[RTL-ifcvt] PR rtl-optimization/68624: Clean up logic that checks for clobbering…

[RTL-ifcvt] PR rtl-optimization/68624: Clean up logic that checks for clobbering conflicts across basic blocks

	PR rtl-optimization/68624
	* ifcvt.c (noce_try_cmove_arith): Check clobbers of temp regs in both
	blocks if they exist and simplify the logic choosing the order to emit
	them in.

	* gcc.c-torture/execute/pr68624.c: New test.

From-SVN: r231226

gcc/ChangeLog

+2015-12-03  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	PR rtl-optimization/68624
+	* ifcvt.c (noce_try_cmove_arith): Check clobbers of temp regs in both
+	blocks if they exist and simplify the logic choosing the order to emit
+	them in.
+
 2015-12-03  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/66051

gcc/ifcvt.c

@@ -2172,10 +2172,6 @@ noce_try_cmove_arith (struct noce_if_info *if_info)
 	}
     }
 
-    /* If insn to set up A clobbers any registers B depends on, try to
-       swap insn that sets up A with the one that sets up B.  If even
-       that doesn't help, punt.  */
-
   modified_in_a = emit_a != NULL_RTX && modified_in_p (orig_b, emit_a);
   if (tmp_b && then_bb)
     {
@@ -2190,10 +2186,9 @@ noce_try_cmove_arith (struct noce_if_info *if_info)
 	  }
 
     }
-  if (emit_a || modified_in_a)
-    {
+
   modified_in_b = emit_b != NULL_RTX && modified_in_p (orig_a, emit_b);
-      if (tmp_b && else_bb)
+  if (tmp_a && else_bb)
     {
       FOR_BB_INSNS (else_bb, tmp_insn)
       /* Don't check inside insn_b.  We will have changed it to emit_b
@@ -2205,16 +2200,19 @@ noce_try_cmove_arith (struct noce_if_info *if_info)
 	  break;
 	}
     }
-      if (modified_in_b)
-	goto end_seq_and_fail;
 
+  /* If insn to set up A clobbers any registers B depends on, try to
+     swap insn that sets up A with the one that sets up B.  If even
+     that doesn't help, punt.  */
+  if (modified_in_a && !modified_in_b)
+    {
       if (!noce_emit_bb (emit_b, else_bb, b_simple))
 	goto end_seq_and_fail;
 
       if (!noce_emit_bb (emit_a, then_bb, a_simple))
 	goto end_seq_and_fail;
     }
-  else
+  else if (!modified_in_a)
     {
       if (!noce_emit_bb (emit_a, then_bb, a_simple))
 	goto end_seq_and_fail;
@@ -2222,6 +2220,8 @@ noce_try_cmove_arith (struct noce_if_info *if_info)
       if (!noce_emit_bb (emit_b, else_bb, b_simple))
 	goto end_seq_and_fail;
     }
+  else
+    goto end_seq_and_fail;
 
   target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
 			    XEXP (if_info->cond, 1), a, b);

gcc/testsuite/ChangeLog

+2015-12-03  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	PR rtl-optimization/68624
+	* gcc.c-torture/execute/pr68624.c: New test.
+
 2015-12-03  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/66051

gcc/testsuite/gcc.c-torture/execute/pr68624.c

+int b, c, d, e = 1, f, g, h, j;
+
+static int
+fn1 ()
+{
+  int a = c;
+  if (h)
+    return 9;
+  g = (c || b) % e;
+  if ((g || f) && b)
+    return 9;
+  e = d;
+  for (c = 0; c > -4; c--)
+    ;
+  if (d)
+    c--;
+  j = c;
+  return d;
+}
+
+int
+main ()
+{
+  fn1 ();
+
+  if (c != -4)
+    __builtin_abort ();
+
+  return 0;
+}