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[PATCH] fix decimal float wrong-code bug, c/39035
- From: Janis Johnson <janis187 at us dot ibm dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 06 Feb 2009 10:49:49 -0800
- Subject: [PATCH] fix decimal float wrong-code bug, c/39035
- Reply-to: janis187 at us dot ibm dot com
A decimal float zero as a conditional expression is treated as true,
not false. Flag rvc_zero is not set for decimal values because there
are many valid representations of decimal float zero. This patch
special-cases comparisons of zero against a decimal float value so
that those different representations can be taken into account; just
setting rvc_zero for a decimal float contant zero breaks several
checks in test gcc.dg/dfp/constants-zero.c
Bootstrapped and regression tested on powerpc64-linux, all languages
except Ada. As a wrong-code bug, is this OK for trunk? Is it also
OK for the 4.3 branch, after I test it there?
2009-02-06 Janis Johnson <janis187@us.ibm.com>
gcc/
PR c/39035
* real.c (do_compare): Special-case compare of zero against
decimal float value.
testsuite/
PR c/39035
* gcc.dg/dfp/pr39035.c: New test.
Index: gcc/real.c
===================================================================
--- gcc/real.c (revision 143946)
+++ gcc/real.c (working copy)
@@ -905,15 +905,23 @@
/* Sign of zero doesn't matter for compares. */
return 0;
+ case CLASS2 (rvc_normal, rvc_zero):
+ /* Decimal float zero is special and uses rvc_normal, not rvc_zero. */
+ if (a->decimal)
+ return decimal_do_compare (a, b, nan_result);
+ /* Fall through. */
case CLASS2 (rvc_inf, rvc_zero):
case CLASS2 (rvc_inf, rvc_normal):
- case CLASS2 (rvc_normal, rvc_zero):
return (a->sign ? -1 : 1);
case CLASS2 (rvc_inf, rvc_inf):
return -a->sign - -b->sign;
case CLASS2 (rvc_zero, rvc_normal):
+ /* Decimal float zero is special and uses rvc_normal, not rvc_zero. */
+ if (b->decimal)
+ return decimal_do_compare (a, b, nan_result);
+ /* Fall through. */
case CLASS2 (rvc_zero, rvc_inf):
case CLASS2 (rvc_normal, rvc_inf):
return (b->sign ? 1 : -1);
Index: gcc/testsuite/gcc.dg/dfp/pr39035.c
===================================================================
--- gcc/testsuite/gcc.dg/dfp/pr39035.c (revision 0)
+++ gcc/testsuite/gcc.dg/dfp/pr39035.c (revision 0)
@@ -0,0 +1,81 @@
+/* { dg-do run } */
+/* { dg-options "-std=gnu99 -O" } */
+
+/* DFP TR 24732 == WG14 / N1176, N1312 */
+/* Based on a test from Fred Tydeman. */
+
+extern void abort (void);
+int failures = 0;
+
+#ifdef DBG
+#include <stdio.h>
+#define FAILURE(MSG) { printf ("line %d: %s\n", __LINE__, MSG); failures++; }
+#else
+#define FAILURE(MSG) failures++;
+#endif
+
+/* Test runtime computations. */
+
+void
+runtime32 (void)
+{
+ volatile _Decimal32 d;
+ d = 0.0DF;
+ if (d)
+ FAILURE ("0.0DF should be zero")
+}
+
+void
+runtime64 (void)
+{
+ volatile _Decimal64 d;
+ d = 0.0DD;
+ if (d)
+ FAILURE ("0.0DD should be zero")
+}
+
+void
+runtime128 (void)
+{
+ volatile _Decimal128 d;
+ d = 0.0DL;
+ if (d)
+ FAILURE ("0.0DL should be zero")
+}
+
+void
+fold32 (void)
+{
+ if (0.0DF)
+ FAILURE ("0.0DF should be zero")
+}
+
+void
+fold64 (void)
+{
+ if (0.0DD)
+ FAILURE ("0.0DD should be zero")
+}
+
+void
+fold128 (void)
+{
+ if (0.0DL)
+ FAILURE ("0.0DL should be zero")
+}
+
+int
+main(void)
+{
+ runtime32 ();
+ runtime64 ();
+ runtime128 ();
+
+ fold32 ();
+ fold64 ();
+ fold128 ();
+
+ if (failures != 0)
+ abort ();
+ return 0;
+}