powerpc: Various P7-optimized string functions

1 files changed, 203 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc32/power7/strchr.S b/sysdeps/powerpc/powerpc32/power7/strchr.S
new file mode 100644
index 0000000000..2f50f93e71
--- /dev/null
+++ b/sysdeps/powerpc/powerpc32/power7/strchr.S
@@ -0,0 +1,203 @@
+/* Optimized strchr implementation for PowerPC32/POWER7 using cmpb insn.
+   Copyright (C) 2010 Free Software Foundation, Inc.
+   Contributed by Luis Machado <luisgpm@br.ibm.com>.
+   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, write to the Free
+   Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA
+   02110-1301 USA.  */
+
+#include <sysdep.h>
+#include <bp-sym.h>
+#include <bp-asm.h>
+
+/* int [r3] strchr (char *s [r3], int c [r4])  */
+	.machine  power7
+ENTRY (BP_SYM(strchr))
+	CALL_MCOUNT
+	dcbt	0,r3
+	clrrwi	r8,r3,2	      /* Align the address to word boundary.  */
+	cmpwi	cr7,r4,0
+	lwz	r12,0(r8)     /* Load word from memory.  */
+	li	r0,0	      /* Word with null chars to use
+				 with cmpb.  */
+
+	rlwinm	r6,r3,3,27,28 /* Calculate padding.  */
+
+	beq	cr7,L(null_match)
+
+	/* Replicate byte to word.  */
+	rlwimi	r4,r4,8,16,23
+	rlwimi	r4,r4,16,0,15
+
+	/* Now r4 has a word of c bytes and r0 has
+	   a word of null bytes.  */
+
+	cmpb	r10,r12,r4     /* Compare each byte against c byte.  */
+	cmpb	r11,r12,r0     /* Compare each byte against null byte.  */
+
+	/* Move the words left and right to discard the bits that are
+	   not part of the string and to bring them back as zeros.  */
+
+	slw	r10,r10,r6
+	slw	r11,r11,r6
+	srw	r10,r10,r6
+	srw	r11,r11,r6
+	or	r5,r10,r11    /* OR the results to speed things up.  */
+	cmpwi	cr7,r5,0      /* If r5 == 0, no c or null bytes
+				 have been found.  */
+	bne	cr7,L(done)
+
+	mtcrf   0x01,r8
+
+	/* Are we now aligned to a doubleword boundary?  If so, skip to
+	   the main loop.  Otherwise, go through the alignment code.  */
+
+	bt	29,L(loop)
+
+	/* Handle WORD2 of pair.  */
+	lwzu	r12,4(r8)
+	cmpb    r10,r12,r4
+	cmpb	r11,r12,r0
+	or	r5,r10,r11
+	cmpwi	cr7,r5,0
+	bne	cr7,L(done)
+	b	L(loop)	      /* We branch here (rather than falling through)
+				 to skip the nops due to heavy alignment
+				 of the loop below.  */
+
+	.p2align  5
+L(loop):
+	/* Load two words, compare and merge in a
+	   single register for speed.  This is an attempt
+	   to speed up the null-checking process for bigger strings.  */
+	lwz	r12,4(r8)
+	lwzu	r9,8(r8)
+	cmpb	r10,r12,r4
+	cmpb	r11,r12,r0
+	cmpb	r6,r9,r4
+	cmpb	r7,r9,r0
+	or	r12,r10,r11
+	or	r9,r6,r7
+	or	r5,r12,r9
+	cmpwi	cr7,r5,0
+	beq	cr7,L(loop)
+
+	/* OK, one (or both) of the words contains a c/null byte.  Check
+	   the first word and decrement the address in case the first
+	   word really contains a c/null byte.  */
+
+	cmpwi	cr6,r12,0
+	addi	r8,r8,-4
+	bne	cr6,L(done)
+
+	/* The c/null byte must be in the second word.  Adjust the address
+	   again and move the result of cmpb to r10 so we can calculate the
+	   pointer.  */
+
+	mr	r10,r6
+	mr	r11,r7
+	addi	r8,r8,4
+
+	/* r5 has the output of the cmpb instruction, that is, it contains
+	   0xff in the same position as the c/null byte in the original
+	   word from the string.  Use that to calculate the pointer.  */
+L(done):
+	cntlzw	r4,r10	      /* Count leading zeroes before c matches.  */
+	cntlzw	r0,r11	      /* Count leading zeroes before null matches.  */
+	cmplw	cr7,r4,r0
+	bgt	cr7,L(no_match)
+	srwi	r0,r4,3	      /* Convert leading zeroes to bytes.  */
+	add	r3,r8,r0      /* Return address of the matching c byte
+				 or null in case c was not found.  */
+	blr
+
+	.align	4
+L(no_match):
+	li	r3,0
+	blr
+
+/* We are here because strchr was called with a null byte.  */
+	.align	4
+L(null_match):
+	/* r0 has a word of null bytes.  */
+
+	cmpb	r5,r12,r0     /* Compare each byte against null bytes.  */
+
+	/* Move the words left and right to discard the bits that are
+	   not part of the string and to bring them back as zeros.  */
+
+	slw	r5,r5,r6
+	srw	r5,r5,r6
+	cmpwi	cr7,r5,0      /* If r10 == 0, no c or null bytes
+				 have been found.  */
+	bne	cr7,L(done_null)
+
+	mtcrf   0x01,r8
+
+	/* Are we now aligned to a doubleword boundary?  If so, skip to
+	   the main loop.  Otherwise, go through the alignment code.  */
+
+	bt	29,L(loop_null)
+
+	/* Handle WORD2 of pair.  */
+	lwzu	r12,4(r8)
+	cmpb    r5,r12,r0
+	cmpwi	cr7,r5,0
+	bne	cr7,L(done_null)
+	b	L(loop_null)  /* We branch here (rather than falling through)
+				 to skip the nops due to heavy alignment
+				 of the loop below.  */
+
+	/* Main loop to look for the end of the string.  Since it's a
+	   small loop (< 8 instructions), align it to 32-bytes.  */
+	.p2align  5
+L(loop_null):
+	/* Load two words, compare and merge in a
+	   single register for speed.  This is an attempt
+	   to speed up the null-checking process for bigger strings.  */
+	lwz	r12,4(r8)
+	lwzu    r11,8(r8)
+	cmpb	r5,r12,r0
+	cmpb	r10,r11,r0
+	or	r6,r5,r10
+	cmpwi	cr7,r6,0
+	beq	cr7,L(loop_null)
+
+	/* OK, one (or both) of the words contains a null byte.  Check
+	   the first word and decrement the address in case the first
+	   word really contains a null byte.  */
+
+	cmpwi	cr6,r5,0
+	addi	r8,r8,-4
+	bne	cr6,L(done_null)
+
+	/* The null byte must be in the second word.  Adjust the address
+	   again and move the result of cmpb to r10 so we can calculate the
+	   pointer.  */
+
+	mr	r5,r10
+	addi	r8,r8,4
+
+	/* r5 has the output of the cmpb instruction, that is, it contains
+	   0xff in the same position as the null byte in the original
+	   word from the string.  Use that to calculate the pointer.  */
+L(done_null):
+	cntlzw	r0,r5	      /* Count leading zeros before the match.  */
+	srwi	r0,r0,3	      /* Convert leading zeros to bytes.  */
+	add	r3,r8,r0      /* Return address of the matching null byte.  */
+	blr
+END (BP_SYM (strchr))
+weak_alias (BP_SYM (strchr), BP_SYM (index))
+libc_hidden_builtin_def (strchr)