[PATCH] D55519: Reuse code from CGDebugInfo::getOrCreateFile() when creating the file for the DICompileUnit

[Pavel Labath via Phabricator via llvm-commits]

labath added a comment.

I am sorry about the late notice Adrian, but it looks like this patch completely breaks DWO file lookup. I think the search for the common prefix of compilation directory and file path is somehow broken. For example this is what I get when compiling a file from `/tmp` with PWD=/home/pavel (so, these paths only share `/` as a prefix):

  ~ $ /tmp/clang.bad  -g -gsplit-dwarf  -c -o foo.o /tmp/foo.cpp 
  ~ $ llvm-dwarfdump foo.o 
  foo.o:	file format ELF64-x86-64
  
  .debug_info contents:
  0x00000000: Compile Unit: length = 0x0000001c version = 0x0004 abbr_offset = 0x0000 addr_size = 0x08 (next unit at 0x00000020)
  
  0x0000000b: DW_TAG_compile_unit
                DW_AT_stmt_list	(0x00000000)
                DW_AT_GNU_dwo_name	("foo.dwo")
                DW_AT_GNU_pubnames	(true)
                DW_AT_GNU_dwo_id	(0x441cbc2aa7bff7c5)
                DW_AT_GNU_addr_base	(0x00000000)

Notice that `DW_AT_comp_dir` is completely missing (so the debugger has no chance of finding the dwo file). If I revert this (and r348866) then I get correct behavior:

  ~ $ /tmp/clang.good  -g -gsplit-dwarf  -c -o foo.o /tmp/foo.cpp 
  ~ $ llvm-dwarfdump foo.o 
  foo.o:	file format ELF64-x86-64
  
  .debug_info contents:
  0x00000000: Compile Unit: length = 0x00000020 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x08 (next unit at 0x00000024)
  
  0x0000000b: DW_TAG_compile_unit
                DW_AT_stmt_list	(0x00000000)
                DW_AT_GNU_dwo_name	("foo.dwo")
                DW_AT_comp_dir	("/home/pavel")
                DW_AT_GNU_pubnames	(true)
                DW_AT_GNU_dwo_id	(0x441cbc2aa7bff7c5)
                DW_AT_GNU_addr_base	(0x00000000)

If I run the same command from `/tmp` then I get the correct compilation directory, no matter which clang I use:

  /tmp $ /tmp/clang.bad  -g -gsplit-dwarf  -c -o foo.o /tmp/foo.cpp 
  /tmp $ llvm-dwarfdump foo.o 
  foo.o:	file format ELF64-x86-64
  
  .debug_info contents:
  0x00000000: Compile Unit: length = 0x00000020 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x08 (next unit at 0x00000024)
  
  0x0000000b: DW_TAG_compile_unit
                DW_AT_stmt_list	(0x00000000)
                DW_AT_GNU_dwo_name	("foo.dwo")
                DW_AT_comp_dir	("/tmp")
                DW_AT_GNU_pubnames	(true)
                DW_AT_GNU_dwo_id	(0xfc9fc3a6ed2d6bbb)
                DW_AT_GNU_addr_base	(0x00000000)

Could you please check this out?

Thank you.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D55519/new/

https://reviews.llvm.org/D55519