[PATCH, ifcvt] Allow CC mode if HAVE_cbranchcc4 (fix s390 build)

["Zhenqiang Chen" <zhenqiang dot chen at arm dot com>]

Hi,

The patch add runtime check to fix s390 build fail
(https://gcc.gnu.org/ml/gcc-patches/2014-11/msg00050.html).

And there is additional code to workaround s390 cstorecc4 issue.

Bootstrap and no make check regression on X86-64.
Build s390-linux-gnu and s390x-linux-gnu.

I do not have env to run full s390 tests. Would anyone in the TO list help
to run the s390 tests?

Thanks!
-Zhenqiang

ChangeLog:
2014-11-06  Zhenqiang Chen  <zhenqiang.chen@arm.com>

	* ifcvt.c (noce_emit_cmove, noce_get_alt_condition,
noce_get_condition):
	Allow CC mode if HAVE_cbranchcc4.
	(noce_emit_store_flag): Change CC REG as cond_complex.

diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
index f4002f9..7f7b7c1 100644
--- a/gcc/ifcvt.c
+++ b/gcc/ifcvt.c
@@ -849,7 +849,10 @@ noce_emit_store_flag (struct noce_if_info *if_info, rtx
x, int reversep,
   enum rtx_code code;
 
   cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
-		  || ! general_operand (XEXP (cond, 1), VOIDmode));
+		  || ! general_operand (XEXP (cond, 1), VOIDmode)
+		     /* For s390, CC REG is general_operand.  But cstorecc4
only
+			handles CCZ1, which can not handle others like CCU.
*/
+		  || GET_MODE_CLASS (GET_MODE (XEXP (cond, 0))) == MODE_CC);
 
   /* If earliest == jump, or when the condition is complex, try to
      build the store_flag insn directly.  */
@@ -1459,10 +1462,18 @@ noce_emit_cmove (struct noce_if_info *if_info, rtx
x, enum rtx_code code,
       end_sequence ();
     }
 
-  /* Don't even try if the comparison operands are weird.  */
+  /* Don't even try if the comparison operands are weird
+     except that the target supports cbranchcc4.  */
   if (! general_operand (cmp_a, GET_MODE (cmp_a))
       || ! general_operand (cmp_b, GET_MODE (cmp_b)))
-    return NULL_RTX;
+    {
+#ifdef HAVE_cbranchcc4
+      if (GET_MODE_CLASS (GET_MODE (cmp_a)) != MODE_CC
+	  || cmp_b != const0_rtx
+	  || !(HAVE_cbranchcc4))
+#endif
+	return NULL_RTX;
+    }
 
 #if HAVE_conditional_move
   unsignedp = (code == LTU || code == GEU
@@ -1788,6 +1799,11 @@ noce_get_alt_condition (struct noce_if_info *if_info,
rtx target,
   rtx cond, set;
   rtx_insn *insn;
   int reverse;
+  int allow_cc_mode = false;
+#ifdef HAVE_cbranchcc4
+  allow_cc_mode = HAVE_cbranchcc4;
+#endif
+
 
   /* If target is already mentioned in the known condition, return it.  */
   if (reg_mentioned_p (target, if_info->cond))
@@ -1909,7 +1925,7 @@ noce_get_alt_condition (struct noce_if_info *if_info,
rtx target,
     }
 
   cond = canonicalize_condition (if_info->jump, cond, reverse,
-				 earliest, target, false, true);
+				 earliest, target, allow_cc_mode, true);
   if (! cond || ! reg_mentioned_p (target, cond))
     return NULL;
 
@@ -2365,6 +2381,10 @@ noce_get_condition (rtx_insn *jump, rtx_insn
**earliest, bool then_else_reversed
 {
   rtx cond, set, tmp;
   bool reverse;
+  int allow_cc_mode = false;
+#ifdef HAVE_cbranchcc4
+  allow_cc_mode = HAVE_cbranchcc4;
+#endif
 
   if (! any_condjump_p (jump))
     return NULL_RTX;
@@ -2401,7 +2421,7 @@ noce_get_condition (rtx_insn *jump, rtx_insn
**earliest, bool then_else_reversed
   /* Otherwise, fall back on canonicalize_condition to do the dirty
      work of manipulating MODE_CC values and COMPARE rtx codes.  */
   tmp = canonicalize_condition (jump, cond, reverse, earliest,
-				NULL_RTX, false, true);
+				NULL_RTX, allow_cc_mode, true);
 
   /* We don't handle side-effects in the condition, like handling
      REG_INC notes and making sure no duplicate conditions are emitted.  */