[Mesa-dev] [PATCH 018/133] nir: add an SSA-based copy propagation pass
Connor Abbott
cwabbott0 at gmail.com
Wed Dec 17 14:26:21 PST 2014
On Wed, Dec 17, 2014 at 5:20 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
>
>
> On Wed, Dec 17, 2014 at 1:10 PM, Jason Ekstrand <jason at jlekstrand.net>
> wrote:
>>
>>
>>
>> On Wed, Dec 17, 2014 at 12:07 PM, Connor Abbott <cwabbott0 at gmail.com>
>> wrote:
>>>
>>> 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.
>>
>>
>> Easy enough to do.
>
>
> Wait, I just remembered that I left them in intentionally. We may want to
> run copy prop after lowering to source mods. In fact, when I wrote
> lower_to_source_mods, I was lazy and just changed sat instructions to mov
> and trusted in copy prop to clan up the swizzles for me. If anything, we
> may want to make copy prop simply handle them correctly.
> --Jason
Ok, that's fine. In that case, we should probably have a separate pass
to move sat/abs/neg out of moves like the comment mentions, similar to
what we do in i965 fs. Or did you already write one?
>
>>
>>
>>>
>>>
>>> > +
>>> > + 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
>>> >
>>> > _______________________________________________
>>> > mesa-dev mailing list
>>> > mesa-dev at lists.freedesktop.org
>>> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
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