Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 | /* * 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 */ .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 /* For backwards module compatibility. */ __memcpy = memcpy .globl __memcpy |