[all-commits] [llvm/llvm-project] 5b3776: [FunctionAttrs] Account for memory effects of inal...

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 5b3776842f8e14b70199c0f76773b2af1cf32d34
      https://github.com/llvm/llvm-project/commit/5b3776842f8e14b70199c0f76773b2af1cf32d34
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2022-10-13 (Thu, 13 Oct 2022)

  Changed paths:
    M llvm/lib/Transforms/IPO/FunctionAttrs.cpp
    M llvm/test/Transforms/FunctionAttrs/readattrs.ll

  Log Message:
  -----------
  [FunctionAttrs] Account for memory effects of inalloca/preallocated

The code for inferring memory attributes on arguments claims that
inalloca/preallocated arguments are always clobbered:
https://github.com/llvm/llvm-project/blob/d71ad4108056d685f48407447095d8d92fd7685d/llvm/lib/Transforms/IPO/FunctionAttrs.cpp#L640-L642

However, we would still infer memory attributes for the whole
function without taking this into account, so we could still end
up inferring readnone for the function. This adds an argument
clobber if there are any inalloca/preallocated arguments.

Differential Revision: https://reviews.llvm.org/D135783