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/*
* Copyright (C) 2019 Ryan Houdek <Sonicadvance1@gmail.com>
*
* 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 "bifrost_opts.h"
#include "compiler_defines.h"
bool
bifrost_opt_branch_fusion(compiler_context *ctx, bifrost_block *block)
{
bool progress = false;
mir_foreach_instr_in_block_safe(block, instr) {
if (instr->op != op_branch) continue;
if (instr->literal_args[0] != BR_COND_EQ) continue;
unsigned src1 = instr->ssa_args.src0;
// Only work on SSA values
if (src1 >= SSA_FIXED_MINIMUM) continue;
// Find the source for this conditional branch instruction
// It'll be a CSEL instruction
// If it's comparision is one of the ops that our conditional branch supports
// then we can merge the two
mir_foreach_instr_in_block_from_rev(block, next_instr, instr) {
if (next_instr->op != op_csel_i32) continue;
if (next_instr->ssa_args.dest == src1) {
// We found the CSEL instruction that is the source here
// Check its condition to make sure it matches what we can fuse
unsigned cond = next_instr->literal_args[0];
if (cond == CSEL_IEQ) {
// This CSEL is doing an IEQ for our conditional branch doing EQ
// We can just emit a conditional branch that does the comparison
struct bifrost_instruction new_instr = {
.op = op_branch,
.dest_components = 0,
.ssa_args = {
.dest = SSA_INVALID_VALUE,
.src0 = next_instr->ssa_args.src0,
.src1 = next_instr->ssa_args.src1,
.src2 = SSA_INVALID_VALUE,
.src3 = SSA_INVALID_VALUE,
},
.literal_args[0] = BR_COND_EQ,
.literal_args[1] = instr->literal_args[1],
};
mir_insert_instr_before(instr, new_instr);
mir_remove_instr(instr);
progress |= true;
break;
}
}
}
}
return progress;
}
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