Re: [PATCH] Use -frounding-math for math testsuite

[Andreas Jaeger <aj at suse dot com>]

On Wednesday, May 02, 2012 14:44:57 Andreas Jaeger wrote:
> Compiling glibc with GCC 4.7 I got today a failure in the testsuite for
> test-ifloat only:
> 
> testing float (inline functions)
> Failure: Test: lrint_upward (0.2) == 1
> Result:
>  is:         0
>  should be:  1
> Failure: Test: lrint_upward (1.4) == 2
> Result:
>  is:         1
>  should be:  2
> Failure: Test: lrint_upward (8388600.3) == 8388601
> Result:
>  is:         8388600
>  should be:  8388601
> 
> Test suite completed:
>   3752 test cases plus 3308 tests for exception flags executed.
>   3 errors occurred.
> 
> This works with checkout 9568c0c2255045456a09b441f89c6641e27a4bec but
> fails with checkout 5ba3cc691c856e5c67a7d4cd4713f20a79f7ba81.
> 
> Talking with Richard, we think we found a GCC bug, he's looking into
> this.
> 
> Still, we should tell GCC that we manipulate the rounding mode and
> therefore add -frounding-math to these files that call fesetround. This
> works around the bug as well and will avoid problems in the future if
> GCC optimizes further.

The gcc bug is:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53190

-frounding-math does *not* fix the problem, so this change does nothing for 
the problem. Still, I think it should be added to be on the safe side...

Andreas

> Tested on Linux/x86-64.
> 
> Ok to commit?
> 
> Andreas
> 
> 2012-05-02  Andreas Jaeger  <aj@suse.de>
> 
> 	* math/Makefile (CPPFLAGS-test-ildoubl.c): Add -frounding-math
> 	since we manipulate rounding mode.
> 	(CPPFLAGS-test-idouble.c): Likewise.
> 	(CPPFLAGS-test-ifloat.c): Likewise.
> 	(CFLAGS-test-ldouble.c): Likewise.
> 	(CFLAGS-test-double.c): Likewise.
> 	(CFLAGS-test-float.c): Likewise.
> 	(CFLAGS-test-misc.c): Likewise.
> 	(CFLAGS-test-test-fenv.c): Likewise.
> 
> diff --git a/math/Makefile b/math/Makefile
> index abeba7a..60e3899 100644
> --- a/math/Makefile
> +++ b/math/Makefile
> @@ -122,19 +122,21 @@ $(objpfx)test-ldouble.o: $(objpfx)libm-test.stmp
>  $(objpfx)test-ildoubl.o: $(objpfx)libm-test.stmp
>  endif
> 
> -CFLAGS-test-float.c = -fno-inline -ffloat-store -fno-builtin
> -CFLAGS-test-double.c = -fno-inline -ffloat-store -fno-builtin
> -CFLAGS-test-ldouble.c = -fno-inline -ffloat-store -fno-builtin
> +CFLAGS-test-float.c = -fno-inline -ffloat-store -fno-builtin
> -frounding-math +CFLAGS-test-double.c = -fno-inline -ffloat-store
> -fno-builtin -frounding-math +CFLAGS-test-ldouble.c = -fno-inline
> -ffloat-store -fno-builtin -frounding-math CFLAGS-test-tgmath.c =
> -fno-builtin
>  CFLAGS-test-tgmath2.c = -fno-builtin
>  CFLAGS-test-tgmath-ret.c = -fno-builtin
>  CFLAGS-test-powl.c = -fno-builtin
> +CFLAGS-test-test-fenv.c = -frounding-math
> +CFLAGS-test-misc.c = -frounding-math
>  CPPFLAGS-test-ifloat.c = -U__LIBC_INTERNAL_MATH_INLINES -D__FAST_MATH__
> \ -			 -DTEST_FAST_MATH -fno-builtin
> +			 -DTEST_FAST_MATH -fno-builtin -frounding-math
>  CPPFLAGS-test-idouble.c = -U__LIBC_INTERNAL_MATH_INLINES
> -D__FAST_MATH__ \ -			 -DTEST_FAST_MATH -fno-builtin
> +			 -DTEST_FAST_MATH -fno-builtin -frounding-math
>  CPPFLAGS-test-ildoubl.c = -U__LIBC_INTERNAL_MATH_INLINES
> -D__FAST_MATH__ \ -			  -DTEST_FAST_MATH -fno-builtin
> +			  -DTEST_FAST_MATH -fno-builtin -frounding-math
> 
> 
>  # The -lieee module sets the _LIB_VERSION_ switch to IEEE mode

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