On Tue, Jun 17, 2014 at 11:29:01PM +0100, Ramana Radhakrishnan wrote:
> On Sun, May 18, 2014 at 10:23 PM, Aurelien Jarno <aurel...@aurel32.net> wrote:
> > On ARM soft-float, the float to double conversion doesn't convert a sNaN
> > to qNaN as the IEEE Std 754 standard mandates:
> >
> > "Under default exception handling, any operation signaling an invalid
> > operation exception and for which a floating-point result is to be
> > delivered shall deliver a quiet NaN."
> >
> > Given the soft float ARM code ignores exceptions and always provides a
> > result, a float to double conversion of a signaling NaN should return a
> > quiet NaN. Fix this in extendsfdf2.
> >
> >
> > 2014-05-18 Aurelien Jarno <aurel...@aurel32.net>
> >
> > PR target/61219
> > * config/arm/ieee754-df.S (extendsfdf2): Convert sNaN to qNaN.
>
> Ok if no regressions along with a testcase to catch this case please
> and fixing the PR number
I have added such a testcase in the new version below. I didn't add it
in the target specific subdirectory, as other architectures might be
affected. Actually aarch64 is also affected, though for different
reasons. I have tested that the testcase correctly catch the issue, and
that the whole patch doesn't cause any regression.
Please find the new patch below. If it is fine, I would appreciate if
someone can commit the patch, as I don't have SVN write access (though I
have done the copyright assignment stuff).
> Sorry about the slow review.
No problem, I am also very often short on time.
Aurelien
gcc/testsuite/ChangeLog
2014-06-18 Aurelien Jarno <aurel...@aurel32.net>
PR target/59833
* gcc.dg/pr59833.c: New testcase.
Index: gcc/testsuite/gcc.dg/pr59833.c
===================================================================
--- gcc/testsuite/gcc.dg/pr59833.c (revision 0)
+++ gcc/testsuite/gcc.dg/pr59833.c (working copy)
@@ -0,0 +1,15 @@
+/* PR target/59833 */
+/* { dg-do run } */
+/* { dg-options "-lm" } */
+
+extern int __issignaling (double);
+
+int
+main ()
+{
+ float sNaN = __builtin_nansf ("");
+ double x = (double) sNaN;
+ if (__issignaling (x))
+ __builtin_abort ();
+ return 0;
+}
libgcc/ChangeLog
2014-06-18 Aurelien Jarno <aurel...@aurel32.net>
PR target/59833
* config/arm/ieee754-df.S (extendsfdf2): Convert sNaN to qNaN.
Index: libgcc/config/arm/ieee754-df.S
===================================================================
--- libgcc/config/arm/ieee754-df.S (revision 211428)
+++ libgcc/config/arm/ieee754-df.S (working copy)
@@ -473,11 +473,15 @@
eorne xh, xh, #0x38000000 @ fixup exponent otherwise.
RETc(ne) @ and return it.
- teq r2, #0 @ if actually 0
- do_it ne, e
- teqne r3, #0xff000000 @ or INF or NAN
+ bics r2, r2, #0xff000000 @ isolate mantissa
+ do_it eq @ if 0, that is ZERO or INF
RETc(eq) @ we are done already.
+ teq r3, #0xff000000 @ check for NAN
+ do_it eq, t
+ orreq xh, xh, #0x00080000 @ change to quiet NAN
+ RETc(eq) @ and return it.
+
@ value was denormalized. We can normalize it now.
do_push {r4, r5, lr}
mov r4, #0x380 @ setup corresponding exponent
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurel...@aurel32.net http://www.aurel32.net
