re PR rtl-optimization/68376 (wrong code at -O1 and above on x86_64-linux-gnu)

PR rtl-optimization/68376
	* ifcvt.c (noce_try_abs): Disable one_cmpl optimization if
	encountering x <= 0 ? ~x : x or x > 0 ? ~x : x.

	* gcc.c-torture/execute/pr68376-1.c: New test.
	* gcc.c-torture/execute/pr68376-2.c: New test.

From-SVN: r230596

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2015-11-19  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/68376
+	* ifcvt.c (noce_try_abs): Disable one_cmpl optimization if
+	encountering x <= 0 ? ~x : x or x > 0 ? ~x : x.
+
 2015-11-19  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/68117

gcc/ifcvt.c

@@ -2595,12 +2595,49 @@ noce_try_abs (struct noce_if_info *if_info)
 
   /* Work around funny ideas get_condition has wrt canonicalization.
      Note that these rtx constants are known to be CONST_INT, and
-     therefore imply integer comparisons.  */
+     therefore imply integer comparisons.
+     The one_cmpl case is more complicated, as we want to handle
+     only x < 0 ? ~x : x or x >= 0 ? ~x : x but not
+     x <= 0 ? ~x : x or x > 0 ? ~x : x, as the latter two
+     have different result for x == 0.  */
   if (c == constm1_rtx && GET_CODE (cond) == GT)
-    ;
+    {
+      if (one_cmpl && negate)
+	return FALSE;
+    }
   else if (c == const1_rtx && GET_CODE (cond) == LT)
-    ;
-  else if (c != CONST0_RTX (GET_MODE (b)))
+    {
+      if (one_cmpl && !negate)
+	return FALSE;
+    }
+  else if (c == CONST0_RTX (GET_MODE (b)))
+    {
+      if (one_cmpl)
+	switch (GET_CODE (cond))
+	  {
+	  case GT:
+	    if (!negate)
+	      return FALSE;
+	    break;
+	  case GE:
+	    /* >= 0 is the same case as above > -1.  */
+	    if (negate)
+	      return FALSE;
+	    break;
+	  case LT:
+	    if (negate)
+	      return FALSE;
+	    break;
+	  case LE:
+	    /* <= 0 is the same case as above < 1.  */
+	    if (!negate)
+	      return FALSE;
+	    break;
+	  default:
+	    return FALSE;
+	  }
+    }
+  else
     return FALSE;
 
   /* Determine what sort of operation this is.  */

gcc/testsuite/ChangeLog

@@ -1,5 +1,9 @@
 2015-11-19  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/68376
+	* gcc.c-torture/execute/pr68376-1.c: New test.
+	* gcc.c-torture/execute/pr68376-2.c: New test.
+
 	PR target/67770
 	* gcc.target/i386/pr67770.c: New test.
 

gcc/testsuite/gcc.c-torture/execute/pr68376-1.c

@@ -0,0 +1,24 @@
+/* PR rtl-optimization/68376 */
+
+int a, b, c = 1;
+signed char d;
+
+int
+main ()
+{
+  for (; a < 1; a++)
+    for (; b < 1; b++)
+      {
+	signed char e = ~d;
+	if (d < 1)
+	  e = d;
+	d = e;
+	if (!c)
+	  __builtin_abort ();
+      }
+
+  if (d != 0)
+    __builtin_abort ();
+
+  return 0;
+}

gcc/testsuite/gcc.c-torture/execute/pr68376-2.c

@@ -0,0 +1,41 @@
+/* PR rtl-optimization/68376 */
+
+extern void abort (void);
+
+__attribute__((noinline, noclone)) int
+f1 (int x)
+{
+  return x < 0 ? ~x : x;
+}
+
+__attribute__((noinline, noclone)) int
+f2 (int x)
+{
+  return x < 0 ? x : ~x;
+}
+
+__attribute__((noinline, noclone)) int
+f3 (int x)
+{
+  return x <= 0 ? ~x : x;
+}
+
+__attribute__((noinline, noclone)) int
+f4 (int x)
+{
+  return x <= 0 ? x : ~x;
+}
+
+int
+main ()
+{
+  if (f1 (5) != 5 || f1 (-5) != 4 || f1 (0) != 0)
+    abort ();
+  if (f2 (5) != -6 || f2 (-5) != -5 || f2 (0) != -1)
+    abort ();
+  if (f3 (5) != 5 || f3 (-5) != 4 || f3 (0) != -1)
+    abort ();
+  if (f4 (5) != -6 || f4 (-5) != -5 || f4 (0) != 0)
+    abort ();
+  return 0;
+}