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authorzhichang.yuan <zhichang.yuan@linaro.org>2014-04-28 06:11:30 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2014-05-23 15:07:35 +0100
commit280adc1951c0c9fc8f2d85571ff563a1c412b1cd (patch)
tree89be4d00570a72fb8b4c30216f6b45d017181e78 /arch/arm64
parent808dbac6b51f3441eb5a07724c0b0d1257046d51 (diff)
downloadlinux-linaro-stable-280adc1951c0c9fc8f2d85571ff563a1c412b1cd.tar.gz
arm64: lib: Implement optimized memmove routine
This patch, based on Linaro's Cortex Strings library, improves the performance of the assembly optimized memmove() function. Signed-off-by: Zhichang Yuan <zhichang.yuan@linaro.org> Signed-off-by: Deepak Saxena <dsaxena@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/lib/memmove.S190
1 files changed, 165 insertions, 25 deletions
diff --git a/arch/arm64/lib/memmove.S b/arch/arm64/lib/memmove.S
index b79fdfa42d39..57b19ea2dad4 100644
--- a/arch/arm64/lib/memmove.S
+++ b/arch/arm64/lib/memmove.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
@@ -16,6 +24,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/cache.h>
/*
* Move a buffer from src to test (alignment handled by the hardware).
@@ -28,30 +37,161 @@
* Returns:
* x0 - dest
*/
+dstin .req x0
+src .req x1
+count .req x2
+tmp1 .req x3
+tmp1w .req w3
+tmp2 .req x4
+tmp2w .req w4
+tmp3 .req x5
+tmp3w .req w5
+dst .req x6
+
+A_l .req x7
+A_h .req x8
+B_l .req x9
+B_h .req x10
+C_l .req x11
+C_h .req x12
+D_l .req x13
+D_h .req x14
+
ENTRY(memmove)
- cmp x0, x1
- b.ls memcpy
- add x4, x0, x2
- add x1, x1, x2
- 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, #-1]
- strb w3, [x4, #-1]
-5: ret
+ cmp dstin, src
+ b.lo memcpy
+ add tmp1, src, count
+ cmp dstin, tmp1
+ b.hs memcpy /* No overlap. */
+
+ add dst, dstin, count
+ add src, src, count
+ cmp count, #16
+ b.lo .Ltail15 /*probably non-alignment accesses.*/
+
+ ands tmp2, src, #15 /* Bytes to reach alignment. */
+ b.eq .LSrcAligned
+ sub count, count, tmp2
+ /*
+ * process the aligned offset length to make the src aligned firstly.
+ * those extra instructions' cost is acceptable. It also make the
+ * coming accesses are based on aligned address.
+ */
+ tbz tmp2, #0, 1f
+ ldrb tmp1w, [src, #-1]!
+ strb tmp1w, [dst, #-1]!
+1:
+ tbz tmp2, #1, 2f
+ ldrh tmp1w, [src, #-2]!
+ strh tmp1w, [dst, #-2]!
+2:
+ tbz tmp2, #2, 3f
+ ldr tmp1w, [src, #-4]!
+ str tmp1w, [dst, #-4]!
+3:
+ 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 .Ltail15
+ 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]!
+
+.Ltail15:
+ tbz count, #3, 1f
+ ldr tmp1, [src, #-8]!
+ str tmp1, [dst, #-8]!
+1:
+ tbz count, #2, 2f
+ ldr tmp1w, [src, #-4]!
+ str tmp1w, [dst, #-4]!
+2:
+ tbz count, #1, 3f
+ ldrh tmp1w, [src, #-2]!
+ strh tmp1w, [dst, #-2]!
+3:
+ tbz count, #0, .Lexitfunc
+ ldrb tmp1w, [src, #-1]
+ strb tmp1w, [dst, #-1]
+
+.Lexitfunc:
+ ret
+
+.Lcpy_over64:
+ subs count, count, #128
+ b.ge .Lcpy_body_large
+ /*
+ * Less than 128 bytes to copy, so handle 64 bytes 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, #-32]
+ ldp C_l, C_h, [src, #-48]
+ stp B_l, B_h, [dst, #-32]
+ stp C_l, C_h, [dst, #-48]
+ ldp D_l, D_h, [src, #-64]!
+ stp D_l, D_h, [dst, #-64]!
+
+ 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 L1_CACHE_SHIFT
+.Lcpy_body_large:
+ /* pre-load 64 bytes data. */
+ ldp A_l, A_h, [src, #-16]
+ ldp B_l, B_h, [src, #-32]
+ ldp C_l, C_h, [src, #-48]
+ ldp D_l, D_h, [src, #-64]!
+1:
+ /*
+ * interlace the load of next 64 bytes data block with store of the last
+ * loaded 64 bytes data.
+ */
+ stp A_l, A_h, [dst, #-16]
+ ldp A_l, A_h, [src, #-16]
+ stp B_l, B_h, [dst, #-32]
+ ldp B_l, B_h, [src, #-32]
+ stp C_l, C_h, [dst, #-48]
+ ldp C_l, C_h, [src, #-48]
+ stp D_l, D_h, [dst, #-64]!
+ ldp D_l, D_h, [src, #-64]!
+ subs count, count, #64
+ b.ge 1b
+ stp A_l, A_h, [dst, #-16]
+ stp B_l, B_h, [dst, #-32]
+ stp C_l, C_h, [dst, #-48]
+ stp D_l, D_h, [dst, #-64]!
+
+ tst count, #0x3f
+ b.ne .Ltail63
+ ret
ENDPROC(memmove)