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813c6ec808
This patch modifies the current POWER9 implementation of strcpy and stpcpy to optimize it for POWER9/10. Since no new POWER10 instructions are used, the original POWER9 strcpy is modified instead of creating a new implementation for POWER10. This implementation is based on both the original POWER9 implementation of strcpy and the preamble of the new POWER10 implementation of strlen. The changes also affect stpcpy, which uses the same implementation with some additional code before returning. On POWER9, averaging improvements across the benchmark inputs (length/source alignment/destination alignment), for an experiment that ran the benchmark five times, bench-strcpy showed an improvement of 5.23%, and bench-stpcpy showed an improvement of 6.59%. On POWER10, bench-strcpy showed 13.16%, and bench-stpcpy showed 13.59%. The changes are: 1. Removed the null string optimization. Although this results in a few extra cycles for the null string, in combination with the second change, this resulted in improvements for for other cases. 2. Adapted the preamble from strlen for POWER10. This is the part of the function that handles up to the first 16 bytes of the string. 3. Increased number of unrolled iterations in the main loop to 6. Reviewed-by: Matheus Castanho <msc@linux.ibm.com> Tested-by: Matheus Castanho <msc@linux.ibm.com>
206 lines
4.3 KiB
ArmAsm
206 lines
4.3 KiB
ArmAsm
/* Optimized strcpy implementation for PowerPC64/POWER9.
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Copyright (C) 2020-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#ifdef USE_AS_STPCPY
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# ifndef STPCPY
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# define FUNC_NAME __stpcpy
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# else
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# define FUNC_NAME STPCPY
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# endif
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#else
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# ifndef STRCPY
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# define FUNC_NAME strcpy
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# else
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# define FUNC_NAME STRCPY
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# endif
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#endif /* !USE_AS_STPCPY */
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/* Implements the function
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char * [r3] strcpy (char *dest [r3], const char *src [r4])
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or
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char * [r3] stpcpy (char *dest [r3], const char *src [r4])
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if USE_AS_STPCPY is defined.
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The implementation can load bytes past a null terminator, but only
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up to the next 16B boundary, so it never crosses a page. */
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/* Load quadword at addr+offset to vreg, check for null bytes,
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and branch to label if any are found. */
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#define CHECK16(vreg,offset,addr,label) \
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lxv vreg+32,offset(addr); \
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vcmpequb. v6,vreg,v18; \
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bne cr6,L(label);
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.machine power9
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ENTRY_TOCLESS (FUNC_NAME, 4)
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CALL_MCOUNT 2
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vspltisb v18,0 /* Zeroes in v18 */
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vspltisb v19,-1 /* 0xFF bytes in v19 */
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/* Next 16B-aligned address. Prepare address for L(loop). */
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addi r5,r4,16
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clrrdi r5,r5,4
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subf r8,r4,r5
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add r11,r3,r8
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/* Align data and fill bytes not loaded with non matching char. */
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lvx v0,0,r4
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lvsr v1,0,r4
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vperm v0,v19,v0,v1
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vcmpequb. v6,v0,v18 /* 0xff if byte is NULL, 0x00 otherwise */
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beq cr6,L(no_null)
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/* There's a null byte. */
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vctzlsbb r8,v6 /* Number of trailing zeroes */
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addi r9,r8,1 /* Add null byte. */
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sldi r10,r9,56 /* stxvl wants size in top 8 bits. */
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stxvl 32+v0,r3,r10 /* Partial store */
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#ifdef USE_AS_STPCPY
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/* stpcpy returns the dest address plus the size not counting the
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final '\0'. */
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add r3,r3,r8
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#endif
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blr
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L(no_null):
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sldi r10,r8,56 /* stxvl wants size in top 8 bits */
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stxvl 32+v0,r3,r10 /* Partial store */
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.p2align 4
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L(loop):
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CHECK16(v0,0,r5,tail1)
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CHECK16(v1,16,r5,tail2)
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CHECK16(v2,32,r5,tail3)
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CHECK16(v3,48,r5,tail4)
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CHECK16(v4,64,r5,tail5)
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CHECK16(v5,80,r5,tail6)
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stxv 32+v0,0(r11)
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stxv 32+v1,16(r11)
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stxv 32+v2,32(r11)
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stxv 32+v3,48(r11)
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stxv 32+v4,64(r11)
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stxv 32+v5,80(r11)
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addi r5,r5,96
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addi r11,r11,96
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b L(loop)
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.p2align 4
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L(tail1):
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vctzlsbb r8,v6 /* Number of trailing zeroes */
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addi r9,r8,1 /* Add null terminator */
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sldi r9,r9,56 /* stxvl wants size in top 8 bits */
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stxvl 32+v0,r11,r9 /* Partial store */
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#ifdef USE_AS_STPCPY
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/* stpcpy returns the dest address plus the size not counting the
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final '\0'. */
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add r3,r11,r8
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#endif
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blr
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.p2align 4
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L(tail2):
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stxv 32+v0,0(r11)
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vctzlsbb r8,v6
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addi r9,r8,1
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sldi r9,r9,56
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addi r11,r11,16
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stxvl 32+v1,r11,r9
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#ifdef USE_AS_STPCPY
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add r3,r11,r8
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#endif
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blr
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.p2align 4
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L(tail3):
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stxv 32+v0,0(r11)
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stxv 32+v1,16(r11)
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vctzlsbb r8,v6
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addi r9,r8,1
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sldi r9,r9,56
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addi r11,r11,32
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stxvl 32+v2,r11,r9
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#ifdef USE_AS_STPCPY
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add r3,r11,r8
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#endif
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blr
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.p2align 4
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L(tail4):
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stxv 32+v0,0(r11)
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stxv 32+v1,16(r11)
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stxv 32+v2,32(r11)
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vctzlsbb r8,v6
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addi r9,r8,1
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sldi r9,r9,56
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addi r11,r11,48
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stxvl 32+v3,r11,r9
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#ifdef USE_AS_STPCPY
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add r3,r11,r8
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#endif
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blr
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.p2align 4
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L(tail5):
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stxv 32+v0,0(r11)
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stxv 32+v1,16(r11)
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stxv 32+v2,32(r11)
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stxv 32+v3,48(r11)
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vctzlsbb r8,v6
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addi r9,r8,1
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sldi r9,r9,56
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addi r11,r11,64
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stxvl 32+v4,r11,r9
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#ifdef USE_AS_STPCPY
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add r3,r11,r8
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#endif
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blr
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.p2align 4
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L(tail6):
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stxv 32+v0,0(r11)
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stxv 32+v1,16(r11)
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stxv 32+v2,32(r11)
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stxv 32+v3,48(r11)
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stxv 32+v4,64(r11)
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vctzlsbb r8,v6
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addi r9,r8,1
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sldi r9,r9,56
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addi r11,r11,80
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stxvl 32+v5,r11,r9
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#ifdef USE_AS_STPCPY
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add r3,r11,r8
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#endif
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blr
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END (FUNC_NAME)
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#ifndef USE_AS_STPCPY
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libc_hidden_builtin_def (strcpy)
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#endif
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