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Diffstat (limited to 'REORG.TODO/sysdeps/powerpc/powerpc64/power8/strncmp.S')
| -rw-r--r-- | REORG.TODO/sysdeps/powerpc/powerpc64/power8/strncmp.S | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/powerpc/powerpc64/power8/strncmp.S b/REORG.TODO/sysdeps/powerpc/powerpc64/power8/strncmp.S new file mode 100644 index 0000000000..3d8df90538 --- /dev/null +++ b/REORG.TODO/sysdeps/powerpc/powerpc64/power8/strncmp.S @@ -0,0 +1,327 @@ +/* Optimized strncmp 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 STRNCMP +# define STRNCMP strncmp +#endif + +/* Implements the function + + int [r3] strncmp (const char *s1 [r3], const char *s2 [r4], size_t [r5] n) + + 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. */ + + .machine power7 +EALIGN (STRNCMP, 4, 0) + /* Check if size is 0. */ + mr. r10,r5 + beq cr0,L(ret0) + + /* 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 r8,r3,0,52 + cmpldi cr7,r8,4096-16 + bgt cr7,L(pagecross) + rldicl r9,r4,0,52 + cmpldi cr7,r9,4096-16 + bgt cr7,L(pagecross) + + /* For short string up to 16 bytes, load both s1 and s2 using + unaligned dwords and compare. */ + ld r7,0(r3) + ld r9,0(r4) + li r8,0 + cmpb r8,r7,r8 + cmpb r6,r7,r9 + orc. r8,r8,r6 + bne cr0,L(different1) + + /* If the string compared are equal, but size is less or equal + to 8, return 0. */ + cmpldi cr7,r10,8 + li r9,0 + ble cr7,L(ret1) + addi r5,r10,-8 + + ld r7,8(r3) + ld r9,8(r4) + cmpb r8,r7,r8 + cmpb r6,r7,r9 + orc. r8,r8,r6 + bne cr0,L(different0) + + cmpldi cr7,r5,8 + mr r9,r8 + ble cr7,L(ret1) + + /* Update pointers and size. */ + addi r10,r10,-16 + addi r3,r3,16 + addi r4,r4,16 + + /* Now it has checked for first 16 bytes, align source1 to doubleword + and adjust source2 address. */ +L(align_8b): + rldicl r5,r3,0,61 + rldicr r3,r3,0,60 + subf r4,r5,r4 + add r10,r10,r5 + + /* 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. r8,r4,0x7 + beq cr0,L(loop_eq_align_0) + + li r5,0 + b L(loop_ne_align_1) + + /* 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 4 +L(loop_ne_align_0): + ld r7,0(r3) + ld r9,0(r4) + cmpb r8,r7,r5 + cmpb r6,r7,r9 + orc. r8,r8,r6 + bne cr0,L(different1) + + cmpldi cr7,r10,8 + ble cr7,L(ret0) + addi r10,r10,-8 + addi r3,r3,8 + addi r4,r4,8 +L(loop_ne_align_1): + rldicl r9,r4,0,52 + cmpldi r7,r9,4088 + ble cr7,L(loop_ne_align_0) + cmpdi cr7,r10,0 + beq cr7,L(ret0) + + lbz r9,0(r3) + lbz r8,0(r4) + cmplw cr7,r9,r8 + bne cr7,L(byte_ne_4) + cmpdi cr7,r9,0 + beq cr7,L(size_reached_0) + + li r9,r7 + addi r8,r3,1 + mtctr r9 + addi r4,r4,1 + addi r10,r10,-1 + addi r3,r3,8 + + /* 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. */ + .align 4 +L(loop_ne_align_byte): + cmpdi cr7,r10,0 + addi r10,r10,-1 + beq cr7,L(ret0) + lbz r9,0(r8) + lbz r7,0(r4) + addi r8,r8,1 + addi r4,r4,1 + cmplw cr7,r9,r7 + cmpdi cr5,r9,0 + bne cr7,L(size_reached_2) + beq cr5,L(size_reached_0) + bdnz L(loop_ne_align_byte) + + cmpdi cr7,r10,0 + bne+ cr7,L(loop_ne_align_0) + + .align 4 +L(ret0): + li r9,0 +L(ret1): + mr r3,r9 + blr + + /* The code now check if r8 and r10 are different by issuing a + cmpb and shift the result based on its output: + + #ifdef __LITTLE_ENDIAN__ + leadzero = (__builtin_ffsl (z1) - 1); + leadzero = leadzero > (n-1)*8 ? (n-1)*8 : leadzero; + r1 = (r1 >> leadzero) & 0xFFUL; + r2 = (r2 >> leadzero) & 0xFFUL; + #else + leadzero = __builtin_clzl (z1); + leadzero = leadzero > (n-1)*8 ? (n-1)*8 : leadzero; + r1 = (r1 >> (56 - leadzero)) & 0xFFUL; + r2 = (r2 >> (56 - leadzero)) & 0xFFUL; + #endif + return r1 - r2; */ + + .align 4 +L(different0): + mr r10,r5 +#ifdef __LITTLE_ENDIAN__ +L(different1): + neg r11,r8 + sldi r10,r10,3 + and r8,r11,r8 + addi r10,r10,-8 + cntlzd r8,r8 + subfic r8,r8,63 + extsw r8,r8 + cmpld cr7,r8,r10 + ble cr7,L(different2) + mr r8,r10 +L(different2): + extsw r8,r8 +#else +L(different1): + addi r10,r10,-1 + cntlzd r8,r8 + sldi r10,r10,3 + cmpld cr7,r8,r10 + blt cr7,L(different2) + mr r8,r10 +L(different2): + subfic r8,r8,56 +#endif + srd r7,r7,r8 + srd r9,r9,r8 + rldicl r3,r7,0,56 + rldicl r9,r9,0,56 + subf r9,r9,3 + extsw r9,r9 + mr r3,r9 + blr + + /* 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. */ + .align 4 +L(pagecross): + lbz r7,0(r3) + lbz r9,0(r4) + subfic r8,r8,4095 + cmplw cr7,r9,r7 + bne cr7,L(byte_ne_3) + cmpdi cr7,r9,0 + beq cr7,L(byte_ne_0) + addi r10,r10,-1 + subf r7,r8,r10 + subf r9,r7,r10 + addi r9,r9,1 + mtctr r9 + b L(pagecross_loop1) + + .align 4 +L(pagecross_loop0): + beq cr7,L(ret0) + lbz r9,0(r3) + lbz r8,0(r4) + addi r10,r10,-1 + cmplw cr7,r9,r8 + cmpdi cr5,r9,0 + bne r7,L(byte_ne_2) + beq r5,L(byte_ne_0) +L(pagecross_loop1): + cmpdi cr7,r10,0 + addi r3,r3,1 + addi r4,r4,1 + bdnz L(pagecross_loop0) + cmpdi cr7,r7,0 + li r9,0 + bne+ cr7,L(align_8b) + b L(ret1) + + /* If both source1 and source2 are doubleword aligned, there is no + need for page boundary cross checks. */ + .align 4 +L(loop_eq_align_0): + ld r7,0(r3) + ld r9,0(r4) + cmpb r8,r7,r8 + cmpb r6,r7,r9 + orc. r8,r8,r6 + bne cr0,L(different1) + + cmpldi cr7,r10,8 + ble cr7,L(ret0) + addi r9,r10,-9 + + li r5,0 + srdi r9,r9,3 + addi r9,r9,1 + mtctr r9 + b L(loop_eq_align_2) + + .align 4 +L(loop_eq_align_1): + bdz L(ret0) +L(loop_eq_align_2): + ldu r7,8(r3) + addi r10,r10,-8 + ldu r9,8(r4) + cmpb r8,r7,r5 + cmpb r6,r7,r9 + orc. r8,r8,r6 + beq cr0,L(loop_eq_align_1) + b L(different1) + + .align 4 +L(byte_ne_0): + li r7,0 +L(byte_ne_1): + subf r9,r9,r7 + extsw r9,r9 + b L(ret1) + + .align 4 +L(byte_ne_2): + extsw r7,r9 + mr r9,r8 + b L(byte_ne_1) +L(size_reached_0): + li r10,0 +L(size_reached_1): + subf r9,r9,r10 + extsw r9,r9 + b L(ret1) +L(size_reached_2): + extsw r10,r9 + mr r9,r7 + b L(size_reached_1) +L(byte_ne_3): + extsw r7,r7 + b L(byte_ne_1) +L(byte_ne_4): + extsw r10,r9 + mr r9,r8 + b L(size_reached_1) +END(STRNCMP) +libc_hidden_builtin_def(strncmp) |