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Diffstat (limited to 'sysdeps/powerpc/powerpc64/power7/strncpy.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc64/power7/strncpy.S | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc64/power7/strncpy.S b/sysdeps/powerpc/powerpc64/power7/strncpy.S new file mode 100644 index 0000000000..51860df8c5 --- /dev/null +++ b/sysdeps/powerpc/powerpc64/power7/strncpy.S @@ -0,0 +1,338 @@ +/* Copyright (C) 2014 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> + +/* Implements the functions + + char * [r3] strncpy (char *dst [r3], const char *src [r4], size_t n [r5]) + + AND + + char * [r3] stpncpy (char *dst [r3], const char *src [r4], size_t n [r5]) + + The algorithm is as follows: + > if src and dest are 8 byte aligned, perform double word copy + else + > copy byte by byte on unaligned addresses. + + The aligned comparison are made using cmpb instructions. */ + +/* The focus on optimization for performance improvements are as follows: + 1. data alignment [gain from aligned memory access on read/write] + 2. POWER7 gains performance with loop unrolling/unwinding + [gain by reduction of branch penalty]. + 3. The final pad with null bytes is done by calling an optimized + memset. */ + +#ifdef USE_AS_STPNCPY +# define FUNC_NAME __stpncpy +#else +# define FUNC_NAME strncpy +#endif + +#define FRAMESIZE (FRAME_MIN_SIZE+32) + +#ifndef MEMSET +/* For builds with no IFUNC support, local calls should be made to internal + GLIBC symbol (created by libc_hidden_builtin_def). */ +# ifdef SHARED +# define MEMSET __GI_memset +# else +# define MEMSET memset +# endif +#endif + + .machine power7 +EALIGN(FUNC_NAME, 4, 0) + CALL_MCOUNT 3 + + mflr r0 /* load link register LR to r0 */ + or r10, r3, r4 /* to verify source and destination */ + rldicl. r8, r10, 0, 61 /* is double word aligned .. ? */ + + std r19, -8(r1) /* save callers register , r19 */ + std r18, -16(r1) /* save callers register , r18 */ + std r0, 16(r1) /* store the link register */ + stdu r1, -FRAMESIZE(r1) /* create the stack frame */ + + mr r9, r3 /* save r3 into r9 for use */ + mr r18, r3 /* save r3 for retCode of strncpy */ + bne 0, L(byte_by_byte) + + + srdi r11, r5, 3 /* compute count for CTR ; count = n/8 */ + cmpldi cr7, r11, 3 /* if count > 4 ; perform unrolling 4 times */ + ble 7, L(update1) + + ld r10, 0(r4) /* load doubleWord from src */ + cmpb r8, r10, r8 /* compare src with NULL ,we read just now */ + cmpdi cr7, r8, 0 /* if cmpb returned NULL ; we continue */ + bne cr7, L(update3) + + std r10, 0(r3) /* copy doubleword at offset=0 */ + ld r10, 8(r4) /* load next doubleword from offset=8 */ + cmpb r8, r10, r8 /* compare src with NULL , we read just now */ + cmpdi cr7, r8, 0 /* if cmpb returned NULL ; we continue */ + bne 7,L(HopBy8) + + addi r8, r11, -4 + mr r7, r3 + srdi r8, r8, 2 + mr r6, r4 + addi r8, r8, 1 + li r12, 0 + mtctr r8 + b L(dwordCopy) + + .p2align 4 +L(dWordUnroll): + std r8, 16(r9) + ld r8, 24(r4) /* load dword,perform loop unrolling again */ + cmpb r10, r8, r10 + cmpdi cr7, r10, 0 + bne cr7, L(HopBy24) + + std r8, 24(r7) /* copy dword at offset=24 */ + addi r9, r9, 32 + addi r4, r4, 32 + bdz L(leftDwords) /* continue with loop on counter */ + + ld r3, 32(r6) + cmpb r8, r3, r10 + cmpdi cr7, r8, 0 + bne cr7, L(update2) + + std r3, 32(r7) + ld r10, 40(r6) + cmpb r8, r10, r8 + cmpdi cr7, r8, 0 + bne cr7, L(HopBy40) + + mr r6, r4 /* update values */ + mr r7, r9 + mr r11, r0 + mr r5, r19 + +L(dwordCopy): + std r10, 8(r9) /* copy dword at offset=8 */ + addi r19, r5, -32 + addi r0, r11, -4 + ld r8, 16(r4) + cmpb r10, r8, r12 + cmpdi cr7, r10, 0 + beq cr7, L(dWordUnroll) + + addi r9, r9, 16 /* increment dst by 16 */ + addi r4, r4, 16 /* increment src by 16 */ + addi r5, r5, -16 /* decrement length 'n' by 16 */ + addi r0, r11, -2 /* decrement loop counter */ + +L(dWordUnrollOFF): + ld r10, 0(r4) /* load first dword */ + li r8, 0 /* load mask */ + cmpb r8, r10, r8 + cmpdi cr7, r8, 0 + bne cr7, L(byte_by_byte) + mtctr r0 + li r7, 0 + b L(CopyDword) + + .p2align 4 +L(loadDWordandCompare): + ld r10, 0(r4) + cmpb r8, r10, r7 + cmpdi cr7, r8, 0 + bne cr7, L(byte_by_byte) + +L(CopyDword): + addi r9, r9, 8 + std r10, -8(r9) + addi r4, r4, 8 + addi r5, r5, -8 + bdnz L(loadDWordandCompare) + +L(byte_by_byte): + cmpldi cr7, r5, 3 + ble cr7, L(verifyByte) + srdi r10, r5, 2 + mr r19, r9 + mtctr r10 + b L(firstByteUnroll) + + .p2align 4 +L(bytes_unroll): + lbz r10, 1(r4) /* load byte from src */ + cmpdi cr7, r10, 0 /* compare for NULL */ + stb r10, 1(r19) /* store byte to dst */ + beq cr7, L(updtDestComputeN2ndByte) + + addi r4, r4, 4 /* advance src */ + + lbz r10, -2(r4) /* perform loop unrolling for byte r/w */ + cmpdi cr7, r10, 0 + stb r10, 2(r19) + beq cr7, L(updtDestComputeN3rdByte) + + lbz r10, -1(r4) /* perform loop unrolling for byte r/w */ + addi r19, r19, 4 + cmpdi cr7, r10, 0 + stb r10, -1(r19) + beq cr7, L(ComputeNByte) + + bdz L(update0) + +L(firstByteUnroll): + lbz r10, 0(r4) /* perform loop unrolling for byte r/w */ + cmpdi cr7, 10, 0 + stb r10, 0(r19) + bne cr7, L(bytes_unroll) + addi r19, r19, 1 + +L(ComputeNByte): + subf r9, r19, r9 /* compute 'n'n bytes to fill */ + add r8, r9, r5 + +L(zeroFill): + cmpdi cr7, r8, 0 /* compare if length is zero */ + beq cr7, L(update3return) + + mr r3, r19 /* fill buffer with */ + li r4, 0 /* zero fill buffer */ + mr r5, r8 /* how many bytes to fill buffer with */ + bl MEMSET /* call optimized memset */ + nop + +L(update3return): +#ifdef USE_AS_STPNCPY + addi r3, r19, -1 /* update return value */ +#endif + +L(hop2return): +#ifndef USE_AS_STPNCPY + mr r3, r18 /* set return value */ +#endif + addi r1, r1, FRAMESIZE /* restore stack pointer */ + ld r0, 16(r1) /* read the saved link register */ + ld r18, -16(r1) /* restore callers save register, r18 */ + ld r19, -8(r1) /* restore callers save register, r19 */ + mtlr r0 /* branch to link register */ + blr /* return */ + + .p2align 4 +L(update0): + mr r9, r19 + + .p2align 4 +L(verifyByte): + rldicl. r8, r5, 0, 62 +#ifdef USE_AS_STPNCPY + mr r3, r9 +#endif + beq cr0, L(hop2return) + mtctr r8 + addi r4, r4, -1 + mr r19, r9 + b L(oneBYone) + + .p2align 4 +L(proceed): + bdz L(done) + +L(oneBYone): + lbzu r10, 1(r4) /* copy byte */ + addi r19, r19, 1 + addi r8, r8, -1 + cmpdi cr7, r10, 0 + stb r10, -1(r19) + bne cr7, L(proceed) + b L(zeroFill) + + .p2align 4 +L(done): + addi r1, r1, FRAMESIZE /* restore stack pointer */ +#ifdef USE_AS_STPNCPY + mr r3, r19 /* set the return value */ +#else + mr r3, r18 /* set the return value */ +#endif + ld r0, 16(r1) /* read the saved link register */ + ld r18, -16(r1) /* restore callers save register, r18 */ + ld r19, -8(r1) /* restore callers save register, r19 */ + mtlr r0 /* branch to link register */ + blr /* return */ + +L(update1): + mr r0, r11 + mr r19, r5 + + .p2align 4 +L(leftDwords): + cmpdi cr7, r0, 0 + mr r5, r19 + bne cr7, L(dWordUnrollOFF) + b L(byte_by_byte) + + .p2align 4 +L(updtDestComputeN2ndByte): + addi r19, r19, 2 /* update dst by 2 */ + subf r9, r19, r9 /* compute distance covered */ + add r8, r9, r5 + b L(zeroFill) + + .p2align 4 +L(updtDestComputeN3rdByte): + addi r19, r19, 3 /* update dst by 3 */ + subf r9, r19, r9 /* compute distance covered */ + add r8, r9, r5 + b L(zeroFill) + + .p2align 4 +L(HopBy24): + addi r9, r9, 24 /* increment dst by 24 */ + addi r4, r4, 24 /* increment src by 24 */ + addi r5, r5, -24 /* decrement length 'n' by 24 */ + addi r0, r11, -3 /* decrement loop counter */ + b L(dWordUnrollOFF) + + .p2align 4 +L(update2): + mr r5, r19 + b L(dWordUnrollOFF) + + .p2align 4 +L(HopBy40): + addi r9, r7, 40 /* increment dst by 40 */ + addi r4, r6, 40 /* increment src by 40 */ + addi r5, r5, -40 /* decrement length 'n' by 40 */ + addi r0, r11, -5 /* decrement loop counter */ + b L(dWordUnrollOFF) + +L(update3): + mr r0, r11 + b L(dWordUnrollOFF) + +L(HopBy8): + addi r9, r3, 8 /* increment dst by 8 */ + addi r4, r4, 8 /* increment src by 8 */ + addi r5, r5, -8 /* decrement length 'n' by 8 */ + addi r0, r11, -1 /* decrement loop counter */ + b L(dWordUnrollOFF) +END(FUNC_NAME) +#ifndef USE_AS_STPNCPY +libc_hidden_builtin_def (strncpy) +#endif |