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Fix i386 FP_TRAPPING_EXCEPTIONS.

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The i386 sfp-machine.h defines FP_TRAPPING_EXCEPTIONS in a way that is
always wrong: it treats a set bit as indicating the exception is
trapping, when actually a set bit (both for 387 and SSE floating
point) indicates it is masked, and a clear bit indicates it is
trapping.  This patch fixes this bug.

Bootstrapped with no regressions on x86_64-unknown-linux-gnu.

libgcc:
	* config/i386/sfp-machine.h (FP_TRAPPING_EXCEPTIONS): Treat clear
	bits not set bits as indicating trapping exceptions.

gcc/testsuite:
	* gcc.dg/torture/float128-exact-underflow.c: New test.

From-SVN: r215347
This commit is contained in:
Joseph Myers 2014-09-18 13:00:21 +01:00 • committed by Joseph Myers
parent b5a2602380
commit e770bfd997
4 changed files with 51 additions and 1 deletions
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4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2014-09-18 Joseph Myers <joseph@codesourcery.com>
* gcc.dg/torture/float128-exact-underflow.c: New test.
2014-09-18 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/61745

41
gcc/testsuite/gcc.dg/torture/float128-exact-underflow.c Normal file
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@ -0,0 +1,41 @@
/* Test that exact underflow in __float128 signals the underflow
exception if trapping is enabled, but does not raise the flag
otherwise. */
/* { dg-do run { target i?86-*-*gnu* x86_64-*-*gnu* ia64-*-*gnu* } } */
/* { dg-options "-D_GNU_SOURCE" } */
/* { dg-require-effective-target fenv_exceptions } */
#include <fenv.h>
#include <setjmp.h>
#include <signal.h>
#include <stdlib.h>
volatile sig_atomic_t caught_sigfpe;
sigjmp_buf buf;
static void
handle_sigfpe (int sig)
{
caught_sigfpe = 1;
siglongjmp (buf, 1);
}
int
main (void)
{
volatile __float128 a = 0x1p-16382q, b = 0x1p-2q;
volatile __float128 r;
r = a * b;
if (fetestexcept (FE_UNDERFLOW))
abort ();
if (r != 0x1p-16384q)
abort ();
feenableexcept (FE_UNDERFLOW);
signal (SIGFPE, handle_sigfpe);
if (sigsetjmp (buf, 1) == 0)
r = a * b;
if (!caught_sigfpe)
abort ();
exit (0);
}

5
libgcc/ChangeLog
View file

@ -1,3 +1,8 @@
2014-09-18 Joseph Myers <joseph@codesourcery.com>
* config/i386/sfp-machine.h (FP_TRAPPING_EXCEPTIONS): Treat clear
bits not set bits as indicating trapping exceptions.
2014-09-17 Nathan sidwell <nathan@acm.org>
* Makefile.in (LIBGCOV_INTERFACE): Add _gcov_dump from ...

2
libgcc/config/i386/sfp-machine.h
View file

@ -60,7 +60,7 @@ void __sfp_handle_exceptions (int);
__sfp_handle_exceptions (_fex); \
} while (0);
#define FP_TRAPPING_EXCEPTIONS ((_fcw >> FP_EX_SHIFT) & FP_EX_ALL)
#define FP_TRAPPING_EXCEPTIONS ((~_fcw >> FP_EX_SHIFT) & FP_EX_ALL)
#define FP_ROUNDMODE (_fcw & FP_RND_MASK)
#endif