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[committed,v6] Backport PR75964

Message ID 2119c4ad-12bc-6778-5bac-15beb4cffbca@gjlay.de
State New
Headers show

Commit Message

Georg-Johann Lay July 25, 2017, 11:58 a.m. UTC 
...also backported to gcc-6-branch:

https://gcc.gnu.org/r250511

Johann

gcc/
      Backport from 2017-05-06 trunk r247719.
      PR rtl-optimization/75964
      * simplify-rtx.c (simplify_const_relational_operation): Remove
      invalid handling of comparisons of integer ABS.

gcc/testsuite/
      Backport from 2017-05-06 trunk r247719.
      PR rtl-optimization/75964
      * gcc.dg/torture/pr75964.c: New test.
diff mbox

Patch

Index: simplify-rtx.c
===================================================================
--- simplify-rtx.c	(revision 250510)
+++ simplify-rtx.c	(working copy)
@@ -5235,34 +5235,14 @@  simplify_const_relational_operation (enu
 	{
 	case LT:
 	  /* Optimize abs(x) < 0.0.  */
-	  if (!HONOR_SNANS (mode)
-	      && (!INTEGRAL_MODE_P (mode)
-		  || (!flag_wrapv && !flag_trapv && flag_strict_overflow)))
-	    {
-	      if (INTEGRAL_MODE_P (mode)
-		  && (issue_strict_overflow_warning
-		      (WARN_STRICT_OVERFLOW_CONDITIONAL)))
-		warning (OPT_Wstrict_overflow,
-			 ("assuming signed overflow does not occur when "
-			  "assuming abs (x) < 0 is false"));
-	       return const0_rtx;
-	    }
+	  if (!INTEGRAL_MODE_P (mode) && !HONOR_SNANS (mode))
+	    return const0_rtx;
 	  break;
 
 	case GE:
 	  /* Optimize abs(x) >= 0.0.  */
-	  if (!HONOR_NANS (mode)
-	      && (!INTEGRAL_MODE_P (mode)
-		  || (!flag_wrapv && !flag_trapv && flag_strict_overflow)))
-	    {
-	      if (INTEGRAL_MODE_P (mode)
-	          && (issue_strict_overflow_warning
-	    	  (WARN_STRICT_OVERFLOW_CONDITIONAL)))
-	        warning (OPT_Wstrict_overflow,
-			 ("assuming signed overflow does not occur when "
-			  "assuming abs (x) >= 0 is true"));
-	      return const_true_rtx;
-	    }
+	  if (!INTEGRAL_MODE_P (mode) && !HONOR_NANS (mode))
+	    return const_true_rtx;
 	  break;
 
 	case UNGE:
Index: testsuite/gcc.dg/torture/pr75964.c
===================================================================
--- testsuite/gcc.dg/torture/pr75964.c	(nonexistent)
+++ testsuite/gcc.dg/torture/pr75964.c	(working copy)
@@ -0,0 +1,28 @@ 
+/* { dg-do run } */
+
+typedef __UINT8_TYPE__ uint8_t;
+
+uint8_t __attribute__ ((noinline, noclone))
+abs8 (uint8_t x)
+{
+  if (x & 0x80)
+    x = -x;
+
+  if (x & 0x80)
+    x = 0x7f;
+
+  return x;
+}
+
+int
+main (void)
+{
+  if (abs8 (0) != 0
+      || abs8 (1) != 1
+      || abs8 (127) != 127
+      || abs8 (128) != 127
+      || abs8 (129) != 127
+      || abs8 (255) != 1)
+    __builtin_abort ();
+  return 0;
+}