#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/Lint.h"
+#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Target/TargetData.h"
void visitInsertElementInst(InsertElementInst &I);
void visitUnreachableInst(UnreachableInst &I);
+ Value *findValue(Value *V, bool OffsetOk) const;
+
public:
Module *Mod;
AliasAnalysis *AA;
+ DominatorTree *DT;
TargetData *TD;
std::string Messages;
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<AliasAnalysis>();
+ AU.addRequired<DominatorTree>();
}
virtual void print(raw_ostream &O, const Module *M) const {}
bool Lint::runOnFunction(Function &F) {
Mod = F.getParent();
AA = &getAnalysis<AliasAnalysis>();
+ DT = &getAnalysis<DominatorTree>();
TD = getAnalysisIfAvailable<TargetData>();
visit(F);
dbgs() << MessagesStr.str();
+ Messages.clear();
return false;
}
visitMemoryReference(I, Callee, 0, 0, MemRef::Callee);
- if (Function *F = dyn_cast<Function>(Callee->stripPointerCasts())) {
+ if (Function *F = dyn_cast<Function>(findValue(Callee, /*OffsetOk=*/false))) {
Assert1(CS.getCallingConv() == F->getCallingConv(),
"Undefined behavior: Caller and callee calling convention differ",
&I);
if (CS.isCall() && cast<CallInst>(CS.getInstruction())->isTailCall())
for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
AI != AE; ++AI) {
- Value *Obj = (*AI)->getUnderlyingObject();
- Assert1(!isa<AllocaInst>(Obj) && !isa<VAArgInst>(Obj),
+ Value *Obj = findValue(*AI, /*OffsetOk=*/true);
+ Assert1(!isa<AllocaInst>(Obj),
"Undefined behavior: Call with \"tail\" keyword references "
- "alloca or va_arg", &I);
+ "alloca", &I);
}
// overlap is not distinguished from the case where nothing is known.
unsigned Size = 0;
if (const ConstantInt *Len =
- dyn_cast<ConstantInt>(MCI->getLength()->stripPointerCasts()))
+ dyn_cast<ConstantInt>(findValue(MCI->getLength(),
+ /*OffsetOk=*/false)))
if (Len->getValue().isIntN(32))
Size = Len->getValue().getZExtValue();
Assert1(AA->alias(MCI->getSource(), Size, MCI->getDest(), Size) !=
break;
case Intrinsic::stackrestore:
+ // Stackrestore doesn't read or write memory, but it sets the
+ // stack pointer, which the compiler may read from or write to
+ // at any time, so check it for both readability and writeability.
visitMemoryReference(I, CS.getArgument(0), 0, 0,
- MemRef::Read);
+ MemRef::Read | MemRef::Write);
break;
}
}
Assert1(!F->doesNotReturn(),
"Unusual: Return statement in function with noreturn attribute",
&I);
+
+ if (Value *V = I.getReturnValue()) {
+ Value *Obj = findValue(V, /*OffsetOk=*/true);
+ Assert1(!isa<AllocaInst>(Obj),
+ "Unusual: Returning alloca value", &I);
+ }
}
// TODO: Add a length argument and check that the reference is in bounds
void Lint::visitMemoryReference(Instruction &I,
Value *Ptr, unsigned Align, const Type *Ty,
unsigned Flags) {
- Value *UnderlyingObject = Ptr->getUnderlyingObject();
+ Value *UnderlyingObject = findValue(Ptr, /*OffsetOk=*/true);
Assert1(!isa<ConstantPointerNull>(UnderlyingObject),
"Undefined behavior: Null pointer dereference", &I);
Assert1(!isa<UndefValue>(UnderlyingObject),
void Lint::visitLShr(BinaryOperator &I) {
if (ConstantInt *CI =
- dyn_cast<ConstantInt>(I.getOperand(1)->stripPointerCasts()))
+ dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
"Undefined result: Shift count out of range", &I);
}
void Lint::visitAShr(BinaryOperator &I) {
if (ConstantInt *CI =
- dyn_cast<ConstantInt>(I.getOperand(1)->stripPointerCasts()))
+ dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
"Undefined result: Shift count out of range", &I);
}
void Lint::visitShl(BinaryOperator &I) {
if (ConstantInt *CI =
- dyn_cast<ConstantInt>(I.getOperand(1)->stripPointerCasts()))
+ dyn_cast<ConstantInt>(findValue(I.getOperand(1), /*OffsetOk=*/false)))
Assert1(CI->getValue().ult(cast<IntegerType>(I.getType())->getBitWidth()),
"Undefined result: Shift count out of range", &I);
}
void Lint::visitExtractElementInst(ExtractElementInst &I) {
if (ConstantInt *CI =
- dyn_cast<ConstantInt>(I.getIndexOperand()->stripPointerCasts()))
+ dyn_cast<ConstantInt>(findValue(I.getIndexOperand(),
+ /*OffsetOk=*/false)))
Assert1(CI->getValue().ult(I.getVectorOperandType()->getNumElements()),
"Undefined result: extractelement index out of range", &I);
}
void Lint::visitInsertElementInst(InsertElementInst &I) {
if (ConstantInt *CI =
- dyn_cast<ConstantInt>(I.getOperand(2)->stripPointerCasts()))
+ dyn_cast<ConstantInt>(findValue(I.getOperand(2),
+ /*OffsetOk=*/false)))
Assert1(CI->getValue().ult(I.getType()->getNumElements()),
"Undefined result: insertelement index out of range", &I);
}
"side effects", &I);
}
+/// findValue - Look through bitcasts and simple memory reference patterns
+/// to identify an equivalent, but more informative, value. If OffsetOk
+/// is true, look through getelementptrs with non-zero offsets too.
+///
+/// Most analysis passes don't require this logic, because instcombine
+/// will simplify most of these kinds of things away. But it's a goal of
+/// this Lint pass to be useful even on non-optimized IR.
+Value *Lint::findValue(Value *V, bool OffsetOk) const {
+ // TODO: Look through sext or zext cast, when the result is known to
+ // be interpreted as signed or unsigned, respectively.
+ // TODO: Look through calls with unique return values.
+ // TODO: Look through vector insert/extract/shuffle.
+ V = OffsetOk ? V->getUnderlyingObject() : V->stripPointerCasts();
+ if (LoadInst *L = dyn_cast<LoadInst>(V)) {
+ BasicBlock::iterator BBI = L;
+ BasicBlock *BB = L->getParent();
+ for (;;) {
+ if (Value *U = FindAvailableLoadedValue(L->getPointerOperand(),
+ BB, BBI, 6, AA))
+ return findValue(U, OffsetOk);
+ BB = L->getParent()->getUniquePredecessor();
+ if (!BB) break;
+ BBI = BB->end();
+ }
+ } else if (CastInst *CI = dyn_cast<CastInst>(V)) {
+ if (CI->isNoopCast(TD ? TD->getIntPtrType(V->getContext()) :
+ Type::getInt64Ty(V->getContext())))
+ return findValue(CI->getOperand(0), OffsetOk);
+ } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
+ if (Value *W = PN->hasConstantValue(DT))
+ return findValue(W, OffsetOk);
+ } else if (ExtractValueInst *Ex = dyn_cast<ExtractValueInst>(V)) {
+ if (Value *W = FindInsertedValue(Ex->getAggregateOperand(),
+ Ex->idx_begin(),
+ Ex->idx_end()))
+ if (W != V)
+ return findValue(W, OffsetOk);
+ }
+
+ // As a last resort, try SimplifyInstruction or constant folding.
+ if (Instruction *Inst = dyn_cast<Instruction>(V)) {
+ if (Value *W = SimplifyInstruction(Inst, TD))
+ if (W != Inst)
+ return findValue(W, OffsetOk);
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
+ if (Value *W = ConstantFoldConstantExpression(CE, TD))
+ if (W != V)
+ return findValue(W, OffsetOk);
+ }
+
+ return V;
+}
+
//===----------------------------------------------------------------------===//
// Implement the public interfaces to this file...
//===----------------------------------------------------------------------===//
}
/// lintModule - Check a module for errors, printing messages on stderr.
-/// Return true if the module is corrupt.
///
-void llvm::lintModule(const Module &M, std::string *ErrorInfo) {
+void llvm::lintModule(const Module &M) {
PassManager PM;
Lint *V = new Lint();
PM.add(V);
PM.run(const_cast<Module&>(M));
-
- if (ErrorInfo)
- *ErrorInfo = V->MessagesStr.str();
}
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