Mesa (master): glsl: Add a new opt_copy_propagation variant that does it channel-wise.
Eric Anholt
anholt at kemper.freedesktop.org
Fri Feb 4 18:45:22 UTC 2011
Module: Mesa
Branch: master
Commit: e31266ed3e3667c043bc5ad1abd65cfdb0fa7fdb
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=e31266ed3e3667c043bc5ad1abd65cfdb0fa7fdb
Author: Eric Anholt <eric at anholt.net>
Date: Tue Jan 25 10:28:13 2011 +1000
glsl: Add a new opt_copy_propagation variant that does it channel-wise.
This patch cleans up many of the extra copies in GLSL IR introduced by
i965's scalarizing passes. It doesn't result in a statistically
significant performance difference on nexuiz high settings (n=3) or my
demo (n=10), due to brw_fs.cpp's register coalescing covering most of
those extra moves anyway. However, it does make the debug of wine's
GLSL shaders much more tractable, and reduces instruction count of
glsl-fs-convolution-2 from 376 to 288.
---
src/glsl/Makefile | 1 +
src/glsl/glsl_parser_extras.cpp | 1 +
src/glsl/ir_optimization.h | 1 +
src/glsl/opt_copy_propagation_elements.cpp | 461 ++++++++++++++++++++++++++++
4 files changed, 464 insertions(+), 0 deletions(-)
diff --git a/src/glsl/Makefile b/src/glsl/Makefile
index 4f30742..ec11c8a 100644
--- a/src/glsl/Makefile
+++ b/src/glsl/Makefile
@@ -69,6 +69,7 @@ CXX_SOURCES = \
opt_constant_propagation.cpp \
opt_constant_variable.cpp \
opt_copy_propagation.cpp \
+ opt_copy_propagation_elements.cpp \
opt_dead_code.cpp \
opt_dead_code_local.cpp \
opt_dead_functions.cpp \
diff --git a/src/glsl/glsl_parser_extras.cpp b/src/glsl/glsl_parser_extras.cpp
index 1fa209c..c2bb59b 100644
--- a/src/glsl/glsl_parser_extras.cpp
+++ b/src/glsl/glsl_parser_extras.cpp
@@ -764,6 +764,7 @@ do_common_optimization(exec_list *ir, bool linked, unsigned max_unroll_iteration
progress = do_if_simplification(ir) || progress;
progress = do_discard_simplification(ir) || progress;
progress = do_copy_propagation(ir) || progress;
+ progress = do_copy_propagation_elements(ir) || progress;
if (linked)
progress = do_dead_code(ir) || progress;
else
diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index dbc9f4a..dd26567 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -43,6 +43,7 @@ bool do_constant_folding(exec_list *instructions);
bool do_constant_variable(exec_list *instructions);
bool do_constant_variable_unlinked(exec_list *instructions);
bool do_copy_propagation(exec_list *instructions);
+bool do_copy_propagation_elements(exec_list *instructions);
bool do_constant_propagation(exec_list *instructions);
bool do_dead_code(exec_list *instructions);
bool do_dead_code_local(exec_list *instructions);
diff --git a/src/glsl/opt_copy_propagation_elements.cpp b/src/glsl/opt_copy_propagation_elements.cpp
new file mode 100644
index 0000000..238a1a7
--- /dev/null
+++ b/src/glsl/opt_copy_propagation_elements.cpp
@@ -0,0 +1,461 @@
+/*
+ * Copyright © 2010 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.
+ */
+
+/**
+ * \file opt_copy_propagation_elements.cpp
+ *
+ * Replaces usage of recently-copied components of variables with the
+ * previous copy of the variable.
+ *
+ * This pass can be compared with opt_copy_propagation, which operands
+ * on arbitrary whole-variable copies. However, in order to handle
+ * the copy propagation of swizzled variables or writemasked writes,
+ * we want to track things on a channel-wise basis. I found that
+ * trying to mix the swizzled/writemasked support here with the
+ * whole-variable stuff in opt_copy_propagation.cpp just made a mess,
+ * so this is separate despite the ACP handling being somewhat
+ * similar.
+ *
+ * This should reduce the number of MOV instructions in the generated
+ * programs unless copy propagation is also done on the LIR, and may
+ * help anyway by triggering other optimizations that live in the HIR.
+ */
+
+#include "ir.h"
+#include "ir_rvalue_visitor.h"
+#include "ir_basic_block.h"
+#include "ir_optimization.h"
+#include "glsl_types.h"
+
+static bool debug = false;
+
+class acp_entry : public exec_node
+{
+public:
+ acp_entry(ir_variable *lhs, ir_variable *rhs, int write_mask, int swizzle[4])
+ {
+ this->lhs = lhs;
+ this->rhs = rhs;
+ this->write_mask = write_mask;
+ memcpy(this->swizzle, swizzle, sizeof(this->swizzle));
+ }
+
+ acp_entry(acp_entry *a)
+ {
+ this->lhs = a->lhs;
+ this->rhs = a->rhs;
+ this->write_mask = a->write_mask;
+ memcpy(this->swizzle, a->swizzle, sizeof(this->swizzle));
+ }
+
+ ir_variable *lhs;
+ ir_variable *rhs;
+ unsigned int write_mask;
+ int swizzle[4];
+};
+
+
+class kill_entry : public exec_node
+{
+public:
+ kill_entry(ir_variable *var, int write_mask)
+ {
+ this->var = var;
+ this->write_mask = write_mask;
+ }
+
+ ir_variable *var;
+ unsigned int write_mask;
+};
+
+class ir_copy_propagation_elements_visitor : public ir_rvalue_visitor {
+public:
+ ir_copy_propagation_elements_visitor()
+ {
+ this->progress = false;
+ this->mem_ctx = ralloc_context(NULL);
+ this->shader_mem_ctx = NULL;
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ }
+ ~ir_copy_propagation_elements_visitor()
+ {
+ ralloc_free(mem_ctx);
+ }
+
+ virtual ir_visitor_status visit_enter(class ir_loop *);
+ virtual ir_visitor_status visit_enter(class ir_function_signature *);
+ virtual ir_visitor_status visit_leave(class ir_assignment *);
+ virtual ir_visitor_status visit_enter(class ir_call *);
+ virtual ir_visitor_status visit_enter(class ir_if *);
+
+ void handle_rvalue(ir_rvalue **rvalue);
+
+ void add_copy(ir_assignment *ir);
+ void kill(kill_entry *k);
+ void handle_if_block(exec_list *instructions);
+
+ /** List of acp_entry: The available copies to propagate */
+ exec_list *acp;
+ /**
+ * List of kill_entry: The variables whose values were killed in this
+ * block.
+ */
+ exec_list *kills;
+
+ bool progress;
+
+ bool killed_all;
+
+ /* Context for our local data structures. */
+ void *mem_ctx;
+ /* Context for allocating new shader nodes. */
+ void *shader_mem_ctx;
+};
+
+ir_visitor_status
+ir_copy_propagation_elements_visitor::visit_enter(ir_function_signature *ir)
+{
+ /* Treat entry into a function signature as a completely separate
+ * block. Any instructions at global scope will be shuffled into
+ * main() at link time, so they're irrelevant to us.
+ */
+ exec_list *orig_acp = this->acp;
+ exec_list *orig_kills = this->kills;
+ bool orig_killed_all = this->killed_all;
+
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ this->killed_all = false;
+
+ visit_list_elements(this, &ir->body);
+
+ this->kills = orig_kills;
+ this->acp = orig_acp;
+ this->killed_all = orig_killed_all;
+
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_copy_propagation_elements_visitor::visit_leave(ir_assignment *ir)
+{
+ ir_dereference_variable *lhs = ir->lhs->as_dereference_variable();
+
+ if (lhs && (lhs->type->is_scalar() || lhs->type->is_vector())) {
+ kill_entry *k = new(mem_ctx) kill_entry(lhs->var, ir->write_mask);
+ kill(k);
+ }
+
+ add_copy(ir);
+
+ return visit_continue;
+}
+
+/**
+ * Replaces dereferences of ACP RHS variables with ACP LHS variables.
+ *
+ * This is where the actual copy propagation occurs. Note that the
+ * rewriting of ir_dereference means that the ir_dereference instance
+ * must not be shared by multiple IR operations!
+ */
+void
+ir_copy_propagation_elements_visitor::handle_rvalue(ir_rvalue **ir)
+{
+ int swizzle_chan[4];
+ ir_dereference_variable *deref_var;
+ ir_variable *source[4] = {NULL, NULL, NULL, NULL};
+ int source_chan[4];
+ int chans;
+
+ if (!*ir)
+ return;
+
+ ir_swizzle *swizzle = (*ir)->as_swizzle();
+ if (swizzle) {
+ deref_var = swizzle->val->as_dereference_variable();
+ if (!deref_var)
+ return;
+
+ swizzle_chan[0] = swizzle->mask.x;
+ swizzle_chan[1] = swizzle->mask.y;
+ swizzle_chan[2] = swizzle->mask.z;
+ swizzle_chan[3] = swizzle->mask.w;
+ chans = swizzle->type->vector_elements;
+ } else {
+ deref_var = (*ir)->as_dereference_variable();
+ if (!deref_var)
+ return;
+
+ swizzle_chan[0] = 0;
+ swizzle_chan[1] = 1;
+ swizzle_chan[2] = 2;
+ swizzle_chan[3] = 3;
+ chans = deref_var->type->vector_elements;
+ }
+
+ if (this->in_assignee)
+ return;
+
+ ir_variable *var = deref_var->var;
+
+ /* Try to find ACP entries covering swizzle_chan[], hoping they're
+ * the same source variable.
+ */
+ foreach_iter(exec_list_iterator, iter, *this->acp) {
+ acp_entry *entry = (acp_entry *)iter.get();
+
+ if (var == entry->lhs) {
+ for (int c = 0; c < chans; c++) {
+ if (entry->write_mask & (1 << swizzle_chan[c])) {
+ source[c] = entry->rhs;
+ source_chan[c] = entry->swizzle[swizzle_chan[c]];
+ }
+ }
+ }
+ }
+
+ /* Make sure all channels are copying from the same source variable. */
+ if (!source[0])
+ return;
+ for (int c = 1; c < chans; c++) {
+ if (source[c] != source[0])
+ return;
+ }
+
+ if (!shader_mem_ctx)
+ shader_mem_ctx = ralloc_parent(deref_var);
+
+ if (debug) {
+ printf("Copy propagation from:\n");
+ (*ir)->print();
+ }
+
+ deref_var = new(shader_mem_ctx) ir_dereference_variable(source[0]);
+ *ir = new(shader_mem_ctx) ir_swizzle(deref_var,
+ source_chan[0],
+ source_chan[1],
+ source_chan[2],
+ source_chan[3],
+ chans);
+
+ if (debug) {
+ printf("to:\n");
+ (*ir)->print();
+ printf("\n");
+ }
+}
+
+
+ir_visitor_status
+ir_copy_propagation_elements_visitor::visit_enter(ir_call *ir)
+{
+ /* Do copy propagation on call parameters, but skip any out params */
+ exec_list_iterator sig_param_iter = ir->get_callee()->parameters.iterator();
+ foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
+ ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
+ ir_instruction *ir = (ir_instruction *)iter.get();
+ if (sig_param->mode != ir_var_out && sig_param->mode != ir_var_inout) {
+ ir->accept(this);
+ }
+ sig_param_iter.next();
+ }
+
+ /* Since we're unlinked, we don't (necessarily) know the side effects of
+ * this call. So kill all copies.
+ */
+ acp->make_empty();
+ this->killed_all = true;
+
+ return visit_continue_with_parent;
+}
+
+void
+ir_copy_propagation_elements_visitor::handle_if_block(exec_list *instructions)
+{
+ exec_list *orig_acp = this->acp;
+ exec_list *orig_kills = this->kills;
+ bool orig_killed_all = this->killed_all;
+
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ this->killed_all = false;
+
+ /* Populate the initial acp with a copy of the original */
+ foreach_iter(exec_list_iterator, iter, *orig_acp) {
+ acp_entry *a = (acp_entry *)iter.get();
+ this->acp->push_tail(new(this->mem_ctx) acp_entry(a));
+ }
+
+ visit_list_elements(this, instructions);
+
+ if (this->killed_all) {
+ orig_acp->make_empty();
+ }
+
+ exec_list *new_kills = this->kills;
+ this->kills = orig_kills;
+ this->acp = orig_acp;
+ this->killed_all = this->killed_all || orig_killed_all;
+
+ /* Move the new kills into the parent block's list, removing them
+ * from the parent's ACP list in the process.
+ */
+ foreach_list_safe(node, new_kills) {
+ kill_entry *k = (kill_entry *)node;
+ kill(k);
+ }
+}
+
+ir_visitor_status
+ir_copy_propagation_elements_visitor::visit_enter(ir_if *ir)
+{
+ ir->condition->accept(this);
+
+ handle_if_block(&ir->then_instructions);
+ handle_if_block(&ir->else_instructions);
+
+ /* handle_if_block() already descended into the children. */
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_copy_propagation_elements_visitor::visit_enter(ir_loop *ir)
+{
+ exec_list *orig_acp = this->acp;
+ exec_list *orig_kills = this->kills;
+ bool orig_killed_all = this->killed_all;
+
+ /* FINISHME: For now, the initial acp for loops is totally empty.
+ * We could go through once, then go through again with the acp
+ * cloned minus the killed entries after the first run through.
+ */
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ this->killed_all = false;
+
+ visit_list_elements(this, &ir->body_instructions);
+
+ if (this->killed_all) {
+ orig_acp->make_empty();
+ }
+
+ exec_list *new_kills = this->kills;
+ this->kills = orig_kills;
+ this->acp = orig_acp;
+ this->killed_all = this->killed_all || orig_killed_all;
+
+ foreach_list_safe(node, new_kills) {
+ kill_entry *k = (kill_entry *)node;
+ kill(k);
+ }
+
+ /* already descended into the children. */
+ return visit_continue_with_parent;
+}
+
+/* Remove any entries currently in the ACP for this kill. */
+void
+ir_copy_propagation_elements_visitor::kill(kill_entry *k)
+{
+ foreach_list_safe(node, acp) {
+ acp_entry *entry = (acp_entry *)node;
+
+ if (entry->lhs == k->var) {
+ entry->write_mask = entry->write_mask & ~k->write_mask;
+ if (entry->write_mask == 0)
+ entry->remove();
+ }
+ if (entry->rhs == k->var) {
+ entry->remove();
+ }
+ }
+
+ /* If we were on a list, remove ourselves before inserting */
+ if (k->next)
+ k->remove();
+
+ this->kills->push_tail(k);
+}
+
+/**
+ * Adds directly-copied channels between vector variables to the available
+ * copy propagation list.
+ */
+void
+ir_copy_propagation_elements_visitor::add_copy(ir_assignment *ir)
+{
+ acp_entry *entry;
+ int orig_swizzle[4] = {0, 1, 2, 3};
+ int swizzle[4];
+
+ if (ir->condition) {
+ ir_constant *condition = ir->condition->as_constant();
+ if (!condition || !condition->value.b[0])
+ return;
+ }
+
+ ir_dereference_variable *lhs = ir->lhs->as_dereference_variable();
+ if (!lhs || !(lhs->type->is_scalar() || lhs->type->is_vector()))
+ return;
+
+ ir_dereference_variable *rhs = ir->rhs->as_dereference_variable();
+ if (!rhs) {
+ ir_swizzle *swiz = ir->rhs->as_swizzle();
+ if (!swiz)
+ return;
+
+ rhs = swiz->val->as_dereference_variable();
+ if (!rhs)
+ return;
+
+ orig_swizzle[0] = swiz->mask.x;
+ orig_swizzle[1] = swiz->mask.y;
+ orig_swizzle[2] = swiz->mask.z;
+ orig_swizzle[3] = swiz->mask.w;
+ }
+
+ /* Move the swizzle channels out to the positions they match in the
+ * destination. We don't want to have to rewrite the swizzle[]
+ * array every time we clear a bit of the write_mask.
+ */
+ int j = 0;
+ for (int i = 0; i < 4; i++) {
+ if (ir->write_mask & (1 << i))
+ swizzle[i] = orig_swizzle[j++];
+ }
+
+ entry = new(this->mem_ctx) acp_entry(lhs->var, rhs->var, ir->write_mask,
+ swizzle);
+ this->acp->push_tail(entry);
+}
+
+bool
+do_copy_propagation_elements(exec_list *instructions)
+{
+ ir_copy_propagation_elements_visitor v;
+
+ visit_list_elements(&v, instructions);
+
+ return v.progress;
+}
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