ELF format question (might be wrong group)

[Chung-Ju Wu]

2013/8/22 Hendrik Greving <hendrik.greving.intel@gmail.com>:
> Does anybody know by any chance why, for x86, I am always getting LFB,
> LFE labels (function begin, function end), even when compiled without
> '-g'? I looked and only dwarf2out seems to write this. Why are there
> dwarf in every x86 .s file?
>

Because there is a common target hook defined in
gcc/common/config/i386/i386-common.c:

#define TARGET_EXCEPT_UNWIND_INFO  i386_except_unwind_info

where i386_except_unwind_info returns UI_DWARF2 in i386 port.
(DWARF2_UNWIND_INFO defaults to 1 in this case, see gcc/defaults.h)

Then how does UI_DWARF2 cause the situation you observed?
You can try to set breakpoints on:

  dwarf2out_do_cfi_asm()
  i386_except_unwind_info()
  dwarf2out_begin_prologue()
  dwarf2out_do_frame()

to see how it effects the flow in dwarf2out_begin_prologue().


Best regards,
jasonwucj