gcc/libgcc/config/cris/arit.c
Richard Sandiford ac1dca3cab Update copyright years in libgcc/
From-SVN: r206295
2014-01-02 22:25:22 +00:00

314 lines
7.6 KiB
C

/* Signed and unsigned multiplication and division and modulus for CRIS.
Contributed by Axis Communications.
Written by Hans-Peter Nilsson <hp@axis.se>, c:a 1992.
Copyright (C) 1998-2014 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
This file is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* Note that we provide prototypes for all "const" functions, to attach
the const attribute. This is necessary in 2.7.2 - adding the
attribute to the function *definition* is a syntax error.
This did not work with e.g. 2.1; back then, the return type had to
be "const". */
#include "config.h"
#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3
#define LZ(v) __builtin_clz (v)
#endif
/* In (at least) the 4.7 series, GCC doesn't automatically choose the
most optimal strategy, possibly related to insufficient modelling of
delay-slot costs. */
#if defined (__CRIS_arch_version) && __CRIS_arch_version >= 10
#define SIGNMULT(s, a) ((s) * (a)) /* Cheap multiplication, better than branch. */
#else
#define SIGNMULT(s, a) ((s) < 0 ? -(a) : (a)) /* Branches are still better. */
#endif
#if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \
|| defined (L_modsi3)
/* Result type of divmod worker function. */
struct quot_rem
{
long quot;
long rem;
};
/* This is the worker function for div and mod. It is inlined into the
respective library function. Parameter A must have bit 31 == 0. */
static __inline__ struct quot_rem
do_31div (unsigned long a, unsigned long b)
__attribute__ ((__const__, __always_inline__));
static __inline__ struct quot_rem
do_31div (unsigned long a, unsigned long b)
{
/* Adjust operands and result if a is 31 bits. */
long extra = 0;
int quot_digits = 0;
if (b == 0)
{
struct quot_rem ret;
ret.quot = 0xffffffff;
ret.rem = 0xffffffff;
return ret;
}
if (a < b)
return (struct quot_rem) { 0, a };
#ifdef LZ
if (b <= a)
{
quot_digits = LZ (b) - LZ (a);
quot_digits += (a >= (b << quot_digits));
b <<= quot_digits;
}
#else
while (b <= a)
{
b <<= 1;
quot_digits++;
}
#endif
/* Is a 31 bits? Note that bit 31 is handled by the caller. */
if (a & 0x40000000)
{
/* Then make b:s highest bit max 0x40000000, because it must have
been 0x80000000 to be 1 bit higher than a. */
b >>= 1;
/* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero. */
if (a >= b)
{
a -= b;
extra = 1 << (quot_digits - 1);
}
else
{
a -= b >> 1;
/* Remember that we adjusted a by subtracting b * 2 ** Something. */
extra = 1 << quot_digits;
}
/* The number of quotient digits will be one less, because
we just adjusted b. */
quot_digits--;
}
/* Now do the division part. */
/* Subtract b and add ones to the right when a >= b
i.e. "a - (b - 1) == (a - b) + 1". */
b--;
#define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b))
switch (quot_digits)
{
case 32: DS; case 31: DS; case 30: DS; case 29: DS;
case 28: DS; case 27: DS; case 26: DS; case 25: DS;
case 24: DS; case 23: DS; case 22: DS; case 21: DS;
case 20: DS; case 19: DS; case 18: DS; case 17: DS;
case 16: DS; case 15: DS; case 14: DS; case 13: DS;
case 12: DS; case 11: DS; case 10: DS; case 9: DS;
case 8: DS; case 7: DS; case 6: DS; case 5: DS;
case 4: DS; case 3: DS; case 2: DS; case 1: DS;
case 0:;
}
{
struct quot_rem ret;
ret.quot = (a & ((1 << quot_digits) - 1)) + extra;
ret.rem = a >> quot_digits;
return ret;
}
}
#ifdef L_udivsi3
unsigned long
__Udiv (unsigned long a, unsigned long b) __attribute__ ((__const__));
unsigned long
__Udiv (unsigned long a, unsigned long b)
{
long extra = 0;
/* Adjust operands and result, if a and/or b is 32 bits. */
/* Effectively: b & 0x80000000. */
if ((long) b < 0)
return a >= b;
/* Effectively: a & 0x80000000. */
if ((long) a < 0)
{
int tmp = 0;
if (b == 0)
return 0xffffffff;
#ifdef LZ
tmp = LZ (b);
#else
for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
;
tmp = 31 - tmp;
#endif
if ((b << tmp) > a)
{
extra = 1 << (tmp-1);
a -= b << (tmp - 1);
}
else
{
extra = 1 << tmp;
a -= b << tmp;
}
}
return do_31div (a, b).quot+extra;
}
#endif /* L_udivsi3 */
#ifdef L_divsi3
long
__Div (long a, long b) __attribute__ ((__const__));
long
__Div (long a, long b)
{
long extra = 0;
long sign = (b < 0) ? -1 : 1;
long res;
/* We need to handle a == -2147483648 as expected and must while
doing that avoid producing a sequence like "abs (a) < 0" as GCC
may optimize out the test. That sequence may not be obvious as
we call inline functions. Testing for a being negative and
handling (presumably much rarer than positive) enables us to get
a bit of optimization for an (accumulated) reduction of the
penalty of the 0x80000000 special-case. */
if (a < 0)
{
sign = -sign;
if ((a & 0x7fffffff) == 0)
{
/* We're at 0x80000000. Tread carefully. */
a -= SIGNMULT (sign, b);
extra = sign;
}
a = -a;
}
res = do_31div (a, __builtin_labs (b)).quot;
return SIGNMULT (sign, res) + extra;
}
#endif /* L_divsi3 */
#ifdef L_umodsi3
unsigned long
__Umod (unsigned long a, unsigned long b) __attribute__ ((__const__));
unsigned long
__Umod (unsigned long a, unsigned long b)
{
/* Adjust operands and result if a and/or b is 32 bits. */
if ((long) b < 0)
return a >= b ? a - b : a;
if ((long) a < 0)
{
int tmp = 0;
if (b == 0)
return a;
#ifdef LZ
tmp = LZ (b);
#else
for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
;
tmp = 31 - tmp;
#endif
if ((b << tmp) > a)
{
a -= b << (tmp - 1);
}
else
{
a -= b << tmp;
}
}
return do_31div (a, b).rem;
}
#endif /* L_umodsi3 */
#ifdef L_modsi3
long
__Mod (long a, long b) __attribute__ ((__const__));
long
__Mod (long a, long b)
{
long sign = 1;
long res;
/* We need to handle a == -2147483648 as expected and must while
doing that avoid producing a sequence like "abs (a) < 0" as GCC
may optimize out the test. That sequence may not be obvious as
we call inline functions. Testing for a being negative and
handling (presumably much rarer than positive) enables us to get
a bit of optimization for an (accumulated) reduction of the
penalty of the 0x80000000 special-case. */
if (a < 0)
{
sign = -1;
if ((a & 0x7fffffff) == 0)
/* We're at 0x80000000. Tread carefully. */
a += __builtin_labs (b);
a = -a;
}
res = do_31div (a, __builtin_labs (b)).rem;
return SIGNMULT (sign, res);
}
#endif /* L_modsi3 */
#endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */
/*
* Local variables:
* eval: (c-set-style "gnu")
* indent-tabs-mode: t
* End:
*/