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[ARM] Fix PR target/59833

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For Aurelien Jarno <aurelien@aurel32.net>

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.

gcc/ChangeLog:

	PR target/59833
	* config/arm/ieee754-df.S (extendsfdf2): Convert sNaN to qNaN.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr59833.c: New testcase.

From-SVN: r238584
This commit is contained in:
Aurelien Jarno 2016-07-21 08:27:47 +00:00 • committed by Ramana Radhakrishnan
parent 2397481934
commit a1b01d3403
3 changed files with 30 additions and 3 deletions
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18
gcc/testsuite/gcc.dg/pr59833.c Normal file
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@ -0,0 +1,18 @@
/* { dg-do run { target { *-*-linux* *-*-gnu* } } } */
/* { dg-options "-O0 -lm" } */
/* { dg-require-effective-target issignaling } */
#define _GNU_SOURCE
#include <math.h>
int main (void)
{
float sNaN = __builtin_nansf ("");
double x = (double) sNaN;
if (issignaling(x))
{
__builtin_abort();
}
return 0;
}

5
libgcc/ChangeLog
View file

@ -1,3 +1,8 @@
2016-07-21 Aurelien Jarno <aurelien@aurel32.net>
PR target/59833
* config/arm/ieee754-df.S (extendsfdf2): Convert sNaN to qNaN.
2016-07-19 Nick Clifton <nickc@redhat.com>
* config.host (m32r): Add m32r/t-m32r to tmake_file.

10
libgcc/config/arm/ieee754-df.S
View file

@ -507,11 +507,15 @@ ARM_FUNC_ALIAS aeabi_f2d extendsfdf2
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}
.cfi_adjust_cfa_offset 12 @ CFA is now sp + previousOffset + 12