Hi!
ubsan/overflow-1.c test ICEs on ppc32, because lopart is SImode, and we
attempt to do a DImode left shift on it by 32.
We don't really care about the upper bits, those are all shifted away
anyway, so this patch fixes it by adding a paradoxical SUBREG, which results
in better generated code compared to e.g. adding there a ZERO_EXTEND.
Bootstrapped/regtested on x86_64-linux and i686-linux, additionally tested
with ubsan tests on x86_64 and i686 with the add/sub/mul/neg with overflow
patterns disabled and tested using ppc* cross on overflow-1.c.
Ok for trunk?
2014-02-04 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 = gen_rtx_SUBREG (mode, lopart, 0);
+ 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
