[all-commits] [llvm/llvm-project] 0a7ff0: [Coroutines] Don't transform cmpinst prematurely i...

[Chuanqi Xu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0a7ff0960e33b6b27961afa5cbb7dd9eb4f1a283
      https://github.com/llvm/llvm-project/commit/0a7ff0960e33b6b27961afa5cbb7dd9eb4f1a283
  Author: Chuanqi Xu <yedeng.yd at linux.alibaba.com>
  Date:   2023-06-30 (Fri, 30 Jun 2023)

  Changed paths:
    M llvm/lib/Transforms/Coroutines/CoroSplit.cpp
    A llvm/test/Transforms/Coroutines/coro-split-musttail12.ll

  Log Message:
  -----------
  [Coroutines] Don't transform cmpinst prematurely in simplifyTerminatorLeadingToRet

Previously, we would try to transform cmpinst in
simplifyTerminatorLeadingToRet if we found it was a constant. However,
this is incorrect.

Since the resolved constants in simplifyTerminatorLeadingToRet are not
truely constants. They are basically constants along cerntain code
paths.

In this way, it is clearly incorrect to transform the compare
instruction to a constant.

It will cause confusing miscompilations. This patch tries to fix this.