================
@@ -1078,22 +1092,44 @@ void
ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
Store->setNoSanitizeMetadata();
}
if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
- // Check stack depth. If it's the deepest so far, record it.
Module *M = F.getParent();
- auto FrameAddrPtr = IRB.CreateIntrinsic(
- Intrinsic::frameaddress,
- IRB.getPtrTy(M->getDataLayout().getAllocaAddrSpace()),
- {Constant::getNullValue(Int32Ty)});
- auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
- auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
- auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
- auto ThenTerm = SplitBlockAndInsertIfThen(
- IsStackLower, &*IP, false,
- MDBuilder(IRB.getContext()).createUnlikelyBranchWeights());
- IRBuilder<> ThenIRB(ThenTerm);
- auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
- LowestStack->setNoSanitizeMetadata();
- Store->setNoSanitizeMetadata();
+ if (Options.StackDepthCallbackMin) {
+ // In callback mode, only add call when stack depth reaches minimum.
+ const DataLayout &DL = M->getDataLayout();
+ uint32_t EstimatedStackSize = 0;
+
+ // Make an estimate on the stack usage.
+ for (auto &I : F.getEntryBlock()) {
+ if (auto *AI = dyn_cast<AllocaInst>(&I)) {
+ if (AI->isStaticAlloca()) {
+ uint32_t TypeSize = DL.getTypeAllocSize(AI->getAllocatedType());
+ EstimatedStackSize += TypeSize;
+ } else {
+ // Over-estimate dynamic sizes.
+ EstimatedStackSize += 4096;
----------------
melver wrote:
This just seems too arbitrary. Can we do something more reliable? Because if
this is used beyond the kernel (where we shouldn't even have all that many VLAs
or dynamic allocas left - right?), it's anyone's guess if 4K is even a generous
over estimation.
I see several options:
- Make this a cl::opt and not a hard-coded constant. The default should be much
larger (8 MiB?), so that even we can't accurately calculate stack size we
always get a callback.
- Just give up if we found a dynamic alloca, and always do the callback.
https://github.com/llvm/llvm-project/pull/138323
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