powerpc: Various P7-optimized string functions

1 files changed, 172 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc32/power7/strnlen.S b/sysdeps/powerpc/powerpc32/power7/strnlen.S
new file mode 100644
index 0000000..2272c7c
--- /dev/null
+++ b/sysdeps/powerpc/powerpc32/power7/strnlen.S
@@ -0,0 +1,172 @@
+/* Optimized strnlen 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] strnlen (char *s [r3], int size [r4])  */
+	.machine  power7
+ENTRY (BP_SYM (__strnlen))
+	CALL_MCOUNT
+	dcbt	0,r3
+	clrrwi	r8,r3,2	      /* Align the address to word boundary.  */
+	add	r7,r3,r4      /* Calculate the last acceptable address.  */
+	cmplwi	r4,16
+	li	r0,0	      /* Word with null chars.  */
+	ble	L(small_range)
+
+	cmplw	cr7,r3,r7     /* Is the address equal or less than r3?  If
+				 it's equal or less, it means size is either 0
+				 or a negative number.  */
+	ble	cr7,L(proceed)
+
+	li	r7,-1	      /* Make r11 the biggest if r4 <= 0.  */
+L(proceed):
+	rlwinm	r6,r3,3,27,28 /* Calculate padding.  */
+	lwz	r12,0(r8)     /* Load word from memory.  */
+	cmpb	r10,r12,r0    /* Check for null bytes in DWORD1.  */
+	slw	r10,r10,r6
+	srw	r10,r10,r6
+	cmplwi	cr7,r10,0     /* If r10 == 0, no null's have been found.  */
+	bne	cr7,L(done)
+
+	/* Are we done already?  */
+	addi	r9,r8,4
+	cmplw	cr6,r9,r7
+	bge	cr6,L(end_max)
+
+	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_setup)
+
+	/* Handle DWORD2 of pair.  */
+	lwzu	r12,4(r8)
+	cmpb	r10,r12,r0
+	cmplwi	cr7,r10,0
+	bne	cr7,L(done)
+
+	/* Are we done already?  */
+	addi	r9,r8,4
+	cmplw	cr6,r9,r7
+	bge	cr6,L(end_max)
+
+L(loop_setup):
+	sub	r5,r7,r9
+	srwi	r6,r5,3	      /* Number of loop iterations.  */
+	mtctr	r6	      /* Setup the counter.  */
+	b	L(loop)
+	/* Main loop to look for the null byte backwards in the string.  Since
+	   it's a small loop (< 8 instructions), align it to 32-bytes.  */
+	.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	r11,8(r8)
+	cmpb	r10,r12,r0
+	cmpb	r9,r11,r0
+	or	r5,r9,r10     /* Merge everything in one word.  */
+	cmplwi	cr7,r5,0
+	bne	cr7,L(found)
+	bdnz	L(loop)
+	/* We're here because the counter reached 0, and that means we
+	   didn't have any matches for null in the whole range.  Just return
+	   the original size.  */
+	addi	r9,r8,4
+	cmplw	cr6,r9,r7
+	blt	cr6,L(loop_small)
+
+L(end_max):
+	sub	r3,r7,r3
+	blr
+
+	/* 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.  */
+	.align	4
+L(found):
+	cmplwi	cr6,r10,0
+	addi	r8,r8,-4
+	bne	cr6,L(done)
+
+	/* 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
+	   length.  */
+
+	mr	r10,r9
+	addi	r8,r8,4
+
+	/* r10 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 length.
+	   We need to make sure the null char is *before* the end of the
+	   range.  */
+L(done):
+	cntlzw	r0,r10	      /* Count leading zeroes before the match.  */
+	srwi	r0,r0,3	      /* Convert leading zeroes to bytes.  */
+	add	r9,r8,r0
+	sub	r6,r9,r3      /* Length until the match.  */
+	cmplw	r9,r7
+	bgt	L(end_max)
+	mr	r3,r6
+	blr
+
+	.align	4
+L(zero):
+	li	r3,0
+	blr
+
+/* Deals with size <= 32.  */
+	.align	4
+L(small_range):
+	cmplwi	r4,0
+	beq	L(zero)
+
+	rlwinm	r6,r3,3,27,28 /* Calculate padding.  */
+	lwz	r12,0(r8)     /* Load word from memory.  */
+	cmpb	r10,r12,r0    /* Check for null bytes in WORD1.  */
+	slw	r10,r10,r6
+	srw	r10,r10,r6
+	cmplwi	cr7,r10,0
+	bne	cr7,L(done)
+
+	addi    r9,r8,4
+	cmplw	r9,r7
+	bge	L(end_max)
+	b	L(loop_small)
+
+	.p2align  5
+L(loop_small):
+	lwzu	r12,4(r8)
+	cmpb	r10,r12,r0
+	addi	r9,r8,4
+	cmplwi	cr6,r10,0
+	bne	cr6,L(done)
+	cmplw	r9,r7
+	bge	L(end_max)
+	b	L(loop_small)
+END (BP_SYM (__strnlen))
+weak_alias (BP_SYM (__strnlen), BP_SYM(strnlen))
+libc_hidden_builtin_def (strnlen)