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/*
* Copyright © 2018 Intel Corporation
*
* 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 "nir_builder.h"
/**
* Some ALU operations may not be supported in hardware in specific bit-sizes.
* This pass allows implementations to selectively lower such operations to
* a bit-size that is supported natively and then converts the result back to
* the original bit-size.
*/
static void
lower_instr(nir_builder *bld, nir_alu_instr *alu, unsigned bit_size)
{
const nir_op op = alu->op;
unsigned dst_bit_size = alu->dest.dest.ssa.bit_size;
bld->cursor = nir_before_instr(&alu->instr);
/* Convert each source to the requested bit-size */
nir_ssa_def *srcs[4] = { NULL, NULL, NULL, NULL };
for (unsigned i = 0; i < nir_op_infos[op].num_inputs; i++) {
nir_ssa_def *src = nir_ssa_for_alu_src(bld, alu, i);
nir_alu_type type = nir_op_infos[op].input_types[i];
if (nir_alu_type_get_type_size(type) == 0)
src = nir_convert_to_bit_size(bld, src, type, bit_size);
if (i == 1 && (op == nir_op_ishl || op == nir_op_ishr || op == nir_op_ushr)) {
assert(util_is_power_of_two_nonzero(dst_bit_size));
src = nir_iand(bld, src, nir_imm_int(bld, dst_bit_size - 1));
}
srcs[i] = src;
}
/* Emit the lowered ALU instruction */
nir_ssa_def *lowered_dst = NULL;
if (op == nir_op_imul_high || op == nir_op_umul_high) {
assert(dst_bit_size * 2 <= bit_size);
nir_ssa_def *lowered_dst = nir_imul(bld, srcs[0], srcs[1]);
if (nir_op_infos[op].output_type & nir_type_uint)
lowered_dst = nir_ushr(bld, lowered_dst, nir_imm_int(bld, dst_bit_size));
else
lowered_dst = nir_ishr(bld, lowered_dst, nir_imm_int(bld, dst_bit_size));
} else {
lowered_dst = nir_build_alu(bld, op, srcs[0], srcs[1], srcs[2], srcs[3]);
}
/* Convert result back to the original bit-size */
nir_alu_type type = nir_op_infos[op].output_type;
nir_ssa_def *dst = nir_convert_to_bit_size(bld, lowered_dst, type, dst_bit_size);
nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa, nir_src_for_ssa(dst));
}
static bool
lower_impl(nir_function_impl *impl,
nir_lower_bit_size_callback callback,
void *callback_data)
{
nir_builder b;
nir_builder_init(&b, impl);
bool progress = false;
nir_foreach_block(block, impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_alu)
continue;
nir_alu_instr *alu = nir_instr_as_alu(instr);
assert(alu->dest.dest.is_ssa);
unsigned lower_bit_size = callback(alu, callback_data);
if (lower_bit_size == 0)
continue;
assert(lower_bit_size != alu->dest.dest.ssa.bit_size);
lower_instr(&b, alu, lower_bit_size);
progress = true;
}
}
if (progress) {
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
}
return progress;
}
bool
nir_lower_bit_size(nir_shader *shader,
nir_lower_bit_size_callback callback,
void *callback_data)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl)
progress |= lower_impl(function->impl, callback, callback_data);
}
return progress;
}
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