Jason Ekstrand <ja...@jlekstrand.net> writes: > diff --git a/src/glsl/nir/nir_lower_phis_to_scalar.c > b/src/glsl/nir/nir_lower_phis_to_scalar.c > new file mode 100644 > index 0000000..9f901d6 > --- /dev/null > +++ b/src/glsl/nir/nir_lower_phis_to_scalar.c > @@ -0,0 +1,238 @@ > +/* > + * Copyright © 2014 Intel Corporation
Possibly update your copyright date?
> + *
> + * 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 (ja...@jlekstrand.net)
> + *
> + */
> +
> +#include "nir.h"
> +
> +/*
> + * Implements common subexpression elimination
> + */
Stale comment.
> +struct lower_phis_to_scalar_state {
> + void *mem_ctx;
> + void *dead_ctx;
> +
> + /* Hash table marking which phi nodes are scalarizable. The key is
> + * pointers to phi instructions and the entry is either NULL for not
> + * scalarizable or non-null for scalarizable.
> + */
> + struct hash_table *phi_table;
> +};
> +
> +/* Determines if the given phi node should be lowered. The only phi nodes
> + * we will scalarize at the moment are those where all of the sources are
> + * scalarizable.
> + */
> +static bool
> +should_lower_phi(nir_phi_instr *phi, struct lower_phis_to_scalar_state
> *state)
> +{
> + /* Already scalar */
> + if (phi->dest.ssa.num_components == 1)
> + return false;
> +
> + struct hash_entry *entry = _mesa_hash_table_search(state->phi_table, phi);
> + if (entry)
> + return entry->data != NULL;
> +
> + nir_foreach_phi_src(phi, src) {
> + /* Don't know what to do with non-ssa sources */
> + if (!src->src.is_ssa)
> + return false;
> + nir_instr *src_instr = src->src.ssa->parent_instr;
> + switch (src_instr->type) {
> + case nir_instr_type_alu: {
> + nir_alu_instr *src_alu = nir_instr_as_alu(src_instr);
> +
> + /* ALU operations with output_size == 0 should be scalarized. We
> + * will also see a bunch of vecN operations from scalarizing ALU
> + * operations and, since they can easily be copy-propagated, they
> + * are ok too.
> + */
> + return nir_op_infos[src_alu->op].output_size == 0 ||
> + src_alu->op != nir_op_vec2 ||
> + src_alu->op != nir_op_vec3 ||
> + src_alu->op != nir_op_vec4;
> + }
> +
> + case nir_instr_type_phi: {
> + nir_phi_instr *src_phi = nir_instr_as_phi(src_instr);
> +
> + /* Insert an entry and mark it as scalarizable for now. That way
> + * we don't recurse forever and a cycle in the depencence graph
> + * won't automatically make us fail to scalarize.
> + */
> + entry = _mesa_hash_table_insert(state->phi_table, src_phi, (void
> *)1);
I expect "(void *)1" will give compiler warnings generally. "(void
*)(uintptr_t)1" is the usual workaround.
Useful comment, though!
> + bool scalarizable = should_lower_phi(src_phi, state);
> + entry->data = (void *)scalarizable;
No need to cast to void *, since not C++.
> +static bool
> +lower_phis_to_scalar_block(nir_block *block, void *void_state)
> +{
> + struct lower_phis_to_scalar_state *state = void_state;
> +
> + /* Find the last phi node in the block */
> + nir_phi_instr *last_phi = NULL;
> + nir_foreach_instr(block, instr) {
> + if (instr->type != nir_instr_type_phi)
> + break;
> +
> + last_phi = nir_instr_as_phi(instr);
> + }
> +
> + /* We have to handle the phi nodes in their own pass due to the way
> + * we're modifying the linked list of instructions.
> + */
> + nir_foreach_instr_safe(block, instr) {
> + if (instr->type != nir_instr_type_phi)
> + break;
> +
> + nir_phi_instr *phi = nir_instr_as_phi(instr);
> +
> + if (!should_lower_phi(phi, state))
> + continue;
> +
> + /* Create a vecN operation to combine the results. Most of these
> + * will be redundant, but copy propagation should clean them up for
> + * us. No need to add the complexity here.
> + */
> + nir_op vec_op;
> + switch (phi->dest.ssa.num_components) {
> + case 2: vec_op = nir_op_vec2; break;
> + case 3: vec_op = nir_op_vec3; break;
> + case 4: vec_op = nir_op_vec4; break;
> + default: unreachable("Invalid number of components");
> + }
> +
> + nir_alu_instr *vec = nir_alu_instr_create(state->mem_ctx, vec_op);
> + vec->dest.dest.is_ssa = true;
> + nir_ssa_def_init(&vec->instr, &vec->dest.dest.ssa,
> + phi->dest.ssa.num_components, NULL);
nir_ssa_dest_init() instead? (throughout the file)
> + vec->dest.write_mask = (1 << phi->dest.ssa.num_components) - 1;
> +
> + for (unsigned i = 0; i < phi->dest.ssa.num_components; i++) {
> + nir_phi_instr *new_phi = nir_phi_instr_create(state->mem_ctx);
> + new_phi->dest.is_ssa = true;
> + nir_ssa_def_init(&new_phi->instr, &new_phi->dest.ssa, 1, NULL);
> +
> + vec->src[i].src.is_ssa = true;
> + vec->src[i].src.ssa = &new_phi->dest.ssa;
> +
> + nir_foreach_phi_src(phi, src) {
> + /* We need to insert a mov to grab the i'th component of src */
> + nir_alu_instr *mov = nir_alu_instr_create(state->mem_ctx,
> + nir_op_imov);
> + mov->dest.dest.is_ssa = true;
> + nir_ssa_def_init(&mov->instr, &mov->dest.dest.ssa, 1, NULL);
> + mov->dest.write_mask = 1;
> + mov->src[0].src = nir_src_copy(src->src, state->mem_ctx);
> + mov->src[0].swizzle[0] = i;
> +
> + /* Insert at the end of the predecessor but before the jump */
> + nir_instr *pred_last_instr = nir_block_last_instr(src->pred);
> + if (pred_last_instr && pred_last_instr->type ==
> nir_instr_type_jump)
> + nir_instr_insert_before(pred_last_instr, &mov->instr);
> + else
> + nir_instr_insert_after_block(src->pred, &mov->instr);
Couldn't you just insert your mov right after the def of the src? I'm
confused.
> +
> + nir_phi_src *new_src = ralloc(state->mem_ctx, nir_phi_src);
> + new_src->pred = src->pred;
> + new_src->src.is_ssa = true;
> + new_src->src.ssa = &mov->dest.dest.ssa;
new_src->src = nir_src_for_ssa(&mov->dest.dest.ssa);
(and elsewhere in the file)
> +
> + exec_list_push_tail(&new_phi->srcs, &new_src->node);
> + }
> +
> + nir_instr_insert_before(&phi->instr, &new_phi->instr);
> + }
> +
> + nir_instr_insert_after(&last_phi->instr, &vec->instr);
> +
> + nir_ssa_def_rewrite_uses(&phi->dest.ssa,
> + nir_src_for_ssa(&vec->dest.dest.ssa),
> + state->mem_ctx);
> +
> + ralloc_steal(state->dead_ctx, phi);
> + nir_instr_remove(&phi->instr);
> +
> + /* We're using the safe iterator and inserting all the newly
> + * scalarized phi nodes before their non-scalarized version so that's
> + * ok. However, we are also inserting vec operations after all of
> + * the last phi node so once we get here, we can't trust even the
> + * safe iterator to stop properly. We have to break manually.
> + */
> + if (instr == &last_phi->instr)
> + break;
> + }
> +
> + return true;
> +}
> +
> +static void
> +lower_phis_to_scalar_impl(nir_function_impl *impl)
> +{
> + struct lower_phis_to_scalar_state state;
> +
> + state.mem_ctx = ralloc_parent(impl);
> + state.dead_ctx = ralloc_context(NULL);
> + state.phi_table = _mesa_hash_table_create(state.dead_ctx,
> _mesa_hash_pointer,
> + _mesa_key_pointer_equal);
> +
> + nir_foreach_block(impl, lower_phis_to_scalar_block, &state);
> +
> + nir_metadata_preserve(impl, nir_metadata_block_index |
> + nir_metadata_dominance);
> +
> + ralloc_free(state.dead_ctx);
> +}
I just notied: When do I need to all nir_metadata_preserve()? I didn't
in my pass.
signature.asc
Description: PGP signature
_______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
