8aa9d6206c
Previously, building `multc3.c` on A64 with GCC 7 or up but 9 and lower
will attempt to reference `__builtin_copysignq`, an [x86-specific
intrinsic][1]:
```
$ gcc -c multc3.c
In file included from fp_lib.h:24,
from multc3.c:14:
multc3.c: In function '__multc3':
int_math.h:71:32: warning: implicit declaration of function '__builtin_copysignq'; did you mean '__builtin_copysign'? [-Wimplicit-function-declaration]
#define crt_copysignf128(x, y) __builtin_copysignq((x), (y))
^~~~~~~~~~~~~~~~~~~
```
This is because `__has_builtin` is from GCC 10, and defined to 0 at the
top of int_math.h for affected GCC versions, so the fallback definition
is used. But `__builtin_copysignq` is unavailable on A64.
Use version detection to find `__builtin_copysignf128` instead. It's
available since GCC 7 and [available][2] on both x86 and A64, given this
macro is only used when `CRT_HAS_IEEE_TF`.
---
I realize this is fixing a problem for an out-of-tree build
configuration, but help would be greatly appreciated. Rust
[builds](https://github.com/rust-lang/compiler-builtins) `multc3.c` with
GCC 8 and this mis-selection is causing [build
issues](https://github.com/rust-lang/rust/issues/125619) way downstream.
ref: d2ce3e9621411f3391def327f89e3a650918989f
[1]: https://gcc.gnu.org/onlinedocs/gcc/x86-Built-in-Functions.html
[2]: https://gcc.gnu.org/gcc-7/changes.html
114 lines
4.0 KiB
C
114 lines
4.0 KiB
C
//===-- int_math.h - internal math inlines --------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is not part of the interface of this library.
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//
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// This file defines substitutes for the libm functions used in some of the
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// compiler-rt implementations, defined in such a way that there is not a direct
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// dependency on libm or math.h. Instead, we use the compiler builtin versions
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// where available. This reduces our dependencies on the system SDK by foisting
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// the responsibility onto the compiler.
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//
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//===----------------------------------------------------------------------===//
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#ifndef INT_MATH_H
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#define INT_MATH_H
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#ifndef __has_builtin
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#define __has_builtin(x) 0
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#include <math.h>
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#include <stdlib.h>
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#define CRT_INFINITY INFINITY
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#else
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#define CRT_INFINITY __builtin_huge_valf()
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#define crt_isfinite(x) _finite((x))
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#define crt_isinf(x) !_finite((x))
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#define crt_isnan(x) _isnan((x))
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#else
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// Define crt_isfinite in terms of the builtin if available, otherwise provide
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// an alternate version in terms of our other functions. This supports some
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// versions of GCC which didn't have __builtin_isfinite.
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#if __has_builtin(__builtin_isfinite)
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#define crt_isfinite(x) __builtin_isfinite((x))
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#elif defined(__GNUC__)
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#define crt_isfinite(x) \
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__extension__(({ \
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__typeof((x)) x_ = (x); \
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!crt_isinf(x_) && !crt_isnan(x_); \
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}))
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#else
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#error "Do not know how to check for infinity"
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#endif // __has_builtin(__builtin_isfinite)
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#define crt_isinf(x) __builtin_isinf((x))
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#define crt_isnan(x) __builtin_isnan((x))
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#endif // _MSC_VER
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#if defined(_MSC_VER) && !defined(__clang__)
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#define crt_copysign(x, y) copysign((x), (y))
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#define crt_copysignf(x, y) copysignf((x), (y))
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#define crt_copysignl(x, y) copysignl((x), (y))
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#else
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#define crt_copysign(x, y) __builtin_copysign((x), (y))
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#define crt_copysignf(x, y) __builtin_copysignf((x), (y))
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#define crt_copysignl(x, y) __builtin_copysignl((x), (y))
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// We define __has_builtin to always return 0 for GCC versions below 10,
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// but __builtin_copysignf128 is available since version 7.
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#if __has_builtin(__builtin_copysignf128) || \
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(defined(__GNUC__) && __GNUC__ >= 7)
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#define crt_copysignf128(x, y) __builtin_copysignf128((x), (y))
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#elif __has_builtin(__builtin_copysignq)
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#define crt_copysignf128(x, y) __builtin_copysignq((x), (y))
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#endif
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#define crt_fabs(x) fabs((x))
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#define crt_fabsf(x) fabsf((x))
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#define crt_fabsl(x) fabs((x))
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#else
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#define crt_fabs(x) __builtin_fabs((x))
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#define crt_fabsf(x) __builtin_fabsf((x))
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#define crt_fabsl(x) __builtin_fabsl((x))
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// We define __has_builtin to always return 0 for GCC versions below 10,
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// but __builtin_fabsf128 is available since version 7.
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#if __has_builtin(__builtin_fabsf128) || (defined(__GNUC__) && __GNUC__ >= 7)
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#define crt_fabsf128(x) __builtin_fabsf128((x))
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#elif __has_builtin(__builtin_fabsq)
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#define crt_fabsf128(x) __builtin_fabsq((x))
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#endif
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#define crt_fmaxl(x, y) __max((x), (y))
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#else
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#define crt_fmaxl(x, y) __builtin_fmaxl((x), (y))
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#define crt_logbl(x) logbl((x))
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#else
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#define crt_logbl(x) __builtin_logbl((x))
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#define crt_scalbnl(x, y) scalbnl((x), (y))
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#else
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#define crt_scalbnl(x, y) __builtin_scalbnl((x), (y))
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#endif
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#endif // INT_MATH_H
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