diff options
Diffstat (limited to 'sysdeps/powerpc/powerpc64/power7/memrchr.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc64/power7/memrchr.S | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc64/power7/memrchr.S b/sysdeps/powerpc/powerpc64/power7/memrchr.S new file mode 100644 index 0000000..e082e5e --- /dev/null +++ b/sysdeps/powerpc/powerpc64/power7/memrchr.S @@ -0,0 +1,180 @@ +/* Optimized memrchr implementation for PowerPC64 using cmpb. + Copyright (C) 2010 Free Software Foundation, Inc. + Contributed by Luis Machado <luisgpm@br.ibm.com>. + 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, write to the Free + Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA + 02110-1301 USA. */ + +#include <sysdep.h> +#include <bp-sym.h> +#include <bp-asm.h> + +/* int [r3] memrchr (char *s [r3], int byte [r4], int size [r5]) */ + .machine power7 +ENTRY (BP_SYM (__memrchr)) + CALL_MCOUNT + dcbt 0,r3 + mr r7,r3 + add r3,r7,r5 /* Calculate the last acceptable address. */ + cmpld cr7,r3,r7 /* Is the address equal or less than r3? */ + + /* Replicate BYTE to doubleword. */ + rlwimi r4,r4,8,16,23 + rlwimi r4,r4,16,0,15 + insrdi r4,r4,32,0 + bge cr7,L(proceed) + + li r3,-1 /* Make r11 the biggest if r4 <= 0. */ +L(proceed): + li r6,-8 + addi r9,r3,-1 + clrrdi r8,r9,3 + addi r8,r8,8 + neg r0,r3 + rlwinm r0,r0,3,26,28 /* Calculate padding. */ + + cmpldi r5,32 + ble L(small_range) + + ldbrx r12,r8,r6 /* Load reversed doubleword from memory. */ + cmpb r10,r12,r4 /* Check for BYTE in DWORD1. */ + sld r10,r10,r0 + srd r10,r10,r0 + cmpldi cr7,r10,0 /* If r10 == 0, no BYTE's have been found. */ + bne cr7,L(done) + + /* Are we done already? */ + addi r9,r8,-8 + cmpld cr6,r9,r7 + ble cr6,L(null) + + mtcrf 0x01,r8 + /* Are we now aligned to a doubleword boundary? If so, skip to + the main loop. Otherwise, go through the alignment code. */ + mr r8,r9 + bt 28,L(loop_setup) + + /* Handle DWORD2 of pair. */ + ldbrx r12,r8,r6 + cmpb r10,r12,r4 + cmpldi cr7,r10,0 + bne cr7,L(done) + + /* Are we done already. */ + addi r8,r8,-8 + cmpld cr6,r8,r7 + ble cr6,L(null) + +L(loop_setup): + li r0,-16 + sub r5,r8,r7 + srdi r9,r5,4 /* Number of loop iterations. */ + mtctr r9 /* Setup the counter. */ + b L(loop) + /* Main loop to look for BYTE backwards in the string. Since it's a + small loop (< 8 instructions), align it to 32-bytes. */ + .p2align 5 +L(loop): + /* Load two doublewords, compare and merge in a + single register for speed. This is an attempt + to speed up the byte-checking process for bigger strings. */ + + ldbrx r12,r8,r6 + ldbrx r11,r8,r0 + addi r8,r8,-8 + cmpb r10,r12,r4 + cmpb r9,r11,r4 + or r5,r9,r10 /* Merge everything in one doubleword. */ + cmpldi cr7,r5,0 + bne cr7,L(found) + addi r8,r8,-8 + bdnz L(loop) + /* We're here because the counter reached 0, and that means we + didn't have any matches for BYTE in the whole range. Just return + the original range. */ + addi r9,r8,8 + cmpld cr6,r9,r7 + bgt cr6,L(loop_small) + b L(null) + + /* OK, one (or both) of the words contains BYTE. Check + the first word and decrement the address in case the first + word really contains BYTE. */ + .align 4 +L(found): + cmpldi cr6,r10,0 + addi r8,r8,8 + bne cr6,L(done) + + /* BYTE must be in the second word. Adjust the address + again and move the result of cmpb to r10 so we can calculate the + pointer. */ + + mr r10,r9 + addi r8,r8,-8 + + /* r10 has the output of the cmpb instruction, that is, it contains + 0xff in the same position as the BYTE in the original + word from the string. Use that to calculate the pointer. + We need to make sure BYTE is *before* the end of the + range. */ +L(done): + cntlzd r0,r10 /* Count leading zeroes before the match. */ + srdi r6,r0,3 /* Convert leading zeroes to bytes. */ + addi r0,r6,1 + sub r3,r8,r0 + cmpld r3,r7 + blt L(null) + blr + + .align 4 +L(null): + li r3,0 + blr + +/* Deals with size <= 32. */ + .align 4 +L(small_range): + cmpldi r5,0 + beq L(null) + + ldbrx r12,r8,r6 /* Load reversed doubleword from memory. */ + cmpb r10,r12,r4 /* Check for BYTE in DWORD1. */ + sld r10,r10,r0 + srd r10,r10,r0 + cmpldi cr7,r10,0 + bne cr7,L(done) + + /* Are we done already? */ + addi r8,r8,-8 + cmpld r8,r7 + ble L(null) + b L(loop_small) + + .p2align 5 +L(loop_small): + ldbrx r12,r8,r6 + cmpb r10,r12,r4 + cmpldi cr6,r10,0 + bne cr6,L(done) + addi r8,r8,-8 + cmpld r8,r7 + ble L(null) + b L(loop_small) + +END (BP_SYM (__memrchr)) +weak_alias (BP_SYM (__memrchr), BP_SYM(memrchr)) +libc_hidden_builtin_def (memrchr) |