On February 15, 2017 7:53:58 AM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>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?
OK.
Richard.
>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
