[PATCH] D122258: [MC] Omit DWARF unwind info if compact unwind is present where eligible

[Mikael Holmén via Phabricator via cfe-commits]

uabelho added a comment.

Hi,

I noticed that on one of our downstream (not public) buildbots the

  clang/test/Driver/femit-dwarf-unwind.s

test seems to fail rather randomly.
So if I run

  clang -target x86_64-apple-macos11.0 -c ../clang/test/Driver/femit-dwarf-unwind.s -o foo.o
  llvm-objdump --macho --dwarf=frames foo.o

a couple of times I sometimes get

  .debug_frame contents:
  
  
  .eh_frame contents:

and sometimes I get

  .debug_frame contents:
  
  
  .eh_frame contents:
  
  00000000 00000014 00000000 CIE
    Format:                DWARF32
    Version:               1
    Augmentation:          "zR"
    Code alignment factor: 1
    Data alignment factor: -8
    Return address column: 16
    Augmentation data:     10
  
    DW_CFA_def_cfa: reg7 +8
    DW_CFA_offset: reg16 -8
    DW_CFA_nop:
    DW_CFA_nop:
  
    CFA=reg7+8: reg16=[CFA-8]
  
  00000018 0000001c 0000001c FDE cie=00000000 pc=00000000...00000001
    Format:       DWARF32
    DW_CFA_def_cfa_offset: +8
    DW_CFA_nop:
    DW_CFA_nop:
    DW_CFA_nop:
    DW_CFA_nop:
    DW_CFA_nop:
  
    0x0: CFA=reg7+8: reg16=[CFA-8]

On another machine I don't seem to get that problem though, even if I compile in the same way so I really don't know what the difference is or why it is happening at all.
Any ideas? Anything anyone else is seeing?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D122258/new/

https://reviews.llvm.org/D122258