Re: [PATCH][optabs] PR63442 libgcc_cmp_return_mode not always return word_mode

[Jiong Wang <jiong dot wang at arm dot com>]

On 24/10/14 19:41, Jeff Law wrote:
> On 10/24/14 08:09, Jiong Wang wrote:
> > ping~
> >
> > thanks.
> >
> > Regards,
> > Jiong
> >
> > On 17/10/14 13:04, Jiong Wang wrote:
> > > the cause should be one minor bug in prepare_cmp_insn.
> > >
> > > the last mode parameter "pmode" of "prepare_cmp_insn" should match the
> > > mode of the first parameter "x", while during the recursive call of
> > > "prepare_cmp_insn",
> > > x is with mode of targetm.libgcc_cmp_return_mode () and pmode is
> > > assign to word_mode.
> > >
> > > generally this is OK, because default libgcc_cmp_return_mode hook
> > > always return word_mode,
> > > but AArch64 has a target private implementation which always return
> > > SImode, so there is a
> > > mismatch which cause a ICE later.
> > >
> > > this minor issue is hidding because nearly all other targets use
> > > default hook, and the
> > > compare is rarely invoked.
> > >
> > > Thanks
> > >
> > > gcc/
> > >      PR target/63442
> > >      * optabs.c (prepare_cmp_insn): Use target hook
> > > "libgcc_cmp_return_mode" instead of word_mode.
> This is fine once you have run it through a bootstrap and regression test.
>
> Any reason not to use RET_MODE since that's already set up with the
> result of the target hook?

Ah, it's better to reuse ret_mode, thanks for your carefulness.

patch updated, bootstrapping OK on x86-64 (--enable-languages=c,c++), no regression. (on top of 216667 which is nearly up-to-date)

ok for trunk?

gcc/
  PR target/63442
  * optabs.c (prepare_cmp_insn): Use "ret_mode" instead of "word_mode".

diff --git a/gcc/optabs.c b/gcc/optabs.c
index 2df84d2..ed415fa 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -4270,7 +4270,7 @@ prepare_cmp_insn (rtx x, rtx y, enum rtx_code comparison, rtx size,
 	    y = const0_rtx;
 	}
 
-      *pmode = word_mode;
+      *pmode = ret_mode;
       prepare_cmp_insn (x, y, comparison, NULL_RTX, unsignedp, methods,
 			ptest, pmode);
     }