* RE: [PATCH][AArch64] NEON-optimised memchr
2014-07-10 17:09 ` Richard Earnshaw
@ 2014-07-10 18:27 ` Kévin PETIT
2014-07-11 9:11 ` Richard Earnshaw
0 siblings, 1 reply; 4+ messages in thread
From: Kévin PETIT @ 2014-07-10 18:27 UTC (permalink / raw)
To: Richard Earnshaw; +Cc: newlib
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Hi Richard,
> ENOPATCH?
Thanks for pointing it out. I hate when I do this.
Apologies everyone, here it is.
Regards,
Kévin
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commit 4fef5d546e9d2ab0f5a3f0a6c6b60538ee16347b
Author: Kévin PETIT <kevin.petit@arm.com>
Date: Thu Jul 10 16:48:42 2014 +0100
NEON optimised memchr
diff --git a/newlib/libc/machine/aarch64/Makefile.am b/newlib/libc/machine/aarch64/Makefile.am
index 43946ba..b9fa7cb 100644
--- a/newlib/libc/machine/aarch64/Makefile.am
+++ b/newlib/libc/machine/aarch64/Makefile.am
@@ -9,6 +9,8 @@ AM_CCASFLAGS = $(INCLUDES)
noinst_LIBRARIES = lib.a
lib_a_SOURCES =
+lib_a_SOURCES += memchr-stub.c
+lib_a_SOURCES += memchr.S
lib_a_SOURCES += memcmp-stub.c
lib_a_SOURCES += memcmp.S
lib_a_SOURCES += memcpy-stub.c
diff --git a/newlib/libc/machine/aarch64/Makefile.in b/newlib/libc/machine/aarch64/Makefile.in
index d1a15f1..fd37695 100644
--- a/newlib/libc/machine/aarch64/Makefile.in
+++ b/newlib/libc/machine/aarch64/Makefile.in
@@ -69,7 +69,8 @@ LIBRARIES = $(noinst_LIBRARIES)
ARFLAGS = cru
lib_a_AR = $(AR) $(ARFLAGS)
lib_a_LIBADD =
-am_lib_a_OBJECTS = lib_a-memcmp-stub.$(OBJEXT) lib_a-memcmp.$(OBJEXT) \
+am_lib_a_OBJECTS = lib_a-memchr-stub.$(OBJEXT) lib_a-memchr.$(OBJEXT) \
+ lib_a-memcmp-stub.$(OBJEXT) lib_a-memcmp.$(OBJEXT) \
lib_a-memcpy-stub.$(OBJEXT) lib_a-memcpy.$(OBJEXT) \
lib_a-memmove-stub.$(OBJEXT) lib_a-memmove.$(OBJEXT) \
lib_a-memset-stub.$(OBJEXT) lib_a-memset.$(OBJEXT) \
@@ -205,11 +206,11 @@ AUTOMAKE_OPTIONS = cygnus
INCLUDES = $(NEWLIB_CFLAGS) $(CROSS_CFLAGS) $(TARGET_CFLAGS)
AM_CCASFLAGS = $(INCLUDES)
noinst_LIBRARIES = lib.a
-lib_a_SOURCES = memcmp-stub.c memcmp.S memcpy-stub.c memcpy.S \
- memmove-stub.c memmove.S memset-stub.c memset.S setjmp.S \
- strchr-stub.c strchr.S strchrnul-stub.c strchrnul.S \
- strcmp-stub.c strcmp.S strlen-stub.c strlen.S strncmp-stub.c \
- strncmp.S strnlen-stub.c strnlen.S
+lib_a_SOURCES = memchr-stub.c memchr.S memcmp-stub.c memcmp.S \
+ memcpy-stub.c memcpy.S memmove-stub.c memmove.S memset-stub.c \
+ memset.S setjmp.S strchr-stub.c strchr.S strchrnul-stub.c \
+ strchrnul.S strcmp-stub.c strcmp.S strlen-stub.c strlen.S \
+ strncmp-stub.c strncmp.S strnlen-stub.c strnlen.S
lib_a_CCASFLAGS = $(AM_CCASFLAGS)
lib_a_CFLAGS = $(AM_CFLAGS)
ACLOCAL_AMFLAGS = -I ../../.. -I ../../../..
@@ -272,6 +273,12 @@ distclean-compile:
.S.obj:
$(CPPASCOMPILE) -c -o $@ `$(CYGPATH_W) '$<'`
+lib_a-memchr.o: memchr.S
+ $(CCAS) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CCASFLAGS) $(CCASFLAGS) -c -o lib_a-memchr.o `test -f 'memchr.S' || echo '$(srcdir)/'`memchr.S
+
+lib_a-memchr.obj: memchr.S
+ $(CCAS) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CCASFLAGS) $(CCASFLAGS) -c -o lib_a-memchr.obj `if test -f 'memchr.S'; then $(CYGPATH_W) 'memchr.S'; else $(CYGPATH_W) '$(srcdir)/memchr.S'; fi`
+
lib_a-memcmp.o: memcmp.S
$(CCAS) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CCASFLAGS) $(CCASFLAGS) -c -o lib_a-memcmp.o `test -f 'memcmp.S' || echo '$(srcdir)/'`memcmp.S
@@ -344,6 +351,12 @@ lib_a-strnlen.obj: strnlen.S
.c.obj:
$(COMPILE) -c `$(CYGPATH_W) '$<'`
+lib_a-memchr-stub.o: memchr-stub.c
+ $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-memchr-stub.o `test -f 'memchr-stub.c' || echo '$(srcdir)/'`memchr-stub.c
+
+lib_a-memchr-stub.obj: memchr-stub.c
+ $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-memchr-stub.obj `if test -f 'memchr-stub.c'; then $(CYGPATH_W) 'memchr-stub.c'; else $(CYGPATH_W) '$(srcdir)/memchr-stub.c'; fi`
+
lib_a-memcmp-stub.o: memcmp-stub.c
$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-memcmp-stub.o `test -f 'memcmp-stub.c' || echo '$(srcdir)/'`memcmp-stub.c
diff --git a/newlib/libc/machine/aarch64/memchr-stub.c b/newlib/libc/machine/aarch64/memchr-stub.c
new file mode 100644
index 0000000..dc550aa
--- /dev/null
+++ b/newlib/libc/machine/aarch64/memchr-stub.c
@@ -0,0 +1,31 @@
+/* Copyright (c) 2013, 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 the Linaro 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. */
+
+#if (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
+# include "../../string/memchr.c"
+#else
+/* See memchr.S */
+#endif
diff --git a/newlib/libc/machine/aarch64/memchr.S b/newlib/libc/machine/aarch64/memchr.S
new file mode 100644
index 0000000..eb59a5a
--- /dev/null
+++ b/newlib/libc/machine/aarch64/memchr.S
@@ -0,0 +1,170 @@
+/*
+ * memchr - find a character in a memory zone
+ *
+ * Copyright (c) 2014, ARM 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 the company 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.
+ */
+
+#if (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
+/* See memchr-stub.c */
+#else
+/* Assumptions:
+ *
+ * ARMv8-a, AArch64
+ * Neon Available.
+ */
+
+/* Arguments and results. */
+#define srcin x0
+#define chrin w1
+#define cntin x2
+
+#define result x0
+
+#define src x3
+#define tmp x4
+#define wtmp2 w5
+#define synd x6
+#define soff x9
+#define cntrem x10
+
+#define vrepchr v0
+#define vdata1 v1
+#define vdata2 v2
+#define vhas_chr1 v3
+#define vhas_chr2 v4
+#define vrepmask v5
+#define vend v6
+
+/*
+ * Core algorithm:
+ *
+ * For each 32-byte chunk we calculate a 64-bit syndrome value, with two bits
+ * per byte. For each tuple, bit 0 is set if the relevant byte matched the
+ * requested character and bit 1 is not used (faster than using a 32bit
+ * syndrome). Since the bits in the syndrome reflect exactly the order in which
+ * things occur in the original string, counting trailing zeros allows to
+ * identify exactly which byte has matched.
+ */
+
+ .macro def_fn f p2align=0
+ .text
+ .p2align \p2align
+ .global \f
+ .type \f, %function
+\f:
+ .endm
+
+def_fn memchr
+ /*
+ * Magic constant 0x40100401 allows us to identify which lane matches
+ * the requested byte.
+ */
+ mov wtmp2, #0x0401
+ movk wtmp2, #0x4010, lsl #16
+ dup vrepchr.16b, chrin
+ /* Work with aligned 32-byte chunks */
+ bic src, srcin, #31
+ dup vrepmask.4s, wtmp2
+ ands soff, srcin, #31
+ and cntrem, cntin, #31
+ b.eq .Lloop
+
+ /*
+ * Input string is not 32-byte aligned. We calculate the syndrome
+ * value for the aligned 32 bytes block containing the first bytes
+ * and mask the irrelevant part.
+ */
+
+ ld1 {vdata1.16b, vdata2.16b}, [src], #32
+ sub tmp, soff, #32
+ adds cntin, cntin, tmp
+ cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
+ cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
+ and vhas_chr1.16b, vhas_chr1.16b, vrepmask.16b
+ and vhas_chr2.16b, vhas_chr2.16b, vrepmask.16b
+ addp vend.16b, vhas_chr1.16b, vhas_chr2.16b /* 256->128 */
+ addp vend.16b, vend.16b, vend.16b /* 128->64 */
+ mov synd, vend.2d[0]
+ /* Clear the soff*2 lower bits */
+ lsl tmp, soff, #1
+ lsr synd, synd, tmp
+ lsl synd, synd, tmp
+ /* The first block can also be the last */
+ b.ls .Lmasklast
+ /* Have we found something already? */
+ cbnz synd, .Ltail
+
+.Lloop:
+ ld1 {vdata1.16b, vdata2.16b}, [src], #32
+ subs cntin, cntin, #32
+ cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
+ cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
+ /* If we're out of data we finish regardless of the result */
+ b.ls .Lend
+ /* Use a fast check for the termination condition */
+ orr vend.16b, vhas_chr1.16b, vhas_chr2.16b
+ addp vend.2d, vend.2d, vend.2d
+ mov synd, vend.2d[0]
+ /* We're not out of data, loop if we haven't found the character */
+ cbz synd, .Lloop
+
+.Lend:
+ /* Termination condition found, let's calculate the syndrome value */
+ and vhas_chr1.16b, vhas_chr1.16b, vrepmask.16b
+ and vhas_chr2.16b, vhas_chr2.16b, vrepmask.16b
+ addp vend.16b, vhas_chr1.16b, vhas_chr2.16b /* 256->128 */
+ addp vend.16b, vend.16b, vend.16b /* 128->64 */
+ mov synd, vend.2d[0]
+ /* Only do the clear for the last possible block */
+ b.hi .Ltail
+
+.Lmasklast:
+ /* Clear the (32 - ((cntrem + soff) % 32)) * 2 upper bits */
+ add tmp, cntrem, soff
+ and tmp, tmp, #31
+ sub tmp, tmp, #32
+ neg tmp, tmp, lsl #1
+ lsl synd, synd, tmp
+ lsr synd, synd, tmp
+
+.Ltail:
+ /* Count the trailing zeros using bit reversing */
+ rbit synd, synd
+ /* Compensate the last post-increment */
+ sub src, src, #32
+ /* Check that we have found a character */
+ cmp synd, #0
+ /* And count the leading zeros */
+ clz synd, synd
+ /* Compute the potential result */
+ add result, src, synd, lsr #1
+ /* Select result or NULL */
+ csel result, xzr, result, eq
+ ret
+
+ .size memchr, . - memchr
+#endif
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