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softfloat: Introduce sh[lr]_double primitives

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Have x86_64 assembly for them, with a fallback.
This avoids shuffling values through %cl in the x86 case.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2020-11-09 19:08:30 -08:00
parent 5ffb6bd9c4
commit 463e45dcb4
2 changed files with 115 additions and 23 deletions
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36
include/fpu/softfloat-macros.h
View file

@ -85,6 +85,42 @@ this code that are retained.
#include "fpu/softfloat-types.h"
#include "qemu/host-utils.h"
/**
* shl_double: double-word merging left shift
* @l: left or most-significant word
* @r: right or least-significant word
* @c: shift count
*
* Shift @l left by @c bits, shifting in bits from @r.
*/
static inline uint64_t shl_double(uint64_t l, uint64_t r, int c)
{
#if defined(__x86_64__)
asm("shld %b2, %1, %0" : "+r"(l) : "r"(r), "ci"(c));
return l;
#else
return c ? (l << c) | (r >> (64 - c)) : l;
#endif
}
/**
* shr_double: double-word merging right shift
* @l: left or most-significant word
* @r: right or least-significant word
* @c: shift count
*
* Shift @r right by @c bits, shifting in bits from @l.
*/
static inline uint64_t shr_double(uint64_t l, uint64_t r, int c)
{
#if defined(__x86_64__)
asm("shrd %b2, %1, %0" : "+r"(r) : "r"(l), "ci"(c));
return r;
#else
return c ? (r >> c) | (l << (64 - c)) : r;
#endif
}
/*----------------------------------------------------------------------------
| Shifts `a' right by the number of bits given in `count'. If any nonzero
| bits are shifted off, they are ``jammed'' into the least significant bit of