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

[Jiong Wang]

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);
     }