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See: https://android-review.googlesource.com/#/c/147915/4 Signed-off-by: Young-Ho Cha <ganadist@gmail.com>
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patches/bionic/0005-libc-arm-add-optimized-memchr-implementation.patch
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From 36cddf3730b4143ea9a08de2ff9d6a9f434e4efb Mon Sep 17 00:00:00 2001 | ||
From: Yingshiuan Pan <yingshiuan.pan@linaro.org> | ||
Date: Thu, 23 Apr 2015 04:07:59 +0100 | ||
Subject: [PATCH 5/5] libc: arm: add optimized memchr implementation | ||
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This optimization is extracted from cortex-strings and bionic-ized, | ||
and applied to arm-v7a cpus (a7, a9, a15, a53, denver, krait). | ||
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I ran stringbench[1] on ARM Juno, this optimization could outperform | ||
origin C implementation by 77%. | ||
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[1] https://android.git.linaro.org/gitweb/platform/external/stringbench.git | ||
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Change-Id: I1c3fb0c89ce2b3ee7e44f492367b6caf6db58ccf | ||
Signed-off-by: Yingshiuan Pan <yingshiuan.pan@linaro.org> | ||
--- | ||
libc/arch-arm/arm.mk | 1 - | ||
libc/arch-arm/cortex-a15/cortex-a15.mk | 1 + | ||
libc/arch-arm/cortex-a9/cortex-a9.mk | 1 + | ||
libc/arch-arm/denver/denver.mk | 1 + | ||
libc/arch-arm/generic/bionic/memchr.S | 155 +++++++++++++++++++++++++++++++++ | ||
libc/arch-arm/generic/generic.mk | 1 + | ||
libc/arch-arm/krait/krait.mk | 1 + | ||
7 files changed, 160 insertions(+), 1 deletion(-) | ||
create mode 100644 libc/arch-arm/generic/bionic/memchr.S | ||
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diff --git a/libc/arch-arm/arm.mk b/libc/arch-arm/arm.mk | ||
index d72a160..d09a93b 100644 | ||
--- a/libc/arch-arm/arm.mk | ||
+++ b/libc/arch-arm/arm.mk | ||
@@ -20,7 +20,6 @@ libc_freebsd_src_files_arm += \ | ||
upstream-freebsd/lib/libc/string/wmemmove.c \ | ||
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libc_openbsd_src_files_arm += \ | ||
- upstream-openbsd/lib/libc/string/memchr.c \ | ||
upstream-openbsd/lib/libc/string/memrchr.c \ | ||
upstream-openbsd/lib/libc/string/stpncpy.c \ | ||
upstream-openbsd/lib/libc/string/strlcat.c \ | ||
diff --git a/libc/arch-arm/cortex-a15/cortex-a15.mk b/libc/arch-arm/cortex-a15/cortex-a15.mk | ||
index 6fa3270..202a3bf 100644 | ||
--- a/libc/arch-arm/cortex-a15/cortex-a15.mk | ||
+++ b/libc/arch-arm/cortex-a15/cortex-a15.mk | ||
@@ -10,6 +10,7 @@ libc_bionic_src_files_arm += \ | ||
arch-arm/cortex-a15/bionic/strlen.S \ | ||
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libc_bionic_src_files_arm += \ | ||
+ arch-arm/generic/bionic/memchr.S \ | ||
arch-arm/generic/bionic/memcmp.S \ | ||
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libc_bionic_src_files_arm += \ | ||
diff --git a/libc/arch-arm/cortex-a9/cortex-a9.mk b/libc/arch-arm/cortex-a9/cortex-a9.mk | ||
index 7b38de1..db4bcc7 100644 | ||
--- a/libc/arch-arm/cortex-a9/cortex-a9.mk | ||
+++ b/libc/arch-arm/cortex-a9/cortex-a9.mk | ||
@@ -10,6 +10,7 @@ libc_bionic_src_files_arm += \ | ||
arch-arm/cortex-a9/bionic/strlen.S \ | ||
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libc_bionic_src_files_arm += \ | ||
+ arch-arm/generic/bionic/memchr.S \ | ||
arch-arm/generic/bionic/memcmp.S \ | ||
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libc_bionic_src_files_arm += \ | ||
diff --git a/libc/arch-arm/denver/denver.mk b/libc/arch-arm/denver/denver.mk | ||
index 5fddf95..e81f8c7 100644 | ||
--- a/libc/arch-arm/denver/denver.mk | ||
+++ b/libc/arch-arm/denver/denver.mk | ||
@@ -1,4 +1,5 @@ | ||
libc_bionic_src_files_arm += \ | ||
+ arch-arm/generic/bionic/memchr.S \ | ||
arch-arm/generic/bionic/memcmp.S \ | ||
arch-arm/denver/bionic/memcpy.S \ | ||
arch-arm/denver/bionic/memmove.S \ | ||
diff --git a/libc/arch-arm/generic/bionic/memchr.S b/libc/arch-arm/generic/bionic/memchr.S | ||
new file mode 100644 | ||
index 0000000..cb00d82 | ||
--- /dev/null | ||
+++ b/libc/arch-arm/generic/bionic/memchr.S | ||
@@ -0,0 +1,155 @@ | ||
+/* Copyright (c) 2010-2015, Linaro Limited | ||
+ All rights reserved. | ||
+ | ||
+ Redistribution and use in source and binary forms, with or without | ||
+ modification, are permitted provided that the following conditions | ||
+ are met: | ||
+ | ||
+ * Redistributions of source code must retain the above copyright | ||
+ notice, this list of conditions and the following disclaimer. | ||
+ | ||
+ * Redistributions in binary form must reproduce the above copyright | ||
+ notice, this list of conditions and the following disclaimer in the | ||
+ documentation and/or other materials provided with the distribution. | ||
+ | ||
+ * Neither the name of Linaro Limited nor the names of its | ||
+ contributors may be used to endorse or promote products derived | ||
+ from this software without specific prior written permission. | ||
+ | ||
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | ||
+ "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | ||
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | ||
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | ||
+ HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | ||
+ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | ||
+ LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | ||
+ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | ||
+ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | ||
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
+ */ | ||
+ | ||
+/* | ||
+ Written by Dave Gilbert <david.gilbert@linaro.org> | ||
+ | ||
+ This memchr routine is optimised on a Cortex-A9 and should work on | ||
+ all ARMv7 processors. It has a fast past for short sizes, and has | ||
+ an optimised path for large data sets; the worst case is finding the | ||
+ match early in a large data set. | ||
+ | ||
+ */ | ||
+ | ||
+#include <private/bionic_asm.h> | ||
+ | ||
+@ 2011-02-07 david.gilbert@linaro.org | ||
+@ Extracted from local git a5b438d861 | ||
+@ 2011-07-14 david.gilbert@linaro.org | ||
+@ Import endianness fix from local git ea786f1b | ||
+@ 2011-12-07 david.gilbert@linaro.org | ||
+@ Removed unneeded cbz from align loop | ||
+ | ||
+ .syntax unified | ||
+ .arch armv7-a | ||
+ | ||
+@ this lets us check a flag in a 00/ff byte easily in either endianness | ||
+#ifdef __ARMEB__ | ||
+#define CHARTSTMASK(c) 1<<(31-(c*8)) | ||
+#else | ||
+#define CHARTSTMASK(c) 1<<(c*8) | ||
+#endif | ||
+ .text | ||
+ .thumb | ||
+ | ||
+@ --------------------------------------------------------------------------- | ||
+ .thumb_func | ||
+ENTRY(memchr) | ||
+ .p2align 4,,15 | ||
+ @ r0 = start of memory to scan | ||
+ @ r1 = character to look for | ||
+ @ r2 = length | ||
+ @ returns r0 = pointer to character or NULL if not found | ||
+ and r1,r1,#0xff @ Don't think we can trust the caller to actually pass a char | ||
+ | ||
+ cmp r2,#16 @ If it's short don't bother with anything clever | ||
+ blt 20f | ||
+ | ||
+ tst r0, #7 @ If it's already aligned skip the next bit | ||
+ beq 10f | ||
+ | ||
+ @ Work up to an aligned point | ||
+5: | ||
+ ldrb r3, [r0],#1 | ||
+ subs r2, r2, #1 | ||
+ cmp r3, r1 | ||
+ beq 50f @ If it matches exit found | ||
+ tst r0, #7 | ||
+ bne 5b @ If not aligned yet then do next byte | ||
+ | ||
+10: | ||
+ @ At this point, we are aligned, we know we have at least 8 bytes to work with | ||
+ push {r4,r5,r6,r7} | ||
+ orr r1, r1, r1, lsl #8 @ expand the match word across to all bytes | ||
+ orr r1, r1, r1, lsl #16 | ||
+ bic r4, r2, #7 @ Number of double words to work with | ||
+ mvns r7, #0 @ all F's | ||
+ movs r3, #0 | ||
+ | ||
+15: | ||
+ ldrd r5,r6,[r0],#8 | ||
+ subs r4, r4, #8 | ||
+ eor r5,r5, r1 @ Get it so that r5,r6 have 00's where the bytes match the target | ||
+ eor r6,r6, r1 | ||
+ uadd8 r5, r5, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0 | ||
+ sel r5, r3, r7 @ bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION | ||
+ uadd8 r6, r6, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0 | ||
+ sel r6, r5, r7 @ chained....bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION | ||
+ cbnz r6, 60f | ||
+ bne 15b @ (Flags from the subs above) If not run out of bytes then go around again | ||
+ | ||
+ pop {r4,r5,r6,r7} | ||
+ and r1,r1,#0xff @ Get r1 back to a single character from the expansion above | ||
+ and r2,r2,#7 @ Leave the count remaining as the number after the double words have been done | ||
+ | ||
+20: | ||
+ cbz r2, 40f @ 0 length or hit the end already then not found | ||
+ | ||
+21: @ Post aligned section, or just a short call | ||
+ ldrb r3,[r0],#1 | ||
+ subs r2,r2,#1 | ||
+ eor r3,r3,r1 @ r3 = 0 if match - doesn't break flags from sub | ||
+ cbz r3, 50f | ||
+ bne 21b @ on r2 flags | ||
+ | ||
+40: | ||
+ movs r0,#0 @ not found | ||
+ bx lr | ||
+ | ||
+50: | ||
+ subs r0,r0,#1 @ found | ||
+ bx lr | ||
+ | ||
+60: @ We're here because the fast path found a hit - now we have to track down exactly which word it was | ||
+ @ r0 points to the start of the double word after the one that was tested | ||
+ @ r5 has the 00/ff pattern for the first word, r6 has the chained value | ||
+ cmp r5, #0 | ||
+ itte eq | ||
+ moveq r5, r6 @ the end is in the 2nd word | ||
+ subeq r0,r0,#3 @ Points to 2nd byte of 2nd word | ||
+ subne r0,r0,#7 @ or 2nd byte of 1st word | ||
+ | ||
+ @ r0 currently points to the 3rd byte of the word containing the hit | ||
+ tst r5, # CHARTSTMASK(0) @ 1st character | ||
+ bne 61f | ||
+ adds r0,r0,#1 | ||
+ tst r5, # CHARTSTMASK(1) @ 2nd character | ||
+ ittt eq | ||
+ addeq r0,r0,#1 | ||
+ tsteq r5, # (3<<15) @ 2nd & 3rd character | ||
+ @ If not the 3rd must be the last one | ||
+ addeq r0,r0,#1 | ||
+ | ||
+61: | ||
+ pop {r4,r5,r6,r7} | ||
+ subs r0,r0,#1 | ||
+ bx lr | ||
+END(memchr) | ||
diff --git a/libc/arch-arm/generic/generic.mk b/libc/arch-arm/generic/generic.mk | ||
index e49d6d2..016c882 100644 | ||
--- a/libc/arch-arm/generic/generic.mk | ||
+++ b/libc/arch-arm/generic/generic.mk | ||
@@ -1,4 +1,5 @@ | ||
libc_bionic_src_files_arm += \ | ||
+ arch-arm/generic/bionic/memchr.S \ | ||
arch-arm/generic/bionic/memcmp.S \ | ||
arch-arm/generic/bionic/memcpy.S \ | ||
arch-arm/generic/bionic/memset.S \ | ||
diff --git a/libc/arch-arm/krait/krait.mk b/libc/arch-arm/krait/krait.mk | ||
index 7580332..5f5b414 100644 | ||
--- a/libc/arch-arm/krait/krait.mk | ||
+++ b/libc/arch-arm/krait/krait.mk | ||
@@ -23,6 +23,7 @@ libc_bionic_src_files_arm += \ | ||
arch-arm/cortex-a15/bionic/strlen.S \ | ||
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libc_bionic_src_files_arm += \ | ||
+ arch-arm/generic/bionic/memchr.S \ | ||
arch-arm/generic/bionic/memcmp.S \ | ||
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-- | ||
2.6.2 | ||
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