[Bug rtl-optimization/110867] ICE in combine after 7cdd0860949c6c3232e6cff1d7ca37bb5234074c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110867
--- Comment #2 from prathamesh3492 at gcc dot gnu.org ---
(In reply to Stefan Schulze Frielinghaus from comment #1)
> The optimization introduced by r14-2879-g7cdd0860949c6c hits during
> combination of insn
>
> (insn 31 3 32 2 (set (reg:SI 118 [ _1 ])
> (mem:SI (reg/v/f:SI 115 [ a ]) [1 *a_4(D)+0 S4 A64])) "t.c":15:7 758
> {*arm_movsi_vfp}
> (nil))
>
> and
>
> (insn 9 32 10 2 (set (reg:CC 100 cc)
> (compare:CC (reg:SI 118 [ _1 ])
> (const_int -2147483648 [0x8000]))) "t.c":15:6 272
> {*arm_cmpsi_insn}
> (nil))
>
> The idea of r14-2879-g7cdd0860949c6c is to get rid of large constants while
> performing an unsigned comparison. In this case it looks like a 32-bit
> constant is sign-extended into a 64-bit constant and then a 32-bit
> comparison is done. While writing the optimization I always assumed that
> the constant does fit into int_mode which is apparently not the case here.
> Thus one possible solution would be to simply bail out in those cases:
>
> diff --git a/gcc/combine.cc b/gcc/combine.cc
> index 0d99fa541c5..e46d202d0a7 100644
> --- a/gcc/combine.cc
> +++ b/gcc/combine.cc
> @@ -11998,11 +11998,15 @@ simplify_compare_const (enum rtx_code code,
> machine_mode mode,
> x0 >= 0x40. */
>if ((code == LEU || code == LTU || code == GEU || code == GTU)
>&& is_a (GET_MODE (op0), _mode)
> + && HWI_COMPUTABLE_MODE_P (int_mode)
>&& MEM_P (op0)
>&& !MEM_VOLATILE_P (op0)
>/* The optimization makes only sense for constants which are big
> enough
> so that we have a chance to chop off something at all. */
>&& (unsigned HOST_WIDE_INT) const_op > 0xff
> + /* Bail out, if the constant does not fit into INT_MODE. */
> + && (unsigned HOST_WIDE_INT) const_op
> +< ((HOST_WIDE_INT_1U << (GET_MODE_PRECISION (int_mode) - 1) << 1) -
> 1)
>/* Ensure that we do not overflow during normalization. */
>&& (code != GTU || (unsigned HOST_WIDE_INT) const_op <
> HOST_WIDE_INT_M1U))
> {
>
> Does this resolve the problem for you?
Yes, it worked thanks! I will do a full bootstrap+test with your fix and let
you know the results.
Thanks,
Prathamesh
[Bug rtl-optimization/110867] ICE in combine after 7cdd0860949c6c3232e6cff1d7ca37bb5234074c
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110867
Stefan Schulze Frielinghaus changed:
What|Removed |Added
CC||stefansf at linux dot ibm.com
--- Comment #1 from Stefan Schulze Frielinghaus
---
The optimization introduced by r14-2879-g7cdd0860949c6c hits during combination
of insn
(insn 31 3 32 2 (set (reg:SI 118 [ _1 ])
(mem:SI (reg/v/f:SI 115 [ a ]) [1 *a_4(D)+0 S4 A64])) "t.c":15:7 758
{*arm_movsi_vfp}
(nil))
and
(insn 9 32 10 2 (set (reg:CC 100 cc)
(compare:CC (reg:SI 118 [ _1 ])
(const_int -2147483648 [0x8000]))) "t.c":15:6 272
{*arm_cmpsi_insn}
(nil))
The idea of r14-2879-g7cdd0860949c6c is to get rid of large constants while
performing an unsigned comparison. In this case it looks like a 32-bit
constant is sign-extended into a 64-bit constant and then a 32-bit comparison
is done. While writing the optimization I always assumed that the constant
does fit into int_mode which is apparently not the case here. Thus one
possible solution would be to simply bail out in those cases:
diff --git a/gcc/combine.cc b/gcc/combine.cc
index 0d99fa541c5..e46d202d0a7 100644
--- a/gcc/combine.cc
+++ b/gcc/combine.cc
@@ -11998,11 +11998,15 @@ simplify_compare_const (enum rtx_code code,
machine_mode mode,
x0 >= 0x40. */
if ((code == LEU || code == LTU || code == GEU || code == GTU)
&& is_a (GET_MODE (op0), _mode)
+ && HWI_COMPUTABLE_MODE_P (int_mode)
&& MEM_P (op0)
&& !MEM_VOLATILE_P (op0)
/* The optimization makes only sense for constants which are big enough
so that we have a chance to chop off something at all. */
&& (unsigned HOST_WIDE_INT) const_op > 0xff
+ /* Bail out, if the constant does not fit into INT_MODE. */
+ && (unsigned HOST_WIDE_INT) const_op
+< ((HOST_WIDE_INT_1U << (GET_MODE_PRECISION (int_mode) - 1) << 1) - 1)
/* Ensure that we do not overflow during normalization. */
&& (code != GTU || (unsigned HOST_WIDE_INT) const_op <
HOST_WIDE_INT_M1U))
{
Does this resolve the problem for you?
