65 lines
2.1 KiB
C
65 lines
2.1 KiB
C
/*
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* Copyright (C) 2021 Alyssa Rosenzweig <alyssa@rosenzweig.io>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include "agx_compiler.h"
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/* SSA-based scalar dead code elimination */
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void
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agx_dce(agx_context *ctx)
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{
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bool progress;
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do {
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progress = false;
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BITSET_WORD *seen = calloc(BITSET_WORDS(ctx->alloc), sizeof(BITSET_WORD));
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agx_foreach_instr_global(ctx, I) {
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agx_foreach_src(I, s) {
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if (I->src[s].type == AGX_INDEX_NORMAL)
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BITSET_SET(seen, I->src[s].value);
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}
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}
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agx_foreach_instr_global_safe_rev(ctx, I) {
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if (!agx_opcodes_info[I->op].can_eliminate) continue;
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bool needed = false;
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agx_foreach_dest(I, d) {
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if (I->dest[d].type == AGX_INDEX_NORMAL)
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needed |= BITSET_TEST(seen, I->dest[d].value);
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else if (I->dest[d].type != AGX_INDEX_NULL)
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needed = true;
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}
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if (!needed) {
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agx_remove_instruction(I);
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progress = true;
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}
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}
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free(seen);
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} while (progress);
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}
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