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Diffstat (limited to '')
| -rw-r--r-- | arch/alpha/lib/ev6-memcpy.S | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/arch/alpha/lib/ev6-memcpy.S b/arch/alpha/lib/ev6-memcpy.S new file mode 100644 index 000000000..ffbd056b6 --- /dev/null +++ b/arch/alpha/lib/ev6-memcpy.S @@ -0,0 +1,250 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * arch/alpha/lib/ev6-memcpy.S + * 21264 version by Rick Gorton <rick.gorton@alpha-processor.com> + * + * Reasonably optimized memcpy() routine for the Alpha 21264 + * + * - memory accessed as aligned quadwords only + * - uses bcmpge to compare 8 bytes in parallel + * + * Much of the information about 21264 scheduling/coding comes from: + * Compiler Writer's Guide for the Alpha 21264 + * abbreviated as 'CWG' in other comments here + * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html + * Scheduling notation: + * E - either cluster + * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 + * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 + * + * Temp usage notes: + * $1,$2, - scratch + */ +#include <asm/export.h> + .set noreorder + .set noat + + .align 4 + .globl memcpy + .ent memcpy +memcpy: + .frame $30,0,$26,0 + .prologue 0 + + mov $16, $0 # E : copy dest to return + ble $18, $nomoredata # U : done with the copy? + xor $16, $17, $1 # E : are source and dest alignments the same? + and $1, 7, $1 # E : are they the same mod 8? + + bne $1, $misaligned # U : Nope - gotta do this the slow way + /* source and dest are same mod 8 address */ + and $16, 7, $1 # E : Are both 0mod8? + beq $1, $both_0mod8 # U : Yes + nop # E : + + /* + * source and dest are same misalignment. move a byte at a time + * until a 0mod8 alignment for both is reached. + * At least one byte more to move + */ + +$head_align: + ldbu $1, 0($17) # L : grab a byte + subq $18, 1, $18 # E : count-- + addq $17, 1, $17 # E : src++ + stb $1, 0($16) # L : + addq $16, 1, $16 # E : dest++ + and $16, 7, $1 # E : Are we at 0mod8 yet? + ble $18, $nomoredata # U : done with the copy? + bne $1, $head_align # U : + +$both_0mod8: + cmple $18, 127, $1 # E : Can we unroll the loop? + bne $1, $no_unroll # U : + and $16, 63, $1 # E : get mod64 alignment + beq $1, $do_unroll # U : no single quads to fiddle + +$single_head_quad: + ldq $1, 0($17) # L : get 8 bytes + subq $18, 8, $18 # E : count -= 8 + addq $17, 8, $17 # E : src += 8 + nop # E : + + stq $1, 0($16) # L : store + addq $16, 8, $16 # E : dest += 8 + and $16, 63, $1 # E : get mod64 alignment + bne $1, $single_head_quad # U : still not fully aligned + +$do_unroll: + addq $16, 64, $7 # E : Initial (+1 trip) wh64 address + cmple $18, 127, $1 # E : Can we go through the unrolled loop? + bne $1, $tail_quads # U : Nope + nop # E : + +$unroll_body: + wh64 ($7) # L1 : memory subsystem hint: 64 bytes at + # ($7) are about to be over-written + ldq $6, 0($17) # L0 : bytes 0..7 + nop # E : + nop # E : + + ldq $4, 8($17) # L : bytes 8..15 + ldq $5, 16($17) # L : bytes 16..23 + addq $7, 64, $7 # E : Update next wh64 address + nop # E : + + ldq $3, 24($17) # L : bytes 24..31 + addq $16, 64, $1 # E : fallback value for wh64 + nop # E : + nop # E : + + addq $17, 32, $17 # E : src += 32 bytes + stq $6, 0($16) # L : bytes 0..7 + nop # E : + nop # E : + + stq $4, 8($16) # L : bytes 8..15 + stq $5, 16($16) # L : bytes 16..23 + subq $18, 192, $2 # E : At least two more trips to go? + nop # E : + + stq $3, 24($16) # L : bytes 24..31 + addq $16, 32, $16 # E : dest += 32 bytes + nop # E : + nop # E : + + ldq $6, 0($17) # L : bytes 0..7 + ldq $4, 8($17) # L : bytes 8..15 + cmovlt $2, $1, $7 # E : Latency 2, extra map slot - Use + # fallback wh64 address if < 2 more trips + nop # E : + + ldq $5, 16($17) # L : bytes 16..23 + ldq $3, 24($17) # L : bytes 24..31 + addq $16, 32, $16 # E : dest += 32 + subq $18, 64, $18 # E : count -= 64 + + addq $17, 32, $17 # E : src += 32 + stq $6, -32($16) # L : bytes 0..7 + stq $4, -24($16) # L : bytes 8..15 + cmple $18, 63, $1 # E : At least one more trip? + + stq $5, -16($16) # L : bytes 16..23 + stq $3, -8($16) # L : bytes 24..31 + nop # E : + beq $1, $unroll_body + +$tail_quads: +$no_unroll: + .align 4 + subq $18, 8, $18 # E : At least a quad left? + blt $18, $less_than_8 # U : Nope + nop # E : + nop # E : + +$move_a_quad: + ldq $1, 0($17) # L : fetch 8 + subq $18, 8, $18 # E : count -= 8 + addq $17, 8, $17 # E : src += 8 + nop # E : + + stq $1, 0($16) # L : store 8 + addq $16, 8, $16 # E : dest += 8 + bge $18, $move_a_quad # U : + nop # E : + +$less_than_8: + .align 4 + addq $18, 8, $18 # E : add back for trailing bytes + ble $18, $nomoredata # U : All-done + nop # E : + nop # E : + + /* Trailing bytes */ +$tail_bytes: + subq $18, 1, $18 # E : count-- + ldbu $1, 0($17) # L : fetch a byte + addq $17, 1, $17 # E : src++ + nop # E : + + stb $1, 0($16) # L : store a byte + addq $16, 1, $16 # E : dest++ + bgt $18, $tail_bytes # U : more to be done? + nop # E : + + /* branching to exit takes 3 extra cycles, so replicate exit here */ + ret $31, ($26), 1 # L0 : + nop # E : + nop # E : + nop # E : + +$misaligned: + mov $0, $4 # E : dest temp + and $0, 7, $1 # E : dest alignment mod8 + beq $1, $dest_0mod8 # U : life doesnt totally suck + nop + +$aligndest: + ble $18, $nomoredata # U : + ldbu $1, 0($17) # L : fetch a byte + subq $18, 1, $18 # E : count-- + addq $17, 1, $17 # E : src++ + + stb $1, 0($4) # L : store it + addq $4, 1, $4 # E : dest++ + and $4, 7, $1 # E : dest 0mod8 yet? + bne $1, $aligndest # U : go until we are aligned. + + /* Source has unknown alignment, but dest is known to be 0mod8 */ +$dest_0mod8: + subq $18, 8, $18 # E : At least a quad left? + blt $18, $misalign_tail # U : Nope + ldq_u $3, 0($17) # L : seed (rotating load) of 8 bytes + nop # E : + +$mis_quad: + ldq_u $16, 8($17) # L : Fetch next 8 + extql $3, $17, $3 # U : masking + extqh $16, $17, $1 # U : masking + bis $3, $1, $1 # E : merged bytes to store + + subq $18, 8, $18 # E : count -= 8 + addq $17, 8, $17 # E : src += 8 + stq $1, 0($4) # L : store 8 (aligned) + mov $16, $3 # E : "rotate" source data + + addq $4, 8, $4 # E : dest += 8 + bge $18, $mis_quad # U : More quads to move + nop + nop + +$misalign_tail: + addq $18, 8, $18 # E : account for tail stuff + ble $18, $nomoredata # U : + nop + nop + +$misalign_byte: + ldbu $1, 0($17) # L : fetch 1 + subq $18, 1, $18 # E : count-- + addq $17, 1, $17 # E : src++ + nop # E : + + stb $1, 0($4) # L : store + addq $4, 1, $4 # E : dest++ + bgt $18, $misalign_byte # U : more to go? + nop + + +$nomoredata: + ret $31, ($26), 1 # L0 : + nop # E : + nop # E : + nop # E : + + .end memcpy + EXPORT_SYMBOL(memcpy) + +/* For backwards module compatibility. */ +__memcpy = memcpy +.globl __memcpy |