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/* Optimized strcmp implementation for PowerPC64/POWER10.
Copyright (C) 2021-2023 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
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#ifndef STRCMP
# define STRCMP strcmp
#endif
/* Implements the function
int [r3] strcmp (const char *s1 [r3], const char *s2 [r4]). */
/* TODO: Change this to actual instructions when minimum binutils is upgraded
to 2.27. Macros are defined below for these newer instructions in order
to maintain compatibility. */
#define LXVP(xtp,dq,ra) \
.long(((6)<<(32-6)) \
| ((((xtp)-32)>>1)<<(32-10)) \
| ((1)<<(32-11)) \
| ((ra)<<(32-16)) \
| dq)
#define COMPARE_16(vreg1,vreg2,offset) \
lxv vreg1+32,offset(r3); \
lxv vreg2+32,offset(r4); \
vcmpnezb. v7,vreg1,vreg2; \
bne cr6,L(different); \
#define COMPARE_32(vreg1,vreg2,offset,label1,label2) \
LXVP(vreg1+32,offset,r3); \
LXVP(vreg2+32,offset,r4); \
vcmpnezb. v7,vreg1+1,vreg2+1; \
bne cr6,L(label1); \
vcmpnezb. v7,vreg1,vreg2; \
bne cr6,L(label2); \
#define TAIL(vreg1,vreg2) \
vctzlsbb r6,v7; \
vextubrx r5,r6,vreg1; \
vextubrx r4,r6,vreg2; \
subf r3,r4,r5; \
blr; \
#define CHECK_N_BYTES(reg1,reg2,len_reg) \
sldi r0,len_reg,56; \
lxvl 32+v4,reg1,r0; \
lxvl 32+v5,reg2,r0; \
add reg1,reg1,len_reg; \
add reg2,reg2,len_reg; \
vcmpnezb. v7,v4,v5; \
vctzlsbb r6,v7; \
cmpld cr7,r6,len_reg; \
blt cr7,L(different); \
/* TODO: change this to .machine power10 when the minimum required
binutils allows it. */
.machine power9
ENTRY_TOCLESS (STRCMP, 4)
li r11,16
/* eq bit of cr1 used as swap status flag to indicate if
source pointers were swapped. */
crclr 4*cr1+eq
vspltisb v19,-1
andi. r7,r3,15
sub r7,r11,r7 /* r7(nalign1) = 16 - (str1 & 15). */
andi. r9,r4,15
sub r5,r11,r9 /* r5(nalign2) = 16 - (str2 & 15). */
cmpld cr7,r7,r5
beq cr7,L(same_aligned)
blt cr7,L(nalign1_min)
/* Swap r3 and r4, and r7 and r5 such that r3 and r7 hold the
pointer which is closer to the next 16B boundary so that only
one CHECK_N_BYTES is needed before entering the loop below. */
mr r8,r4
mr r4,r3
mr r3,r8
mr r12,r7
mr r7,r5
mr r5,r12
crset 4*cr1+eq /* Set bit on swapping source pointers. */
.p2align 5
L(nalign1_min):
CHECK_N_BYTES(r3,r4,r7)
.p2align 5
L(s1_aligned):
/* r9 and r5 is number of bytes to be read after and before
page boundary correspondingly. */
sub r5,r5,r7
subfic r9,r5,16
/* Now let r7 hold the count of quadwords which can be
checked without crossing a page boundary. quadword offset is
(str2>>4)&0xFF. */
rlwinm r7,r4,28,0xFF
/* Below check is required only for first iteration. For second
iteration and beyond, the new loop counter is always 255. */
cmpldi r7,255
beq L(L3)
/* Get the initial loop count by 255-((str2>>4)&0xFF). */
subfic r11,r7,255
.p2align 5
L(L1):
mtctr r11
.p2align 5
L(L2):
COMPARE_16(v4,v5,0) /* Load 16B blocks using lxv. */
addi r3,r3,16
addi r4,r4,16
bdnz L(L2)
/* Cross the page boundary of s2, carefully. */
.p2align 5
L(L3):
CHECK_N_BYTES(r3,r4,r5)
CHECK_N_BYTES(r3,r4,r9)
li r11,255 /* Load the new loop counter. */
b L(L1)
.p2align 5
L(same_aligned):
CHECK_N_BYTES(r3,r4,r7)
/* Align s1 to 32B and adjust s2 address.
Use lxvp only if both s1 and s2 are 32B aligned. */
COMPARE_16(v4,v5,0)
COMPARE_16(v4,v5,16)
COMPARE_16(v4,v5,32)
COMPARE_16(v4,v5,48)
addi r3,r3,64
addi r4,r4,64
COMPARE_16(v4,v5,0)
COMPARE_16(v4,v5,16)
clrldi r6,r3,59
subfic r5,r6,32
add r3,r3,r5
add r4,r4,r5
andi. r5,r4,0x1F
beq cr0,L(32B_aligned_loop)
.p2align 5
L(16B_aligned_loop):
COMPARE_16(v4,v5,0)
COMPARE_16(v4,v5,16)
COMPARE_16(v4,v5,32)
COMPARE_16(v4,v5,48)
addi r3,r3,64
addi r4,r4,64
b L(16B_aligned_loop)
/* Calculate and return the difference. */
L(different):
vctzlsbb r6,v7
vextubrx r5,r6,v4
vextubrx r4,r6,v5
bt 4*cr1+eq,L(swapped)
subf r3,r4,r5
blr
/* If src pointers were swapped, then swap the
indices and calculate the return value. */
L(swapped):
subf r3,r5,r4
blr
.p2align 5
L(32B_aligned_loop):
COMPARE_32(v14,v16,0,tail1,tail2)
COMPARE_32(v18,v20,32,tail3,tail4)
COMPARE_32(v22,v24,64,tail5,tail6)
COMPARE_32(v26,v28,96,tail7,tail8)
addi r3,r3,128
addi r4,r4,128
b L(32B_aligned_loop)
L(tail1): TAIL(v15,v17)
L(tail2): TAIL(v14,v16)
L(tail3): TAIL(v19,v21)
L(tail4): TAIL(v18,v20)
L(tail5): TAIL(v23,v25)
L(tail6): TAIL(v22,v24)
L(tail7): TAIL(v27,v29)
L(tail8): TAIL(v26,v28)
END (STRCMP)
libc_hidden_builtin_def (strcmp)
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