On Thu, Feb 06, 2014 at 08:27:09AM -0800, Richard Henderson wrote:
> > All I know is that the generated code with the ZERO_EXTEND has been larger
> > than with the paradoxical subreg. But if you prefer, I can surely emit a
> > ZERO_EXTEND and open a PR for GCC 5.0 that we should investigate why we
> > generate worse code then.
>
> Yes please.
Ok, I'll retest this before committing then:
2014-02-06 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/60030
* internal-fn.c (ubsan_expand_si_overflow_mul_check): Surround
lopart with paradoxical subreg before shifting it up by hprec.
--- gcc/internal-fn.c.jj 2014-01-29 12:43:24.000000000 +0100
+++ gcc/internal-fn.c 2014-02-03 10:40:57.000000000 +0100
@@ -646,7 +646,8 @@ ubsan_expand_si_overflow_mul_check (gimp
emit_cmp_and_jump_insns (hipart, const0_rtx, GE, NULL_RTX, hmode,
false, after_hipart_neg, PROB_EVEN);
- tem = expand_shift (LSHIFT_EXPR, mode, lopart, hprec, NULL_RTX, 1);
+ tem = convert_modes (mode, hmode, lopart, 1);
+ tem = expand_shift (LSHIFT_EXPR, mode, tem, hprec, NULL_RTX, 1);
tem = expand_simple_binop (mode, MINUS, loxhi, tem, NULL_RTX,
1, OPTAB_DIRECT);
emit_move_insn (loxhi, tem);
Jakub
