mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-05 09:14:03 +00:00
Avoid raising unexpected floating point exceptions in libm
When using clang with x86_64 CPUs that support AVX, some floating point transformations may raise exceptions that would not have been raised by the original code. To avoid this, use the -fp-exception-behavior=maytrap flag, introduced in clang 10.0.0. In particular, this fixes a number of test failures with ctanhf(3) and ctanf(3), when libm is compiled with -mavx. An unexpected FE_INVALID exception is then raised, because clang emits vdivps instructions to perform certain divides. (The vdivps instruction operates on multiple single-precision float operands simultaneously, but the exceptions may be influenced by unused parts of the XMM registers. In this particular case, it was calculating 0 / 0, which results in FE_INVALID.) If -fp-exception-behavior=maytrap is specified however, clang uses vdivss instructions instead, which work on one operand, and should not raise unexpected exceptions. Reported by: olivier Reviewed by: arichardson PR: 254911 MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D29686
This commit is contained in:
parent
44faff9f4a
commit
3b00222f15
@ -34,6 +34,16 @@ CFLAGS+= -I${.CURDIR}/ld128
|
|||||||
|
|
||||||
CFLAGS+= -I${.CURDIR}/${ARCH_SUBDIR}
|
CFLAGS+= -I${.CURDIR}/${ARCH_SUBDIR}
|
||||||
|
|
||||||
|
.include <bsd.compiler.mk>
|
||||||
|
.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 100000
|
||||||
|
# When using clang with x86_64 CPUs that support AVX, some floating point
|
||||||
|
# transformations may raise exceptions that would not have been raised by the
|
||||||
|
# original code. To avoid this, use the -fp-exception-behavior=maytrap flag,
|
||||||
|
# introduced in clang 10.0.0.
|
||||||
|
# See also: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=254911
|
||||||
|
CFLAGS+= -ffp-exception-behavior=maytrap
|
||||||
|
.endif
|
||||||
|
|
||||||
.PATH: ${.CURDIR}/bsdsrc
|
.PATH: ${.CURDIR}/bsdsrc
|
||||||
.PATH: ${.CURDIR}/src
|
.PATH: ${.CURDIR}/src
|
||||||
.PATH: ${.CURDIR}/man
|
.PATH: ${.CURDIR}/man
|
||||||
@ -113,7 +123,6 @@ COMMON_SRCS+= catrigl.c \
|
|||||||
# 'long double' [-Werror=overflow]
|
# 'long double' [-Werror=overflow]
|
||||||
# if( y >= LDBL_MAX )
|
# if( y >= LDBL_MAX )
|
||||||
# See also: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=130067
|
# See also: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=130067
|
||||||
.include <bsd.compiler.mk>
|
|
||||||
.if ${COMPILER_TYPE} == "gcc"
|
.if ${COMPILER_TYPE} == "gcc"
|
||||||
CFLAGS.e_powl.c+= -Wno-error=overflow
|
CFLAGS.e_powl.c+= -Wno-error=overflow
|
||||||
.endif
|
.endif
|
||||||
|
Loading…
Reference in New Issue
Block a user