Comment 10 for bug 440172

Put this in main.c and build it with a 4.4-branch compiler using recent binutils:

int main ()
{
  return 0;
}

Versions:

GNU assembler (GNU Binutils) 2.19.51.20090611
i686-pc-linux-gnu-gcc (GCC) 4.4.1 20090611 (prerelease)

% i686-pc-linux-gnu-gcc -c main.c; objdump --wide -h main.o | grep ALLOC
  0 .text 0000000a 00000000 00000000 00000034 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .data 00000000 00000000 00000000 00000040 2**2 CONTENTS, ALLOC, LOAD, DATA
  2 .bss 00000000 00000000 00000000 00000040 2**2 ALLOC

% i686-pc-linux-gnu-gcc -c -g main.c; objdump --wide -h main.o | grep ALLOC
  0 .text 0000000a 00000000 00000000 00000034 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .data 00000000 00000000 00000000 00000040 2**2 CONTENTS, ALLOC, LOAD, DATA
  2 .bss 00000000 00000000 00000000 00000040 2**2 ALLOC
 12 .eh_frame 00000034 00000000 00000000 000001c0 2**2 CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA

We're using GAS's .cfi_startproc et cetera directives to generate debug information. But they only generate .eh_frame, not .debug_frame.

I also noticed this problem on an ARM EABI target. ARM EABI does not use .eh_frame, only .debug_frame and .ARM.exidx.

The easiest fix is to disable use of the CFI directives when we are trying to generate .debug_frame. I believe GCC used to generate both .debug_frame and .eh_frame for the same function. If we want both to gain the advantages of using CFI directives (e.g. potentially accurate across inline asm), then we need to teach gas to emit .debug_frame/.eh_frame/both as requested.