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-rw-r--r--REORG.TODO/sysdeps/powerpc/powerpc64/power8/strcmp.S247
1 files changed, 247 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/powerpc/powerpc64/power8/strcmp.S b/REORG.TODO/sysdeps/powerpc/powerpc64/power8/strcmp.S
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index 0000000000..770484f1e1
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+++ b/REORG.TODO/sysdeps/powerpc/powerpc64/power8/strcmp.S
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+/* Optimized strcmp implementation for PowerPC64/POWER8.
+   Copyright (C) 2015-2017 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/>.  */
+
+#include <sysdep.h>
+
+#ifndef STRCMP
+# define STRCMP strcmp
+#endif
+
+/* Implements the function
+
+   size_t [r3] strcmp (const char *s1 [r3], const char *s2 [r4])
+
+   The implementation uses unaligned doubleword access to avoid specialized
+   code paths depending of data alignment.  Although recent powerpc64 uses
+   64K as default, the page cross handling assumes minimum page size of
+   4k.  */
+
+EALIGN (STRCMP, 4, 0)
+	li	r0,0
+
+	/* Check if [s1]+16 or [s2]+16 will cross a 4K page boundary using
+	   the code:
+
+	    (((size_t) s1) % PAGE_SIZE > (PAGE_SIZE - ITER_SIZE))
+
+	   with PAGE_SIZE being 4096 and ITER_SIZE begin 16.  */
+
+	rldicl	r7,r3,0,52
+	rldicl	r9,r4,0,52
+	cmpldi	cr7,r7,4096-16
+	bgt	cr7,L(pagecross_check)
+	cmpldi	cr5,r9,4096-16
+	bgt	cr5,L(pagecross_check)
+
+	/* For short string up to 16 bytes, load both s1 and s2 using
+	   unaligned dwords and compare.  */
+	ld	r8,0(r3)
+	ld	r10,0(r4)
+	cmpb	r12,r8,r0
+	cmpb	r11,r8,r10
+	orc.	r9,r12,r11
+	bne	cr0,L(different_nocmpb)
+
+	ld	r8,8(r3)
+	ld	r10,8(r4)
+	cmpb	r12,r8,r0
+	cmpb	r11,r8,r10
+	orc.	r9,r12,r11
+	bne	cr0,L(different_nocmpb)
+
+	addi	r7,r3,16
+	addi	r4,r4,16
+
+L(align_8b):
+	/* Now it has checked for first 16 bytes, align source1 to doubleword
+	   and adjust source2 address.  */
+	rldicl	r9,r7,0,61	/* source1 alignment to doubleword  */
+	subf	r4,r9,r4	/* Adjust source2 address based on source1
+				   alignment.  */
+	rldicr	r7,r7,0,60	/* Align source1 to doubleword.  */
+
+	/* At this point, source1 alignment is 0 and source2 alignment is
+	   between 0 and 7.  Check is source2 alignment is 0, meaning both
+	   sources have the same alignment.  */
+	andi.	r9,r4,0x7
+	bne	cr0,L(loop_diff_align)
+
+	/* If both source1 and source2 are doubleword aligned, there is no
+	   need for page boundary cross checks.  */
+
+	ld	r8,0(r7)
+	ld	r10,0(r4)
+	cmpb	r12,r8,r0
+	cmpb	r11,r8,r10
+	orc.	r9,r12,r11
+	bne	cr0,L(different_nocmpb)
+
+	.align 4
+L(loop_equal_align):
+	ld	r8,8(r7)
+	ld	r10,8(r4)
+	cmpb	r12,r8,r0
+	cmpb	r11,r8,r10
+	orc.	r9,r12,r11
+	bne	cr0,L(different_nocmpb)
+
+	ld	r8,16(r7)
+	ld	r10,16(r4)
+	cmpb	r12,r8,r0
+	cmpb	r11,r8,r10
+	orc.	r9,r12,r11
+	bne	cr0,L(different_nocmpb)
+
+	ldu	r8,24(r7)
+	ldu	r10,24(r4)
+	cmpb	r12,r8,r0
+	cmpb	r11,r8,r10
+	orc.	r9,r12,r11
+	bne	cr0,L(different_nocmpb)
+
+	b	L(loop_equal_align)
+
+	/* A zero byte was found in r8 (s1 dword), r9 contains the cmpb
+	   result and r10 the dword from s2.  To code isolate the byte
+	   up to end (including the '\0'), masking with 0xFF the remaining
+	   ones:
+
+           #if __LITTLE_ENDIAN__
+	     (__builtin_ffsl (x) - 1) = counting trailing zero bits
+	     r9 = (__builtin_ffsl (r9) - 1) + 8;
+	     r9 = -1UL << r9
+	   #else
+	     r9  = __builtin_clzl (r9) + 8;
+	     r9  = -1UL >> r9
+	   #endif
+	     r8  = r8  | r9
+	     r10 = r10 | r9  */
+
+#ifdef __LITTLE_ENDIAN__
+	nor 	r9,r9,r9
+L(different_nocmpb):
+	neg	r3,r9
+	and	r9,r9,r3
+	cntlzd	r9,r9
+	subfic	r9,r9,63
+#else
+	not	r9,r9
+L(different_nocmpb):
+	cntlzd	r9,r9
+	subfic	r9,r9,56
+#endif
+	srd	r3,r8,r9
+	srd	r10,r10,r9
+	rldicl	r10,r10,0,56
+	rldicl	r3,r3,0,56
+	subf	r3,r10,r3
+	extsw	r3,r3
+	blr
+
+	.align	4
+L(pagecross_check):
+	subfic	r9,r9,4096
+	subfic	r7,r7,4096
+	cmpld	cr7,r7,r9
+	bge	cr7,L(pagecross)
+	mr	r7,r9
+
+	/* If unaligned 16 bytes reads across a 4K page boundary, it uses
+	   a simple byte a byte comparison until the page alignment for s1
+	   is reached.  */
+L(pagecross):
+	add	r7,r3,r7
+	subf	r9,r3,r7
+	mtctr	r9
+
+	.align	4
+L(pagecross_loop):
+	/* Loads a byte from s1 and s2, compare if *s1 is equal to *s2
+	   and if *s1 is '\0'.  */
+	lbz	r9,0(r3)
+	lbz	r10,0(r4)
+	addi	r3,r3,1
+	addi	r4,r4,1
+	cmplw	cr7,r9,r10
+	cmpdi	cr5,r9,r0
+	bne	cr7,L(pagecross_ne)
+	beq	cr5,L(pagecross_nullfound)
+	bdnz	L(pagecross_loop)
+	b	L(align_8b)
+
+	.align	4
+	/* The unaligned read of source2 will cross a 4K page boundary,
+	   and the different byte or NULL maybe be in the remaining page
+	   bytes. Since it can not use the unaligned load, the algorithm
+	   reads and compares 8 bytes to keep source1 doubleword aligned.  */
+L(check_source2_byte):
+	li	r9,8
+	mtctr	r9
+
+	.align	4
+L(check_source2_byte_loop):
+	lbz	r9,0(r7)
+	lbz	r10,0(r4)
+	addi	r7,r7,1
+	addi	r4,r4,1
+	cmplw	cr7,r9,10
+	cmpdi	r5,r9,0
+	bne	cr7,L(pagecross_ne)
+	beq	cr5,L(pagecross_nullfound)
+	bdnz	L(check_source2_byte_loop)
+
+	/* If source2 is unaligned to doubleword, the code needs to check
+	   on each interation if the unaligned doubleword access will cross
+	   a 4k page boundary.  */
+	.align	5
+L(loop_unaligned):
+	ld	r8,0(r7)
+	ld	r10,0(r4)
+	cmpb	r12,r8,r0
+	cmpb	r11,r8,r10
+	orc.	r9,r12,r11
+	bne	cr0,L(different_nocmpb)
+	addi	r7,r7,8
+	addi	r4,r4,8
+
+L(loop_diff_align):
+	/* Check if [src2]+8 cross a 4k page boundary:
+
+	     srcin2 % PAGE_SIZE > (PAGE_SIZE - 8)
+
+	     with PAGE_SIZE being 4096.  */
+	rldicl	r9,r4,0,52
+	cmpldi	cr7,r9,4088
+	ble	cr7,L(loop_unaligned)
+	b	L(check_source2_byte)
+
+	.align	4
+L(pagecross_ne):
+	extsw	r3,r9
+	mr	r9,r10
+L(pagecross_retdiff):
+	subf	r9,r9,r3
+	extsw	r3,r9
+	blr
+
+	.align	4
+L(pagecross_nullfound):
+	li	r3,0
+	b	L(pagecross_retdiff)
+END (STRCMP)
+libc_hidden_builtin_def (strcmp)
generated by cgit-pink 1.4.1 (git 2.36.1) at 2024-06-12 01:44:02 +0000