[all-commits] [llvm/llvm-project] f9ac16: [DebugInfo][InstrRef] Fix error in copy handling i...

[Stephen Tozer via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f9ac161af9d9c3af03cda25497a7280f51fd92ac
      https://github.com/llvm/llvm-project/commit/f9ac161af9d9c3af03cda25497a7280f51fd92ac
  Author: Stephen Tozer <stephen.tozer at sony.com>
  Date:   2022-07-11 (Mon, 11 Jul 2022)

  Changed paths:
    M llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
    A llvm/test/DebugInfo/X86/instr-ref-track-clobbers.mir

  Log Message:
  -----------
  [DebugInfo][InstrRef] Fix error in copy handling in InstrRefLDV

Currently, an error exists when InstrRefBasedLDV observes transfers of
variables across copies, which causes it to lose track of variables
under certain circumstances, resulting in shorter lifetimes for those
variables as LDV gives up searching for live locations for them. This
patch fixes this issue by storing the currently tracked values in
the destination first, then updating them manually later without
clobbering or assigning them the wrong value.

Differential Revision: https://reviews.llvm.org/D128101