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linux/arch/ia64/lib/memcpy_mck.S
Jörn Engel 6ab3d5624e Remove obsolete #include <linux/config.h> 
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-06-30 19:25:36 +02:00

667 lines
18 KiB
ArmAsm
Raw Blame History

/*
* Itanium 2-optimized version of memcpy and copy_user function
*
* Inputs:
* in0: destination address
* in1: source address
* in2: number of bytes to copy
* Output:
* for memcpy: return dest
* for copy_user: return 0 if success,
* or number of byte NOT copied if error occurred.
*
* Copyright (C) 2002 Intel Corp.
* Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com>
*/
#include <asm/asmmacro.h>
#include <asm/page.h>
#define EK(y...) EX(y)
/* McKinley specific optimization */
#define retval r8
#define saved_pfs r31
#define saved_lc r10
#define saved_pr r11
#define saved_in0 r14
#define saved_in1 r15
#define saved_in2 r16
#define src0 r2
#define src1 r3
#define dst0 r17
#define dst1 r18
#define cnt r9
/* r19-r30 are temp for each code section */
#define PREFETCH_DIST 8
#define src_pre_mem r19
#define dst_pre_mem r20
#define src_pre_l2 r21
#define dst_pre_l2 r22
#define t1 r23
#define t2 r24
#define t3 r25
#define t4 r26
#define t5 t1 // alias!
#define t6 t2 // alias!
#define t7 t3 // alias!
#define n8 r27
#define t9 t5 // alias!
#define t10 t4 // alias!
#define t11 t7 // alias!
#define t12 t6 // alias!
#define t14 t10 // alias!
#define t13 r28
#define t15 r29
#define tmp r30
/* defines for long_copy block */
#define A 0
#define B (PREFETCH_DIST)
#define C (B + PREFETCH_DIST)
#define D (C + 1)
#define N (D + 1)
#define Nrot ((N + 7) & ~7)
/* alias */
#define in0 r32
#define in1 r33
#define in2 r34
GLOBAL_ENTRY(memcpy)
and r28=0x7,in0
and r29=0x7,in1
mov f6=f0
mov retval=in0
br.cond.sptk .common_code
;;
END(memcpy)
GLOBAL_ENTRY(__copy_user)
.prologue
// check dest alignment
and r28=0x7,in0
and r29=0x7,in1
mov f6=f1
mov saved_in0=in0 // save dest pointer
mov saved_in1=in1 // save src pointer
mov retval=r0 // initialize return value
;;
.common_code:
cmp.gt p15,p0=8,in2 // check for small size
cmp.ne p13,p0=0,r28 // check dest alignment
cmp.ne p14,p0=0,r29 // check src alignment
add src0=0,in1
sub r30=8,r28 // for .align_dest
mov saved_in2=in2 // save len
;;
add dst0=0,in0
add dst1=1,in0 // dest odd index
cmp.le p6,p0 = 1,r30 // for .align_dest
(p15) br.cond.dpnt .memcpy_short
(p13) br.cond.dpnt .align_dest
(p14) br.cond.dpnt .unaligned_src
;;
// both dest and src are aligned on 8-byte boundary
.aligned_src:
.save ar.pfs, saved_pfs
alloc saved_pfs=ar.pfs,3,Nrot-3,0,Nrot
.save pr, saved_pr
mov saved_pr=pr
shr.u cnt=in2,7 // this much cache line
;;
cmp.lt p6,p0=2*PREFETCH_DIST,cnt
cmp.lt p7,p8=1,cnt
.save ar.lc, saved_lc
mov saved_lc=ar.lc
.body
add cnt=-1,cnt
add src_pre_mem=0,in1 // prefetch src pointer
add dst_pre_mem=0,in0 // prefetch dest pointer
;;
(p7) mov ar.lc=cnt // prefetch count
(p8) mov ar.lc=r0
(p6) br.cond.dpnt .long_copy
;;
.prefetch:
lfetch.fault [src_pre_mem], 128
lfetch.fault.excl [dst_pre_mem], 128
br.cloop.dptk.few .prefetch
;;
.medium_copy:
and tmp=31,in2 // copy length after iteration
shr.u r29=in2,5 // number of 32-byte iteration
add dst1=8,dst0 // 2nd dest pointer
;;
add cnt=-1,r29 // ctop iteration adjustment
cmp.eq p10,p0=r29,r0 // do we really need to loop?
add src1=8,src0 // 2nd src pointer
cmp.le p6,p0=8,tmp
;;
cmp.le p7,p0=16,tmp
mov ar.lc=cnt // loop setup
cmp.eq p16,p17 = r0,r0
mov ar.ec=2
(p10) br.dpnt.few .aligned_src_tail
;;
TEXT_ALIGN(32)
1:
EX(.ex_handler, (p16) ld8 r34=[src0],16)
EK(.ex_handler, (p16) ld8 r38=[src1],16)
EX(.ex_handler, (p17) st8 [dst0]=r33,16)
EK(.ex_handler, (p17) st8 [dst1]=r37,16)
;;
EX(.ex_handler, (p16) ld8 r32=[src0],16)
EK(.ex_handler, (p16) ld8 r36=[src1],16)
EX(.ex_handler, (p16) st8 [dst0]=r34,16)
EK(.ex_handler, (p16) st8 [dst1]=r38,16)
br.ctop.dptk.few 1b
;;
.aligned_src_tail:
EX(.ex_handler, (p6) ld8 t1=[src0])
mov ar.lc=saved_lc
mov ar.pfs=saved_pfs
EX(.ex_hndlr_s, (p7) ld8 t2=[src1],8)
cmp.le p8,p0=24,tmp
and r21=-8,tmp
;;
EX(.ex_hndlr_s, (p8) ld8 t3=[src1])
EX(.ex_handler, (p6) st8 [dst0]=t1) // store byte 1
and in2=7,tmp // remaining length
EX(.ex_hndlr_d, (p7) st8 [dst1]=t2,8) // store byte 2
add src0=src0,r21 // setting up src pointer
add dst0=dst0,r21 // setting up dest pointer
;;
EX(.ex_handler, (p8) st8 [dst1]=t3) // store byte 3
mov pr=saved_pr,-1
br.dptk.many .memcpy_short
;;
/* code taken from copy_page_mck */
.long_copy:
.rotr v[2*PREFETCH_DIST]
.rotp p[N]
mov src_pre_mem = src0
mov pr.rot = 0x10000
mov ar.ec = 1 // special unrolled loop
mov dst_pre_mem = dst0
add src_pre_l2 = 8*8, src0
add dst_pre_l2 = 8*8, dst0
;;
add src0 = 8, src_pre_mem // first t1 src
mov ar.lc = 2*PREFETCH_DIST - 1
shr.u cnt=in2,7 // number of lines
add src1 = 3*8, src_pre_mem // first t3 src
add dst0 = 8, dst_pre_mem // first t1 dst
add dst1 = 3*8, dst_pre_mem // first t3 dst
;;
and tmp=127,in2 // remaining bytes after this block
add cnt = -(2*PREFETCH_DIST) - 1, cnt
// same as .line_copy loop, but with all predicated-off instructions removed:
.prefetch_loop:
EX(.ex_hndlr_lcpy_1, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0
EK(.ex_hndlr_lcpy_1, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2
br.ctop.sptk .prefetch_loop
;;
cmp.eq p16, p0 = r0, r0 // reset p16 to 1
mov ar.lc = cnt
mov ar.ec = N // # of stages in pipeline
;;
.line_copy:
EX(.ex_handler, (p[D]) ld8 t2 = [src0], 3*8) // M0
EK(.ex_handler, (p[D]) ld8 t4 = [src1], 3*8) // M1
EX(.ex_handler_lcpy, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2 prefetch dst from memory
EK(.ex_handler_lcpy, (p[D]) st8 [dst_pre_l2] = n8, 128) // M3 prefetch dst from L2
;;
EX(.ex_handler_lcpy, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0 prefetch src from memory
EK(.ex_handler_lcpy, (p[C]) ld8 n8 = [src_pre_l2], 128) // M1 prefetch src from L2
EX(.ex_handler, (p[D]) st8 [dst0] = t1, 8) // M2
EK(.ex_handler, (p[D]) st8 [dst1] = t3, 8) // M3
;;
EX(.ex_handler, (p[D]) ld8 t5 = [src0], 8)
EK(.ex_handler, (p[D]) ld8 t7 = [src1], 3*8)
EX(.ex_handler, (p[D]) st8 [dst0] = t2, 3*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t4, 3*8)
;;
EX(.ex_handler, (p[D]) ld8 t6 = [src0], 3*8)
EK(.ex_handler, (p[D]) ld8 t10 = [src1], 8)
EX(.ex_handler, (p[D]) st8 [dst0] = t5, 8)
EK(.ex_handler, (p[D]) st8 [dst1] = t7, 3*8)
;;
EX(.ex_handler, (p[D]) ld8 t9 = [src0], 3*8)
EK(.ex_handler, (p[D]) ld8 t11 = [src1], 3*8)
EX(.ex_handler, (p[D]) st8 [dst0] = t6, 3*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t10, 8)
;;
EX(.ex_handler, (p[D]) ld8 t12 = [src0], 8)
EK(.ex_handler, (p[D]) ld8 t14 = [src1], 8)
EX(.ex_handler, (p[D]) st8 [dst0] = t9, 3*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t11, 3*8)
;;
EX(.ex_handler, (p[D]) ld8 t13 = [src0], 4*8)
EK(.ex_handler, (p[D]) ld8 t15 = [src1], 4*8)
EX(.ex_handler, (p[D]) st8 [dst0] = t12, 8)
EK(.ex_handler, (p[D]) st8 [dst1] = t14, 8)
;;
EX(.ex_handler, (p[C]) ld8 t1 = [src0], 8)
EK(.ex_handler, (p[C]) ld8 t3 = [src1], 8)
EX(.ex_handler, (p[D]) st8 [dst0] = t13, 4*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t15, 4*8)
br.ctop.sptk .line_copy
;;
add dst0=-8,dst0
add src0=-8,src0
mov in2=tmp
.restore sp
br.sptk.many .medium_copy
;;
#define BLOCK_SIZE 128*32
#define blocksize r23
#define curlen r24
// dest is on 8-byte boundary, src is not. We need to do
// ld8-ld8, shrp, then st8. Max 8 byte copy per cycle.
.unaligned_src:
.prologue
.save ar.pfs, saved_pfs
alloc saved_pfs=ar.pfs,3,5,0,8
.save ar.lc, saved_lc
mov saved_lc=ar.lc
.save pr, saved_pr
mov saved_pr=pr
.body
.4k_block:
mov saved_in0=dst0 // need to save all input arguments
mov saved_in2=in2
mov blocksize=BLOCK_SIZE
;;
cmp.lt p6,p7=blocksize,in2
mov saved_in1=src0
;;
(p6) mov in2=blocksize
;;
shr.u r21=in2,7 // this much cache line
shr.u r22=in2,4 // number of 16-byte iteration
and curlen=15,in2 // copy length after iteration
and r30=7,src0 // source alignment
;;
cmp.lt p7,p8=1,r21
add cnt=-1,r21
;;
add src_pre_mem=0,src0 // prefetch src pointer
add dst_pre_mem=0,dst0 // prefetch dest pointer
and src0=-8,src0 // 1st src pointer
(p7) mov ar.lc = cnt
(p8) mov ar.lc = r0
;;
TEXT_ALIGN(32)
1: lfetch.fault [src_pre_mem], 128
lfetch.fault.excl [dst_pre_mem], 128
br.cloop.dptk.few 1b
;;
shladd dst1=r22,3,dst0 // 2nd dest pointer
shladd src1=r22,3,src0 // 2nd src pointer
cmp.eq p8,p9=r22,r0 // do we really need to loop?
cmp.le p6,p7=8,curlen; // have at least 8 byte remaining?
add cnt=-1,r22 // ctop iteration adjustment
;;
EX(.ex_handler, (p9) ld8 r33=[src0],8) // loop primer
EK(.ex_handler, (p9) ld8 r37=[src1],8)
(p8) br.dpnt.few .noloop
;;
// The jump address is calculated based on src alignment. The COPYU
// macro below need to confine its size to power of two, so an entry
// can be caulated using shl instead of an expensive multiply. The
// size is then hard coded by the following #define to match the
// actual size. This make it somewhat tedious when COPYU macro gets
// changed and this need to be adjusted to match.
#define LOOP_SIZE 6
1:
mov r29=ip // jmp_table thread
mov ar.lc=cnt
;;
add r29=.jump_table - 1b - (.jmp1-.jump_table), r29
shl r28=r30, LOOP_SIZE // jmp_table thread
mov ar.ec=2 // loop setup
;;
add r29=r29,r28 // jmp_table thread
cmp.eq p16,p17=r0,r0
;;
mov b6=r29 // jmp_table thread
;;
br.cond.sptk.few b6
// for 8-15 byte case
// We will skip the loop, but need to replicate the side effect
// that the loop produces.
.noloop:
EX(.ex_handler, (p6) ld8 r37=[src1],8)
add src0=8,src0
(p6) shl r25=r30,3
;;
EX(.ex_handler, (p6) ld8 r27=[src1])
(p6) shr.u r28=r37,r25
(p6) sub r26=64,r25
;;
(p6) shl r27=r27,r26
;;
(p6) or r21=r28,r27
.unaligned_src_tail:
/* check if we have more than blocksize to copy, if so go back */
cmp.gt p8,p0=saved_in2,blocksize
;;
(p8) add dst0=saved_in0,blocksize
(p8) add src0=saved_in1,blocksize
(p8) sub in2=saved_in2,blocksize
(p8) br.dpnt .4k_block
;;
/* we have up to 15 byte to copy in the tail.
* part of work is already done in the jump table code
* we are at the following state.
* src side:
*
* xxxxxx xx <----- r21 has xxxxxxxx already
* -------- -------- --------
* 0 8 16
* ^
* |
* src1
*
* dst
* -------- -------- --------
* ^
* |
* dst1
*/
EX(.ex_handler, (p6) st8 [dst1]=r21,8) // more than 8 byte to copy
(p6) add curlen=-8,curlen // update length
mov ar.pfs=saved_pfs
;;
mov ar.lc=saved_lc
mov pr=saved_pr,-1
mov in2=curlen // remaining length
mov dst0=dst1 // dest pointer
add src0=src1,r30 // forward by src alignment
;;
// 7 byte or smaller.
.memcpy_short:
cmp.le p8,p9 = 1,in2
cmp.le p10,p11 = 2,in2
cmp.le p12,p13 = 3,in2
cmp.le p14,p15 = 4,in2
add src1=1,src0 // second src pointer
add dst1=1,dst0 // second dest pointer
;;
EX(.ex_handler_short, (p8) ld1 t1=[src0],2)
EK(.ex_handler_short, (p10) ld1 t2=[src1],2)
(p9) br.ret.dpnt rp // 0 byte copy
;;
EX(.ex_handler_short, (p8) st1 [dst0]=t1,2)
EK(.ex_handler_short, (p10) st1 [dst1]=t2,2)
(p11) br.ret.dpnt rp // 1 byte copy
EX(.ex_handler_short, (p12) ld1 t3=[src0],2)
EK(.ex_handler_short, (p14) ld1 t4=[src1],2)
(p13) br.ret.dpnt rp // 2 byte copy
;;
cmp.le p6,p7 = 5,in2
cmp.le p8,p9 = 6,in2
cmp.le p10,p11 = 7,in2
EX(.ex_handler_short, (p12) st1 [dst0]=t3,2)
EK(.ex_handler_short, (p14) st1 [dst1]=t4,2)
(p15) br.ret.dpnt rp // 3 byte copy
;;
EX(.ex_handler_short, (p6) ld1 t5=[src0],2)
EK(.ex_handler_short, (p8) ld1 t6=[src1],2)
(p7) br.ret.dpnt rp // 4 byte copy
;;
EX(.ex_handler_short, (p6) st1 [dst0]=t5,2)
EK(.ex_handler_short, (p8) st1 [dst1]=t6,2)
(p9) br.ret.dptk rp // 5 byte copy
EX(.ex_handler_short, (p10) ld1 t7=[src0],2)
(p11) br.ret.dptk rp // 6 byte copy
;;
EX(.ex_handler_short, (p10) st1 [dst0]=t7,2)
br.ret.dptk rp // done all cases
/* Align dest to nearest 8-byte boundary. We know we have at
* least 7 bytes to copy, enough to crawl to 8-byte boundary.
* Actual number of byte to crawl depend on the dest alignment.
* 7 byte or less is taken care at .memcpy_short
* src0 - source even index
* src1 - source odd index
* dst0 - dest even index
* dst1 - dest odd index
* r30 - distance to 8-byte boundary
*/
.align_dest:
add src1=1,in1 // source odd index
cmp.le p7,p0 = 2,r30 // for .align_dest
cmp.le p8,p0 = 3,r30 // for .align_dest
EX(.ex_handler_short, (p6) ld1 t1=[src0],2)
cmp.le p9,p0 = 4,r30 // for .align_dest
cmp.le p10,p0 = 5,r30
;;
EX(.ex_handler_short, (p7) ld1 t2=[src1],2)
EK(.ex_handler_short, (p8) ld1 t3=[src0],2)
cmp.le p11,p0 = 6,r30
EX(.ex_handler_short, (p6) st1 [dst0] = t1,2)
cmp.le p12,p0 = 7,r30
;;
EX(.ex_handler_short, (p9) ld1 t4=[src1],2)
EK(.ex_handler_short, (p10) ld1 t5=[src0],2)
EX(.ex_handler_short, (p7) st1 [dst1] = t2,2)
EK(.ex_handler_short, (p8) st1 [dst0] = t3,2)
;;
EX(.ex_handler_short, (p11) ld1 t6=[src1],2)
EK(.ex_handler_short, (p12) ld1 t7=[src0],2)
cmp.eq p6,p7=r28,r29
EX(.ex_handler_short, (p9) st1 [dst1] = t4,2)
EK(.ex_handler_short, (p10) st1 [dst0] = t5,2)
sub in2=in2,r30
;;
EX(.ex_handler_short, (p11) st1 [dst1] = t6,2)
EK(.ex_handler_short, (p12) st1 [dst0] = t7)
add dst0=in0,r30 // setup arguments
add src0=in1,r30
(p6) br.cond.dptk .aligned_src
(p7) br.cond.dpnt .unaligned_src
;;
/* main loop body in jump table format */
#define COPYU(shift) \
1: \
EX(.ex_handler, (p16) ld8 r32=[src0],8); /* 1 */ \
EK(.ex_handler, (p16) ld8 r36=[src1],8); \
(p17) shrp r35=r33,r34,shift;; /* 1 */ \
EX(.ex_handler, (p6) ld8 r22=[src1]); /* common, prime for tail section */ \
nop.m 0; \
(p16) shrp r38=r36,r37,shift; \
EX(.ex_handler, (p17) st8 [dst0]=r35,8); /* 1 */ \
EK(.ex_handler, (p17) st8 [dst1]=r39,8); \
br.ctop.dptk.few 1b;; \
(p7) add src1=-8,src1; /* back out for <8 byte case */ \
shrp r21=r22,r38,shift; /* speculative work */ \
br.sptk.few .unaligned_src_tail /* branch out of jump table */ \
;;
TEXT_ALIGN(32)
.jump_table:
COPYU(8) // unaligned cases
.jmp1:
COPYU(16)
COPYU(24)
COPYU(32)
COPYU(40)
COPYU(48)
COPYU(56)
#undef A
#undef B
#undef C
#undef D
/*
* Due to lack of local tag support in gcc 2.x assembler, it is not clear which
* instruction failed in the bundle. The exception algorithm is that we
* first figure out the faulting address, then detect if there is any
* progress made on the copy, if so, redo the copy from last known copied
* location up to the faulting address (exclusive). In the copy_from_user
* case, remaining byte in kernel buffer will be zeroed.
*
* Take copy_from_user as an example, in the code there are multiple loads
* in a bundle and those multiple loads could span over two pages, the
* faulting address is calculated as page_round_down(max(src0, src1)).
* This is based on knowledge that if we can access one byte in a page, we
* can access any byte in that page.
*
* predicate used in the exception handler:
* p6-p7: direction
* p10-p11: src faulting addr calculation
* p12-p13: dst faulting addr calculation
*/
#define A r19
#define B r20
#define C r21
#define D r22
#define F r28
#define memset_arg0 r32
#define memset_arg2 r33
#define saved_retval loc0
#define saved_rtlink loc1
#define saved_pfs_stack loc2
.ex_hndlr_s:
add src0=8,src0
br.sptk .ex_handler
;;
.ex_hndlr_d:
add dst0=8,dst0
br.sptk .ex_handler
;;
.ex_hndlr_lcpy_1:
mov src1=src_pre_mem
mov dst1=dst_pre_mem
cmp.gtu p10,p11=src_pre_mem,saved_in1
cmp.gtu p12,p13=dst_pre_mem,saved_in0
;;
(p10) add src0=8,saved_in1
(p11) mov src0=saved_in1
(p12) add dst0=8,saved_in0
(p13) mov dst0=saved_in0
br.sptk .ex_handler
.ex_handler_lcpy:
// in line_copy block, the preload addresses should always ahead
// of the other two src/dst pointers. Furthermore, src1/dst1 should
// always ahead of src0/dst0.
mov src1=src_pre_mem
mov dst1=dst_pre_mem
.ex_handler:
mov pr=saved_pr,-1 // first restore pr, lc, and pfs
mov ar.lc=saved_lc
mov ar.pfs=saved_pfs
;;
.ex_handler_short: // fault occurred in these sections didn't change pr, lc, pfs
cmp.ltu p6,p7=saved_in0, saved_in1 // get the copy direction
cmp.ltu p10,p11=src0,src1
cmp.ltu p12,p13=dst0,dst1
fcmp.eq p8,p0=f6,f0 // is it memcpy?
mov tmp = dst0
;;
(p11) mov src1 = src0 // pick the larger of the two
(p13) mov dst0 = dst1 // make dst0 the smaller one
(p13) mov dst1 = tmp // and dst1 the larger one
;;
(p6) dep F = r0,dst1,0,PAGE_SHIFT // usr dst round down to page boundary
(p7) dep F = r0,src1,0,PAGE_SHIFT // usr src round down to page boundary
;;
(p6) cmp.le p14,p0=dst0,saved_in0 // no progress has been made on store
(p7) cmp.le p14,p0=src0,saved_in1 // no progress has been made on load
mov retval=saved_in2
(p8) ld1 tmp=[src1] // force an oops for memcpy call
(p8) st1 [dst1]=r0 // force an oops for memcpy call
(p14) br.ret.sptk.many rp
/*
* The remaining byte to copy is calculated as:
*
* A = (faulting_addr - orig_src) -> len to faulting ld address
* or
* (faulting_addr - orig_dst) -> len to faulting st address
* B = (cur_dst - orig_dst) -> len copied so far
* C = A - B -> len need to be copied
* D = orig_len - A -> len need to be zeroed
*/
(p6) sub A = F, saved_in0
(p7) sub A = F, saved_in1
clrrrb
;;
alloc saved_pfs_stack=ar.pfs,3,3,3,0
cmp.lt p8,p0=A,r0
sub B = dst0, saved_in0 // how many byte copied so far
;;
(p8) mov A = 0; // A shouldn't be negative, cap it
;;
sub C = A, B
sub D = saved_in2, A
;;
cmp.gt p8,p0=C,r0 // more than 1 byte?
add memset_arg0=saved_in0, A
(p6) mov memset_arg2=0 // copy_to_user should not call memset
(p7) mov memset_arg2=D // copy_from_user need to have kbuf zeroed
mov r8=0
mov saved_retval = D
mov saved_rtlink = b0
add out0=saved_in0, B
add out1=saved_in1, B
mov out2=C
(p8) br.call.sptk.few b0=__copy_user // recursive call
;;
add saved_retval=saved_retval,r8 // above might return non-zero value
cmp.gt p8,p0=memset_arg2,r0 // more than 1 byte?
mov out0=memset_arg0 // *s
mov out1=r0 // c
mov out2=memset_arg2 // n
(p8) br.call.sptk.few b0=memset
;;
mov retval=saved_retval
mov ar.pfs=saved_pfs_stack
mov b0=saved_rtlink
br.ret.sptk.many rp
/* end of McKinley specific optimization */
END(__copy_user)
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