Backported to v7:
https://gcc.gnu.org/r250509
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.
Index: testsuite/gcc.dg/torture/pr75964.c
===================================================================
--- testsuite/gcc.dg/torture/pr75964.c (nonexistent)
+++ testsuite/gcc.dg/torture/pr75964.c (revision 250509)
@@ -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;
+}
Index: simplify-rtx.c
===================================================================
--- simplify-rtx.c (revision 250508)
+++ simplify-rtx.c (revision 250509)
@@ -5314,34 +5314,14 @@ 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:
