[PATCH] D83495: [DebugInfo] Add DWARF emission for DBG_VALUE_LIST

[Stephen Tozer via Phabricator via llvm-commits]

StephenTozer marked an inline comment as done.
StephenTozer added inline comments.


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Comment at: llvm/test/DebugInfo/X86/dbg_value_list_emission.mir:63
+    ; (3) Check that multiple references to one reg arg works.
+    ;     XXX What was the consensus on this - are we allowing it?
+    DBG_VALUE_LIST !25, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 0, DW_OP_minus, DW_OP_stack_value), $eax, debug-location !15
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Orlando wrote:
> Can remove this XXX note. As you mentioned offline, having multiple references to the same arg (i.e. multiple `DW_OP_LLVM_arg, 0` in the expr) is never a problem.
> 
> Though, slightly tangentially, I'm still a little unclear on what the final decision was on how to handle duplicate register arg operands. In D82363 you said 'always treat DBG_VALUE_LISTs as potentially having them'. Please could you explain a little further? (i.e. is it an error state, do we need to add extra checks when dealing with DBG_VALUE_LISTs etc).
It is not an error state, just a slightly more inconvenient form than one without duplicates. It requires some extra work in a few places (operating on a vector instead of a single pointer), but there is no reason for it to be invalid.


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