[all-commits] [llvm/llvm-project] 32417b: [DebugInfo] ValueMapper impl for DIArgList respect...

[Stephen Tozer via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 32417b32033925b26b3695b753b38fbc6fdcd93d
      https://github.com/llvm/llvm-project/commit/32417b32033925b26b3695b753b38fbc6fdcd93d
  Author: Stephen Tozer <stephen.tozer at sony.com>
  Date:   2022-01-17 (Mon, 17 Jan 2022)

  Changed paths:
    M llvm/lib/Transforms/Utils/ValueMapper.cpp
    A llvm/test/Linker/debug-info-use-before-def.ll
    M llvm/unittests/Transforms/Utils/ValueMapperTest.cpp

  Log Message:
  -----------
  [DebugInfo] ValueMapper impl for DIArgList respects IgnoreMissingLocals

This patch fixes an issue in which SSA value reference within a
DIArgList would be unnecessarily dropped by llvm-link, even when
invoking on a single file (which should be a no-op). The reason for the
difference is that the ValueMapper does not refer to the
RF_IgnoreMissingLocals flag for LocalAsMetadata contained within a
DIArgList; this flag is used for direct LocalAsMetadata uses to preserve
SSA references even when the ValueMapper does not have an explicit
mapping for the referenced SSA value, which appears to always be the
case when using llvm-link in this manner.

Differential Revision: https://reviews.llvm.org/D114355