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arch/mips/lib/multi3.c
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// SPDX-License-Identifier: GPL-2.0 #include <linux/export.h> #include "libgcc.h" /* |
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* GCC 7 & older can suboptimally generate __multi3 calls for mips64r6, so for * that specific case only we implement that intrinsic here. |
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* * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82981 */ |
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#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) && (__GNUC__ < 8) |
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/* multiply 64-bit values, low 64-bits returned */
static inline long long notrace dmulu(long long a, long long b)
{
long long res;
asm ("dmulu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
return res;
}
/* multiply 64-bit unsigned values, high 64-bits of 128-bit result returned */
static inline long long notrace dmuhu(long long a, long long b)
{
long long res;
asm ("dmuhu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
return res;
}
/* multiply 128-bit values, low 128-bits returned */
ti_type notrace __multi3(ti_type a, ti_type b)
{
TWunion res, aa, bb;
aa.ti = a;
bb.ti = b;
/*
* a * b = (a.lo * b.lo)
* + 2^64 * (a.hi * b.lo + a.lo * b.hi)
* [+ 2^128 * (a.hi * b.hi)]
*/
res.s.low = dmulu(aa.s.low, bb.s.low);
res.s.high = dmuhu(aa.s.low, bb.s.low);
res.s.high += dmulu(aa.s.high, bb.s.low);
res.s.high += dmulu(aa.s.low, bb.s.high);
return res.ti;
}
EXPORT_SYMBOL(__multi3);
#endif /* 64BIT && CPU_MIPSR6 && GCC7 */
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