smeenai added inline comments.
================
Comment at: llvm/lib/Transforms/Instrumentation/BoundsChecking.cpp:189
auto GetTrapBB = [&TrapBB](BuilderTy &IRB) {
- if (TrapBB && SingleTrapBB)
- return TrapBB;
-
- Function *Fn = IRB.GetInsertBlock()->getParent();
- // FIXME: This debug location doesn't make a lot of sense in the
- // `SingleTrapBB` case.
- auto DebugLoc = IRB.getCurrentDebugLocation();
- IRBuilder<>::InsertPointGuard Guard(IRB);
- TrapBB = BasicBlock::Create(Fn->getContext(), "trap", Fn);
- IRB.SetInsertPoint(TrapBB);
-
- auto *F = Intrinsic::getDeclaration(Fn->getParent(), Intrinsic::trap);
- CallInst *TrapCall = IRB.CreateCall(F, {});
- TrapCall->setDoesNotReturn();
- TrapCall->setDoesNotThrow();
- TrapCall->setDebugLoc(DebugLoc);
- IRB.CreateUnreachable();
-
+ if (DebugTrapBB) {
+ Function *Fn = IRB.GetInsertBlock()->getParent();
----------------
oskarwirga wrote:
> nlopes wrote:
> > this seems like code duplication. This pass already has the single-trap
> > flag to exactly control if you get a single trap BB or one per check for
> > better debug info.
> Unfortunately, even with the single trap flag it gets optimized out in later
> passes because the machine code emitted is the exact same
I believe we end up tail merging the trap instructions. A previous iteration of
this patch attempted to use the `nomerge` attribute to directly avoid the tail
merging, but that only works for function calls, not for the `trap` instruction
ultimately emitted here.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D148654/new/
https://reviews.llvm.org/D148654
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