160 lines
3.7 KiB
NASM
160 lines
3.7 KiB
NASM
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; AMD64 mpn_sub_n
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; Copyright 2016 Alexander Kruppa
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; This file is part of the MPIR Library.
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; The MPIR Library is free software; you can redistribute it and/or modify
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; it under the terms of the GNU Lesser General Public License as published
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; by the Free Software Foundation; either version 2.1 of the License, or (at
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; your option) any later version.
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; The MPIR Library is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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; License for more details.
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; You should have received a copy of the GNU Lesser General Public License
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; along with the MPIR Library; see the file COPYING.LIB. If not, write
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; to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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; Boston, MA 02110-1301, USA.
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; (rdi,rcx) = (rsi,rcx)-(rdx,rcx)
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; rax = borrow
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%include 'yasm_mac.inc'
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%define USE_WIN64
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%ifdef USE_WIN64
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%define SumP rcx
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%define Inp1P rdx
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%define Inp2P r8
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%define Size r9
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%define SizeRest r11
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%define LIMB1 rax
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%define LIMB2 r10
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%else
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%define SumP rdi
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%define Inp1P rsi
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%define Inp2P rdx
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%define Size rcx
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%define SizeRest r11
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%define LIMB1 rax
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%define LIMB2 r8
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%endif
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%define ADDSUB sub
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%define ADCSBB sbb
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; Skylake has problems sustaining 2 read and 1 write per clock cycle.
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; It sometimes gets into a "mode" (for the lack of a better word) where
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; it does not fully utilize port 7, causing store uops to compete with
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; the reads for ports 2,3. We try to alleviate the problem by turning
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; some of the 64-bit writes into 128-bit writes, reducing the number of
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; write instructions. Unfortunately, SSE2/AVX2 do not have particularly
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; good instructions for assembling an SSE2 128-bit word from two GPR
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; 64-bit words, so the instruction count is greatly inflated.
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%macro STORE 1
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mov [SumP %1], LIMB1
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mov [SumP %1 + 8], LIMB2
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%endmacro
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%macro SSESTORE 1
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movq xmm0, LIMB1
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movq xmm1, LIMB2
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vpermilpd xmm1, xmm1, 0
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pblendw xmm0, xmm1, 0xf0
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movaps [SumP %1], xmm0
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%endmacro
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BITS 64
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LEAF_PROC mpn_sub_n
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; Make dest 16-bytes aligned
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test SumP, 8
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jz .aligned
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dec Size
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mov SizeRest, Size
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and SizeRest, 7
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shr Size, 3
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; Unaligned and Size > 8: do one limb separately, then the normal loop
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jnz .unaligned
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; Unaligned and Size <= 8: do all with .rest loop
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inc SizeRest
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clc
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jmp .rest ;ajs:notshortform
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.aligned:
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mov SizeRest, Size
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and SizeRest, 7
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shr Size, 3
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clc
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jz .rest ;ajs:notshortform
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jmp .loop1
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.unaligned:
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mov LIMB1, [Inp1P]
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ADDSUB LIMB1, [Inp2P]
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mov [SumP], LIMB1
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lea Inp1P, [Inp1P+8]
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lea Inp2P, [Inp2P+8]
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lea SumP, [SumP+8]
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align 16
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.loop1:
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mov LIMB1, [Inp1P]
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mov LIMB2, [Inp1P+8]
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ADCSBB LIMB1, [Inp2P]
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ADCSBB LIMB2, [Inp2P+8]
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SSESTORE +0
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mov LIMB1, [Inp1P+16]
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mov LIMB2, [Inp1P+24]
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ADCSBB LIMB1, [Inp2P+16]
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ADCSBB LIMB2, [Inp2P+24]
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STORE +16
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mov LIMB1, [Inp1P+32]
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mov LIMB2, [Inp1P+40]
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ADCSBB LIMB1, [Inp2P+32]
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ADCSBB LIMB2, [Inp2P+40]
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STORE +32
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mov LIMB1, [Inp1P+48]
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mov LIMB2, [Inp1P+56]
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ADCSBB LIMB1, [Inp2P+48]
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ADCSBB LIMB2, [Inp2P+56]
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STORE +48
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lea Inp1P, [Inp1P+64]
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lea Inp2P, [Inp2P+64]
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lea SumP, [SumP+64]
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dec Size
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jnz .loop1
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inc SizeRest
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dec SizeRest
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jz .end
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.rest:
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mov LIMB1, [Inp1P]
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ADCSBB LIMB1, [Inp2P]
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mov [SumP], LIMB1
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dec SizeRest
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jz .end
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mov LIMB1, [Inp1P+8]
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ADCSBB LIMB1, [Inp2P+8]
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mov [SumP+8], LIMB1
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dec SizeRest
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jz .end
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mov LIMB1, [Inp1P+16]
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ADCSBB LIMB1, [Inp2P+16]
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mov [SumP+16], LIMB1
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dec SizeRest
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jz .end
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mov LIMB1, [Inp1P+24]
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ADCSBB LIMB1, [Inp2P+24]
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mov [SumP+24], LIMB1
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dec SizeRest
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jz .end
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lea Inp1P, [Inp1P+32]
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lea Inp2P, [Inp2P+32]
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lea SumP, [SumP+32]
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jmp .rest
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.end:
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mov eax, 0
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adc eax, eax
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ret
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