Hi!
As e.g. decimal_from_decnumber shows, the REAL_VALUE_TYPE representation
contains a decimal128 embedded in ->sig only if it is rvc_normal, for
other kinds like rvc_inf or rvc_nan, ->sig is ignored and everything is
contained in the REAL_VALUE_TYPE flags (cl, sign, signalling and decimal).
decimal_to_binary which is used when folding a decimal{32,64,128} constant
to a binary floating point type ignores this and thus folds infinities and
NaNs into +0.0.
The following patch fixes that by only doing that for rvc_normal.
Similarly to the binary to decimal folding, it goes through a string, in
order to e.g. deal with canonical NaN mantissas, or binary float formats
that don't support infinities and/or NaNs.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2020-03-11 Jakub Jelinek <ja...@redhat.com>
PR middle-end/94111
* dfp.c (decimal_to_binary): Only use decimal128ToString if from->cl
is rvc_normal, otherwise use real_to_decimal to print the number to
string.
* gcc.dg/dfp/pr94111.c: New test.
--- gcc/dfp.c.jj 2020-01-12 11:54:36.530411644 +0100
+++ gcc/dfp.c 2020-03-10 12:32:07.246961100 +0100
@@ -342,9 +342,13 @@ decimal_to_binary (REAL_VALUE_TYPE *to,
const real_format *fmt)
{
char string[256];
- const decimal128 *const d128 = (const decimal128 *) from->sig;
-
- decimal128ToString (d128, string);
+ if (from->cl == rvc_normal)
+ {
+ const decimal128 *const d128 = (const decimal128 *) from->sig;
+ decimal128ToString (d128, string);
+ }
+ else
+ real_to_decimal (string, from, sizeof (string), 0, 1);
real_from_string3 (to, string, fmt);
}
--- gcc/testsuite/gcc.dg/dfp/pr94111.c.jj 2020-03-10 12:38:20.175451924
+0100
+++ gcc/testsuite/gcc.dg/dfp/pr94111.c 2020-03-10 12:38:12.832560341 +0100
@@ -0,0 +1,12 @@
+/* PR middle-end/94111 */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+int
+main ()
+{
+ _Decimal32 d = (_Decimal32) __builtin_inff ();
+ if (!__builtin_isinf ((double) d))
+ __builtin_abort ();
+ return 0;
+}
Jakub
