[PATCH] D56788: [DebugInfo][InstCombine] Prefer salvaging dbg.values over sinking them

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope added inline comments.


================
Comment at: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp:3122
+        Value *Undef = UndefValue::get(I->getType());
+        DII->setOperand(0, MetadataAsValue::get(DII->getContext(),
+                                                ValueAsMetadata::get(Undef)));
----------------
(post commit comment)
I see things like this in the IR after this:

  call void @llvm.dbg.value(metadata %foo * undef, metadata !2292, metadata !DIExpression(DW_OP_plus_uconst, 3, DW_OP_stack_value)), !dbg !2760

It doesn't fill any purpose to have a complicated DIExpression when being based on an undef value afaict.
Maybe we should strip away the DIExpression right away here, or what do you think? 


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56788/new/

https://reviews.llvm.org/D56788