dnl x86 mpn_gcd_1 optimised for AMD K7.
dnl Contributed to the GNU project by by Kevin Ryde. Rehacked by Torbjorn
dnl Granlund.
dnl Copyright 2000-2002, 2005, 2009, 2011, 2012, 2014, 2015 Free Software
dnl Foundation, Inc.
dnl This file is part of the GNU MP Library.
dnl
dnl The GNU MP Library is free software; you can redistribute it and/or modify
dnl it under the terms of either:
dnl
dnl * the GNU Lesser General Public License as published by the Free
dnl Software Foundation; either version 3 of the License, or (at your
dnl option) any later version.
dnl
dnl or
dnl
dnl * the GNU General Public License as published by the Free Software
dnl Foundation; either version 2 of the License, or (at your option) any
dnl later version.
dnl
dnl or both in parallel, as here.
dnl
dnl The GNU MP Library is distributed in the hope that it will be useful, but
dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
dnl for more details.
dnl
dnl You should have received copies of the GNU General Public License and the
dnl GNU Lesser General Public License along with the GNU MP Library. If not,
dnl see https://www.gnu.org/licenses/.
include(`../config.m4')
C cycles/bit (approx)
C AMD K7 5.31
C AMD K8,K9 5.33
C AMD K10 5.30
C AMD bd1 ?
C AMD bobcat 7.02
C Intel P4-2 10.1
C Intel P4-3/4 10.0
C Intel P6/13 5.88
C Intel core2 6.26
C Intel NHM 6.83
C Intel SBR 8.50
C Intel atom 8.90
C VIA nano ?
C Numbers measured with: speed -CD -s16-32 -t16 mpn_gcd_1
C TODO
C * Tune overhead, this takes 2-3 cycles more than old code when v0 is tiny.
C * Stream things better through registers, avoiding some copying.
C * For ELF, avoid putting GOT base in both ebx and esi. Needs special
C LEA/LEAL or else discrete code here.
C ctz_table[n] is the number of trailing zeros on n, or MAXSHIFT if n==0.
deflit(MAXSHIFT, 6)
deflit(MASK, eval((m4_lshift(1,MAXSHIFT))-1))
DEF_OBJECT(ctz_table,64)
.byte MAXSHIFT
forloop(i,1,MASK,
` .byte m4_count_trailing_zeros(i)
')
END_OBJECT(ctz_table)
C Threshold of when to call bmod when U is one limb. Should be about
C (time_in_cycles(bmod_1,1) + call_overhead) / (cycles/bit).
define(`DIV_THRES_LOG2', 7)
define(`up', `%edi')
define(`n', `%esi')
define(`v0', `%edx')
ASM_START()
TEXT
ALIGN(16)
PROLOGUE(mpn_gcd_1)
push %edi
push %esi
mov 12(%esp), up
mov 16(%esp), n
mov 20(%esp), v0
mov (up), %eax C U low limb
or v0, %eax C x | y
mov $-1, %ecx
L(twos):
inc %ecx
shr %eax
jnc L(twos)
shr %cl, v0
mov %ecx, %eax C common twos
L(divide_strip_y):
shr v0
jnc L(divide_strip_y)
adc v0, v0
push %eax
push v0
cmp $1, n
jnz L(reduce_nby1)
C Both U and V are single limbs, reduce with bmod if u0 >> v0.
mov (up), %ecx
mov %ecx, %eax
shr $DIV_THRES_LOG2, %ecx
cmp %ecx, v0
ja L(reduced)
mov v0, %esi
xor %edx, %edx
div %esi
mov %edx, %eax
jmp L(reduced)
L(reduce_nby1):
ifdef(`PIC_WITH_EBX',`dnl
push %ebx
add $-4, %esp
call L(movl_eip_ebx)
add $_GLOBAL_OFFSET_TABLE_, %ebx
')
push v0 C param 3
push n C param 2
push up C param 1
cmp $BMOD_1_TO_MOD_1_THRESHOLD, n
jl L(bmod)
CALL( mpn_mod_1)
jmp L(called)
L(bmod):
CALL( mpn_modexact_1_odd)
L(called):
ifdef(`PIC_WITH_EBX',`dnl
add $16, %esp C deallocate params
pop %ebx
',`
add $12, %esp C deallocate params
')
L(reduced):
pop %edx
LEAL( ctz_table, %esi)
test %eax, %eax
mov %eax, %ecx
jnz L(mid)
jmp L(end)
ALIGN(16) C K8 BC P4 NHM SBR
L(top): cmovc( %ecx, %eax) C if x-y < 0 0
cmovc( %edi, %edx) C use x,y-x 0
L(mid): and $MASK, %ecx C 0
movzbl (%esi,%ecx), %ecx C 1
jz L(shift_alot) C 1
shr %cl, %eax C 3
mov %eax, %edi C 4
mov %edx, %ecx C 3
sub %eax, %ecx C 4
sub %edx, %eax C 4
jnz L(top) C 5
L(end): pop %ecx
mov %edx, %eax
shl %cl, %eax
pop %esi
pop %edi
ret
L(shift_alot):
shr $MAXSHIFT, %eax
mov %eax, %ecx
jmp L(mid)
ifdef(`PIC_WITH_EBX',`dnl
L(movl_eip_ebx):
mov (%esp), %ebx
ret
')
EPILOGUE()
ASM_END()