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* [glibc] math: x86 floor traps when FE_INEXACT is enabled (BZ 31601)
@ 2024-04-04 17:36 Adhemerval Zanella
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From: Adhemerval Zanella @ 2024-04-04 17:36 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=932544efa469568525455bcb53d4eabeba0eb295
commit 932544efa469568525455bcb53d4eabeba0eb295
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Wed Apr 3 16:39:18 2024 -0300
math: x86 floor traps when FE_INEXACT is enabled (BZ 31601)
The implementations of floor functions using x87 floating point (i386 and
86_64 long double only) traps when FE_INEXACT is enabled. Although
this is a GNU extension outside the scope of the C standard, other
architectures that also support traps do not show this behavior.
The fix moves the implementation to a common one that holds any
exceptions with a 'fnclex' (libc_feholdexcept_setround_387).
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diff:
---
math/Makefile | 2 ++
math/test-floor-except-2.c | 67 +++++++++++++++++++++++++++++++++++++++++++
sysdeps/i386/fpu/s_floor.S | 34 ----------------------
sysdeps/i386/fpu/s_floor.c | 25 ++++++++++++++++
sysdeps/i386/fpu/s_floorf.S | 34 ----------------------
sysdeps/i386/fpu/s_floorf.c | 25 ++++++++++++++++
sysdeps/i386/fpu/s_floorl.S | 39 -------------------------
sysdeps/x86/fpu/s_floorl.c | 25 ++++++++++++++++
sysdeps/x86_64/fpu/s_floorl.S | 33 ---------------------
9 files changed, 144 insertions(+), 140 deletions(-)
diff --git a/math/Makefile b/math/Makefile
index d2a740eebe..121fe2881a 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -511,6 +511,7 @@ tests = \
test-fetestexceptflag \
test-fexcept \
test-fexcept-traps \
+ test-floor-except-2 \
test-flt-eval-method \
test-fp-ilogb-constants \
test-fp-llogb-constants \
@@ -991,6 +992,7 @@ CFLAGS-test-fe-snans-always-signal.c += $(config-cflags-signaling-nans)
CFLAGS-test-nan-const.c += -fno-builtin
CFLAGS-test-ceil-except-2.c += -fno-builtin
+CFLAGS-test-floor-except-2.c += -fno-builtin
include ../Rules
diff --git a/math/test-floor-except-2.c b/math/test-floor-except-2.c
new file mode 100644
index 0000000000..d99e835909
--- /dev/null
+++ b/math/test-floor-except-2.c
@@ -0,0 +1,67 @@
+/* Test floor functions do not disable exception traps.
+ Copyright (C) 2024 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 <fenv.h>
+#include <math.h>
+#include <stdio.h>
+
+#ifndef FE_INEXACT
+# define FE_INEXACT 0
+#endif
+
+#define TEST_FUNC(NAME, FLOAT, SUFFIX) \
+static int \
+NAME (void) \
+{ \
+ int result = 0; \
+ volatile FLOAT a, b __attribute__ ((unused)); \
+ a = 1.5; \
+ /* floor must work when traps on "inexact" are enabled. */ \
+ b = floor ## SUFFIX (a); \
+ /* And it must have left those traps enabled. */ \
+ if (fegetexcept () == FE_INEXACT) \
+ puts ("PASS: " #FLOAT); \
+ else \
+ { \
+ puts ("FAIL: " #FLOAT); \
+ result = 1; \
+ } \
+ return result; \
+}
+
+TEST_FUNC (float_test, float, f)
+TEST_FUNC (double_test, double, )
+TEST_FUNC (ldouble_test, long double, l)
+
+static int
+do_test (void)
+{
+ if (feenableexcept (FE_INEXACT) == -1)
+ {
+ puts ("enabling FE_INEXACT traps failed, cannot test");
+ return 77;
+ }
+ int result = float_test ();
+ feenableexcept (FE_INEXACT);
+ result |= double_test ();
+ feenableexcept (FE_INEXACT);
+ result |= ldouble_test ();
+ return result;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/i386/fpu/s_floor.S b/sysdeps/i386/fpu/s_floor.S
deleted file mode 100644
index 7143fdcc9a..0000000000
--- a/sysdeps/i386/fpu/s_floor.S
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Public domain.
- */
-
-#include <machine/asm.h>
-#include <libm-alias-double.h>
-
-RCSID("$NetBSD: s_floor.S,v 1.4 1995/05/09 00:01:59 jtc Exp $")
-
-ENTRY(__floor)
- fldl 4(%esp)
- subl $32,%esp
- cfi_adjust_cfa_offset (32)
-
- fnstenv 4(%esp) /* store fpu environment */
-
- /* We use here %edx although only the low 1 bits are defined.
- But none of the operations should care and they are faster
- than the 16 bit operations. */
- movl $0x400,%edx /* round towards -oo */
- orl 4(%esp),%edx
- andl $0xf7ff,%edx
- movl %edx,(%esp)
- fldcw (%esp) /* load modified control word */
-
- frndint /* round */
-
- fldenv 4(%esp) /* restore original environment */
-
- addl $32,%esp
- cfi_adjust_cfa_offset (-32)
- ret
-END (__floor)
-libm_alias_double (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floor.c b/sysdeps/i386/fpu/s_floor.c
new file mode 100644
index 0000000000..cc50e33b59
--- /dev/null
+++ b/sysdeps/i386/fpu/s_floor.c
@@ -0,0 +1,25 @@
+/* Return smallest integral value not less than argument. i386 version.
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <libm-alias-double.h>
+
+#define FUNC __floor
+#define TYPE double
+#define FE_OPTION FE_DOWNWARD
+#include "s_nearestint_387_template.c"
+libm_alias_double (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floorf.S b/sysdeps/i386/fpu/s_floorf.S
deleted file mode 100644
index 8fad9c0698..0000000000
--- a/sysdeps/i386/fpu/s_floorf.S
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Public domain.
- */
-
-#include <machine/asm.h>
-#include <libm-alias-float.h>
-
-RCSID("$NetBSD: s_floorf.S,v 1.3 1995/05/09 00:04:32 jtc Exp $")
-
-ENTRY(__floorf)
- flds 4(%esp)
- subl $32,%esp
- cfi_adjust_cfa_offset (32)
-
- fnstenv 4(%esp) /* store fpu environment */
-
- /* We use here %edx although only the low 1 bits are defined.
- But none of the operations should care and they are faster
- than the 16 bit operations. */
- movl $0x400,%edx /* round towards -oo */
- orl 4(%esp),%edx
- andl $0xf7ff,%edx
- movl %edx,(%esp)
- fldcw (%esp) /* load modified control word */
-
- frndint /* round */
-
- fldenv 4(%esp) /* restore original environment */
-
- addl $32,%esp
- cfi_adjust_cfa_offset (-32)
- ret
-END (__floorf)
-libm_alias_float (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floorf.c b/sysdeps/i386/fpu/s_floorf.c
new file mode 100644
index 0000000000..fa9454e56b
--- /dev/null
+++ b/sysdeps/i386/fpu/s_floorf.c
@@ -0,0 +1,25 @@
+/* Largest integral value not greater than argument i386 version.
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <libm-alias-float.h>
+
+#define FUNC __floorf
+#define TYPE float
+#define FE_OPTION FE_DOWNWARD
+#include "s_nearestint_387_template.c"
+libm_alias_float (__floor, floor)
diff --git a/sysdeps/i386/fpu/s_floorl.S b/sysdeps/i386/fpu/s_floorl.S
deleted file mode 100644
index 3ec28b477b..0000000000
--- a/sysdeps/i386/fpu/s_floorl.S
+++ /dev/null
@@ -1,39 +0,0 @@
-/*
- * Public domain.
- */
-
-#include <libm-alias-ldouble.h>
-#include <machine/asm.h>
-
-RCSID("$NetBSD: $")
-
-ENTRY(__floorl)
- fldt 4(%esp)
- subl $32,%esp
- cfi_adjust_cfa_offset (32)
-
- fnstenv 4(%esp) /* store fpu environment */
-
- /* We use here %edx although only the low 1 bits are defined.
- But none of the operations should care and they are faster
- than the 16 bit operations. */
- movl $0x400,%edx /* round towards -oo */
- orl 4(%esp),%edx
- andl $0xf7ff,%edx
- movl %edx,(%esp)
- fldcw (%esp) /* load modified control word */
-
- frndint /* round */
-
- /* Preserve "invalid" exceptions from sNaN input. */
- fnstsw
- andl $0x1, %eax
- orl %eax, 8(%esp)
-
- fldenv 4(%esp) /* restore original environment */
-
- addl $32,%esp
- cfi_adjust_cfa_offset (-32)
- ret
-END (__floorl)
-libm_alias_ldouble (__floor, floor)
diff --git a/sysdeps/x86/fpu/s_floorl.c b/sysdeps/x86/fpu/s_floorl.c
new file mode 100644
index 0000000000..9c92d33fbe
--- /dev/null
+++ b/sysdeps/x86/fpu/s_floorl.c
@@ -0,0 +1,25 @@
+/* Return largest integral value not less than argument. x86 version.
+ Copyright (C) 2024 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 <libm-alias-ldouble.h>
+
+#define FUNC __floorl
+#define TYPE long double
+#define FE_OPTION FE_DOWNWARD
+#include "s_nearestint_387_template.c"
+libm_alias_ldouble (__floor, floor)
diff --git a/sysdeps/x86_64/fpu/s_floorl.S b/sysdeps/x86_64/fpu/s_floorl.S
deleted file mode 100644
index b74d1a4d6b..0000000000
--- a/sysdeps/x86_64/fpu/s_floorl.S
+++ /dev/null
@@ -1,33 +0,0 @@
-/*
- * Public domain.
- */
-
-#include <libm-alias-ldouble.h>
-#include <machine/asm.h>
-
-ENTRY(__floorl)
- fldt 8(%rsp)
-
- fnstenv -28(%rsp) /* store fpu environment */
-
- /* We use here %edx although only the low 1 bits are defined.
- But none of the operations should care and they are faster
- than the 16 bit operations. */
- movl $0x400,%edx /* round towards -oo */
- orl -28(%rsp),%edx
- andl $0xf7ff,%edx
- movl %edx,-32(%rsp)
- fldcw -32(%rsp) /* load modified control word */
-
- frndint /* round */
-
- /* Preserve "invalid" exceptions from sNaN input. */
- fnstsw
- andl $0x1, %eax
- orl %eax, -24(%rsp)
-
- fldenv -28(%rsp) /* restore original environment */
-
- ret
-END (__floorl)
-libm_alias_ldouble (__floor, floor)
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