dnl AMD64 mpn_rshift optimised
for CPUs with fast SSE including fast movdqu.
dnl Contributed to the GNU project by Torbjorn Granlund.
dnl Copyright 2010-2012 Free Software 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/limb cycles/limb cycles/limb good
C aligned unaligned best seen
for cpu?
C AMD K8,K9 3 3 2.35 no, use shl/
shr
C AMD K10 1.5-1.8 1.5-1.8 1.33 yes
C AMD bd1 1.7-1.9 1.7-1.9 1.33 yes
C AMD bobcat 3.17 3.17 yes, bad
for n < 20
C Intel P4 4.67 4.67 2.7 no, slow movdqu
C Intel core2 2.15 2.15 1.25 no, use shld/shrd
C Intel NHM 1.66 1.66 1.25 no, use shld/shrd
C Intel SBR 1.3 1.3 1.25 yes, bad
for n = 4-6
C Intel atom 11.7 11.7 4.5 no
C VIA nano 5.7 5.95 2.0 no, slow movdqu
C We try to do as many aligned 16-
byte operations as possible. The top-most
C
and bottom-most writes might need 8-
byte operations.
C
C
This variant rely on fast load movdqu,
and uses it
even for aligned operands,
C in order to avoid the need
for two separate loops.
C
C TODO
C * Could 2-limb wind-down
code be simplified?
C * Improve basecase
code, using shld/shrd
for SBR, discrete integer shifts
C
for other affected CPUs.
C INPUT PARAMETERS
define(`rp
', `%rdi')
define(`ap
', `%rsi')
define(`n
', `%rdx')
define(`cnt
', `%rcx')
ASM_START()
TEXT
ALIGN(64)
PROLOGUE(mpn_rshift)
FUNC_ENTRY(4)
movd R32(%rcx), %xmm4
mov $64, R32(%rax)
sub R32(%rcx), R32(%rax)
movd R32(%rax), %xmm5
neg R32(%rcx)
mov (ap), %rax
shl R8(%rcx), %rax
cmp $3, n
jle L(bc)
test $8, R8(rp)
jz L(rp_aligned)
C Do one initial limb in order to make rp aligned
movq (ap), %xmm0
movq 8(ap), %xmm1
psrlq %xmm4, %xmm0
psllq %xmm5, %xmm1
por %xmm1, %xmm0
movq %xmm0, (rp)
lea 8(ap), ap
lea 8(rp), rp
dec n
L(rp_aligned):
lea 1(n), %r8d
lea (ap,n,8), ap
lea (rp,n,8), rp
neg n
and $6, R32(%r8)
jz L(bu0)
cmp $4, R32(%r8)
jz L(bu4)
jc L(bu2)
L(bu6):
add $4, n
jmp L(i56)
L(bu0):
add $6, n
jmp L(i70)
L(bu4):
add $2, n
jmp L(i34)
L(bu2):
add $8, n
jge L(
end)
ALIGN(16)
L(top): movdqu -64(ap,n,8), %xmm1
movdqu -56(ap,n,8), %xmm0
psllq %xmm5, %xmm0
psrlq %xmm4, %xmm1
por %xmm1, %xmm0
movdqa %xmm0, -64(rp,n,8)
L(i70):
movdqu -48(ap,n,8), %xmm1
movdqu -40(ap,n,8), %xmm0
psllq %xmm5, %xmm0
psrlq %xmm4, %xmm1
por %xmm1, %xmm0
movdqa %xmm0, -48(rp,n,8)
L(i56):
movdqu -32(ap,n,8), %xmm1
movdqu -24(ap,n,8), %xmm0
psllq %xmm5, %xmm0
psrlq %xmm4, %xmm1
por %xmm1, %xmm0
movdqa %xmm0, -32(rp,n,8)
L(i34):
movdqu -16(ap,n,8), %xmm1
movdqu -8(ap,n,8), %xmm0
psllq %xmm5, %xmm0
psrlq %xmm4, %xmm1
por %xmm1, %xmm0
movdqa %xmm0, -16(rp,n,8)
add $8, n
jl L(top)
L(
end): test $1, R8(n)
jnz L(e1)
movdqu -16(ap), %xmm1
movq -8(ap), %xmm0
psrlq %xmm4, %xmm1
psllq %xmm5, %xmm0
por %xmm1, %xmm0
movdqa %xmm0, -16(rp)
FUNC_EXIT()
ret
L(e1): movq -8(ap), %xmm0
psrlq %xmm4, %xmm0
movq %xmm0, -8(rp)
FUNC_EXIT()
ret
C Basecase
ALIGN(16)
L(bc):
dec R32(n)
jnz 1f
movq (ap), %xmm0
psrlq %xmm4, %xmm0
movq %xmm0, (rp)
FUNC_EXIT()
ret
1: movq (ap), %xmm1
movq 8(ap), %xmm0
psrlq %xmm4, %xmm1
psllq %xmm5, %xmm0
por %xmm1, %xmm0
movq %xmm0, (rp)
dec R32(n)
jnz 1f
movq 8(ap), %xmm0
psrlq %xmm4, %xmm0
movq %xmm0, 8(rp)
FUNC_EXIT()
ret
1: movq 8(ap), %xmm1
movq 16(ap), %xmm0
psrlq %xmm4, %xmm1
psllq %xmm5, %xmm0
por %xmm1, %xmm0
movq %xmm0, 8(rp)
movq 16(ap), %xmm0
psrlq %xmm4, %xmm0
movq %xmm0, 16(rp)
FUNC_EXIT()
ret
EPILOGUE()
