[PATCH] D128830: [Pipelines] Introduce DAE after ArgumentPromotion

Wed Aug 24 09:32:46 PDT 2022

dblaikie added a comment.

In D128830#3745031 <https://reviews.llvm.org/D128830#3745031>, @Michael137 wrote:

> FYI, this broke the LLDB build bot: https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/46324/execution/node/74/log/
>
> Looks like we're testing that inlined unused parameters display correctly...
>
>   AssertionError: '(void *) unused1 = <no location, value may have been optimized out>' not found in '(void *) unused1 = 0x000000016fdff4d0\n'
>
> But with this patch DWARF contains this extra entry for the unused parameter:
>
>   0x00000045:     DW_TAG_formal_parameter                                                                             
>                     DW_AT_location    (0x00000000:                                                                    
>                        [0x0000000100003f1c, 0x0000000100003f20): DW_OP_reg0 W0                                        
>                        [0x0000000100003f20, 0x0000000100003f24): DW_OP_entry_value(DW_OP_reg0 W0), DW_OP_stack_value) 
>                     DW_AT_abstract_origin (0x00000067 "unused1")
>
> whereas previously it was,
>
>   0x00000045:     DW_TAG_formal_parameter                       
>                     DW_AT_abstract_origin (0x00000061 "unused1")

Based on that debug info it looks like the patch might've improved things - the 'previous' description has no location, the new one has a location (if it's correct - is there evidence it's incorrect?)

What was the expected behavior of the test? What's the new behavior? Oh, I can read the assertion now.

The assertion was that there is no location - but now there is a location. That looks like a good thing?

> Maybe a flaw in the test? Any idea if this is a debug-info regression?

Repository:
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  https://reviews.llvm.org/D128830/new/

https://reviews.llvm.org/D128830