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[Sanitizers] Add metadata to memsets created in zeroInit for LLDB #85558

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[Sanitizers] Add metadata to memsets created in zeroInit for LLDB #85558

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16 changes: 13 additions & 3 deletions lib/IRGen/IRGenSIL.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -746,9 +746,19 @@ class IRGenSILFunction :
getEarliestInsertionPoint()->getIterator());
// No debug location is how LLVM marks prologue instructions.
ZeroInitBuilder.SetCurrentDebugLocation(nullptr);
ZeroInitBuilder.CreateMemSet(
AI, llvm::ConstantInt::get(IGM.Int8Ty, 0),
Size, llvm::MaybeAlign(AI->getAlign()));
// note that this memset is before lifetime.start which is Undefined
// Behaviour in LLVM
llvm::CallInst *Memset =
ZeroInitBuilder.CreateMemSet(AI, llvm::ConstantInt::get(IGM.Int8Ty, 0),
Size, llvm::MaybeAlign(AI->getAlign()));

// memtag-stack tagging needs to use this metadata to determine whether to
// delay tagging until after the memset. This can be removed if the memset
// is removed or moved after the lifetime.start
llvm::LLVMContext *Ctx = &Memset->getContext();
llvm::MDNode *Meta =
llvm::MDNode::get(*Ctx, llvm::MDString::get(*Ctx, "true"));
Memset->setMetadata("Swift.isSwiftLLDBpreinit", Meta);
}

/// Try to emit an inline assembly gadget which extends the lifetime of
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