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/*
* Copyright (C) 2020 Collabora, Ltd.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "compiler.h"
/* The scheduler packs multiple instructions into a clause (grouped as tuple),
* and the packing code takes in a clause and emits it to the wire. During
* scheduling, we need to lay out the instructions (tuples) and constants
* within the clause so constraints can be resolved during scheduling instead
* of failing packing. These routines will help building clauses from
* instructions so the scheduler can focus on the high-level algorithm, and
* manipulating clause layouts.
*/
/* Helper to see if a tuple can be inserted. We must satisfy the invariant:
*
* constant_count + tuple_count <= 13
*
* ...which is equivalent to the clause ending up with 8 or fewer quardwords.
* Inserting a tuple increases tuple_count by one, and if it reads a unique
* constant, it increases constant_count by one.
*/
bool
bi_can_insert_tuple(bi_clause *clause, bool constant)
{
unsigned constant_count = clause->constant_count + (constant ? 1 : 0);
unsigned tuple_count = clause->tuple_count + 1;
return (constant_count + tuple_count) <= 13;
}
/* Helper to calculate the number of quadwords in a clause. This is a function
* of the number of instructions and constants; it doesn't require actually
* packing, which is useful for branch offsets.
*
* Table of instruction count to instruction quadwords, per the packing
* algorithm, where * indicates a constant is packed for free:
*
* X | Y
* ---|---
* 1 | 1
* 2 | 2
* 3 | 3*
* 4 | 3
* 5 | 4*
* 6 | 5*
* 7 | 5
* 8 | 6*
*
* Y = { X if X <= 3
* { X - 1 if 4 <= X <= 6
* { X - 2 if 7 <= X <= 8
*
* and there is a constant for free if X is in {3, 5, 6, 8}. The remaining
* constants are packed two-by-two as constant quadwords.
*/
unsigned
bi_clause_quadwords(bi_clause *clause)
{
unsigned X = clause->tuple_count;
unsigned Y = X - ((X >= 7) ? 2 : (X >= 4) ? 1 : 0);
unsigned constants = clause->constant_count;
if ((X != 4) && (X != 7) && (X >= 3) && constants)
constants--;
return Y + DIV_ROUND_UP(constants, 2);
}
/* Measures the number of quadwords a branch jumps. Bifrost relative offsets
* are from the beginning of a clause so to jump forward we count the current
* clause length, but to jump backwards we do not. */
signed
bi_block_offset(bi_context *ctx, bi_clause *start, bi_block *target)
{
/* Signed since we might jump backwards */
signed ret = 0;
/* Determine if the block we're branching to is strictly greater in
* source order */
bool forwards = target->base.name > start->block->base.name;
if (forwards) {
/* We have to jump through this block from the start of this
* clause to the end */
bi_foreach_clause_in_block_from(start->block, clause, start) {
ret += bi_clause_quadwords(clause);
}
/* We then need to jump through every clause of every following
* block until the target */
bi_foreach_block_from(ctx, start->block, _blk) {
bi_block *blk = (bi_block *) _blk;
/* Don't double-count the first block */
if (blk == start->block)
continue;
/* End just before the target */
if (blk == target)
break;
/* Count every clause in the block */
bi_foreach_clause_in_block(blk, clause) {
ret += bi_clause_quadwords(clause);
}
}
} else {
/* We start at the beginning of the clause but have to jump
* through the clauses before us in the block */
bi_foreach_clause_in_block_from_rev(start->block, clause, start) {
if (clause == start)
continue;
ret -= bi_clause_quadwords(clause);
}
/* And jump back every clause of preceding blocks up through
* and including the target to get to the beginning of the
* target */
bi_foreach_block_from_rev(ctx, start->block, _blk) {
bi_block *blk = (bi_block *) _blk;
if (blk == start->block)
continue;
bi_foreach_clause_in_block(blk, clause) {
ret -= bi_clause_quadwords(clause);
}
/* End just after the target */
if (blk == target)
break;
}
}
return ret;
}
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