aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Transforms/Instrumentation/BoundsChecking.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/Transforms/Instrumentation/BoundsChecking.cpp')
-rw-r--r--lib/Transforms/Instrumentation/BoundsChecking.cpp82
1 files changed, 43 insertions, 39 deletions
diff --git a/lib/Transforms/Instrumentation/BoundsChecking.cpp b/lib/Transforms/Instrumentation/BoundsChecking.cpp
index e13db08e263c..a0c78e0468c6 100644
--- a/lib/Transforms/Instrumentation/BoundsChecking.cpp
+++ b/lib/Transforms/Instrumentation/BoundsChecking.cpp
@@ -47,21 +47,17 @@ STATISTIC(ChecksUnable, "Bounds checks unable to add");
using BuilderTy = IRBuilder<TargetFolder>;
-/// Adds run-time bounds checks to memory accessing instructions.
+/// Gets the conditions under which memory accessing instructions will overflow.
///
/// \p Ptr is the pointer that will be read/written, and \p InstVal is either
/// the result from the load or the value being stored. It is used to determine
/// the size of memory block that is touched.
///
-/// \p GetTrapBB is a callable that returns the trap BB to use on failure.
-///
-/// Returns true if any change was made to the IR, false otherwise.
-template <typename GetTrapBBT>
-static bool instrumentMemAccess(Value *Ptr, Value *InstVal,
- const DataLayout &DL, TargetLibraryInfo &TLI,
- ObjectSizeOffsetEvaluator &ObjSizeEval,
- BuilderTy &IRB, GetTrapBBT GetTrapBB,
- ScalarEvolution &SE) {
+/// Returns the condition under which the access will overflow.
+static Value *getBoundsCheckCond(Value *Ptr, Value *InstVal,
+ const DataLayout &DL, TargetLibraryInfo &TLI,
+ ObjectSizeOffsetEvaluator &ObjSizeEval,
+ BuilderTy &IRB, ScalarEvolution &SE) {
uint64_t NeededSize = DL.getTypeStoreSize(InstVal->getType());
LLVM_DEBUG(dbgs() << "Instrument " << *Ptr << " for " << Twine(NeededSize)
<< " bytes\n");
@@ -70,7 +66,7 @@ static bool instrumentMemAccess(Value *Ptr, Value *InstVal,
if (!ObjSizeEval.bothKnown(SizeOffset)) {
++ChecksUnable;
- return false;
+ return nullptr;
}
Value *Size = SizeOffset.first;
@@ -107,13 +103,23 @@ static bool instrumentMemAccess(Value *Ptr, Value *InstVal,
Or = IRB.CreateOr(Cmp1, Or);
}
+ return Or;
+}
+
+/// Adds run-time bounds checks to memory accessing instructions.
+///
+/// \p Or is the condition that should guard the trap.
+///
+/// \p GetTrapBB is a callable that returns the trap BB to use on failure.
+template <typename GetTrapBBT>
+static void insertBoundsCheck(Value *Or, BuilderTy IRB, GetTrapBBT GetTrapBB) {
// check if the comparison is always false
ConstantInt *C = dyn_cast_or_null<ConstantInt>(Or);
if (C) {
++ChecksSkipped;
// If non-zero, nothing to do.
if (!C->getZExtValue())
- return true;
+ return;
}
++ChecksAdded;
@@ -127,12 +133,11 @@ static bool instrumentMemAccess(Value *Ptr, Value *InstVal,
// FIXME: We should really handle this differently to bypass the splitting
// the block.
BranchInst::Create(GetTrapBB(IRB), OldBB);
- return true;
+ return;
}
// Create the conditional branch.
BranchInst::Create(GetTrapBB(IRB), Cont, Or, OldBB);
- return true;
}
static bool addBoundsChecking(Function &F, TargetLibraryInfo &TLI,
@@ -143,11 +148,25 @@ static bool addBoundsChecking(Function &F, TargetLibraryInfo &TLI,
// check HANDLE_MEMORY_INST in include/llvm/Instruction.def for memory
// touching instructions
- std::vector<Instruction *> WorkList;
+ SmallVector<std::pair<Instruction *, Value *>, 4> TrapInfo;
for (Instruction &I : instructions(F)) {
- if (isa<LoadInst>(I) || isa<StoreInst>(I) || isa<AtomicCmpXchgInst>(I) ||
- isa<AtomicRMWInst>(I))
- WorkList.push_back(&I);
+ Value *Or = nullptr;
+ BuilderTy IRB(I.getParent(), BasicBlock::iterator(&I), TargetFolder(DL));
+ if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
+ Or = getBoundsCheckCond(LI->getPointerOperand(), LI, DL, TLI,
+ ObjSizeEval, IRB, SE);
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(&I)) {
+ Or = getBoundsCheckCond(SI->getPointerOperand(), SI->getValueOperand(),
+ DL, TLI, ObjSizeEval, IRB, SE);
+ } else if (AtomicCmpXchgInst *AI = dyn_cast<AtomicCmpXchgInst>(&I)) {
+ Or = getBoundsCheckCond(AI->getPointerOperand(), AI->getCompareOperand(),
+ DL, TLI, ObjSizeEval, IRB, SE);
+ } else if (AtomicRMWInst *AI = dyn_cast<AtomicRMWInst>(&I)) {
+ Or = getBoundsCheckCond(AI->getPointerOperand(), AI->getValOperand(), DL,
+ TLI, ObjSizeEval, IRB, SE);
+ }
+ if (Or)
+ TrapInfo.push_back(std::make_pair(&I, Or));
}
// Create a trapping basic block on demand using a callback. Depending on
@@ -176,29 +195,14 @@ static bool addBoundsChecking(Function &F, TargetLibraryInfo &TLI,
return TrapBB;
};
- bool MadeChange = false;
- for (Instruction *Inst : WorkList) {
+ // Add the checks.
+ for (const auto &Entry : TrapInfo) {
+ Instruction *Inst = Entry.first;
BuilderTy IRB(Inst->getParent(), BasicBlock::iterator(Inst), TargetFolder(DL));
- if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
- MadeChange |= instrumentMemAccess(LI->getPointerOperand(), LI, DL, TLI,
- ObjSizeEval, IRB, GetTrapBB, SE);
- } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
- MadeChange |=
- instrumentMemAccess(SI->getPointerOperand(), SI->getValueOperand(),
- DL, TLI, ObjSizeEval, IRB, GetTrapBB, SE);
- } else if (AtomicCmpXchgInst *AI = dyn_cast<AtomicCmpXchgInst>(Inst)) {
- MadeChange |=
- instrumentMemAccess(AI->getPointerOperand(), AI->getCompareOperand(),
- DL, TLI, ObjSizeEval, IRB, GetTrapBB, SE);
- } else if (AtomicRMWInst *AI = dyn_cast<AtomicRMWInst>(Inst)) {
- MadeChange |=
- instrumentMemAccess(AI->getPointerOperand(), AI->getValOperand(), DL,
- TLI, ObjSizeEval, IRB, GetTrapBB, SE);
- } else {
- llvm_unreachable("unknown Instruction type");
- }
+ insertBoundsCheck(Entry.second, IRB, GetTrapBB);
}
- return MadeChange;
+
+ return !TrapInfo.empty();
}
PreservedAnalyses BoundsCheckingPass::run(Function &F, FunctionAnalysisManager &AM) {