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/*
* Copyright © 2014 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.
*
* Authors:
* Jason Ekstrand (jason@jlekstrand.net)
*
*/
#include "nir_constant_expressions.h"
#include <math.h>
/*
* Implements SSA-based constant folding.
*/
struct constant_fold_state {
void *mem_ctx;
nir_function_impl *impl;
bool progress;
};
static bool
constant_fold_alu_instr(nir_alu_instr *instr, void *mem_ctx)
{
nir_const_value src[NIR_MAX_VEC_COMPONENTS];
if (!instr->dest.dest.is_ssa)
return false;
/* In the case that any outputs/inputs have unsized types, then we need to
* guess the bit-size. In this case, the validator ensures that all
* bit-sizes match so we can just take the bit-size from first
* output/input with an unsized type. If all the outputs/inputs are sized
* then we don't need to guess the bit-size at all because the code we
* generate for constant opcodes in this case already knows the sizes of
* the types involved and does not need the provided bit-size for anything
* (although it still requires to receive a valid bit-size).
*/
unsigned bit_size = 0;
if (!nir_alu_type_get_type_size(nir_op_infos[instr->op].output_type))
bit_size = instr->dest.dest.ssa.bit_size;
for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
if (!instr->src[i].src.is_ssa)
return false;
if (bit_size == 0 &&
!nir_alu_type_get_type_size(nir_op_infos[instr->op].input_types[i]))
bit_size = instr->src[i].src.ssa->bit_size;
nir_instr *src_instr = instr->src[i].src.ssa->parent_instr;
if (src_instr->type != nir_instr_type_load_const)
return false;
nir_load_const_instr* load_const = nir_instr_as_load_const(src_instr);
for (unsigned j = 0; j < nir_ssa_alu_instr_src_components(instr, i);
j++) {
switch(load_const->def.bit_size) {
case 64:
src[i].u64[j] = load_const->value.u64[instr->src[i].swizzle[j]];
break;
case 32:
src[i].u32[j] = load_const->value.u32[instr->src[i].swizzle[j]];
break;
case 16:
src[i].u16[j] = load_const->value.u16[instr->src[i].swizzle[j]];
break;
case 8:
src[i].u8[j] = load_const->value.u8[instr->src[i].swizzle[j]];
break;
case 1:
src[i].b[j] = load_const->value.b[instr->src[i].swizzle[j]];
break;
default:
unreachable("Invalid bit size");
}
}
/* We shouldn't have any source modifiers in the optimization loop. */
assert(!instr->src[i].abs && !instr->src[i].negate);
}
if (bit_size == 0)
bit_size = 32;
/* We shouldn't have any saturate modifiers in the optimization loop. */
assert(!instr->dest.saturate);
nir_const_value dest =
nir_eval_const_opcode(instr->op, instr->dest.dest.ssa.num_components,
bit_size, src);
nir_load_const_instr *new_instr =
nir_load_const_instr_create(mem_ctx,
instr->dest.dest.ssa.num_components,
instr->dest.dest.ssa.bit_size);
new_instr->value = dest;
nir_instr_insert_before(&instr->instr, &new_instr->instr);
nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
nir_src_for_ssa(&new_instr->def));
nir_instr_remove(&instr->instr);
ralloc_free(instr);
return true;
}
static bool
constant_fold_intrinsic_instr(nir_intrinsic_instr *instr)
{
bool progress = false;
if (instr->intrinsic == nir_intrinsic_discard_if &&
nir_src_is_const(instr->src[0])) {
if (nir_src_as_bool(instr->src[0])) {
/* This method of getting a nir_shader * from a nir_instr is
* admittedly gross, but given the rarity of hitting this case I think
* it's preferable to plumbing an otherwise unused nir_shader *
* parameter through four functions to get here.
*/
nir_cf_node *cf_node = &instr->instr.block->cf_node;
nir_function_impl *impl = nir_cf_node_get_function(cf_node);
nir_shader *shader = impl->function->shader;
nir_intrinsic_instr *discard =
nir_intrinsic_instr_create(shader, nir_intrinsic_discard);
nir_instr_insert_before(&instr->instr, &discard->instr);
nir_instr_remove(&instr->instr);
progress = true;
} else {
/* We're not discarding, just delete the instruction */
nir_instr_remove(&instr->instr);
progress = true;
}
}
return progress;
}
static bool
constant_fold_block(nir_block *block, void *mem_ctx)
{
bool progress = false;
nir_foreach_instr_safe(instr, block) {
switch (instr->type) {
case nir_instr_type_alu:
progress |= constant_fold_alu_instr(nir_instr_as_alu(instr), mem_ctx);
break;
case nir_instr_type_intrinsic:
progress |=
constant_fold_intrinsic_instr(nir_instr_as_intrinsic(instr));
break;
default:
/* Don't know how to constant fold */
break;
}
}
return progress;
}
static bool
nir_opt_constant_folding_impl(nir_function_impl *impl)
{
void *mem_ctx = ralloc_parent(impl);
bool progress = false;
nir_foreach_block(block, impl) {
progress |= constant_fold_block(block, mem_ctx);
}
if (progress) {
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
} else {
#ifndef NDEBUG
impl->valid_metadata &= ~nir_metadata_not_properly_reset;
#endif
}
return progress;
}
bool
nir_opt_constant_folding(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl)
progress |= nir_opt_constant_folding_impl(function->impl);
}
return progress;
}
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