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Diffstat (limited to 'sysdeps/powerpc/powerpc64/power7/strncat.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc64/power7/strncat.S | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc64/power7/strncat.S b/sysdeps/powerpc/powerpc64/power7/strncat.S new file mode 100644 index 0000000000..f5ea52d3d4 --- /dev/null +++ b/sysdeps/powerpc/powerpc64/power7/strncat.S @@ -0,0 +1,228 @@ +/* Optimized strncat implementation for PowerPC64/POWER7. + + 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/>. */ + +/* The algorithm is as follows for aligned memory access : + + if address of s2 is divisible by 0x7UL, + perform aligned doubleword catenation + else + perform unaligned catenation + + The aligned comparison are made using cmpb instructions. */ + +/* char* [r3] strncat (const char *s1 [r3], + const char *s2 [r4], + size_t size [r5]) */ + +#include <sysdep.h> + +#ifndef STRNCAT +# undef strncat +# define STRNCAT strncat +#endif + +#ifndef STRLEN +/* For builds with no IFUNC support, local calls should be made to internal + GLIBC symbol (created by libc_hidden_builtin_def). */ +# ifdef SHARED +# define STRLEN __GI_strlen +# else +# define STRLEN strlen +# endif +#endif + +#define FRAMESIZE (FRAME_MIN_SIZE+32) + + .machine power7 +EALIGN(STRNCAT, 4, 0) + CALL_MCOUNT 3 + + mflr r0 /* Load link register LR to r0. */ + +/* We shall use r29, r30 and r31 non volatile register for retention. + Save all the callee registers in the GPR save area. */ + std r29, -24(r1) /* Save callers register r29. */ + std r30, -16(r1) /* Save callers register r30. */ + std r31, -8(r1) /* Save callers register r31. */ + + std r0, 16(r1) /* Store the link register. */ + stdu r1, -FRAMESIZE(r1) /* Create the stack frame. */ + +/* Improve performance with CPU pre-fetch. */ + dcbt 0, r3 /* Pre-fetch str to avoid cache + miss. */ + dcbt 0, r4 /* Pre-fetch accept to avoid cache + miss. */ + + mr. r29, r5 /* Save "n" in r29. */ + mr r30, r3 /* Save "s1" in r30 from r3. */ + beq cr0,L(done) + + mr r31, r4 /* Save "s2" in r31 from r4. */ + bl STRLEN /* Call optimized strlen on s1; goto + end of s1. */ + nop + cmpldi cr7, r29, 7 /* If s2 is <=7 process + byte-by-byte. */ + add r3, r30, r3 /* Grab the last character of s1. */ + bgt cr7,L(alignment) /* Process by aligned strings. */ + + cmpldi cr7, r29, 3 /* If n is >= 4, we can + byte-unroll. */ + addi r9, r3, -1 /* Make "s1" point before next + character, increment when read. */ + bgt cr7, L(bytes_unroll) /* Process each byte. */ + +L(byte_by_byte): + lbz r10, 0(r31) + addi r8, r9, 1 + cmpdi cr7, r10, 0 /* Check for NULL in "s2". */ + stb r10, 1(r9) + beq cr7, L(done) + add r9, r9, r29 + subf r9, r8, r9 + addi r9, r9, 1 + mtctr r9 + b L(branch2) + .p2align 4 +L(branch1): + lbzu r10, 1(r31) + cmpdi cr7, r10, 0 + stbu r10, 1(r8) + beq cr7,L(done) +L(branch2): + mr r9, r8 + bdnz L(branch1) + beq cr7,L(done) +L(nullTerminate): + li r10, 0 /* Load NULL for termination. */ + stb r10, 1(r9) /* Append or terminate s1 with + NULL. */ + .p2align 4 /* A small section here. */ +L(done): /* We return now. */ + addi r1, r1, FRAMESIZE /* Restore stack pointer. */ + mr r3, r30 /* Set the return value length of + string. */ + ld r0, 16(r1) /* Read the saved link register. */ + ld r29, -24(r1) /* Restore save register r29. */ + ld r30, -16(r1) /* Restore save register r30. */ + ld r31, -8(r1) /* Restore save register r31. */ + mtlr r0 /* Restore link register. */ + blr /* Branch to link register. */ + + .p2align 4 +L(alignment): + rldicl. r9, r31, 0, 61 /* Check if s2 is 8byte aligned */ + beq cr0,L(dwordAligned) + + .p2align 4 +/* Unaligned bytes in string, so process byte by byte. + POWER7 has performance gains over loop unroll. */ +L(bytes_unroll): + addi r9, r3, -1 + srdi r10, r29, 2 + mtctr r10 + b L(L10) + .p2align 4 +L(L44): + lbz r10, 1(r31) /* Load byte. */ + cmpdi cr7, r10, 0 /* Compare ; if byte not zero, + continue. */ + stb r10, 2(r9) /* Store byte */ + beq cr7, L(done) + addi r31, r31, 4 + + lbz r10, -2(r31) /* Perform loop unroll here on byte + load and store. */ + cmpdi cr7, r10, 0 + stb r10, 3(r9) + beq cr7, L(done) + + lbz r10, -1(r31) /* Loop unroll here. */ + cmpdi cr7, r10, 0 + stbu r10, 4(r9) + beq cr7, L(done) + + bdz L(leftNbytes) + +L(L10): + lbz r10, 0(r31) /* Loop unroll here. */ + cmpdi cr7, r10, 0 + stb r10, 1(r9) + bne cr7,L(L44) + b L(done) + .p2align 4 +/* If s2 is double word aligned, we load and store double word. */ +L(dwordAligned): +/* read, write 8 bytes at a time */ + srdi r8, r29, 3 /* Compute count for CTR to loop; + count = n/8. */ + li r7, 0 /* Load r7 with NULL. */ + li r10, 0 /* Load r10 with MASK '0'. */ + + mtctr r8 /* Move count to CTR. */ +L(loop8): + ld r9, 0(r31) /* Read double word from s2. */ + cmpb r6, r9, r10 /* Compare bytes in s2 we read + just now. */ + cmpdi r6, 0 /* If cmpb returned NULL, + we continue. */ + bne+ L(a8) + std r9, 0(r3) /* Append double word from s2 + with s1. */ + addi r3, r3, 8 /* Increment s1. */ + addi r31, r31, 8 /* Increment s2. */ + subi r29, r29, 8 /* Decrement count by 8. */ + bdnz L(loop8) /* Continue until "count" is + non zero. */ + +L(a8): + cmpdi r29, 0 /* If "n" is already zero, we skip. */ + beq+ L(align8align) + + mtctr r29 /* Process left over bytes in "n". */ +L(unaligned0): + lbz r9, 0(r31) /* Read a byte from s2. */ + cmpw r9, r7 /* If byte is NULL, we stop here . */ + beq+ L(align8align) /* Skip processing further if NULL. */ + stb r9, 0(r3) /* If not NULL, store byte into s1. */ + addi r3, r3, 1 /* Increment s1 by 1. */ + addi r31, r31, 1 /* Increment s2 by 1. */ + bdnz L(unaligned0) /* Decrement counter "n" and loop + until non zero. */ +L(align8align): + stb r7, 0(r3) /* Terminate s1 with NULL. */ + + addi r1, r1, FRAMESIZE /* Restore stack pointer. */ + mr r3, r30 /* Set the return value, length of + string. */ + ld r0, 16(r1) /* Read the saved link register. */ + ld r29, -24(r1) /* Restore save register r29. */ + ld r30, -16(r1) /* Restore save register r30. */ + ld r31, -8(r1) /* Restore save register r31. */ + mtlr r0 /* Restore link register. */ + blr /* Branch to link register */ + + .p2align 4 +L(leftNbytes): + rldicl. r29, r29, 0, 62 /* Check if n>0 and n < 4 bytes. */ + bne cr0,L(byte_by_byte) /* Process bytes one by one. */ + b L(nullTerminate) /* Now, finish catenation with + NULL termination. */ +END(STRNCAT) |