On 01/01/2014 06:23 AM, Jan Hubicka wrote:
> last_sp_adjust = 0;
> + /* We no longer adjust stack size. Whoever adjusted it earlier
> + hopefully got the note right. */
> + note = find_reg_note (insn, REG_ARGS_SIZE, NULL_RTX);
> + if (note)
> + remove_note (insn, note);
> continue;
This is a totally unfounded hope, by the way. I'm certain that I tried this
the first time around, with similarly poor results.
See the g++.dg/opt/pr52727.C test case that fails with this patch. I can only
assume you didn't examine i686 test results when you committed this?
The problem is that the last adjustment _did_ apply the correct note
adjustment, for the stack at that time. But neither moving the note nor
dropping the note is correct.
Consider
// args_size 4
add $4, %esp // args_size 0
push %eax // no note; fpu, not call related
transformed by csa to
mov %eax, (%esp)
If we move the note from the add to the mov, as we did prior to your patch, we
retain the essence of the pop, that we're no longer queueing arguments. But if
we drop the note, as we do with your patch, then we still believe that we have
4 bytes of arguments on the stack.
You say a bootstrap with Go was the testcase that sent you in this direction?
I'll have a look...
r~
