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Save all fpcr/fpsr bits in the AArch64 fenv_t

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The existing code masked off all bits that it didn't know about. To be
future-proof, we should save and restore the entire fpcr/fpsr registers.
Additionally, the existing fesetenv() was incorrectly setting the rounding
mode in fpsr instead of fpcr.

This patch stores fpcr in the high 32 bits of fenv_t and fpsr in the low
bits instead of trying to interleave them in a single 32-bit field.

Technically, this is an ABI break if you re-compile parts of your code or
pass a fenv_t between DSOs that were compiled with different versions
of fenv.h. However, I believe we should fix this since the existing code
was broken and passing fenv_t across DSOs should rarely happen.

Reviewed By:	andrew
Differential Revision: https://reviews.freebsd.org/D29160
This commit is contained in:
Alex Richardson 2021-03-12 17:01:37 +00:00
parent b8e12d2d5c
commit 34cc08e336
1 changed files with 10 additions and 10 deletions
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20
lib/msun/aarch64/fenv.h
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@ -35,6 +35,7 @@
#define __fenv_static static
#endif
/* The high 32 bits contain fpcr, low 32 contain fpsr. */
typedef __uint64_t fenv_t;
typedef __uint64_t fexcept_t;
@ -156,13 +157,12 @@ fesetround(int __round)
__fenv_static inline int
fegetenv(fenv_t *__envp)
{
fenv_t __r;
__uint64_t fpcr;
__uint64_t fpsr;
__mrs_fpcr(__r);
*__envp = __r & _ENABLE_MASK;
__mrs_fpsr(__r);
*__envp |= __r & (FE_ALL_EXCEPT | (_ROUND_MASK << _ROUND_SHIFT));
__mrs_fpcr(fpcr);
__mrs_fpsr(fpsr);
*__envp = fpsr | (fpcr << 32);
return (0);
}
@ -173,12 +173,12 @@ feholdexcept(fenv_t *__envp)
fenv_t __r;
__mrs_fpcr(__r);
*__envp = __r & _ENABLE_MASK;
*__envp = __r << 32;
__r &= ~(_ENABLE_MASK);
__msr_fpcr(__r);
__mrs_fpsr(__r);
*__envp |= __r & (FE_ALL_EXCEPT | (_ROUND_MASK << _ROUND_SHIFT));
*__envp |= (__uint32_t)__r;
__r &= ~(_ENABLE_MASK);
__msr_fpsr(__r);
return (0);
@ -188,8 +188,8 @@ __fenv_static inline int
fesetenv(const fenv_t *__envp)
{
__msr_fpcr((*__envp) & _ENABLE_MASK);
__msr_fpsr((*__envp) & (FE_ALL_EXCEPT | (_ROUND_MASK << _ROUND_SHIFT)));
__msr_fpcr((*__envp) >> 32);
__msr_fpsr((fenv_t)(__uint32_t)*__envp);
return (0);
}