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dnl AMD64 mpn_popcount -- population count.
dnl Copyright 2008, 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
C AMD K8,K9 n/a
C AMD K10 1.125
C Intel P4 n/a
C Intel core2 n/a
C Intel corei 1.25
C Intel atom n/a
C VIA nano n/a
C * The zero-offset of popcount is misassembled to the offset-less form, which
C is one byte shorter and therefore will mess up the switching code.
C * The outdated gas used in FreeBSD and NetBSD cannot handle the POPCNT insn,
C which is the main reason for our usage of '.byte'.
C TODO
C * Improve switching code, the current code sucks.
define(`up', `%rdi')
define(`n', `%rsi')
ABI_SUPPORT(DOS64)
ABI_SUPPORT(STD64)
ASM_START()
TEXT
ALIGN(32)
PROLOGUE(mpn_popcount)
FUNC_ENTRY(2)
ifelse(1,1,`
lea (up,n,8), up
C mov R32(n), R32(%rcx)
C neg R32(%rcx)
imul $-1, R32(n), R32(%rcx)
and $8-1, R32(%rcx)
neg n
mov R32(%rcx), R32(%rax)
neg %rax
lea (up,%rax,8),up
xor R32(%rax), R32(%rax)
lea (%rcx,%rcx,4), %rcx
lea L(top)(%rip), %rdx
lea (%rdx,%rcx,2), %rdx
jmp *%rdx
',`
lea (up,n,8), up
mov R32(n), R32(%rcx)
neg R32(%rcx)
and $8-1, R32(%rcx)
neg n
mov R32(%rcx), R32(%rax)
shl $3, R32(%rax)
sub %rax, up
xor R32(%rax), R32(%rax)
C add R32(%rcx), R32(%rcx) C 2x
C lea (%rcx,%rcx,4), %rcx C 10x
imul $10, R32(%rcx)
lea L(top)(%rip), %rdx
add %rcx, %rdx
jmp *%rdx
')
ALIGN(32)
L(top):
C 0 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x44,0xf7,0x00 C popcnt 0(up,n,8), %r8
add %r8, %rax
C 7 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x4c,0xf7,0x08 C popcnt 8(up,n,8), %r9
add %r9, %rax
C 6 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x44,0xf7,0x10 C popcnt 16(up,n,8), %r8
add %r8, %rax
C 5 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x4c,0xf7,0x18 C popcnt 24(up,n,8), %r9
add %r9, %rax
C 4 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x44,0xf7,0x20 C popcnt 32(up,n,8), %r8
add %r8, %rax
C 3 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x4c,0xf7,0x28 C popcnt 40(up,n,8), %r9
add %r9, %rax
C 2 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x44,0xf7,0x30 C popcnt 48(up,n,8), %r8
add %r8, %rax
C 1 = n mod 8
.byte 0xf3,0x4c,0x0f,0xb8,0x4c,0xf7,0x38 C popcnt 56(up,n,8), %r9
add %r9, %rax
add $8, n
js L(top)
FUNC_EXIT()
ret
EPILOGUE()
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