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) {
250 AA->alias(*AI, ~0u, *BI, ~0u) != AliasAnalysis::MustAlias,
251 "Unusual: noalias argument aliases another argument", &I);
254 // Check that an sret argument points to valid memory.
255 if (Formal->hasStructRetAttr() && Actual->getType()->isPointerTy()) {
257 cast<PointerType>(Formal->getType())->getElementType();
258 visitMemoryReference(I, Actual, AA->getTypeStoreSize(Ty),
259 TD ? TD->getABITypeAlignment(Ty) : 0,
260 Ty, MemRef::Read | MemRef::Write);
266 if (CS.isCall() && cast<CallInst>(CS.getInstruction())->isTailCall())
267 for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
269 Value *Obj = findValue(*AI, /*OffsetOk=*/true);
270 Assert1(!isa<AllocaInst>(Obj),
271 "Undefined behavior: Call with \"tail\" keyword references "
276 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I))
277 switch (II->getIntrinsicID()) {
280 // TODO: Check more intrinsics
282 case Intrinsic::memcpy: {
283 MemCpyInst *MCI = cast<MemCpyInst>(&I);
284 // TODO: If the size is known, use it.
285 visitMemoryReference(I, MCI->getDest(), ~0u, MCI->getAlignment(), 0,
287 visitMemoryReference(I, MCI->getSource(), ~0u, MCI->getAlignment(), 0,
290 // Check that the memcpy arguments don't overlap. The AliasAnalysis API
291 // isn't expressive enough for what we really want to do. Known partial
292 // overlap is not distinguished from the case where nothing is known.
294 if (const ConstantInt *Len =
295 dyn_cast<ConstantInt>(findValue(MCI->getLength(),
296 /*OffsetOk=*/false)))
297 if (Len->getValue().isIntN(32))
298 Size = Len->getValue().getZExtValue();
299 Assert1(AA->alias(MCI->getSource(), Size, MCI->getDest(), Size) !=
300 AliasAnalysis::MustAlias,
301 "Undefined behavior: memcpy source and destination overlap", &I);
304 case Intrinsic::memmove: {
305 MemMoveInst *MMI = cast<MemMoveInst>(&I);
306 // TODO: If the size is known, use it.
307 visitMemoryReference(I, MMI->getDest(), ~0u, MMI->getAlignment(), 0,
309 visitMemoryReference(I, MMI->getSource(), ~0u, MMI->getAlignment(), 0,
313 case Intrinsic::memset: {
314 MemSetInst *MSI = cast<MemSetInst>(&I);
315 // TODO: If the size is known, use it.
316 visitMemoryReference(I, MSI->getDest(), ~0u, MSI->getAlignment(), 0,
321 case Intrinsic::vastart:
322 Assert1(I.getParent()->getParent()->isVarArg(),
323 "Undefined behavior: va_start called in a non-varargs function",
326 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
327 MemRef::Read | MemRef::Write);
329 case Intrinsic::vacopy:
330 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0, MemRef::Write);
331 visitMemoryReference(I, CS.getArgument(1), ~0u, 0, 0, MemRef::Read);
333 case Intrinsic::vaend:
334 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
335 MemRef::Read | MemRef::Write);
338 case Intrinsic::stackrestore:
339 // Stackrestore doesn't read or write memory, but it sets the
340 // stack pointer, which the compiler may read from or write to
341 // at any time, so check it for both readability and writeability.
342 visitMemoryReference(I, CS.getArgument(0), ~0u, 0, 0,
343 MemRef::Read | MemRef::Write);
348 void Lint::visitCallInst(CallInst &I) {
349 return visitCallSite(&I);
352 void Lint::visitInvokeInst(InvokeInst &I) {
353 return visitCallSite(&I);
356 void Lint::visitReturnInst(ReturnInst &I) {
357 Function *F = I.getParent()->getParent();
358 Assert1(!F->doesNotReturn(),
359 "Unusual: Return statement in function with noreturn attribute",
362 if (Value *V = I.getReturnValue()) {
363 Value *Obj = findValue(V, /*OffsetOk=*/true);
364 Assert1(!isa<AllocaInst>(Obj),
365 "Unusual: Returning alloca value", &I);
369 // TODO: Check that the reference is in bounds.
370 // TODO: Check readnone/readonly function attributes.
371 void Lint::visitMemoryReference(Instruction &I,
372 Value *Ptr, unsigned Size, unsigned Align,
373 const Type *Ty, unsigned Flags) {
374 // If no memory is being referenced, it doesn't matter if the pointer
379 Value *UnderlyingObject = findValue(Ptr, /*OffsetOk=*/true);
380 Assert1(!isa<ConstantPointerNull>(UnderlyingObject),
381 "Undefined behavior: Null pointer dereference", &I);
382 Assert1(!isa<UndefValue>(UnderlyingObject),
383 "Undefined behavior: Undef pointer dereference", &I);
384 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
385 !cast<ConstantInt>(UnderlyingObject)->isAllOnesValue(),
386 "Unusual: All-ones pointer dereference", &I);
387 Assert1(!isa<ConstantInt>(UnderlyingObject) ||
388 !cast<ConstantInt>(UnderlyingObject)->isOne(),
389 "Unusual: Address one pointer dereference", &I);
391 if (Flags & MemRef::Write) {
392 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(UnderlyingObject))
393 Assert1(!GV->isConstant(),
394 "Undefined behavior: Write to read-only memory", &I);
395 Assert1(!isa<Function>(UnderlyingObject) &&
396 !isa<BlockAddress>(UnderlyingObject),
397 "Undefined behavior: Write to text section", &I);
399 if (Flags & MemRef::Read) {
400 Assert1(!isa<Function>(UnderlyingObject),
401 "Unusual: Load from function body", &I);
402 Assert1(!isa<BlockAddress>(UnderlyingObject),
403 "Undefined behavior: Load from block address", &I);
405 if (Flags & MemRef::Callee) {
406 Assert1(!isa<BlockAddress>(UnderlyingObject),
407 "Undefined behavior: Call to block address", &I);
409 if (Flags & MemRef::Branchee) {
410 Assert1(!isa<Constant>(UnderlyingObject) ||
411 isa<BlockAddress>(UnderlyingObject),
412 "Undefined behavior: Branch to non-blockaddress", &I);
416 if (Align == 0 && Ty) Align = TD->getABITypeAlignment(Ty);
419 unsigned BitWidth = TD->getTypeSizeInBits(Ptr->getType());
420 APInt Mask = APInt::getAllOnesValue(BitWidth),
421 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
422 ComputeMaskedBits(Ptr, Mask, KnownZero, KnownOne, TD);
423 Assert1(!(KnownOne & APInt::getLowBitsSet(BitWidth, Log2_32(Align))),
424 "Undefined behavior: Memory reference address is misaligned", &I);
429 void Lint::visitLoadInst(LoadInst &I) {
430 visitMemoryReference(I, I.getPointerOperand(),
431 AA->getTypeStoreSize(I.getType()), I.getAlignment(),
432 I.getType(), MemRef::Read);
435 void Lint::visitStoreInst(StoreInst &I) {
436 visitMemoryReference(I, I.getPointerOperand(),
437 AA->getTypeStoreSize(I.getOperand(0)->getType()),
439 I.getOperand(0)->getType(), MemRef::Write);
442 void Lint::visitXor(BinaryOperator &I) {
443 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
444 !isa<UndefValue>(I.getOperand(1)),
445 "Undefined result: xor(undef, undef)", &I);
448 void Lint::visitSub(BinaryOperator &I) {
449 Assert1(!isa<UndefValue>(I.getOperand(0)) ||
450 !isa<UndefValue>(I.getOperand(1)),
451 "Undefined result: sub(undef, undef)", &I);
454 void Lint::visitLShr(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::visitAShr(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 void Lint::visitShl(BinaryOperator &I) {
469 if (ConstantInt *CI =
470 dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
471 Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
472 "Undefined result: Shift count out of range", &I);
475 static bool isZero(Value *V, TargetData *TD) {
476 // Assume undef could be zero.
477 if (isa<UndefValue>(V)) return true;
479 unsigned BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
480 APInt Mask = APInt::getAllOnesValue(BitWidth),
481 KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
482 ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD);
483 return KnownZero.isAllOnesValue();
486 void Lint::visitSDiv(BinaryOperator &I) {
487 Assert1(!isZero(I.getOperand(1), TD),
488 "Undefined behavior: Division by zero", &I);
491 void Lint::visitUDiv(BinaryOperator &I) {
492 Assert1(!isZero(I.getOperand(1), TD),
493 "Undefined behavior: Division by zero", &I);
496 void Lint::visitSRem(BinaryOperator &I) {
497 Assert1(!isZero(I.getOperand(1), TD),
498 "Undefined behavior: Division by zero", &I);
501 void Lint::visitURem(BinaryOperator &I) {
502 Assert1(!isZero(I.getOperand(1), TD),
503 "Undefined behavior: Division by zero", &I);
506 void Lint::visitAllocaInst(AllocaInst &I) {
507 if (isa<ConstantInt>(I.getArraySize()))
508 // This isn't undefined behavior, it's just an obvious pessimization.
509 Assert1(&I.getParent()->getParent()->getEntryBlock() == I.getParent(),
510 "Pessimization: Static alloca outside of entry block", &I);
512 // TODO: Check for an unusual size (MSB set?)
515 void Lint::visitVAArgInst(VAArgInst &I) {
516 visitMemoryReference(I, I.getOperand(0), ~0u, 0, 0,
517 MemRef::Read | MemRef::Write);
520 void Lint::visitIndirectBrInst(IndirectBrInst &I) {
521 visitMemoryReference(I, I.getAddress(), ~0u, 0, 0, MemRef::Branchee);
523 Assert1(I.getNumDestinations() != 0,
524 "Undefined behavior: indirectbr with no destinations", &I);
527 void Lint::visitExtractElementInst(ExtractElementInst &I) {
528 if (ConstantInt *CI =
529 dyn_cast<ConstantInt>(findValue(I.getIndexOperand(),
530 /*OffsetOk=*/false)))
531 Assert1(CI->getValue().ult(I.getVectorOperandType()->getNumElements()),
532 "Undefined result: extractelement index out of range", &I);
535 void Lint::visitInsertElementInst(InsertElementInst &I) {
536 if (ConstantInt *CI =
537 dyn_cast<ConstantInt>(findValue(I.getOperand(2),
538 /*OffsetOk=*/false)))
539 Assert1(CI->getValue().ult(I.getType()->getNumElements()),
540 "Undefined result: insertelement index out of range", &I);
543 void Lint::visitUnreachableInst(UnreachableInst &I) {
544 // This isn't undefined behavior, it's merely suspicious.
545 Assert1(&I == I.getParent()->begin() ||
546 prior(BasicBlock::iterator(&I))->mayHaveSideEffects(),
547 "Unusual: unreachable immediately preceded by instruction without "
551 /// findValue - Look through bitcasts and simple memory reference patterns
552 /// to identify an equivalent, but more informative, value. If OffsetOk
553 /// is true, look through getelementptrs with non-zero offsets too.
555 /// Most analysis passes don't require this logic, because instcombine
556 /// will simplify most of these kinds of things away. But it's a goal of
557 /// this Lint pass to be useful even on non-optimized IR.
558 Value *Lint::findValue(Value *V, bool OffsetOk) const {
559 SmallPtrSet<Value *, 4> Visited;
560 return findValueImpl(V, OffsetOk, Visited);
563 /// findValueImpl - Implementation helper for findValue.
564 Value *Lint::findValueImpl(Value *V, bool OffsetOk,
565 SmallPtrSet<Value *, 4> &Visited) const {
566 // Detect self-referential values.
567 if (!Visited.insert(V))
568 return UndefValue::get(V->getType());
570 // TODO: Look through sext or zext cast, when the result is known to
571 // be interpreted as signed or unsigned, respectively.
572 // TODO: Look through eliminable cast pairs.
573 // TODO: Look through calls with unique return values.
574 // TODO: Look through vector insert/extract/shuffle.
575 V = OffsetOk ? V->getUnderlyingObject() : V->stripPointerCasts();
576 if (LoadInst *L = dyn_cast<LoadInst>(V)) {
577 BasicBlock::iterator BBI = L;
578 BasicBlock *BB = L->getParent();
579 SmallPtrSet<BasicBlock *, 4> VisitedBlocks;
581 if (!VisitedBlocks.insert(BB)) break;
582 if (Value *U = FindAvailableLoadedValue(L->getPointerOperand(),
584 return findValueImpl(U, OffsetOk, Visited);
585 if (BBI != BB->begin()) break;
586 BB = BB->getUniquePredecessor();
590 } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
591 if (Value *W = PN->hasConstantValue(DT))
592 return findValueImpl(W, OffsetOk, Visited);
593 } else if (CastInst *CI = dyn_cast<CastInst>(V)) {
594 if (CI->isNoopCast(TD ? TD->getIntPtrType(V->getContext()) :
595 Type::getInt64Ty(V->getContext())))
596 return findValueImpl(CI->getOperand(0), OffsetOk, Visited);
597 } else if (ExtractValueInst *Ex = dyn_cast<ExtractValueInst>(V)) {
598 if (Value *W = FindInsertedValue(Ex->getAggregateOperand(),
602 return findValueImpl(W, OffsetOk, Visited);
603 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
604 // Same as above, but for ConstantExpr instead of Instruction.
605 if (Instruction::isCast(CE->getOpcode())) {
606 if (CastInst::isNoopCast(Instruction::CastOps(CE->getOpcode()),
607 CE->getOperand(0)->getType(),
609 TD ? TD->getIntPtrType(V->getContext()) :
610 Type::getInt64Ty(V->getContext())))
611 return findValueImpl(CE->getOperand(0), OffsetOk, Visited);
612 } else if (CE->getOpcode() == Instruction::ExtractValue) {
613 const SmallVector<unsigned, 4> &Indices = CE->getIndices();
614 if (Value *W = FindInsertedValue(CE->getOperand(0),
618 return findValueImpl(W, OffsetOk, Visited);
622 // As a last resort, try SimplifyInstruction or constant folding.
623 if (Instruction *Inst = dyn_cast<Instruction>(V)) {
624 if (Value *W = SimplifyInstruction(Inst, TD))
626 return findValueImpl(W, OffsetOk, Visited);
627 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
628 if (Value *W = ConstantFoldConstantExpression(CE, TD))
630 return findValueImpl(W, OffsetOk, Visited);
636 //===----------------------------------------------------------------------===//
637 // Implement the public interfaces to this file...
638 //===----------------------------------------------------------------------===//
640 FunctionPass *llvm::createLintPass() {
644 /// lintFunction - Check a function for errors, printing messages on stderr.
646 void llvm::lintFunction(const Function &f) {
647 Function &F = const_cast<Function&>(f);
648 assert(!F.isDeclaration() && "Cannot lint external functions");
650 FunctionPassManager FPM(F.getParent());
651 Lint *V = new Lint();
656 /// lintModule - Check a module for errors, printing messages on stderr.
658 void llvm::lintModule(const Module &M) {
660 Lint *V = new Lint();
662 PM.run(const_cast<Module&>(M));