freebsd-dev/lib/msun/amd64/fenv.h
David Schultz 8185b32b5a Fix a problem relating to fesetenv() clobbering i387 register stack.
Details: As a side-effect of restoring a saved FP environment,
fesetenv() overwrites the tag word, which indicates which i387
registers are in use.  Normally this isn't a problem because
the calling convention requires the register stack to be empty
on function entry and exit.  However, fesetenv() is inlined, so we
need to tell gcc explicitly that the i387 registers get clobbered.

PR:	85101
2007-01-06 21:46:23 +00:00

215 lines
5.6 KiB
C

/*-
* Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef _FENV_H_
#define _FENV_H_
#include <sys/cdefs.h>
#include <sys/_types.h>
typedef struct {
struct {
__uint32_t __control;
__uint32_t __status;
__uint32_t __tag;
char __other[16];
} __x87;
__uint32_t __mxcsr;
} fenv_t;
typedef __uint16_t fexcept_t;
/* Exception flags */
#define FE_INVALID 0x01
#define FE_DENORMAL 0x02
#define FE_DIVBYZERO 0x04
#define FE_OVERFLOW 0x08
#define FE_UNDERFLOW 0x10
#define FE_INEXACT 0x20
#define FE_ALL_EXCEPT (FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
/* Rounding modes */
#define FE_TONEAREST 0x0000
#define FE_DOWNWARD 0x0400
#define FE_UPWARD 0x0800
#define FE_TOWARDZERO 0x0c00
#define _ROUND_MASK (FE_TONEAREST | FE_DOWNWARD | \
FE_UPWARD | FE_TOWARDZERO)
/*
* As compared to the x87 control word, the SSE unit's control word
* has the rounding control bits offset by 3 and the exception mask
* bits offset by 7.
*/
#define _SSE_ROUND_SHIFT 3
#define _SSE_EMASK_SHIFT 7
__BEGIN_DECLS
/* Default floating-point environment */
extern const fenv_t __fe_dfl_env;
#define FE_DFL_ENV (&__fe_dfl_env)
#define __fldcw(__cw) __asm __volatile("fldcw %0" : : "m" (__cw))
#define __fldenv(__env) __asm __volatile("fldenv %0" : : "m" (__env))
#define __fldenvx(__env) __asm __volatile("fldenv %0" : : "m" (__env) \
: "st", "st(1)", "st(2)", "st(3)", "st(4)", \
"st(5)", "st(6)", "st(7)")
#define __fnclex() __asm __volatile("fnclex")
#define __fnstenv(__env) __asm __volatile("fnstenv %0" : "=m" (*(__env)))
#define __fnstcw(__cw) __asm __volatile("fnstcw %0" : "=m" (*(__cw)))
#define __fnstsw(__sw) __asm __volatile("fnstsw %0" : "=am" (*(__sw)))
#define __fwait() __asm __volatile("fwait")
#define __ldmxcsr(__csr) __asm __volatile("ldmxcsr %0" : : "m" (__csr))
#define __stmxcsr(__csr) __asm __volatile("stmxcsr %0" : "=m" (*(__csr)))
static __inline int
feclearexcept(int __excepts)
{
fenv_t __env;
if (__excepts == FE_ALL_EXCEPT) {
__fnclex();
} else {
__fnstenv(&__env.__x87);
__env.__x87.__status &= ~__excepts;
__fldenv(__env.__x87);
}
__stmxcsr(&__env.__mxcsr);
__env.__mxcsr &= ~__excepts;
__ldmxcsr(__env.__mxcsr);
return (0);
}
static __inline int
fegetexceptflag(fexcept_t *__flagp, int __excepts)
{
int __mxcsr, __status;
__stmxcsr(&__mxcsr);
__fnstsw(&__status);
*__flagp = (__mxcsr | __status) & __excepts;
return (0);
}
int fesetexceptflag(const fexcept_t *__flagp, int __excepts);
int feraiseexcept(int __excepts);
static __inline int
fetestexcept(int __excepts)
{
int __mxcsr, __status;
__stmxcsr(&__mxcsr);
__fnstsw(&__status);
return ((__status | __mxcsr) & __excepts);
}
static __inline int
fegetround(void)
{
int __control;
/*
* We assume that the x87 and the SSE unit agree on the
* rounding mode. Reading the control word on the x87 turns
* out to be about 5 times faster than reading it on the SSE
* unit on an Opteron 244.
*/
__fnstcw(&__control);
return (__control & _ROUND_MASK);
}
static __inline int
fesetround(int __round)
{
int __mxcsr, __control;
if (__round & ~_ROUND_MASK)
return (-1);
__fnstcw(&__control);
__control &= ~_ROUND_MASK;
__control |= __round;
__fldcw(__control);
__stmxcsr(&__mxcsr);
__mxcsr &= ~(_ROUND_MASK << _SSE_ROUND_SHIFT);
__mxcsr |= __round << _SSE_ROUND_SHIFT;
__ldmxcsr(__mxcsr);
return (0);
}
int fegetenv(fenv_t *__envp);
int feholdexcept(fenv_t *__envp);
static __inline int
fesetenv(const fenv_t *__envp)
{
/*
* XXX Using fldenvx() instead of fldenv() tells the compiler that this
* instruction clobbers the i387 register stack. This happens because
* we restore the tag word from the saved environment. Normally, this
* would happen anyway and we wouldn't care, because the ABI allows
* function calls to clobber the i387 regs. However, fesetenv() is
* inlined, so we need to be more careful.
*/
__fldenvx(__envp->__x87);
__ldmxcsr(__envp->__mxcsr);
return (0);
}
int feupdateenv(const fenv_t *__envp);
#if __BSD_VISIBLE
int feenableexcept(int __mask);
int fedisableexcept(int __mask);
static __inline int
fegetexcept(void)
{
int __control;
/*
* We assume that the masks for the x87 and the SSE unit are
* the same.
*/
__fnstcw(&__control);
return (~__control & FE_ALL_EXCEPT);
}
#endif /* __BSD_VISIBLE */
__END_DECLS
#endif /* !_FENV_H_ */