[PATCH] D92270: [ConstantFold] Fold more operations to poison

Wed Jan 6 16:02:27 PST 2021

aqjune added a comment.

In D92270#2482741 <https://reviews.llvm.org/D92270#2482741>, @thakis wrote:

> We bisected a test failure to this (https://bugs.chromium.org/p/angleproject/issues/detail?id=5500#c17). Can you expand a bit on what this patch means in practice? I'm guessing it makes UB in C++ code have bad effects more often? If so, what type of UB?

This patch makes the result of erroneous operations in source to participate in constant folding in more eager manner.
BTW, I am aware that this patch interacts with existing old (but hard to fix) bug in LLVM and miscompiles codes in certain code that has conditional branch + shifts. https://bugs.llvm.org/show_bug.cgi?id=48353 has more context.
Do you think your bug is related to this bug report?

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D92270/new/

https://reviews.llvm.org/D92270