[Mesa-dev] [PATCH 018/133] nir: add an SSA-based copy propagation pass
Connor Abbott
cwabbott0 at gmail.com
Wed Dec 17 12:07:42 PST 2014
On Tue, Dec 16, 2014 at 1:04 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> From: Connor Abbott <connor.abbott at intel.com>
>
> ---
> src/glsl/Makefile.sources | 1 +
> src/glsl/nir/nir.h | 3 +
> src/glsl/nir/nir_opt_copy_propagate.c | 313 ++++++++++++++++++++++++++++++++++
> 3 files changed, 317 insertions(+)
> create mode 100644 src/glsl/nir/nir_opt_copy_propagate.c
>
> diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
> index 0aaea58..556648b 100644
> --- a/src/glsl/Makefile.sources
> +++ b/src/glsl/Makefile.sources
> @@ -25,6 +25,7 @@ NIR_FILES = \
> $(GLSL_SRCDIR)/nir/nir_lower_variables_scalar.c \
> $(GLSL_SRCDIR)/nir/nir_opcodes.c \
> $(GLSL_SRCDIR)/nir/nir_opcodes.h \
> + $(GLSL_SRCDIR)/nir/nir_opt_copy_propagate.c \
> $(GLSL_SRCDIR)/nir/nir_opt_global_to_local.c \
> $(GLSL_SRCDIR)/nir/nir_print.c \
> $(GLSL_SRCDIR)/nir/nir_remove_dead_variables.c \
> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
> index c2b4724..a5cb5ed 100644
> --- a/src/glsl/nir/nir.h
> +++ b/src/glsl/nir/nir.h
> @@ -1293,6 +1293,9 @@ void nir_convert_to_ssa(nir_shader *shader);
>
> bool nir_opt_global_to_local(nir_shader *shader);
>
> +bool nir_copy_prop_impl(nir_function_impl *impl);
> +bool nir_copy_prop(nir_shader *shader);
> +
> #ifdef __cplusplus
> } /* extern "C" */
> #endif
> diff --git a/src/glsl/nir/nir_opt_copy_propagate.c b/src/glsl/nir/nir_opt_copy_propagate.c
> new file mode 100644
> index 0000000..a2be047
> --- /dev/null
> +++ b/src/glsl/nir/nir_opt_copy_propagate.c
> @@ -0,0 +1,313 @@
> +/*
> + * 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:
> + * Connor Abbott (cwabbott0 at gmail.com)
> + *
> + */
> +
> +#include "nir.h"
> +#include <main/imports.h>
> +
> +/**
> + * SSA-based copy propagation
> + */
> +
> +static bool is_move(nir_alu_instr *instr)
> +{
> + if (instr->op != nir_op_fmov &&
> + instr->op != nir_op_imov)
> + return false;
> +
> + if (instr->dest.saturate)
> + return false;
> +
> + /* we handle modifiers in a separate pass */
This comment is stale now, since this pass should never see
modifiers... maybe we should replace those if's with asserts to make
that clear.
> +
> + if (instr->src[0].abs || instr->src[0].negate)
> + return false;
> +
> + if (!instr->src[0].src.is_ssa)
> + return false;
> +
> + return true;
> +
> +}
> +
> +static bool
> +is_swizzleless_move(nir_alu_instr *instr)
> +{
> + if (!is_move(instr))
> + return false;
> +
> + for (unsigned i = 0; i < 4; i++) {
> + if (!((instr->dest.write_mask >> i) & 1))
> + break;
> + if (instr->src[0].swizzle[i] != i)
> + return false;
> + }
> +
> + return true;
> +}
> +
> +static bool is_vec(nir_alu_instr *instr)
> +{
> + for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++)
> + if (!instr->src[i].src.is_ssa)
> + return false;
> +
> + return instr->op == nir_op_vec2 ||
> + instr->op == nir_op_vec3 ||
> + instr->op == nir_op_vec4;
> +}
> +
> +typedef struct {
> + nir_ssa_def *def;
> + bool found;
> +} search_def_state;
> +
> +static bool
> +search_def(nir_src *src, void *_state)
> +{
> + search_def_state *state = (search_def_state *) _state;
> +
> + if (src->is_ssa && src->ssa == state->def)
> + state->found = true;
> +
> + return true;
> +}
> +
> +static void
> +rewrite_src_instr(nir_src *src, nir_ssa_def *new_def, nir_instr *parent_instr)
> +{
> + nir_ssa_def *old_def = src->ssa;
> +
> + src->ssa = new_def;
> +
> + /*
> + * The instruction could still use the old definition in one of its other
> + * sources, so only remove the instruction from the uses if there are no
> + * more uses left.
> + */
> +
> + search_def_state search_state;
> + search_state.def = old_def;
> + search_state.found = false;
> + nir_foreach_src(parent_instr, search_def, &search_state);
> + if (!search_state.found) {
> + struct set_entry *entry =
> + _mesa_set_search(old_def->uses, _mesa_hash_pointer(parent_instr),
> + parent_instr);
> + assert(entry);
> + _mesa_set_remove(old_def->uses, entry);
> + }
> +
> + _mesa_set_add(new_def->uses, _mesa_hash_pointer(parent_instr),
> + parent_instr);
> +}
> +
> +static void
> +rewrite_src_if(nir_if *if_stmt, nir_ssa_def *new_def)
> +{
> + nir_ssa_def *old_def = if_stmt->condition.ssa;
> +
> + if_stmt->condition.ssa = new_def;
> +
> + struct set_entry *entry =
> + _mesa_set_search(old_def->if_uses, _mesa_hash_pointer(if_stmt), if_stmt);
> + assert(entry);
> + _mesa_set_remove(old_def->if_uses, entry);
> +
> + _mesa_set_add(new_def->if_uses, _mesa_hash_pointer(if_stmt), if_stmt);
> +}
> +
> +static bool
> +copy_prop_src(nir_src *src, nir_instr *parent_instr, nir_if *parent_if)
> +{
> + if (!src->is_ssa) {
> + if (src->reg.indirect)
> + return copy_prop_src(src, parent_instr, parent_if);
> + return false;
> + }
> +
> + nir_instr *src_instr = src->ssa->parent_instr;
> + if (src_instr->type != nir_instr_type_alu)
> + return false;
> +
> + nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
> + if (!is_swizzleless_move(alu_instr))
> + return false;
> +
> + if (parent_instr)
> + rewrite_src_instr(src, alu_instr->src[0].src.ssa, parent_instr);
> + else
> + rewrite_src_if(parent_if, alu_instr->src[0].src.ssa);
> +
> + return true;
> +}
> +
> +static bool
> +copy_prop_alu_src(nir_alu_instr *parent_alu_instr, unsigned index)
> +{
> + nir_alu_src *src = &parent_alu_instr->src[index];
> + if (!src->src.is_ssa) {
> + if (src->src.reg.indirect)
> + return copy_prop_src(src->src.reg.indirect, &parent_alu_instr->instr,
> + NULL);
> + return false;
> + }
> +
> + nir_instr *src_instr = src->src.ssa->parent_instr;
> + if (src_instr->type != nir_instr_type_alu)
> + return false;
> +
> + nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
> + if (!is_move(alu_instr) && !is_vec(alu_instr))
> + return false;
> +
> + nir_ssa_def *def;
> + unsigned new_swizzle[4] = {0, 0, 0, 0};
> +
> + if (alu_instr->op == nir_op_fmov ||
> + alu_instr->op == nir_op_imov) {
> + for (unsigned i = 0; i < 4; i++)
> + new_swizzle[i] = alu_instr->src[0].swizzle[src->swizzle[i]];
> + def = alu_instr->src[0].src.ssa;
> + } else {
> + def = NULL;
> +
> + for (unsigned i = 0; i < 4; i++) {
> + if (!nir_alu_instr_channel_used(parent_alu_instr, index, i))
> + continue;
> +
> + nir_ssa_def *new_def = alu_instr->src[src->swizzle[i]].src.ssa;
> + if (def == NULL)
> + def = new_def;
> + else {
> + if (def != new_def)
> + return false;
> + }
> + new_swizzle[i] = alu_instr->src[src->swizzle[i]].swizzle[0];
> + }
> + }
> +
> + for (unsigned i = 0; i < 4; i++)
> + src->swizzle[i] = new_swizzle[i];
> +
> + rewrite_src_instr(&src->src, def, &parent_alu_instr->instr);
> +
> + return true;
> +}
> +
> +typedef struct {
> + nir_instr *parent_instr;
> + bool progress;
> +} copy_prop_state;
> +
> +static bool
> +copy_prop_src_cb(nir_src *src, void *_state)
> +{
> + copy_prop_state *state = (copy_prop_state *) _state;
> + while (copy_prop_src(src, state->parent_instr, NULL))
> + state->progress = true;
> +
> + return true;
> +}
> +
> +static bool
> +copy_prop_instr(nir_instr *instr)
> +{
> + if (instr->type == nir_instr_type_alu) {
> + nir_alu_instr *alu_instr = nir_instr_as_alu(instr);
> + bool progress = false;
> +
> + for (unsigned i = 0; i < nir_op_infos[alu_instr->op].num_inputs; i++)
> + while (copy_prop_alu_src(alu_instr, i))
> + progress = true;
> +
> + if (alu_instr->has_predicate)
> + while (copy_prop_src(&alu_instr->predicate, instr, NULL))
> + progress = true;
> +
> + if (!alu_instr->dest.dest.is_ssa && alu_instr->dest.dest.reg.indirect)
> + while (copy_prop_src(alu_instr->dest.dest.reg.indirect, instr, NULL))
> + progress = true;
> +
> + return progress;
> + }
> +
> + copy_prop_state state;
> + state.parent_instr = instr;
> + state.progress = false;
> + nir_foreach_src(instr, copy_prop_src_cb, &state);
> +
> + return state.progress;
> +}
> +
> +static bool
> +copy_prop_if(nir_if *if_stmt)
> +{
> + return copy_prop_src(&if_stmt->condition, NULL, if_stmt);
> +}
> +
> +static bool
> +copy_prop_block(nir_block *block, void *_state)
> +{
> + bool *progress = (bool *) _state;
> +
> + nir_foreach_instr(block, instr) {
> + if (copy_prop_instr(instr))
> + *progress = true;
> + }
> +
> + if (block->cf_node.node.next != NULL && /* check that we aren't the end node */
> + !nir_cf_node_is_last(&block->cf_node) &&
> + nir_cf_node_next(&block->cf_node)->type == nir_cf_node_if) {
> + nir_if *if_stmt = nir_cf_node_as_if(nir_cf_node_next(&block->cf_node));
> + if (copy_prop_if(if_stmt))
> + *progress = true;
> + }
> +
> + return true;
> +}
> +
> +bool
> +nir_copy_prop_impl(nir_function_impl *impl)
> +{
> + bool progress = false;
> +
> + nir_foreach_block(impl, copy_prop_block, &progress);
> + return progress;
> +}
> +
> +bool
> +nir_copy_prop(nir_shader *shader)
> +{
> + bool progress = false;
> +
> + nir_foreach_overload(shader, overload) {
> + if (overload->impl && nir_copy_prop_impl(overload->impl))
> + progress = true;
> + }
> +
> + return progress;
> +}
> --
> 2.2.0
>
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