* sysdeps/x86_64/strchr.S: Likewise.

ChangeLog

@@ -1,6 +1,7 @@
 2009-04-05  Ulrich Drepper  <drepper@redhat.com>
 
 	* sysdeps/x86_64/strlen.S: Optimize by using SSE2 instructions.
+	* sysdeps/x86_64/strchr.S: Likewise.
 
 2009-04-03  Ulrich Drepper  <drepper@redhat.com>
 

NEWS

@@ -37,7 +37,7 @@ Version 2.10
 
 * New locale: nan_TW@latin
 
-* Faster strlen on x86-64.
+* Faster strlen and strchr on x86-64.
   Implemented by Ulrich Drepper.
 
 

sysdeps/x86_64/strchr.S

@@ -1,6 +1,6 @@
 /* strchr (str, ch) -- Return pointer to first occurrence of CH in STR.
    For AMD x86-64.
-   Copyright (C) 2002, 2005 Free Software Foundation, Inc.
+   Copyright (C) 2009 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
@@ -19,273 +19,52 @@
    02111-1307 USA.  */
 
 #include <sysdep.h>
-#include "asm-syntax.h"
-#include "bp-sym.h"
-#include "bp-asm.h"
 
 
 	.text
-ENTRY (BP_SYM (strchr))
+ENTRY (strchr)
+	movd	%esi, %xmm1
+	movq	%rdi, %rcx
+	punpcklbw %xmm1, %xmm1
+	andq	$~15, %rdi
+	pxor	%xmm2, %xmm2
+	punpcklbw %xmm1, %xmm1
+	orl	$0xffffffff, %esi
+	movdqa	(%rdi), %xmm0
+	pshufd	$0, %xmm1, %xmm1
+	subq	%rdi, %rcx
+	movdqa	%xmm0, %xmm3
+	leaq	16(%rdi), %rdi
+	pcmpeqb	%xmm1, %xmm0
+	pcmpeqb	%xmm2, %xmm3
+	shl	%cl, %esi
+	pmovmskb %xmm0, %edx
+	pmovmskb %xmm3, %ecx
+	andl	%esi, %edx
+	andl	%esi, %ecx
+	orl	%edx, %ecx
+	jnz	1f
 
-	/* Before we start with the main loop we process single bytes
+2:	movdqa	(%rdi), %xmm0
-	   until the source pointer is aligned.  This has two reasons:
+	leaq	16(%rdi), %rdi
-	   1. aligned 64-bit memory access is faster
+	movdqa	%xmm0, %xmm3
-	   and (more important)
+	pcmpeqb	%xmm1, %xmm0
-	   2. we process in the main loop 64 bit in one step although
+	pcmpeqb	%xmm2, %xmm3
-	      we don't know the end of the string.  But accessing at
+	pmovmskb %xmm0, %edx
-	      8-byte alignment guarantees that we never access illegal
+	pmovmskb %xmm3, %ecx
-	      memory if this would not also be done by the trivial
+	orl	%edx, %ecx
-	      implementation (this is because all processor inherent
+	jz	2b
-	      boundaries are multiples of 8).  */
 
-	movq	%rdi, %rdx
+1:	bsfl	%edx, %edx
-	andl	$7, %edx	/* Mask alignment bits  */
+	jz	4f
-	movq	%rdi, %rax	/* duplicate destination.  */
+	bsfl	%ecx, %ecx
-	jz	1f		/* aligned => start loop */
+	leaq	-16(%rdi,%rdx), %rax
-	neg	%edx
+	cmpl	%edx, %ecx
-	addl	$8, %edx	/* Align to 8 bytes.  */
+	je	5f
+4:	xorl	%eax, %eax
+5:	ret
+END (strchr)
 
-	/* Search the first bytes directly.  */
+weak_alias (strchr, index)
-0:	movb	(%rax), %cl	/* load byte  */
-	cmpb	%cl,%sil	/* compare byte.  */
-	je	6f		/* target found */
-	testb	%cl,%cl		/* is byte NUL? */
-	je	7f		/* yes => return NULL */
-	incq	%rax		/* increment pointer */
-	decl	%edx
-	jnz	0b
-
-
-1:
-	/* At the moment %rsi contains C.  What we need for the
-	   algorithm is C in all bytes of the register.  Avoid
-	   operations on 16 bit words because these require an
-	   prefix byte (and one more cycle).  */
-	/* Populate 8 bit data to full 64-bit.  */
-	movabs	$0x0101010101010101,%r9
-	movzbl	%sil,%edx
-	imul	%rdx,%r9
-
-	movq $0xfefefefefefefeff, %r8 /* Save magic.  */
-
-      /* We exit the loop if adding MAGIC_BITS to LONGWORD fails to
-	 change any of the hole bits of LONGWORD.
-
-	 1) Is this safe?  Will it catch all the zero bytes?
-	 Suppose there is a byte with all zeros.  Any carry bits
-	 propagating from its left will fall into the hole at its
-	 least significant bit and stop.  Since there will be no
-	 carry from its most significant bit, the LSB of the
-	 byte to the left will be unchanged, and the zero will be
-	 detected.
-
-	 2) Is this worthwhile?  Will it ignore everything except
-	 zero bytes?  Suppose every byte of QUARDWORD has a bit set
-	 somewhere.  There will be a carry into bit 8.	If bit 8
-	 is set, this will carry into bit 16.  If bit 8 is clear,
-	 one of bits 9-15 must be set, so there will be a carry
-	 into bit 16.  Similarly, there will be a carry into bit
-	 24 tec..  If one of bits 54-63 is set, there will be a carry
-	 into bit 64 (=carry flag), so all of the hole bits will
-	 be changed.
-
-	 3) But wait!  Aren't we looking for C, not zero?
-	 Good point.  So what we do is XOR LONGWORD with a longword,
-	 each of whose bytes is C.  This turns each byte that is C
-	 into a zero.  */
-
-	.p2align 4
-4:
-	/* Main Loop is unrolled 4 times.  */
-	/* First unroll.  */
-	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
-	addq $8,%rax		/* adjust pointer for next word */
-	movq %r8, %rdx		/* magic value */
-	xorq %r9, %rcx		/* XOR with qword c|...|c => bytes of str == c
-				   are now 0 */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 3f			/* highest byte is NUL => return pointer */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jnz 3f			/* found c => return pointer */
-
-	/* The quadword we looked at does not contain the value we're looking
-	   for.  Let's search now whether we have reached the end of the
-	   string.  */
-	xorq %r9, %rcx		/* restore original dword without reload */
-	movq %r8, %rdx		/* magic value */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 7f			/* highest byte is NUL => return NULL */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jnz 7f			/* found NUL => return NULL */
-
-	/* Second unroll.  */
-	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
-	addq $8,%rax		/* adjust pointer for next word */
-	movq %r8, %rdx		/* magic value */
-	xorq %r9, %rcx		/* XOR with qword c|...|c => bytes of str == c
-				   are now 0 */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 3f			/* highest byte is NUL => return pointer */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jnz 3f			/* found c => return pointer */
-
-	/* The quadword we looked at does not contain the value we're looking
-	   for.  Let's search now whether we have reached the end of the
-	   string.  */
-	xorq %r9, %rcx		/* restore original dword without reload */
-	movq %r8, %rdx		/* magic value */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 7f			/* highest byte is NUL => return NULL */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jnz 7f			/* found NUL => return NULL */
-	/* Third unroll.  */
-	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
-	addq $8,%rax		/* adjust pointer for next word */
-	movq %r8, %rdx		/* magic value */
-	xorq %r9, %rcx		/* XOR with qword c|...|c => bytes of str == c
-				   are now 0 */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 3f			/* highest byte is NUL => return pointer */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jnz 3f			/* found c => return pointer */
-
-	/* The quadword we looked at does not contain the value we're looking
-	   for.  Let's search now whether we have reached the end of the
-	   string.  */
-	xorq %r9, %rcx		/* restore original dword without reload */
-	movq %r8, %rdx		/* magic value */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 7f			/* highest byte is NUL => return NULL */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jnz 7f			/* found NUL => return NULL */
-	/* Fourth unroll.  */
-	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
-	addq $8,%rax		/* adjust pointer for next word */
-	movq %r8, %rdx		/* magic value */
-	xorq %r9, %rcx		/* XOR with qword c|...|c => bytes of str == c
-				   are now 0 */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 3f			/* highest byte is NUL => return pointer */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jnz 3f			/* found c => return pointer */
-
-	/* The quadword we looked at does not contain the value we're looking
-	   for.  Let's search now whether we have reached the end of the
-	   string.  */
-	xorq %r9, %rcx		/* restore original dword without reload */
-	movq %r8, %rdx		/* magic value */
-	addq %rcx, %rdx		/* add the magic value to the word.  We get
-				   carry bits reported for each byte which
-				   is *not* 0 */
-	jnc 7f			/* highest byte is NUL => return NULL */
-	xorq %rcx, %rdx		/* (word+magic)^word */
-	orq %r8, %rdx		/* set all non-carry bits */
-	incq %rdx		/* add 1: if one carry bit was *not* set
-				   the addition will not result in 0.  */
-	jz 4b			/* no NUL found => restart loop */
-
-
-7:	/* Return NULL.  */
-	xorl %eax, %eax
-	retq
-
-
-	/* We now scan for the byte in which the character was matched.
-	   But we have to take care of the case that a NUL char is
-	   found before this in the dword.  Note that we XORed %rcx
-	   with the byte we're looking for, therefore the tests below look
-	   reversed.  */
-
-
-	.p2align 4		/* Align, it's a jump target.  */
-3:	movq	%r9,%rdx	/* move to %rdx so that we can access bytes */
-	subq	$8,%rax		/* correct pointer increment.  */
-	testb %cl, %cl		/* is first byte C? */
-	jz 6f			/* yes => return pointer */
-	cmpb %dl, %cl		/* is first byte NUL? */
-	je 7b			/* yes => return NULL */
-	incq %rax		/* increment pointer */
-
-	testb %ch, %ch		/* is second byte C? */
-	jz 6f			/* yes => return pointer */
-	cmpb %dl, %ch		/* is second byte NUL? */
-	je 7b			/* yes => return NULL? */
-	incq %rax		/* increment pointer */
-
-	shrq $16, %rcx		/* make upper bytes accessible */
-	testb %cl, %cl		/* is third byte C? */
-	jz 6f			/* yes => return pointer */
-	cmpb %dl, %cl		/* is third byte NUL? */
-	je 7b			/* yes => return NULL */
-	incq %rax		/* increment pointer */
-
-	testb %ch, %ch		/* is fourth byte C? */
-	jz 6f			/* yes => return pointer */
-	cmpb %dl, %ch		/* is fourth byte NUL? */
-	je 7b			/* yes => return NULL? */
-	incq %rax		/* increment pointer */
-
-	shrq $16, %rcx		/* make upper bytes accessible */
-	testb %cl, %cl		/* is fifth byte C? */
-	jz 6f			/* yes => return pointer */
-	cmpb %dl, %cl		/* is fifth byte NUL? */
-	je 7b			/* yes => return NULL */
-	incq %rax		/* increment pointer */
-
-	testb %ch, %ch		/* is sixth byte C? */
-	jz 6f			/* yes => return pointer */
-	cmpb %dl, %ch		/* is sixth byte NUL? */
-	je 7b			/* yes => return NULL? */
-	incq %rax		/* increment pointer */
-
-	shrq $16, %rcx		/* make upper bytes accessible */
-	testb %cl, %cl		/* is seventh byte C? */
-	jz 6f			/* yes => return pointer */
-	cmpb %dl, %cl		/* is seventh byte NUL? */
-	je 7b			/* yes => return NULL */
-
-	/* It must be in the eigth byte and it cannot be NUL.  */
-	incq %rax
-
-6:
-	nop
-	retq
-END (BP_SYM (strchr))
-
-weak_alias (BP_SYM (strchr), BP_SYM (index))
 libc_hidden_builtin_def (strchr)
+