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authorSteve Ellcey <sellcey@mips.com>2014-10-01 13:45:50 -0700
committerSteve Ellcey <sellcey@mips.com>2014-10-01 13:45:50 -0700
commitb925285f989f156f85897fbf6a2f97e168df6e5d (patch)
tree6a2e1e4ede23b0198db22d5bf06a9348e5896d6c
parent754a15c61cd6834685386a134d0a0fed5f3ac4c1 (diff)
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* sysdeps/mips/strcmp.S: New.
-rw-r--r--ChangeLog4
-rw-r--r--sysdeps/mips/strcmp.S249
2 files changed, 253 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index 6ea47510673..cd987d90841 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2014-10-01 Steve Ellcey <sellcey@mips.com>
+
+ * sysdeps/mips/strcmp.S: New.
+
2014-09-30 Joseph Myers <joseph@codesourcery.com>
[BZ #14138]
diff --git a/sysdeps/mips/strcmp.S b/sysdeps/mips/strcmp.S
new file mode 100644
index 00000000000..e0c82127d97
--- /dev/null
+++ b/sysdeps/mips/strcmp.S
@@ -0,0 +1,249 @@
+/* Copyright (C) 2014 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifdef ANDROID_CHANGES
+# include "machine/asm.h"
+# include "machine/regdef.h"
+#elif _LIBC
+# include <sysdep.h>
+# include <regdef.h>
+# include <sys/asm.h>
+#elif _COMPILING_NEWLIB
+# include "machine/asm.h"
+# include "machine/regdef.h"
+#else
+# include <regdef.h>
+# include <sys/asm.h>
+#endif
+
+/* Technically strcmp should not read past the end of the strings being
+ compared. We will read a full word that may contain excess bits beyond
+ the NULL string terminator but unless ENABLE_READAHEAD is set, we will not
+ read the next word after the end of string. Setting ENABLE_READAHEAD will
+ improve performance but is technically illegal based on the definition of
+ strcmp. */
+#ifdef ENABLE_READAHEAD
+# define DELAY_READ
+#else
+# define DELAY_READ nop
+#endif
+
+/* Testing on a little endian machine showed using CLZ was a
+ performance loss, so we are not turning it on by default. */
+#if defined(ENABLE_CLZ) && (__mips_isa_rev > 1)
+# define USE_CLZ
+#endif
+
+/* Some asm.h files do not have the L macro definition. */
+#ifndef L
+# if _MIPS_SIM == _ABIO32
+# define L(label) $L ## label
+# else
+# define L(label) .L ## label
+# endif
+#endif
+
+/* Some asm.h files do not have the PTR_ADDIU macro definition. */
+#ifndef PTR_ADDIU
+# ifdef USE_DOUBLE
+# define PTR_ADDIU daddiu
+# else
+# define PTR_ADDIU addiu
+# endif
+#endif
+
+/* Allow the routine to be named something else if desired. */
+#ifndef STRCMP_NAME
+# define STRCMP_NAME strcmp
+#endif
+
+#ifdef ANDROID_CHANGES
+LEAF(STRCMP_NAME, 0)
+#else
+LEAF(STRCMP_NAME)
+#endif
+ .set nomips16
+ .set noreorder
+
+ or t0, a0, a1
+ andi t0,0x3
+ bne t0, zero, L(byteloop)
+
+/* Both strings are 4 byte aligned at this point. */
+
+ lui t8, 0x0101
+ ori t8, t8, 0x0101
+ lui t9, 0x7f7f
+ ori t9, 0x7f7f
+
+#define STRCMP32(OFFSET) \
+ lw v0, OFFSET(a0); \
+ lw v1, OFFSET(a1); \
+ subu t0, v0, t8; \
+ bne v0, v1, L(worddiff); \
+ nor t1, v0, t9; \
+ and t0, t0, t1; \
+ bne t0, zero, L(returnzero)
+
+L(wordloop):
+ STRCMP32(0)
+ DELAY_READ
+ STRCMP32(4)
+ DELAY_READ
+ STRCMP32(8)
+ DELAY_READ
+ STRCMP32(12)
+ DELAY_READ
+ STRCMP32(16)
+ DELAY_READ
+ STRCMP32(20)
+ DELAY_READ
+ STRCMP32(24)
+ DELAY_READ
+ STRCMP32(28)
+ PTR_ADDIU a0, a0, 32
+ b L(wordloop)
+ PTR_ADDIU a1, a1, 32
+
+L(returnzero):
+ j ra
+ move v0, zero
+
+L(worddiff):
+#ifdef USE_CLZ
+ subu t0, v0, t8
+ nor t1, v0, t9
+ and t1, t0, t1
+ xor t0, v0, v1
+ or t0, t0, t1
+# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ wsbh t0, t0
+ rotr t0, t0, 16
+# endif
+ clz t1, t0
+ and t1, 0xf8
+# if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+ neg t1
+ addu t1, 24
+# endif
+ rotrv v0, v0, t1
+ rotrv v1, v1, t1
+ and v0, v0, 0xff
+ and v1, v1, 0xff
+ j ra
+ subu v0, v0, v1
+#else /* USE_CLZ */
+# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ andi t0, v0, 0xff
+ beq t0, zero, L(wexit01)
+ andi t1, v1, 0xff
+ bne t0, t1, L(wexit01)
+
+ srl t8, v0, 8
+ srl t9, v1, 8
+ andi t8, t8, 0xff
+ beq t8, zero, L(wexit89)
+ andi t9, t9, 0xff
+ bne t8, t9, L(wexit89)
+
+ srl t0, v0, 16
+ srl t1, v1, 16
+ andi t0, t0, 0xff
+ beq t0, zero, L(wexit01)
+ andi t1, t1, 0xff
+ bne t0, t1, L(wexit01)
+
+ srl t8, v0, 24
+ srl t9, v1, 24
+# else /* __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ */
+ srl t0, v0, 24
+ beq t0, zero, L(wexit01)
+ srl t1, v1, 24
+ bne t0, t1, L(wexit01)
+
+ srl t8, v0, 16
+ srl t9, v1, 16
+ andi t8, t8, 0xff
+ beq t8, zero, L(wexit89)
+ andi t9, t9, 0xff
+ bne t8, t9, L(wexit89)
+
+ srl t0, v0, 8
+ srl t1, v1, 8
+ andi t0, t0, 0xff
+ beq t0, zero, L(wexit01)
+ andi t1, t1, 0xff
+ bne t0, t1, L(wexit01)
+
+ andi t8, v0, 0xff
+ andi t9, v1, 0xff
+# endif /* __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ */
+
+L(wexit89):
+ j ra
+ subu v0, t8, t9
+L(wexit01):
+ j ra
+ subu v0, t0, t1
+#endif /* USE_CLZ */
+
+/* It might seem better to do the 'beq' instruction between the two 'lbu'
+ instructions so that the nop is not needed but testing showed that this
+ code is actually faster (based on glibc strcmp test). */
+#define BYTECMP01(OFFSET) \
+ lbu v0, OFFSET(a0); \
+ lbu v1, OFFSET(a1); \
+ beq v0, zero, L(bexit01); \
+ nop; \
+ bne v0, v1, L(bexit01)
+
+#define BYTECMP89(OFFSET) \
+ lbu t8, OFFSET(a0); \
+ lbu t9, OFFSET(a1); \
+ beq t8, zero, L(bexit89); \
+ nop; \
+ bne t8, t9, L(bexit89)
+
+L(byteloop):
+ BYTECMP01(0)
+ BYTECMP89(1)
+ BYTECMP01(2)
+ BYTECMP89(3)
+ BYTECMP01(4)
+ BYTECMP89(5)
+ BYTECMP01(6)
+ BYTECMP89(7)
+ PTR_ADDIU a0, a0, 8
+ b L(byteloop)
+ PTR_ADDIU a1, a1, 8
+
+L(bexit01):
+ j ra
+ subu v0, v0, v1
+L(bexit89):
+ j ra
+ subu v0, t8, t9
+
+ .set at
+ .set reorder
+
+END(STRCMP_NAME)
+#ifndef ANDROID_CHANGES
+# ifdef _LIBC
+libc_hidden_builtin_def (STRCMP_NAME)
+# endif
+#endif