[PATCH] D127383: Don't treat readnone call in presplit coroutine as not access memory

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

Compile-time impact is low / acceptable: http://llvm-compile-time-tracker.com/compare.php?from=40a4078e14c2c6c5e2d0a1776285aa7491e791b3&to=d753f388d52778fff19b5a6d82a5b9c4869a4273&stat=instructions

I'm fine with this change, but I didn't follow the original discussion.



================
Comment at: llvm/docs/LangRef.rst:1943
+
+    Note that the readnone calls may access ``thread-id`` in a presplit coroutine.
 ``readonly``
----------------
Drop "the"


================
Comment at: llvm/lib/Analysis/BasicAliasAnalysis.cpp:778-780
+  if (Call->hasFnAttr(Attribute::ReadNone) &&
+      Call->getFunction()->isPresplitCoroutine())
+    return FMRB_OnlyReadsMemory;
----------------
ChuanqiXu wrote:
> This early return is necessary otherwise it would fall to the combine operation at line 804, which would return FMRB_DoesNotAccessMemory.
You mean the getModRefBehavior call on the function below? I think it may be better to guard that call instead.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D127383/new/

https://reviews.llvm.org/D127383