[PATCH] D48277: [DebugInfo] Keep DBG_VALUE undef in LiveDebugVariables

[Mikael Holmén via Phabricator via llvm-commits]

uabelho created this revision.
uabelho added a reviewer: aprantl.
Herald added a subscriber: JDevlieghere.

[DebugInfo] Keep DBG_VALUE undef in LiveDebugVariables

Fixes PR36579.

For cases where we had e.g.

DBG_VALUE 42
 [...]
 DBG_VALUE undef

LiveDebugVariables would discard all undef DBG_VALUEs and then it would
look like the variable had the value 42 throughout the rest of the
function, which is incorrect.

With this patch we don't remove all undef DBG_VALUEs in LiveDebugVariables
so they will be kept after register allocation just like other DBG_VALUEs
which will yield more correct debug information.


https://reviews.llvm.org/D48277

Files:
  lib/CodeGen/LiveDebugVariables.cpp
  test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
  test/DebugInfo/X86/live-debug-vars-keep-undef.ll

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