[PATCH] D58453: [DebugInfo][CGP] Limit placeDbgValues movement of dbg.value intrinsics

[Jeremy Morse via Phabricator via llvm-commits]

jmorse updated this revision to Diff 209508.
jmorse added a comment.

I've added some changes to the patch that makes collectDebugValues behave in the way I described, returning all debug users of a VReg, optionally limited to only the basic block of the source MachineInst. This should be useful for testing; and it's immediately caused the test/DebugInfo/WebAssembly/dbg-value-move-reg-stackify.mir [0] test to fail. The output is:

  %0:i64 = ARGUMENT_i64 0, implicit $arguments
  dead %1:i32 = I32_WRAP_I64 %0, implicit-def dead $arguments
  dead %1:i32 = CALL_i32 @bar, implicit-def dead $arguments, implicit $sp32, implicit $sp64
  %2:i32 = CALL_i32 @bar, implicit-def dead $arguments, implicit $sp32, implicit $sp64, implicit-def $value_stack, implicit $value_stack
  DBG_VALUE %2, $noreg, <0x5490d00>, !DIExpression(), debug-location !DILocation(line: 359, column: 12, scope: <0x548f5f0>)
  DBG_VALUE %2, $noreg, <0x5490cb0>, !DIExpression(), debug-location !DILocation(line: 358, column: 12, scope: <0x548f5f0>)
  DBG_VALUE %2, $noreg, <0x5490a50>, !DIExpression(), debug-location !DILocation(line: 357, column: 12, scope: <0x548f5f0>)
  CALL_VOID @foo, %2, implicit-def dead $arguments, implicit $sp32, implicit $sp64, implicit-def $value_stack, implicit $value_stack
  RETURN_VOID implicit-def dead $arguments

While I don't know webassembly, it seems clear that a) the test post-SSA, and b) the test expects collectDebugValues to only return DBG_VALUEs that refer to the same vreg def that the source instruction does.

Is that a fair assessment, or some kind of test artefact? That behaviour is almost certainly achievable after this patch lands, although it might require more plumbing somewhere.

[0] https://github.com/llvm/llvm-project/blob/a1d97a960e622ee21550d92809512cb0870be499/llvm/test/DebugInfo/WebAssembly/dbg-value-move-reg-stackify.mir


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D58453/new/

https://reviews.llvm.org/D58453

Files:
  include/llvm/CodeGen/MachineInstr.h
  lib/CodeGen/CodeGenPrepare.cpp
  lib/CodeGen/MachineInstr.cpp
  test/DebugInfo/COFF/register-variables.ll
  test/DebugInfo/NVPTX/debug-info.ll
  test/DebugInfo/X86/PR37234.ll

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