[PATCH 2/2] Revert "x86: Do not use __builtin_fpclassify for _Float64x/long double"
Adhemerval Zanella
adhemerval.zanella@linaro.org
Tue Jan 13 14:19:29 GMT 2026
This reverts commit 50112103993b042f52fb6afb0e4eee24fe4cb9af. It
breaks libstdc++ and other languages bootstrap.
---
bits/fp-builtin-denormal.h | 28 --------
math/Makefile | 1 -
math/math.h | 89 +------------------------
sysdeps/x86/bits/fp-builtin-denormal.h | 25 -------
sysdeps/x86/fpu/Makefile | 1 -
sysdeps/x86/fpu/test-builtin-denormal.c | 53 ---------------
6 files changed, 2 insertions(+), 195 deletions(-)
delete mode 100644 bits/fp-builtin-denormal.h
delete mode 100644 sysdeps/x86/bits/fp-builtin-denormal.h
delete mode 100644 sysdeps/x86/fpu/test-builtin-denormal.c
diff --git a/bits/fp-builtin-denormal.h b/bits/fp-builtin-denormal.h
deleted file mode 100644
index 457ab0c97a..0000000000
--- a/bits/fp-builtin-denormal.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/* Denormal number definitions.
- Copyright (C) 2025-2026 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/>. */
-
-#ifndef _MATH_H
-# error "Never use <bits/fp-builtin-denormal.h> directly; include <math.h> instead."
-#endif
-
-/* __FP_BUILTIN_FPCLASSIFY_DENORMAL is defined to 1 if compiler supports
- handling pseudo-denormal numbers with fpclassify builtin. Pseudo-denormal
- is a non-standard denormalized floating-point number only supported by
- Intel double extended-precision (long double). By default assume 1 to
- enable the usage of compiler builtin on math.h. */
-#define __FP_BUILTIN_FPCLASSIFY_DENORMAL 1
diff --git a/math/Makefile b/math/Makefile
index 69f80e143f..b546626f15 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -28,7 +28,6 @@ headers := \
bits/floatn-common.h \
bits/floatn.h \
bits/flt-eval-method.h \
- bits/fp-builtin-denormal.h \
bits/fp-fast.h \
bits/fp-logb.h \
bits/iscanonical.h \
diff --git a/math/math.h b/math/math.h
index 77dfcdc36b..75830d7696 100644
--- a/math/math.h
+++ b/math/math.h
@@ -1064,86 +1064,6 @@ extern int signgam;
: FUNC ## l ARGS)
#endif
-
-/* Depending on the type of TG_ARG and extra DEFINE to check, either call the
- BUILTIN with ARGS_B or an appropriately suffixed version of FUNC with
- arguments (including parentheses) ARGS_B. The function call is used for
- long double and/or _Float64x is the builtin can not be safely used on all
- arguments (defined by DEFINE). */
-
-#include <bits/fp-builtin-denormal.h>
-
-#ifdef __NO_LONG_DOUBLE_MATH
-# define __MATH_TG_BUILTIN_CLASSIFY(TG_ARG, BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- BUILTIN ARGS_B
-#elif __HAVE_DISTINCT_FLOAT128
-# if __HAVE_GENERIC_SELECTION
-# if __HAVE_FLOATN_NOT_TYPEDEF && __HAVE_FLOAT32
-# define __MATH_TG_BUILTIN_CLASSIFY_F32(BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- _Float32: BUILTIN ARGS_B,
-# else
-# define __MATH_TG_BUILTIN_CLASSIFY_F32(BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE)
-# endif
-# define __MATH_TG_BUILTIN_CLASSIFY_LDOUBLE(BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- long double: DEFINE ? BUILTIN ARGS_B : __ ## FUNC ## l ARGS_F,
-# if __HAVE_FLOATN_NOT_TYPEDEF && __HAVE_FLOAT64X
-# if __HAVE_FLOAT64X_LONG_DOUBLE
-# define __MATH_TG_BUILTIN_CLASSIFY_F64X(BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- _Float64x: DEFINE ? BUILTIN ARGS_B : __ ## FUNC ## l ARGS_F,
-# else
-# define __MATH_TG_BUILTIN_CLASSIFY_F64X(BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- _Float64x: DEFINE ? BUILTIN ARGS_B : __ ## FUNC ## f128 ARGS_F,
-# endif
-# else
-# define __MATH_TG_BUILTIN_CLASSIFY_F64X(BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE)
-# endif
-# define __MATH_TG_BUILTIN_CLASSIFY_F128(BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- _Float128: BUILTIN ARGS_B
-# define __MATH_TG_BUILTIN_CLASSIFY(TG_ARG, BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- _Generic ((TG_ARG), \
- float: BUILTIN ARGS_B, \
- __MATH_TG_BUILTIN_CLASSIFY_F32 (BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- default: BUILTIN ARGS_B, \
- __MATH_TG_BUILTIN_CLASSIFY_LDOUBLE (BUILTIN, ARGS_B, FUNC, \
- ARGS_F, DEFINE) \
- __MATH_TG_BUILTIN_CLASSIFY_F64X (BUILTIN, ARGS_B, FUNC, ARGS_F,\
- DEFINE) \
- __MATH_TG_BUILTIN_CLASSIFY_F128 (BUILTIN, ARGS_B, FUNC, ARGS_F,\
- DEFINE))
-# else
-# define __MATH_TG_BUILTIN_CLASSIFY(TG_ARG, BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- __builtin_choose_expr \
- (__builtin_types_compatible_p (__typeof (TG_ARG), float), \
- __builtin ## BUILTIN ARGS_B, \
- __builtin_choose_expr \
- (__builtin_types_compatible_p (__typeof (TG_ARG), double), \
- __builtin ## BUILTIN ARGS_B, \
- __builtin_choose_expr \
- (__builtin_types_compatible_p (__typeof (TG_ARG), long double), \
- DEFINE ? BUILTIN ARGS_B : __ ## FUNC ## l ARGS_F, \
- BUILTIN ARGS_B)))
-# endif
-#else
-# define __MATH_TG_BUILTIN_CLASSIFY(TG_ARG, BUILTIN, ARGS_B, FUNC, ARGS_F, \
- DEFINE) \
- (sizeof (TG_ARG) == sizeof (float) \
- ? BUILTIN ARGS_B \
- : sizeof (TG_ARG) == sizeof (double) \
- ? BUILTIN ARGS_B \
- : DEFINE ? BUILTIN ARGS_B : __ ## FUNC ## l ARGS_F)
-#endif
-
/* ISO C99 defines some generic macros which work on any data type. */
#ifdef __USE_ISOC99
@@ -1181,13 +1101,8 @@ enum
with -Os. No further use of this definition of fpclassify is
expected in C++ mode, since libstdc++ provides its own version
of fpclassify in cmath (which undefines fpclassify). */
-# define fpclassify(x) \
- __MATH_TG_BUILTIN_CLASSIFY ((x), \
- __builtin_fpclassify, (FP_NAN, FP_INFINITE, \
- FP_NORMAL, FP_SUBNORMAL, \
- FP_ZERO, x), \
- fpclassify, (x), \
- __FP_BUILTIN_FPCLASSIFY_DENORMAL)
+# define fpclassify(x) __builtin_fpclassify (FP_NAN, FP_INFINITE, \
+ FP_NORMAL, FP_SUBNORMAL, FP_ZERO, x)
# else
# define fpclassify(x) __MATH_TG ((x), __fpclassify, (x))
# endif
diff --git a/sysdeps/x86/bits/fp-builtin-denormal.h b/sysdeps/x86/bits/fp-builtin-denormal.h
deleted file mode 100644
index 33549c876a..0000000000
--- a/sysdeps/x86/bits/fp-builtin-denormal.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/* Define __FP_BUILTIN_DENORMAL.
- Copyright (C) 2025-2026 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/>. */
-
-#ifndef _MATH_H
-# error "Never use <bits/fp-builtin-denormal.h> directly; include <math.h> instead."
-#endif
-
-/* Neither GCC (bug 123161) nor clang (issue 172533) handles pseudo-normal
- numbers correctly with fpclassify builtin. */
-#define __FP_BUILTIN_FPCLASSIFY_DENORMAL 0
diff --git a/sysdeps/x86/fpu/Makefile b/sysdeps/x86/fpu/Makefile
index 8566d3c80f..91b2444f3a 100644
--- a/sysdeps/x86/fpu/Makefile
+++ b/sysdeps/x86/fpu/Makefile
@@ -4,7 +4,6 @@ CPPFLAGS += -I../soft-fp
libm-support += powl_helper
tests += \
- test-builtin-denormal \
test-fenv-clear-sse \
test-fenv-sse \
test-fenv-sse-2 \
diff --git a/sysdeps/x86/fpu/test-builtin-denormal.c b/sysdeps/x86/fpu/test-builtin-denormal.c
deleted file mode 100644
index 6584ec339f..0000000000
--- a/sysdeps/x86/fpu/test-builtin-denormal.c
+++ /dev/null
@@ -1,53 +0,0 @@
-/* Ccheck if math.h optimizations to call compiler builtin
- does not trigger FE_INVALID on x86 denormal numbers.
- Copyright (C) 2025-2026 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 <array_length.h>
-#include <fenv.h>
-#include <math.h>
-#include <math_ldbl.h>
-#include <support/check.h>
-
-#define pseudo_inf { .parts = { 0x00000000, 0x00000000, 0x7fff }}
-#define pseudo_zero { .parts = { 0x00000000, 0x00000000, 0x0100 }}
-#define pseudo_qnan { .parts = { 0x00000001, 0x00000000, 0x7fff }}
-#define pseudo_snan { .parts = { 0x00000001, 0x40000000, 0x7fff }}
-#define pseudo_unnormal { .parts = { 0x00000001, 0x40000000, 0x0100 }}
-
-static const ieee_long_double_shape_type inputs[] = {
- pseudo_inf,
- pseudo_zero,
- pseudo_qnan,
- pseudo_snan,
- pseudo_unnormal
-};
-
-static int
-do_test (void)
-{
- for (int i = 0; i < array_length (inputs); i++)
- {
- TEST_COMPARE (feclearexcept (FE_INVALID), 0);
- TEST_COMPARE (fpclassify (inputs[i].value), FP_NAN);
- TEST_COMPARE (fetestexcept (FE_INVALID), 0);
- }
-
- return 0;
-}
-
-#include <support/test-driver.c>
--
2.43.0
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