Hi!
As the following testcase shows, we store decimal REAL_CSTs always in
_Decimal128 internal form and perform all the arithmetics on that, but while
for arithmetics we then ensure rounding to the actual type (_Decimal{32,64}
or for _Decimal128 no further rounding), e.g. const_binop calls
inexact = real_arithmetic (&value, code, &d1, &d2);
real_convert (&result, mode, &value);
when converting integers to _Decimal{32,64} we do nothing like that.
We do that only for non-decimal conversions from INTEGER_CSTs to REAL_CSTs.
The following patch fixes that. Bootstrapped/regtested on x86_64-linux
(i686-linux fails to bootstrap for other reason), and on 6.x branch on
x86_64-linux and i686-linux. Dominik has kindly tested it on s390x (where
the bug has been originally reported on the float-cast-overflow-10.c test).
Ok for trunk?
2017-02-15 Jakub Jelinek <ja...@redhat.com>
PR target/79487
* real.c (real_from_integer): Call real_convert even for decimal.
* gcc.dg/dfp/pr79487.c: New test.
* c-c++-common/ubsan/float-cast-overflow-8.c (TEST): Revert
2017-02-13 change.
--- gcc/real.c.jj 2017-01-01 12:45:37.000000000 +0100
+++ gcc/real.c 2017-02-14 21:35:35.868906203 +0100
@@ -2266,7 +2266,7 @@ real_from_integer (REAL_VALUE_TYPE *r, f
if (fmt.decimal_p ())
decimal_from_integer (r);
- else if (fmt)
+ if (fmt)
real_convert (r, fmt, r);
}
--- gcc/testsuite/gcc.dg/dfp/pr79487.c.jj 2017-02-14 22:42:33.137938789
+0100
+++ gcc/testsuite/gcc.dg/dfp/pr79487.c 2017-02-14 22:42:22.000000000 +0100
@@ -0,0 +1,16 @@
+/* PR target/79487 */
+/* { dg-options "-O2" } */
+
+int
+main ()
+{
+ _Decimal32 a = (-9223372036854775807LL - 1LL);
+ _Decimal32 b = -9.223372E+18DF;
+ if (b - a != 0.0DF)
+ __builtin_abort ();
+ _Decimal64 c = (-9223372036854775807LL - 1LL);
+ _Decimal64 d = -9.223372036854776E+18DD;
+ if (d - c != 0.0DD)
+ __builtin_abort ();
+ return 0;
+}
--- gcc/testsuite/c-c++-common/ubsan/float-cast-overflow-8.c.jj 2017-02-14
00:08:33.000000000 +0100
+++ gcc/testsuite/c-c++-common/ubsan/float-cast-overflow-8.c 2017-02-15
07:46:46.780778627 +0100
@@ -8,7 +8,7 @@
#define TEST(type1, type2) \
if (type1##_MIN) \
{ \
- volatile type2 min = type1##_MIN; \
+ type2 min = type1##_MIN; \
type2 add = -1.0; \
while (1) \
{ \
@@ -28,7 +28,7 @@
volatile type1 tem3 = cvt_##type1##_##type2 (-1.0f); \
} \
{ \
- volatile type2 max = type1##_MAX; \
+ type2 max = type1##_MAX; \
type2 add = 1.0; \
while (1) \
{ \
Jakub
