| Message ID | 20121106.075813.150568568.kkojima@rr.iij4u.or.jp |
|---|---|
| State | New |
| Headers | show |
> 2012-11-05 Uros Bizjak <ubizjak@gmail.com> > Kaz Kojima <kkojima@gcc.gnu.org> > > PR target/41993 > * mode-switching.c (create_pre_exit): Set return_copy to > last_insn when copy_start is a pseudo reg. OK, thanks. The number of special cases dealt with in the function is on the verge of making it barely understandable though. Why couldn't a backward scan based only on: /* If the return register is not likely spilled, - as is the case for floating point on SH4 - then it might be set by an arithmetic operation that needs a different mode than the exit block. */ for (j = n_entities - 1; j >= 0; j--) { int e = entity_map[j]; int mode = MODE_NEEDED (e, return_copy); if (mode != num_modes[e] && mode != MODE_EXIT (e)) break; } (with a few shortcuts to speed it up) be sufficient?
Eric Botcazou <ebotcazou@adacore.com> wrote: > OK, thanks. The number of special cases dealt with in the function is on the > verge of making it barely understandable though. Why couldn't a backward scan > based only on: > > /* If the return register is not likely spilled, - as is > the case for floating point on SH4 - then it might > be set by an arithmetic operation that needs a > different mode than the exit block. */ > for (j = n_entities - 1; j >= 0; j--) > { > int e = entity_map[j]; > int mode = MODE_NEEDED (e, return_copy); > > if (mode != num_modes[e] && mode != MODE_EXIT (e)) > break; > } > > (with a few shortcuts to speed it up) be sufficient? Although I might be getting you wrong, the current code does a scan based on those lines but builtin_return, functions with no return value and exceptions require special treatments and made things complex. Regards, kaz
> Although I might be getting you wrong, the current code does a scan > based on those lines but builtin_return, functions with no return > value and exceptions require special treatments and made things > complex. I was referring to the ret_start/reg_end/nregs business: why is it necessary?
Eric Botcazou <ebotcazou@adacore.com> wrote:
> I was referring to the ret_start/reg_end/nregs business: why is it necessary?
I thought that they are for the return value which requires
multiple hard registers.
Regards,
kaz
On Mon, Nov 5, 2012 at 11:58 PM, Kaz Kojima <kkojima@rr.iij4u.or.jp> wrote: > The attached patch is to solve PR target/41993 which will affect > targets using MODE_EXIT. > Without it, we can't find all return registers for __builtin_return > in mode-switching.c:create_pre_exit. See the trail #4 by Uros in > the PR for the details. The patch is tested with bootstrap and > regtested on i686-pc-linux-gnu with no new failures. It's also > tested on cross sh4-unknown-linux-gnu. Attached patch adds the testcase from PR to the testsuite. 2012-11-06 Uros Bizjak <ubizjak@gmail.com> PR middle-end/41993 * gcc.dg/torture/pr41993.c: New test. Tested on x86_64-pc-linux-gnu {,-m32}, committed to mainline SVN. Uros. /* { dg-do compile } */ /* { dg-options "-mavx -mvzeroupper" { target { i?86-*-* x86_64-*-* } } } */ short retframe_short (void *rframe) { __builtin_return (rframe); }
--- ORIG/trunk/gcc/mode-switching.c 2012-11-05 08:07:55.000000000 +0900 +++ trunk/gcc/mode-switching.c 2012-11-05 19:22:56.000000000 +0900 @@ -324,7 +324,10 @@ create_pre_exit (int n_entities, int *en else break; if (copy_start >= FIRST_PSEUDO_REGISTER) - break; + { + last_insn = return_copy; + continue; + } copy_num = hard_regno_nregs[copy_start][GET_MODE (copy_reg)];