522 if (ConstantInt *CI =
523 dyn_cast<ConstantInt>(findValue(I.getIndexOperand(),
524 /*OffsetOk=*/false)))
525 Assert1(CI->getValue().ult(I.getVectorOperandType()->getNumElements()),
526 "Undefined result: extractelement index out of range", &I);
529 void Lint::visitInsertElementInst(InsertElementInst &I) {
530 if (ConstantInt *CI =
531 dyn_cast<ConstantInt>(findValue(I.getOperand(2),
532 /*OffsetOk=*/false)))
533 Assert1(CI->getValue().ult(I.getType()->getNumElements()),
534 "Undefined result: insertelement index out of range", &I);
537 void Lint::visitUnreachableInst(UnreachableInst &I) {
538 // This isn't undefined behavior, it's merely suspicious.
539 Assert1(&I == I.getParent()->begin() ||
540 prior(BasicBlock::iterator(&I))->mayHaveSideEffects(),
541 "Unusual: unreachable immediately preceded by instruction without "
545 /// findValue - Look through bitcasts and simple memory reference patterns
546 /// to identify an equivalent, but more informative, value. If OffsetOk
547 /// is true, look through getelementptrs with non-zero offsets too.
549 /// Most analysis passes don't require this logic, because instcombine
550 /// will simplify most of these kinds of things away. But it's a goal of
551 /// this Lint pass to be useful even on non-optimized IR.
552 Value *Lint::findValue(Value *V, bool OffsetOk) const {
553 SmallPtrSet<Value *, 4> Visited;
554 return findValueImpl(V, OffsetOk, Visited);
557 /// findValueImpl - Implementation helper for findValue.
558 Value *Lint::findValueImpl(Value *V, bool OffsetOk,
559 SmallPtrSet<Value *, 4> &Visited) const {
560 // Detect self-referential values.
561 if (!Visited.insert(V))
562 return UndefValue::get(V->getType());
564 // TODO: Look through sext or zext cast, when the result is known to
565 // be interpreted as signed or unsigned, respectively.
566 // TODO: Look through eliminable cast pairs.
567 // TODO: Look through calls with unique return values.
568 // TODO: Look through vector insert/extract/shuffle.
569 V = OffsetOk ? V->getUnderlyingObject() : V->stripPointerCasts();
570 if (LoadInst *L = dyn_cast<LoadInst>(V)) {
571 BasicBlock::iterator BBI = L;
572 BasicBlock *BB = L->getParent();
573 SmallPtrSet<BasicBlock *, 4> VisitedBlocks;
575 if (!VisitedBlocks.insert(BB)) break;
576 if (Value *U = FindAvailableLoadedValue(L->getPointerOperand(),
578 return findValueImpl(U, OffsetOk, Visited);
579 if (BBI != BB->begin()) break;
580 BB = BB->getUniquePredecessor();
584 } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
585 if (Value *W = PN->hasConstantValue())
587 return findValueImpl(W, OffsetOk, Visited);
588 } else if (CastInst *CI = dyn_cast<CastInst>(V)) {
589 if (CI->isNoopCast(TD ? TD->getIntPtrType(V->getContext()) :
590 Type::getInt64Ty(V->getContext())))
591 return findValueImpl(CI->getOperand(0), OffsetOk, Visited);
592 } else if (ExtractValueInst *Ex = dyn_cast<ExtractValueInst>(V)) {
593 if (Value *W = FindInsertedValue(Ex->getAggregateOperand(),
597 return findValueImpl(W, OffsetOk, Visited);
598 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
599 // Same as above, but for ConstantExpr instead of Instruction.
600 if (Instruction::isCast(CE->getOpcode())) {
601 if (CastInst::isNoopCast(Instruction::CastOps(CE->getOpcode()),
602 CE->getOperand(0)->getType(),
604 TD ? TD->getIntPtrType(V->getContext()) :
605 Type::getInt64Ty(V->getContext())))
606 return findValueImpl(CE->getOperand(0), OffsetOk, Visited);
607 } else if (CE->getOpcode() == Instruction::ExtractValue) {
608 const SmallVector<unsigned, 4> &Indices = CE->getIndices();
609 if (Value *W = FindInsertedValue(CE->getOperand(0),
613 return findValueImpl(W, OffsetOk, Visited);
617 // As a last resort, try SimplifyInstruction or constant folding.
618 if (Instruction *Inst = dyn_cast<Instruction>(V)) {
619 if (Value *W = SimplifyInstruction(Inst, TD, DT))
620 return findValueImpl(W, OffsetOk, Visited);
621 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
622 if (Value *W = ConstantFoldConstantExpression(CE, TD))
624 return findValueImpl(W, OffsetOk, Visited);
630 //===----------------------------------------------------------------------===//
631 // Implement the public interfaces to this file...
632 //===----------------------------------------------------------------------===//
634 FunctionPass *llvm::createLintPass() {
638 /// lintFunction - Check a function for errors, printing messages on stderr.
640 void llvm::lintFunction(const Function &f) {
641 Function &F = const_cast<Function&>(f);
642 assert(!F.isDeclaration() && "Cannot lint external functions");
644 FunctionPassManager FPM(F.getParent());
645 Lint *V = new Lint();
650 /// lintModule - Check a module for errors, printing messages on stderr.
652 void llvm::lintModule(const Module &M) {
654 Lint *V = new Lint();
656 PM.run(const_cast<Module&>(M));