mirror of https://gitlab.freedesktop.org/mesa/mesa
79 lines
2.2 KiB
C++
79 lines
2.2 KiB
C++
/*
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* Copyright © 2018 Valve Corporation
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*
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* SPDX-License-Identifier: MIT
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*/
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#ifndef ACO_DOMINANCE_CPP
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#define ACO_DOMINANCE_CPP
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#include "aco_ir.h"
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/*
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* Implements the algorithms for computing the dominator tree from
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* "A Simple, Fast Dominance Algorithm" by Cooper, Harvey, and Kennedy.
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*
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* Different from the paper, our CFG allows to compute the dominator tree
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* in a single pass as it is guaranteed that the dominating predecessors
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* are processed before the current block.
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*/
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namespace aco {
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void
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dominator_tree(Program* program)
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{
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for (unsigned i = 0; i < program->blocks.size(); i++) {
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Block& block = program->blocks[i];
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/* If this block has no predecessor, it dominates itself by definition */
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if (block.linear_preds.empty()) {
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block.linear_idom = block.index;
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block.logical_idom = block.index;
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continue;
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}
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int new_logical_idom = -1;
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int new_linear_idom = -1;
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for (unsigned pred_idx : block.logical_preds) {
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if ((int)program->blocks[pred_idx].logical_idom == -1)
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continue;
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if (new_logical_idom == -1) {
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new_logical_idom = pred_idx;
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continue;
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}
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while ((int)pred_idx != new_logical_idom) {
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if ((int)pred_idx > new_logical_idom)
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pred_idx = program->blocks[pred_idx].logical_idom;
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if ((int)pred_idx < new_logical_idom)
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new_logical_idom = program->blocks[new_logical_idom].logical_idom;
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}
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}
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for (unsigned pred_idx : block.linear_preds) {
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if ((int)program->blocks[pred_idx].linear_idom == -1)
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continue;
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if (new_linear_idom == -1) {
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new_linear_idom = pred_idx;
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continue;
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}
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while ((int)pred_idx != new_linear_idom) {
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if ((int)pred_idx > new_linear_idom)
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pred_idx = program->blocks[pred_idx].linear_idom;
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if ((int)pred_idx < new_linear_idom)
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new_linear_idom = program->blocks[new_linear_idom].linear_idom;
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}
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}
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block.logical_idom = new_logical_idom;
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block.linear_idom = new_linear_idom;
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}
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}
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} // namespace aco
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#endif
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