diff options
Diffstat (limited to 'ports/sysdeps/alpha/alphaev6/memset.S')
| -rw-r--r-- | ports/sysdeps/alpha/alphaev6/memset.S | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/ports/sysdeps/alpha/alphaev6/memset.S b/ports/sysdeps/alpha/alphaev6/memset.S new file mode 100644 index 0000000000..78b43b2e8d --- /dev/null +++ b/ports/sysdeps/alpha/alphaev6/memset.S @@ -0,0 +1,223 @@ +/* Copyright (C) 2000, 2003 Free Software Foundation, Inc. + Contributed by Richard Henderson (rth@tamu.edu) + EV6 optimized by Rick Gorton <rick.gorton@alpha-processor.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, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + + .arch ev6 + .set noat + .set noreorder + +ENTRY(memset) +#ifdef PROF + ldgp gp, 0(pv) + lda AT, _mcount + jsr AT, (AT), _mcount + .prologue 1 +#else + .prologue 0 +#endif + + /* + * Serious stalling happens. The only way to mitigate this is to + * undertake a major re-write to interleave the constant materialization + * with other parts of the fall-through code. This is important, even + * though it makes maintenance tougher. + * Do this later. + */ + and $17, 255, $1 # E : 00000000000000ch + insbl $17, 1, $2 # U : 000000000000ch00 + mov $16, $0 # E : return value + ble $18, $end # U : zero length requested? + + addq $18, $16, $6 # E : max address to write to + or $1, $2, $17 # E : 000000000000chch + insbl $1, 2, $3 # U : 0000000000ch0000 + insbl $1, 3, $4 # U : 00000000ch000000 + + or $3, $4, $3 # E : 00000000chch0000 + inswl $17, 4, $5 # U : 0000chch00000000 + xor $16, $6, $1 # E : will complete write be within one quadword? + inswl $17, 6, $2 # U : chch000000000000 + + or $17, $3, $17 # E : 00000000chchchch + or $2, $5, $2 # E : chchchch00000000 + bic $1, 7, $1 # E : fit within a single quadword? + and $16, 7, $3 # E : Target addr misalignment + + or $17, $2, $17 # E : chchchchchchchch + beq $1, $within_quad # U : + nop # E : + beq $3, $aligned # U : target is 0mod8 + + /* + * Target address is misaligned, and won't fit within a quadword. + */ + ldq_u $4, 0($16) # L : Fetch first partial + mov $16, $5 # E : Save the address + insql $17, $16, $2 # U : Insert new bytes + subq $3, 8, $3 # E : Invert (for addressing uses) + + addq $18, $3, $18 # E : $18 is new count ($3 is negative) + mskql $4, $16, $4 # U : clear relevant parts of the quad + subq $16, $3, $16 # E : $16 is new aligned destination + or $2, $4, $1 # E : Final bytes + + nop + stq_u $1,0($5) # L : Store result + nop + nop + + .align 4 +$aligned: + /* + * We are now guaranteed to be quad aligned, with at least + * one partial quad to write. + */ + + sra $18, 3, $3 # U : Number of remaining quads to write + and $18, 7, $18 # E : Number of trailing bytes to write + mov $16, $5 # E : Save dest address + beq $3, $no_quad # U : tail stuff only + + /* + * It's worth the effort to unroll this and use wh64 if possible. + * At this point, entry values are: + * $16 Current destination address + * $5 A copy of $16 + * $6 The max quadword address to write to + * $18 Number trailer bytes + * $3 Number quads to write + */ + + and $16, 0x3f, $2 # E : Forward work (only useful for unrolled loop) + subq $3, 16, $4 # E : Only try to unroll if > 128 bytes + subq $2, 0x40, $1 # E : bias counter (aligning stuff 0mod64) + blt $4, $loop # U : + + /* + * We know we've got at least 16 quads, minimum of one trip + * through unrolled loop. Do a quad at a time to get us 0mod64 + * aligned. + */ + + nop # E : + nop # E : + nop # E : + beq $1, $bigalign # U : + +$alignmod64: + stq $17, 0($5) # L : + subq $3, 1, $3 # E : For consistency later + addq $1, 8, $1 # E : Increment towards zero for alignment + addq $5, 8, $4 # E : Initial wh64 address (filler instruction) + + nop + nop + addq $5, 8, $5 # E : Inc address + blt $1, $alignmod64 # U : + +$bigalign: + /* + * $3 - number quads left to go + * $5 - target address (aligned 0mod64) + * $17 - mask of stuff to store + * Scratch registers available: $7, $2, $4, $1 + * We know that we'll be taking a minimum of one trip through. + * CWG Section 3.7.6: do not expect a sustained store rate of > 1/cycle + * Assumes the wh64 needs to be for 2 trips through the loop in the future. + * The wh64 is issued on for the starting destination address for trip +2 + * through the loop, and if there are less than two trips left, the target + * address will be for the current trip. + */ + +$do_wh64: + wh64 ($4) # L1 : memory subsystem write hint + subq $3, 24, $2 # E : For determining future wh64 addresses + stq $17, 0($5) # L : + nop # E : + + addq $5, 128, $4 # E : speculative target of next wh64 + stq $17, 8($5) # L : + stq $17, 16($5) # L : + addq $5, 64, $7 # E : Fallback address for wh64 (== next trip addr) + + stq $17, 24($5) # L : + stq $17, 32($5) # L : + cmovlt $2, $7, $4 # E : Latency 2, extra mapping cycle + nop + + stq $17, 40($5) # L : + stq $17, 48($5) # L : + subq $3, 16, $2 # E : Repeat the loop at least once more? + nop + + stq $17, 56($5) # L : + addq $5, 64, $5 # E : + subq $3, 8, $3 # E : + bge $2, $do_wh64 # U : + + nop + nop + nop + beq $3, $no_quad # U : Might have finished already + + .align 4 + /* + * Simple loop for trailing quadwords, or for small amounts + * of data (where we can't use an unrolled loop and wh64) + */ +$loop: + stq $17, 0($5) # L : + subq $3, 1, $3 # E : Decrement number quads left + addq $5, 8, $5 # E : Inc address + bne $3, $loop # U : more? + +$no_quad: + /* + * Write 0..7 trailing bytes. + */ + nop # E : + beq $18, $end # U : All done? + ldq $7, 0($5) # L : + mskqh $7, $6, $2 # U : Mask final quad + + insqh $17, $6, $4 # U : New bits + or $2, $4, $1 # E : Put it all together + stq $1, 0($5) # L : And back to memory + ret $31,($26),1 # L0 : + +$within_quad: + ldq_u $1, 0($16) # L : + insql $17, $16, $2 # U : New bits + mskql $1, $16, $4 # U : Clear old + or $2, $4, $2 # E : New result + + mskql $2, $6, $4 # U : + mskqh $1, $6, $2 # U : + or $2, $4, $1 # E : + stq_u $1, 0($16) # L : + +$end: + nop + nop + nop + ret $31,($26),1 # L0 : + + END(memset) +libc_hidden_builtin_def (memset) |