Hi! This patch is just a partial fix, combine.c has lots of other code that was written before vector modes were introduced and won't work well with them.
The patch also uses ? x : const_true_rtx rather than ? CONSTM1_RTX (GET_MODE (x)) : const_true_rtx or some new CONST_TRUE_RTX (GET_MODE (x)), so that it is backportable, that can be changed on the trunk incrementally. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk and release branches? 2018-08-27 Jakub Jelinek <ja...@redhat.com> PR rtl-optimization/87065 * combine.c (simplify_if_then_else): Formatting fix. (if_then_else_cond): Guard MULT optimization with SCALAR_INT_MODE_P check. (known_cond): Don't return const_true_rtx for vector modes. Use CONST0_RTX instead of const0_rtx. Formatting fixes. * gcc.target/i386/pr87065.c: New test. --- gcc/combine.c.jj 2018-08-26 22:42:24.053753908 +0200 +++ gcc/combine.c 2018-08-27 08:58:26.867124011 +0200 @@ -6495,7 +6495,7 @@ simplify_if_then_else (rtx x) pc_rtx, pc_rtx, 0, 0, 0); if (reg_mentioned_p (from, false_rtx)) false_rtx = subst (known_cond (copy_rtx (false_rtx), false_code, - from, false_val), + from, false_val), pc_rtx, pc_rtx, 0, 0, 0); SUBST (XEXP (x, 1), swapped ? false_rtx : true_rtx); @@ -9335,6 +9335,7 @@ if_then_else_cond (rtx x, rtx *ptrue, rt if (COMPARISON_P (cond0) && COMPARISON_P (cond1) + && SCALAR_INT_MODE_P (mode) && ((GET_CODE (cond0) == reversed_comparison_code (cond1, NULL) && rtx_equal_p (XEXP (cond0, 0), XEXP (cond1, 0)) && rtx_equal_p (XEXP (cond0, 1), XEXP (cond1, 1))) @@ -9515,12 +9516,12 @@ known_cond (rtx x, enum rtx_code cond, r if (COMPARISON_P (x)) { if (comparison_dominates_p (cond, code)) - return const_true_rtx; + return VECTOR_MODE_P (GET_MODE (x)) ? x : const_true_rtx; code = reversed_comparison_code (x, NULL); if (code != UNKNOWN && comparison_dominates_p (cond, code)) - return const0_rtx; + return CONST0_RTX (GET_MODE (x)); else return x; } @@ -9563,7 +9564,7 @@ known_cond (rtx x, enum rtx_code cond, r /* We must simplify subreg here, before we lose track of the original inner_mode. */ new_rtx = simplify_subreg (GET_MODE (x), r, - inner_mode, SUBREG_BYTE (x)); + inner_mode, SUBREG_BYTE (x)); if (new_rtx) return new_rtx; else @@ -9588,7 +9589,7 @@ known_cond (rtx x, enum rtx_code cond, r /* We must simplify the zero_extend here, before we lose track of the original inner_mode. */ new_rtx = simplify_unary_operation (ZERO_EXTEND, GET_MODE (x), - r, inner_mode); + r, inner_mode); if (new_rtx) return new_rtx; else --- gcc/testsuite/gcc.target/i386/pr87065.c.jj 2018-08-27 08:46:16.302406144 +0200 +++ gcc/testsuite/gcc.target/i386/pr87065.c 2018-08-27 08:50:37.179025375 +0200 @@ -0,0 +1,22 @@ +/* PR rtl-optimization/87065 */ +/* { dg-do compile } */ +/* { dg-options "-O3 -mxop -mprefer-vector-width=128" } */ + +int a, c, d, e; +short *b; + +void +foo (void) +{ + short *g = b; + int h = 1; + unsigned i; + for (; h <= 1; h++) + g = (short *) &c; + for (; c; c++) + { + for (; i <= 1; i++) + ; + a ^= (a > 0 <= i) + ((e += d) == 0 ?: (*g = 8)); + } +} Jakub