// those aren't comprehensive either. Second, many conditions cannot be
// checked statically. This pass does no dynamic instrumentation, so it
// can't check for all possible problems.
-//
+//
// Another limitation is that it assumes all code will be executed. A store
// through a null pointer in a basic block which is never reached is harmless,
// but this pass will warn about it anyway. This is the main reason why most
// less obvious. If an optimization pass appears to be introducing a warning,
// it may be that the optimization pass is merely exposing an existing
// condition in the code.
-//
+//
// This code may be run before instcombine. In many cases, instcombine checks
// for the same kinds of things and turns instructions with undefined behavior
// into unreachable (or equivalent). Because of this, this pass makes some
// effort to look through bitcasts and so on.
-//
+//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Lint.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Assembly/Writer.h"
+#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
+#include "llvm/IR/InstVisitor.h"
#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/InstVisitor.h"
#include "llvm/Pass.h"
#include "llvm/PassManager.h"
-#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLibraryInfo.h"
Module *Mod;
AliasAnalysis *AA;
DominatorTree *DT;
- DataLayout *TD;
+ const DataLayout *DL;
TargetLibraryInfo *TLI;
std::string Messages;
initializeLintPass(*PassRegistry::getPassRegistry());
}
- virtual bool runOnFunction(Function &F);
+ bool runOnFunction(Function &F) override;
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
AU.addRequired<AliasAnalysis>();
AU.addRequired<TargetLibraryInfo>();
- AU.addRequired<DominatorTree>();
+ AU.addRequired<DominatorTreeWrapperPass>();
}
- virtual void print(raw_ostream &O, const Module *M) const {}
+ void print(raw_ostream &O, const Module *M) const override {}
void WriteValue(const Value *V) {
if (!V) return;
if (isa<Instruction>(V)) {
MessagesStr << *V << '\n';
} else {
- WriteAsOperand(MessagesStr, V, true, Mod);
+ V->printAsOperand(MessagesStr, true, Mod);
MessagesStr << '\n';
}
}
INITIALIZE_PASS_BEGIN(Lint, "lint", "Statically lint-checks LLVM IR",
false, true)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_END(Lint, "lint", "Statically lint-checks LLVM IR",
false, true)
bool Lint::runOnFunction(Function &F) {
Mod = F.getParent();
AA = &getAnalysis<AliasAnalysis>();
- DT = &getAnalysis<DominatorTree>();
- TD = getAnalysisIfAvailable<DataLayout>();
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+ DL = DLP ? &DLP->getDataLayout() : 0;
TLI = &getAnalysis<TargetLibraryInfo>();
visit(F);
dbgs() << MessagesStr.str();
&I);
FunctionType *FT = F->getFunctionType();
- unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
+ unsigned NumActualArgs = CS.arg_size();
Assert1(FT->isVarArg() ?
FT->getNumParams() <= NumActualArgs :
Type *Ty =
cast<PointerType>(Formal->getType())->getElementType();
visitMemoryReference(I, Actual, AA->getTypeStoreSize(Ty),
- TD ? TD->getABITypeAlignment(Ty) : 0,
+ DL ? DL->getABITypeAlignment(Ty) : 0,
Ty, MemRef::Read | MemRef::Write);
}
}
// Only handles memory references that read/write something simple like an
// alloca instruction or a global variable.
int64_t Offset = 0;
- if (Value *Base = GetPointerBaseWithConstantOffset(Ptr, Offset, TD)) {
+ if (Value *Base = GetPointerBaseWithConstantOffset(Ptr, Offset, DL)) {
// OK, so the access is to a constant offset from Ptr. Check that Ptr is
// something we can handle and if so extract the size of this base object
// along with its alignment.
if (AllocaInst *AI = dyn_cast<AllocaInst>(Base)) {
Type *ATy = AI->getAllocatedType();
- if (TD && !AI->isArrayAllocation() && ATy->isSized())
- BaseSize = TD->getTypeAllocSize(ATy);
+ if (DL && !AI->isArrayAllocation() && ATy->isSized())
+ BaseSize = DL->getTypeAllocSize(ATy);
BaseAlign = AI->getAlignment();
- if (TD && BaseAlign == 0 && ATy->isSized())
- BaseAlign = TD->getABITypeAlignment(ATy);
+ if (DL && BaseAlign == 0 && ATy->isSized())
+ BaseAlign = DL->getABITypeAlignment(ATy);
} else if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Base)) {
// If the global may be defined differently in another compilation unit
// then don't warn about funky memory accesses.
if (GV->hasDefinitiveInitializer()) {
Type *GTy = GV->getType()->getElementType();
- if (TD && GTy->isSized())
- BaseSize = TD->getTypeAllocSize(GTy);
+ if (DL && GTy->isSized())
+ BaseSize = DL->getTypeAllocSize(GTy);
BaseAlign = GV->getAlignment();
- if (TD && BaseAlign == 0 && GTy->isSized())
- BaseAlign = TD->getABITypeAlignment(GTy);
+ if (DL && BaseAlign == 0 && GTy->isSized())
+ BaseAlign = DL->getABITypeAlignment(GTy);
}
}
// Accesses that say that the memory is more aligned than it is are not
// defined.
- if (TD && Align == 0 && Ty && Ty->isSized())
- Align = TD->getABITypeAlignment(Ty);
+ if (DL && Align == 0 && Ty && Ty->isSized())
+ Align = DL->getABITypeAlignment(Ty);
Assert1(!BaseAlign || Align <= MinAlign(BaseAlign, Offset),
"Undefined behavior: Memory reference address is misaligned", &I);
}
"Undefined result: Shift count out of range", &I);
}
-static bool isZero(Value *V, DataLayout *TD) {
+static bool isZero(Value *V, const DataLayout *DL) {
// Assume undef could be zero.
- if (isa<UndefValue>(V)) return true;
+ if (isa<UndefValue>(V))
+ return true;
+
+ VectorType *VecTy = dyn_cast<VectorType>(V->getType());
+ if (!VecTy) {
+ unsigned BitWidth = V->getType()->getIntegerBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ ComputeMaskedBits(V, KnownZero, KnownOne, DL);
+ return KnownZero.isAllOnesValue();
+ }
- unsigned BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
- APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
- ComputeMaskedBits(V, KnownZero, KnownOne, TD);
- return KnownZero.isAllOnesValue();
+ // Per-component check doesn't work with zeroinitializer
+ Constant *C = dyn_cast<Constant>(V);
+ if (!C)
+ return false;
+
+ if (C->isZeroValue())
+ return true;
+
+ // For a vector, KnownZero will only be true if all values are zero, so check
+ // this per component
+ unsigned BitWidth = VecTy->getElementType()->getIntegerBitWidth();
+ for (unsigned I = 0, N = VecTy->getNumElements(); I != N; ++I) {
+ Constant *Elem = C->getAggregateElement(I);
+ if (isa<UndefValue>(Elem))
+ return true;
+
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ ComputeMaskedBits(Elem, KnownZero, KnownOne, DL);
+ if (KnownZero.isAllOnesValue())
+ return true;
+ }
+
+ return false;
}
void Lint::visitSDiv(BinaryOperator &I) {
- Assert1(!isZero(I.getOperand(1), TD),
+ Assert1(!isZero(I.getOperand(1), DL),
"Undefined behavior: Division by zero", &I);
}
void Lint::visitUDiv(BinaryOperator &I) {
- Assert1(!isZero(I.getOperand(1), TD),
+ Assert1(!isZero(I.getOperand(1), DL),
"Undefined behavior: Division by zero", &I);
}
void Lint::visitSRem(BinaryOperator &I) {
- Assert1(!isZero(I.getOperand(1), TD),
+ Assert1(!isZero(I.getOperand(1), DL),
"Undefined behavior: Division by zero", &I);
}
void Lint::visitURem(BinaryOperator &I) {
- Assert1(!isZero(I.getOperand(1), TD),
+ Assert1(!isZero(I.getOperand(1), DL),
"Undefined behavior: Division by zero", &I);
}
void Lint::visitUnreachableInst(UnreachableInst &I) {
// This isn't undefined behavior, it's merely suspicious.
Assert1(&I == I.getParent()->begin() ||
- prior(BasicBlock::iterator(&I))->mayHaveSideEffects(),
+ std::prev(BasicBlock::iterator(&I))->mayHaveSideEffects(),
"Unusual: unreachable immediately preceded by instruction without "
"side effects", &I);
}
// TODO: Look through eliminable cast pairs.
// TODO: Look through calls with unique return values.
// TODO: Look through vector insert/extract/shuffle.
- V = OffsetOk ? GetUnderlyingObject(V, TD) : V->stripPointerCasts();
+ V = OffsetOk ? GetUnderlyingObject(V, DL) : V->stripPointerCasts();
if (LoadInst *L = dyn_cast<LoadInst>(V)) {
BasicBlock::iterator BBI = L;
BasicBlock *BB = L->getParent();
if (W != V)
return findValueImpl(W, OffsetOk, Visited);
} else if (CastInst *CI = dyn_cast<CastInst>(V)) {
- if (CI->isNoopCast(TD ? TD->getIntPtrType(V->getContext()) :
- Type::getInt64Ty(V->getContext())))
+ if (CI->isNoopCast(DL))
return findValueImpl(CI->getOperand(0), OffsetOk, Visited);
} else if (ExtractValueInst *Ex = dyn_cast<ExtractValueInst>(V)) {
if (Value *W = FindInsertedValue(Ex->getAggregateOperand(),
if (CastInst::isNoopCast(Instruction::CastOps(CE->getOpcode()),
CE->getOperand(0)->getType(),
CE->getType(),
- TD ? TD->getIntPtrType(V->getContext()) :
+ DL ? DL->getIntPtrType(V->getType()) :
Type::getInt64Ty(V->getContext())))
return findValueImpl(CE->getOperand(0), OffsetOk, Visited);
} else if (CE->getOpcode() == Instruction::ExtractValue) {
// As a last resort, try SimplifyInstruction or constant folding.
if (Instruction *Inst = dyn_cast<Instruction>(V)) {
- if (Value *W = SimplifyInstruction(Inst, TD, TLI, DT))
+ if (Value *W = SimplifyInstruction(Inst, DL, TLI, DT))
return findValueImpl(W, OffsetOk, Visited);
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
- if (Value *W = ConstantFoldConstantExpression(CE, TD, TLI))
+ if (Value *W = ConstantFoldConstantExpression(CE, DL, TLI))
if (W != V)
return findValueImpl(W, OffsetOk, Visited);
}
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