================
@@ -1078,22 +1091,61 @@ 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();
+
+ // Find an insertion point after last "alloca".
+ llvm::Instruction *InsertBefore = NULL;
+ for (auto &I : BB) {
+ if (llvm::isa<llvm::AllocaInst>(I))
+ InsertBefore = I.getNextNode(); // Move past the "alloca".
+ }
+ // But only use it if we actually found an "alloca".
+ if (InsertBefore)
+ IRB.SetInsertPoint(InsertBefore);
+
+ 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 : BB) {
+ if (auto *AI = dyn_cast<AllocaInst>(&I)) {
+ if (AI->isStaticAlloca()) {
+ uint32_t Bytes = DL.getTypeAllocSize(AI->getAllocatedType());
+ if (AI->isArrayAllocation()) {
+ if (const ConstantInt *arraySize =
+ dyn_cast<ConstantInt>(AI->getArraySize()))
+ Bytes *= arraySize->getZExtValue();
+ }
+ EstimatedStackSize += Bytes;
----------------
kees wrote:
I think you're asking why I can't use Intrinsic::frameaddress in the callback
case? (This is what the `__sancov_lowest_stack` mode does.) At this point the
actual size of the stack space is unknown (since it hasn't gone through
CodeGen). We need to know this early to minimize the number of places where
instrumentation is happening. So to estimate how much space is in use, this
manually adds it up to decide whether or not to insert the callback call. (In
the `__sancov_lowest_stack` mode, the instrumentation is _always_ added.)
https://github.com/llvm/llvm-project/pull/138323
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