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369 lines
9.4 KiB
ArmAsm
369 lines
9.4 KiB
ArmAsm
/* Optimized memcpy implementation for PowerPC64.
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Copyright (C) 2003 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <sysdep.h>
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#include <bp-sym.h>
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#include <bp-asm.h>
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/* __ptr_t [r3] memcpy (__ptr_t dst [r3], __ptr_t src [r4], size_t len [r5]);
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Returns 'dst'.
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Memcpy handles short copies (< 32-bytes) using a binary move blocks
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(no loops) of lwz/stw. The tail (remaining 1-3) bytes is handled
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with the appropriate combination of byte and halfword load/stores.
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There is minimal effort to optimize the alignment of short moves.
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The 64-bit implementations of POWER3 and POWER4 do a reasonable job
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of handling unligned load/stores that do not cross 32-byte boundries.
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Longer moves (>= 32-bytes) justify the effort to get at least the
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destination doubleword (8-byte) aligned. Further optimization is
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posible when both source and destination are doubleword aligned.
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Each case has a optimized unrolled loop. */
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EALIGN (BP_SYM (memcpy), 5, 0)
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CALL_MCOUNT 3
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cmpldi cr1,5,31
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neg 0,3
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std 3,-16(1)
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std 31,-8(1)
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andi. 11,3,7 /* check alignement of dst. */
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clrldi 0,0,61 /* Number of bytes until the 1st doubleword of dst. */
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clrldi 10,4,61 /* check alignement of src. */
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cmpldi cr6,5,8
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ble- cr1,.L2 /* If move < 32 bytes use short move code. */
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cmpld cr6,10,11
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mr 12,4
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srdi 9,5,3 /* Number of full double words remaining. */
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mtcrf 0x01,0
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mr 31,5
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beq .L0
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subf 31,0,5
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/* Move 0-7 bytes as needed to get the destination doubleword alligned. */
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1: bf 31,2f
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lbz 6,0(12)
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addi 12,12,1
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stb 6,0(3)
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addi 3,3,1
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2: bf 30,4f
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lhz 6,0(12)
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addi 12,12,2
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sth 6,0(3)
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addi 3,3,2
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4: bf 29,0f
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lwz 6,0(12)
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addi 12,12,4
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stw 6,0(3)
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addi 3,3,4
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0:
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clrldi 10,12,61 /* check alignement of src again. */
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srdi 9,31,3 /* Number of full double words remaining. */
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/* Copy doublewords from source to destination, assumpting the
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destination is aligned on a doubleword boundary.
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At this point we know there are at least 25 bytes left (32-7) to copy.
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The next step is to determine if the source is also doubleword aligned.
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If not branch to the unaligned move code at .L6. which uses
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a load, shift, store strategy.
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Otherwise source and destination are doubleword aligned, and we can
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the optimized doubleword copy loop. */
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.L0:
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clrldi 11,31,61
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mtcrf 0x01,9
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bne- cr6,.L6 /* If source is not DW aligned. */
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/* Move doublewords where destination and source are DW aligned.
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Use a unrolled loop to copy 4 doubleword (32-bytes) per iteration.
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If the the copy is not an exact multiple of 32 bytes, 1-3
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doublewords are copied as needed to set up the main loop. After
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the main loop exits there may be a tail of 1-7 bytes. These byte are
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copied a word/halfword/byte at a time as needed to preserve alignment. */
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srdi 8,31,5
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cmpldi cr1,9,4
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cmpldi cr6,11,0
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mr 11,12
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bf 30,1f
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ld 6,0(12)
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ld 7,8(12)
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addi 11,12,16
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mtctr 8
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std 6,0(3)
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std 7,8(3)
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addi 10,3,16
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bf 31,4f
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ld 0,16(12)
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std 0,16(3)
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blt cr1,3f
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addi 11,12,24
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addi 10,3,24
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b 4f
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.align 4
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1:
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mr 10,3
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mtctr 8
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bf 31,4f
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ld 6,0(12)
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addi 11,12,8
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std 6,0(3)
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addi 10,3,8
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.align 4
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4:
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ld 6,0(11)
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ld 7,8(11)
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ld 8,16(11)
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ld 0,24(11)
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addi 11,11,32
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2:
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std 6,0(10)
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std 7,8(10)
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std 8,16(10)
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std 0,24(10)
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addi 10,10,32
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bdnz 4b
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3:
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rldicr 0,31,0,60
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mtcrf 0x01,31
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beq cr6,0f
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.L9:
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add 3,3,0
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add 12,12,0
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/* At this point we have a tail of 0-7 bytes and we know that the
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destiniation is double word aligned. */
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4: bf 29,2f
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lwz 6,0(12)
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addi 12,12,4
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stw 6,0(3)
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addi 3,3,4
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2: bf 30,1f
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lhz 6,0(12)
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addi 12,12,2
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sth 6,0(3)
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addi 3,3,2
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1: bf 31,0f
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lbz 6,0(12)
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stb 6,0(3)
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0:
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/* Return original dst pointer. */
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ld 31,-8(1)
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ld 3,-16(1)
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blr
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/* Copy up to 31 bytes. This divided into two cases 0-8 bytes and 9-31
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bytes. Each case is handled without loops, using binary (1,2,4,8)
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tests.
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In the short (0-8 byte) case no attempt is made to force alignment
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of either source or destination. The hardware will handle the
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unaligned load/stores with small delays for crossing 32- 64-byte, and
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4096-byte boundaries. Since these short moves are unlikely to be
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unaligned or cross these boundaries, the overhead to force
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alignment is not justified.
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The longer (9-31 byte) move is more likely to cross 32- or 64-byte
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boundaries. Since only loads are sensitive to the 32-/64-byte
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boundaries it is more important to align the source then the
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destination. If the source is not already word aligned, we first
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move 1-3 bytes as needed. Since we are only word aligned we don't
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use double word load/stores to insure that all loads are aligned.
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While the destination and stores may still be unaligned, this
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is only an issue for page (4096 byte boundary) crossing, which
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should be rare for these short moves. The hardware handles this
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case automatically with a small delay. */
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.align 4
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.L2:
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mtcrf 0x01,5
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neg 8,4
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clrrdi 11,4,2
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andi. 0,8,3
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ble cr6,.LE8 /* Handle moves of 0-8 bytes. */
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/* At least 9 bytes left. Get the source word aligned. */
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cmpldi cr1,5,16
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mr 10,5
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mr 12,4
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cmpldi cr6,0,2
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beq .L3 /* If the source is already word aligned skip this. */
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/* Copy 1-3 bytes to get source address word aligned. */
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lwz 6,0(11)
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subf 10,0,5
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add 12,4,0
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blt cr6,5f
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srdi 7,6,16
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bgt cr6,3f
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sth 6,0(3)
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b 7f
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.align 4
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3:
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stb 7,0(3)
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sth 6,1(3)
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b 7f
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.align 4
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5:
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stb 6,0(3)
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7:
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cmpldi cr1,10,16
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add 3,3,0
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mtcrf 0x01,10
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.align 4
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.L3:
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/* At least 6 bytes left and the source is word aligned. */
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blt cr1,8f
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16: /* Move 16 bytes. */
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lwz 6,0(12)
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lwz 7,4(12)
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stw 6,0(3)
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lwz 6,8(12)
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stw 7,4(3)
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lwz 7,12(12)
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addi 12,12,16
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stw 6,8(3)
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stw 7,12(3)
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addi 3,3,16
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8: /* Move 8 bytes. */
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bf 28,4f
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lwz 6,0(12)
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lwz 7,4(12)
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addi 12,12,8
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stw 6,0(3)
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stw 7,4(3)
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addi 3,3,8
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4: /* Move 4 bytes. */
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bf 29,2f
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lwz 6,0(12)
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addi 12,12,4
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stw 6,0(3)
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addi 3,3,4
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2: /* Move 2-3 bytes. */
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bf 30,1f
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lhz 6,0(12)
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sth 6,0(3)
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bf 31,0f
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lbz 7,2(12)
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stb 7,2(3)
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ld 3,-16(1)
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blr
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1: /* Move 1 byte. */
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bf 31,0f
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lbz 6,0(12)
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stb 6,0(3)
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0:
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/* Return original dst pointer. */
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ld 3,-16(1)
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blr
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/* Special case to copy 0-8 bytes. */
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.align 4
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.LE8:
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mr 12,4
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bne cr6,4f
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/* Would have liked to use use ld/std here but the 630 processors are
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slow for load/store doubles that are not at least word aligned.
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Unaligned Load/Store word execute with only a 1 cycle penaltity. */
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lwz 6,0(4)
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lwz 7,4(4)
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stw 6,0(3)
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stw 7,4(3)
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/* Return original dst pointer. */
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ld 3,-16(1)
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blr
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.align 4
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4: bf 29,2b
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lwz 6,0(4)
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stw 6,0(3)
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6:
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bf 30,5f
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lhz 7,4(4)
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sth 7,4(3)
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bf 31,0f
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lbz 8,6(4)
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stb 8,6(3)
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ld 3,-16(1)
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blr
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.align 4
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5:
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bf 31,0f
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lbz 6,4(4)
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stb 6,4(3)
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.align 4
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0:
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/* Return original dst pointer. */
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ld 3,-16(1)
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blr
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.align 4
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.L6:
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/* Copy doublewords where the destination is aligned but the source is
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not. Use aligned doubleword loads from the source, shifted to realign
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the data, to allow aligned destination stores. */
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subf 5,10,12
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andi. 0,9,1
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cmpldi cr6,11,0
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sldi 10,10,3
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mr 11,9
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mr 4,3
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ld 6,0(5)
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ld 7,8(5)
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subfic 9,10,64
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beq 2f
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sld 0,6,10
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cmpldi 11,1
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mr 6,7
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addi 4,4,-8
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addi 11,11,-1
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b 1f
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2: addi 5,5,8
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.align 4
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0: sld 0,6,10
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srd 8,7,9
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cmpldi 11,2
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ld 6,8(5)
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or 0,0,8
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addi 11,11,-2
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std 0,0(4)
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sld 0,7,10
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1: srd 8,6,9
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or 0,0,8
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beq 8f
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ld 7,16(5)
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std 0,8(4)
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addi 5,5,16
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addi 4,4,16
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b 0b
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.align 4
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8:
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std 0,8(4)
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rldicr 0,31,0,60
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mtcrf 0x01,31
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bne cr6,.L9 /* If the tail is 0 bytes we are done! */
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/* Return original dst pointer. */
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ld 31,-8(1)
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ld 3,-16(1)
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blr
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END_GEN_TB (BP_SYM (memcpy),TB_TOCLESS)
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libc_hidden_builtin_def (memcpy)
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