https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65871
--- Comment #11 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Uroš Bizjak from comment #10)
> Because of the cost model. Combine pass says:
Testing the patch:
--cut here--
Index: i386.c
===================================================================
--- i386.c (revision 224630)
+++ i386.c (working copy)
@@ -42533,6 +42533,12 @@ ix86_rtx_costs (rtx x, int code_i, int outer_code_
+ rtx_cost (const1_rtx, outer_code, opno, speed));
return true;
}
+
+ /* The embedded comparison operand is completely free. */
+ if (!general_operand (XEXP (x, 0), GET_MODE (XEXP (x, 0)))
+ && XEXP (x, 1) == const0_rtx)
+ *total = 0;
+
return false;
case FLOAT_EXTEND:
--cut here--
