[PATCH v2] x86-64: Properly compile ISA optimized modf and modff
H.J. Lu
hjl.tools@gmail.com
Fri Jul 18 11:33:02 GMT 2025
There are 3 variants of modf and modff: SSE2, SSE4.1 and AVX. s_modf.c
and s_modff.c include the generic implementation compiled with the minimum
x86 ISA level. The IFUNC selector is used only if the minimum ISA level
is less than AVX. SSE4.1 variant is included only if the ISA level is
less than SSE4.1. AVX variant is included only the ISA level is less than
AVX.
AVX variant should be compiled with -mavx, not -msse2avx -DSSE2AVX which
are used to encode SSE assembly sources with EVEX encoding.
The routines that are shared between libc and libm should use different
rules to avoid using the same MODULE_NAME, to avoid potential issues
like BZ #33165 where __stack_chk_fail not being routed to the internal
symbol.
Tested with -march=x86-64, -march=x86-64-v2, -march=x86-64-v3 and
-march=x86-64-v4.
This fixes BZ #33165 and BZ #33173.
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
sysdeps/x86/configure | 4 ++
sysdeps/x86/configure.ac | 2 +
sysdeps/x86_64/fpu/multiarch/Makefile | 50 ++++++++-----------
.../x86_64/fpu/multiarch/ifunc-sse4_1-avx.h | 41 +++++++++++++++
sysdeps/x86_64/fpu/multiarch/s_modf-avx.c | 2 +
sysdeps/x86_64/fpu/multiarch/s_modf-c.c | 2 -
sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c | 6 +--
sysdeps/x86_64/fpu/multiarch/s_modf.c | 10 +++-
sysdeps/x86_64/fpu/multiarch/s_modff-avx.c | 2 +
sysdeps/x86_64/fpu/multiarch/s_modff-c.c | 2 -
sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c | 6 +--
sysdeps/x86_64/fpu/multiarch/s_modff.c | 10 +++-
12 files changed, 90 insertions(+), 47 deletions(-)
create mode 100644 sysdeps/x86_64/fpu/multiarch/ifunc-sse4_1-avx.h
delete mode 100644 sysdeps/x86_64/fpu/multiarch/s_modf-c.c
delete mode 100644 sysdeps/x86_64/fpu/multiarch/s_modff-c.c
diff --git a/sysdeps/x86/configure b/sysdeps/x86/configure
index c7ea9ac6ad..dff26e9b83 100644
--- a/sysdeps/x86/configure
+++ b/sysdeps/x86/configure
@@ -171,8 +171,12 @@ fi
config_vars="$config_vars
have-x86-isa-level = $libc_cv_have_x86_isa_level"
config_vars="$config_vars
+x86-isa-level-2-or-above = 2 3 4"
+config_vars="$config_vars
x86-isa-level-3-or-above = 3 4"
config_vars="$config_vars
+x86-isa-level-4-or-above = 4"
+config_vars="$config_vars
enable-x86-isa-level = $libc_cv_include_x86_isa_level"
diff --git a/sysdeps/x86/configure.ac b/sysdeps/x86/configure.ac
index 031f91719d..54960a71c9 100644
--- a/sysdeps/x86/configure.ac
+++ b/sysdeps/x86/configure.ac
@@ -117,7 +117,9 @@ else
AC_DEFINE_UNQUOTED(MINIMUM_X86_ISA_LEVEL, $libc_cv_have_x86_isa_level)
fi
LIBC_CONFIG_VAR([have-x86-isa-level], [$libc_cv_have_x86_isa_level])
+LIBC_CONFIG_VAR([x86-isa-level-2-or-above], [2 3 4])
LIBC_CONFIG_VAR([x86-isa-level-3-or-above], [3 4])
+LIBC_CONFIG_VAR([x86-isa-level-4-or-above], [4])
LIBC_CONFIG_VAR([enable-x86-isa-level], [$libc_cv_include_x86_isa_level])
dnl Check if TEST_CC supports -mfpmath=387
diff --git a/sysdeps/x86_64/fpu/multiarch/Makefile b/sysdeps/x86_64/fpu/multiarch/Makefile
index 81a870d3b1..708b14297f 100644
--- a/sysdeps/x86_64/fpu/multiarch/Makefile
+++ b/sysdeps/x86_64/fpu/multiarch/Makefile
@@ -26,19 +26,21 @@ CFLAGS-s_sinf-fma.c = -mfma -mavx2
CFLAGS-s_cosf-fma.c = -mfma -mavx2
CFLAGS-s_sincosf-fma.c = -mfma -mavx2
+# Check if ISA level is 2 or above.
+ifeq (,$(filter $(have-x86-isa-level),$(x86-isa-level-2-or-above)))
+sysdep_calls += \
+ s_modf-sse4_1 \
+ s_modff-sse4_1 \
+# sysdep_calls
+endif
+
# Check if ISA level is 3 or above.
ifneq (,$(filter $(have-x86-isa-level),$(x86-isa-level-3-or-above)))
-sysdep_routines += \
- s_modf-avx \
- s_modff-avx \
-# sysdep_routines
libm-sysdep_routines += \
s_ceil-avx \
s_ceilf-avx \
s_floor-avx \
s_floorf-avx \
- s_modf-avx \
- s_modff-avx \
s_nearbyint-avx \
s_nearbyintf-avx \
s_rint-avx \
@@ -49,6 +51,10 @@ libm-sysdep_routines += \
s_truncf-avx \
# libm-sysdep_routines
else
+sysdep_calls += \
+ s_modf-avx \
+ s_modff-avx \
+# sysdep_calls
ifeq (no,$(have-x86-apx))
libm-sysdep_routines += \
e_asin-fma4 \
@@ -62,10 +68,6 @@ libm-sysdep_routines += \
s_tan-fma4 \
# libm-sysdep_routines
endif
-sysdep_routines += \
- s_modf-sse4_1 \
- s_modff-sse4_1 \
-# sysdep_routines
libm-sysdep_routines += \
e_asin-fma \
e_atan2-avx \
@@ -95,8 +97,6 @@ libm-sysdep_routines += \
s_floor-sse4_1 \
s_floorf-sse4_1 \
s_log1p-fma \
- s_modf-sse4_1 \
- s_modff-sse4_1 \
s_nearbyint-sse4_1 \
s_nearbyintf-sse4_1 \
s_rint-sse4_1 \
@@ -118,17 +118,11 @@ libm-sysdep_routines += \
s_truncf-sse4_1 \
# libm-sysdep_routines
ifeq ($(have-x86-isa-level),baseline)
-sysdep_routines += \
- s_modf-c \
- s_modff-c \
-# sysdep-routines
libm-sysdep_routines += \
s_ceil-c \
s_ceilf-c \
s_floor-c \
s_floorf-c \
- s_modf-c \
- s_modff-c \
s_nearbyint-c \
s_nearbyintf-c \
s_rint-c \
@@ -139,6 +133,11 @@ libm-sysdep_routines += \
s_truncf-c \
# libm-sysdep_routines
endif
+
+# $(sysdep_calls) functions are built both for libc and libm. While the
+# libc objects have the prefix s_, the libm ones are prefixed with m_.
+sysdep_routines += $(sysdep_calls)
+libm-sysdep_routines += $(sysdep_calls:s_%=m_%)
endif
CFLAGS-e_asin-fma4.c = -mfma4
@@ -159,18 +158,11 @@ CFLAGS-s_sin-avx.c = -msse2avx -DSSE2AVX
CFLAGS-s_tan-avx.c = -msse2avx -DSSE2AVX
CFLAGS-s_sincos-avx.c = -msse2avx -DSSE2AVX
-CFLAGS-s_modf-c.c = $(no-stack-protector)
-CFLAGS-s_modff-c.c = $(no-stack-protector)
-
-CFLAGS-s_modf-sse4_1.c = -msse4.1 -fno-builtin-modff32x \
- -fno-builtin-modff64 $(no-stack-protector)
-CFLAGS-s_modff-sse4_1.c = -msse4.1 -fno-builtin-modff32 \
- $(no-stack-protector)
+CFLAGS-s_modf-sse4_1.c = -msse4.1 -fno-builtin-modff32x -fno-builtin-modff64
+CFLAGS-s_modff-sse4_1.c = -msse4.1 -fno-builtin-modff32
-CFLAGS-s_modf-avx.c = -msse2avx -DSSE2AVX -fno-builtin-modff32x \
- $(no-stack-protector) -fno-builtin-modff64
-CFLAGS-s_modff-avx.c = -msse2avx -DSSE2AVX -fno-builtin-modff32 \
- $(no-stack-protector)
+CFLAGS-s_modf-avx.c = -mavx -fno-builtin-modff32x -fno-builtin-modff64
+CFLAGS-s_modff-avx.c = -mavx -fno-builtin-modff32
endif
ifeq ($(subdir),mathvec)
diff --git a/sysdeps/x86_64/fpu/multiarch/ifunc-sse4_1-avx.h b/sysdeps/x86_64/fpu/multiarch/ifunc-sse4_1-avx.h
new file mode 100644
index 0000000000..071595f757
--- /dev/null
+++ b/sysdeps/x86_64/fpu/multiarch/ifunc-sse4_1-avx.h
@@ -0,0 +1,41 @@
+/* Common definition for ifunc selections optimized with SSE4.1 and AVX.
+ Copyright (C) 2025 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <init-arch.h>
+
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse41) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (avx) attribute_hidden;
+
+static inline void *
+IFUNC_SELECTOR (void)
+{
+ const struct cpu_features* cpu_features = __get_cpu_features ();
+
+ if (CPU_FEATURE_USABLE_P (cpu_features, AVX))
+ return OPTIMIZE (avx);
+
+#if MINIMUM_X86_ISA_LEVEL == SSE4_1_X86_ISA_LEVEL
+ return OPTIMIZE (sse41);
+#else
+ if (CPU_FEATURE_USABLE_P (cpu_features, SSE4_1))
+ return OPTIMIZE (sse41);
+
+ return OPTIMIZE (sse2);
+#endif
+}
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c b/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c
index db32398b4a..ab4f03db0e 100644
--- a/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c
+++ b/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c
@@ -1 +1,3 @@
+#define __modf __modf_avx
+
#include <sysdeps/ieee754/dbl-64/s_modf.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modf-c.c b/sysdeps/x86_64/fpu/multiarch/s_modf-c.c
deleted file mode 100644
index 6679d322cc..0000000000
--- a/sysdeps/x86_64/fpu/multiarch/s_modf-c.c
+++ /dev/null
@@ -1,2 +0,0 @@
-#define __modf __modf_c
-#include <sysdeps/ieee754/dbl-64/s_modf.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c b/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c
index 6ef4c19a7e..00aa8cd736 100644
--- a/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c
+++ b/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c
@@ -1,7 +1,3 @@
-#include <sysdeps/x86/isa-level.h>
-
-#if MINIMUM_X86_ISA_LEVEL != SSE4_1_X86_ISA_LEVEL
-# define __modf __modf_sse41
-#endif
+#define __modf __modf_sse41
#include <sysdeps/ieee754/dbl-64/s_modf.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modf.c b/sysdeps/x86_64/fpu/multiarch/s_modf.c
index d65977d69a..e365bfcef7 100644
--- a/sysdeps/x86_64/fpu/multiarch/s_modf.c
+++ b/sysdeps/x86_64/fpu/multiarch/s_modf.c
@@ -17,7 +17,7 @@
<https://www.gnu.org/licenses/>. */
#include <sysdeps/x86/isa-level.h>
-#if MINIMUM_X86_ISA_LEVEL < SSE4_1_X86_ISA_LEVEL
+#if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
# define NO_MATH_REDIRECT
# include <libm-alias-double.h>
@@ -28,8 +28,14 @@
# undef __modf
# define SYMBOL_NAME modf
-# include "ifunc-sse4_1.h"
+# include "ifunc-sse4_1-avx.h"
libc_ifunc_redirected (__redirect_modf, __modf, IFUNC_SELECTOR ());
libm_alias_double (__modf, modf)
+# if MINIMUM_X86_ISA_LEVEL == SSE4_1_X86_ISA_LEVEL
+# define __modf __modf_sse41
+# else
+# define __modf __modf_sse2
+# endif
#endif
+#include <sysdeps/ieee754/dbl-64/s_modf.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c b/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c
index 804b0426b7..07cb9c1036 100644
--- a/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c
+++ b/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c
@@ -1 +1,3 @@
+#define __modff __modff_avx
+
#include <sysdeps/ieee754/flt-32/s_modff.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modff-c.c b/sysdeps/x86_64/fpu/multiarch/s_modff-c.c
deleted file mode 100644
index f54f8eacb6..0000000000
--- a/sysdeps/x86_64/fpu/multiarch/s_modff-c.c
+++ /dev/null
@@ -1,2 +0,0 @@
-#define __modff __modff_c
-#include <sysdeps/ieee754/flt-32/s_modff.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c b/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c
index 0437e044f3..060c5e3979 100644
--- a/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c
+++ b/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c
@@ -1,7 +1,3 @@
-#include <sysdeps/x86/isa-level.h>
-
-#if MINIMUM_X86_ISA_LEVEL != SSE4_1_X86_ISA_LEVEL
-# define __modff __modff_sse41
-#endif
+#define __modff __modff_sse41
#include <sysdeps/ieee754/flt-32/s_modff.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_modff.c b/sysdeps/x86_64/fpu/multiarch/s_modff.c
index 89d0a32c23..a4b5429037 100644
--- a/sysdeps/x86_64/fpu/multiarch/s_modff.c
+++ b/sysdeps/x86_64/fpu/multiarch/s_modff.c
@@ -17,7 +17,7 @@
<https://www.gnu.org/licenses/>. */
#include <sysdeps/x86/isa-level.h>
-#if MINIMUM_X86_ISA_LEVEL < SSE4_1_X86_ISA_LEVEL
+#if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
# define NO_MATH_REDIRECT
# include <libm-alias-float.h>
@@ -28,8 +28,14 @@
# undef __modff
# define SYMBOL_NAME modff
-# include "ifunc-sse4_1.h"
+# include "ifunc-sse4_1-avx.h"
libc_ifunc_redirected (__redirect_modff, __modff, IFUNC_SELECTOR ());
libm_alias_float (__modf, modf)
+# if MINIMUM_X86_ISA_LEVEL == SSE4_1_X86_ISA_LEVEL
+# define __modff __modff_sse41
+# else
+# define __modff __modff_sse2
+# endif
#endif
+#include <sysdeps/ieee754/flt-32/s_modff.c>
--
2.50.1
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