From mboxrd@z Thu Jan 1 00:00:00 1970 From: zhichang.yuan@linaro.org (zhichang.yuan at linaro.org) Date: Wed, 11 Dec 2013 14:24:37 +0800 Subject: [PATCH 1/6] arm64: lib: Implement optimized memcpy routine In-Reply-To: <1386743082-5231-1-git-send-email-zhichang.yuan@linaro.org> References: <1386743082-5231-1-git-send-email-zhichang.yuan@linaro.org> Message-ID: <1386743082-5231-2-git-send-email-zhichang.yuan@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: "zhichang.yuan" This patch, based on Linaro's Cortex Strings library, improves the performance of the assembly optimized memcpy() function. Signed-off-by: Zhichang Yuan Signed-off-by: Deepak Saxena --- arch/arm64/lib/memcpy.S | 182 +++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 160 insertions(+), 22 deletions(-) diff --git a/arch/arm64/lib/memcpy.S b/arch/arm64/lib/memcpy.S index 27b5003..e3bab71 100644 --- a/arch/arm64/lib/memcpy.S +++ b/arch/arm64/lib/memcpy.S @@ -1,5 +1,13 @@ /* * Copyright (C) 2013 ARM Ltd. + * Copyright (C) 2013 Linaro. + * + * This code is based on glibc cortex strings work originally authored by Linaro + * and re-licensed under GPLv2 for the Linux kernel. The original code can + * be found @ + * + * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/ + * files/head:/src/aarch64/ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -27,27 +35,157 @@ * Returns: * x0 - dest */ +#define dstin x0 +#define src x1 +#define count x2 +#define tmp1 x3 +#define tmp1w w3 +#define tmp2 x4 +#define tmp2w w4 +#define tmp3 x5 +#define tmp3w w5 +#define dst x6 + +#define A_l x7 +#define A_h x8 +#define B_l x9 +#define B_h x10 +#define C_l x11 +#define C_h x12 +#define D_l x13 +#define D_h x14 + ENTRY(memcpy) - mov x4, x0 - subs x2, x2, #8 - b.mi 2f -1: ldr x3, [x1], #8 - subs x2, x2, #8 - str x3, [x4], #8 - b.pl 1b -2: adds x2, x2, #4 - b.mi 3f - ldr w3, [x1], #4 - sub x2, x2, #4 - str w3, [x4], #4 -3: adds x2, x2, #2 - b.mi 4f - ldrh w3, [x1], #2 - sub x2, x2, #2 - strh w3, [x4], #2 -4: adds x2, x2, #1 - b.mi 5f - ldrb w3, [x1] - strb w3, [x4] -5: ret + mov dst, dstin + cmp count, #16 + /*If memory length is less than 16, stp or ldp can not be used.*/ + b.lo .Ltiny15 +.Lover16: + neg tmp2, src + ands tmp2, tmp2, #15/* Bytes to reach alignment. */ + b.eq .LSrcAligned + sub count, count, tmp2 + /* + * Use ldp and sdp to copy 16 bytes,then backward the src to + * aligned address.This way is more efficient. + * But the risk overwriting the source area exists.Here,prefer to + * access memory forward straight,no backward.It will need a bit + * more instructions, but on the same time,the accesses are aligned. + */ + tbz tmp2, #0, 1f + ldrb tmp1w, [src], #1 + strb tmp1w, [dst], #1 +1: + tbz tmp2, #1, 1f + ldrh tmp1w, [src], #2 + strh tmp1w, [dst], #2 +1: + tbz tmp2, #2, 1f + ldr tmp1w, [src], #4 + str tmp1w, [dst], #4 +1: + tbz tmp2, #3, .LSrcAligned + ldr tmp1, [src],#8 + str tmp1, [dst],#8 + +.LSrcAligned: + cmp count, #64 + b.ge .Lcpy_over64 + /* + * Deal with small copies quickly by dropping straight into the + * exit block. + */ +.Ltail63: + /* + * Copy up to 48 bytes of data. At this point we only need the + * bottom 6 bits of count to be accurate. + */ + ands tmp1, count, #0x30 + b.eq .Ltiny15 + cmp tmp1w, #0x20 + b.eq 1f + b.lt 2f + ldp A_l, A_h, [src], #16 + stp A_l, A_h, [dst], #16 +1: + ldp A_l, A_h, [src], #16 + stp A_l, A_h, [dst], #16 +2: + ldp A_l, A_h, [src], #16 + stp A_l, A_h, [dst], #16 +.Ltiny15: + /* + * To make memmove simpler, here don't make src backwards. + * since backwards will probably overwrite the src area where src + * data for nex copy located,if dst is not so far from src. + */ + tbz count, #3, 1f + ldr tmp1, [src], #8 + str tmp1, [dst], #8 +1: + tbz count, #2, 1f + ldr tmp1w, [src], #4 + str tmp1w, [dst], #4 +1: + tbz count, #1, 1f + ldrh tmp1w, [src], #2 + strh tmp1w, [dst], #2 +1: + tbz count, #0, .Lexitfunc + ldrb tmp1w, [src] + strb tmp1w, [dst] + +.Lexitfunc: + ret + +.Lcpy_over64: + subs count, count, #128 + b.ge .Lcpy_body_large + /* + * Less than 128 bytes to copy, so handle 64 here and then jump + * to the tail. + */ + ldp A_l, A_h, [src],#16 + stp A_l, A_h, [dst],#16 + ldp B_l, B_h, [src],#16 + ldp C_l, C_h, [src],#16 + stp B_l, B_h, [dst],#16 + stp C_l, C_h, [dst],#16 + ldp D_l, D_h, [src],#16 + stp D_l, D_h, [dst],#16 + + tst count, #0x3f + b.ne .Ltail63 + ret + + /* + * Critical loop. Start at a new cache line boundary. Assuming + * 64 bytes per line this ensures the entire loop is in one line. + */ + .p2align 6 +.Lcpy_body_large: + /* There are at least 128 bytes to copy. */ + ldp A_l, A_h, [src],#16 + ldp B_l, B_h, [src],#16 + ldp C_l, C_h, [src],#16 + ldp D_l, D_h, [src],#16 +1: + stp A_l, A_h, [dst],#16 + ldp A_l, A_h, [src],#16 + stp B_l, B_h, [dst],#16 + ldp B_l, B_h, [src],#16 + stp C_l, C_h, [dst],#16 + ldp C_l, C_h, [src],#16 + stp D_l, D_h, [dst],#16 + ldp D_l, D_h, [src],#16 + subs count, count, #64 + b.ge 1b + stp A_l, A_h, [dst],#16 + stp B_l, B_h, [dst],#16 + stp C_l, C_h, [dst],#16 + stp D_l, D_h, [dst],#16 + + tst count, #0x3f + b.ne .Ltail63 + ret ENDPROC(memcpy) -- 1.7.9.5