[Mesa-dev] [PATCH 4/4] glsl: Fold constant folding of assignments into constant propagation
Thomas Helland
thomashelland90 at gmail.com
Thu Apr 6 19:49:08 UTC 2017
We are already calling constant folding functions in our constant
propagation pass. So there is no point in also running a separate
constant folding pass. Port over the remaining functionality from
constant folding, and delete the pass.
---
src/compiler/Makefile.sources | 1 -
src/compiler/glsl/glsl_parser_extras.cpp | 1 -
src/compiler/glsl/ir_optimization.h | 2 -
src/compiler/glsl/opt_constant_folding.cpp | 211 -------------------------
src/compiler/glsl/opt_constant_propagation.cpp | 97 ++++++++++++
5 files changed, 97 insertions(+), 215 deletions(-)
delete mode 100644 src/compiler/glsl/opt_constant_folding.cpp
diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index 817ab3a755..c0be25bb66 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -114,7 +114,6 @@ LIBGLSL_FILES = \
glsl/lower_ubo_reference.cpp \
glsl/opt_algebraic.cpp \
glsl/opt_array_splitting.cpp \
- glsl/opt_constant_folding.cpp \
glsl/opt_constant_propagation.cpp \
glsl/opt_constant_variable.cpp \
glsl/opt_copy_propagation.cpp \
diff --git a/src/compiler/glsl/glsl_parser_extras.cpp b/src/compiler/glsl/glsl_parser_extras.cpp
index fe25c23ccc..5c47f0bd25 100644
--- a/src/compiler/glsl/glsl_parser_extras.cpp
+++ b/src/compiler/glsl/glsl_parser_extras.cpp
@@ -2160,7 +2160,6 @@ do_common_optimization(exec_list *ir, bool linked,
OPT(do_constant_variable, ir);
else
OPT(do_constant_variable_unlinked, ir);
- OPT(do_constant_folding, ir);
OPT(do_minmax_prune, ir);
OPT(do_rebalance_tree, ir);
OPT(do_algebraic, ir, native_integers, options);
diff --git a/src/compiler/glsl/ir_optimization.h b/src/compiler/glsl/ir_optimization.h
index 022b7ab12f..165a2c68ca 100644
--- a/src/compiler/glsl/ir_optimization.h
+++ b/src/compiler/glsl/ir_optimization.h
@@ -88,8 +88,6 @@ bool do_common_optimization(exec_list *ir, bool linked,
const struct gl_shader_compiler_options *options,
bool native_integers);
-bool ir_constant_fold(ir_rvalue **rvalue);
-
bool do_rebalance_tree(exec_list *instructions);
bool do_algebraic(exec_list *instructions, bool native_integers,
const struct gl_shader_compiler_options *options);
diff --git a/src/compiler/glsl/opt_constant_folding.cpp b/src/compiler/glsl/opt_constant_folding.cpp
deleted file mode 100644
index 97dcc7e1ac..0000000000
--- a/src/compiler/glsl/opt_constant_folding.cpp
+++ /dev/null
@@ -1,211 +0,0 @@
-/*
- * 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_constant_folding.cpp
- * Replace constant-valued expressions with references to constant values.
- */
-
-#include "ir.h"
-#include "ir_visitor.h"
-#include "ir_rvalue_visitor.h"
-#include "ir_optimization.h"
-#include "compiler/glsl_types.h"
-
-namespace {
-
-/**
- * Visitor class for replacing expressions with ir_constant values.
- */
-
-class ir_constant_folding_visitor : public ir_rvalue_visitor {
-public:
- ir_constant_folding_visitor()
- {
- this->progress = false;
- }
-
- virtual ~ir_constant_folding_visitor()
- {
- /* empty */
- }
-
- virtual ir_visitor_status visit_enter(ir_discard *ir);
- virtual ir_visitor_status visit_enter(ir_assignment *ir);
- virtual ir_visitor_status visit_enter(ir_call *ir);
-
- virtual void handle_rvalue(ir_rvalue **rvalue);
-
- bool progress;
-};
-
-} /* unnamed namespace */
-
-bool
-ir_constant_fold(ir_rvalue **rvalue)
-{
- if (*rvalue == NULL || (*rvalue)->ir_type == ir_type_constant)
- return false;
-
- /* Note that we do rvalue visitoring on leaving. So if an
- * expression has a non-constant operand, no need to go looking
- * down it to find if it's constant. This cuts the time of this
- * pass down drastically.
- */
- ir_expression *expr = (*rvalue)->as_expression();
- if (expr) {
- for (unsigned int i = 0; i < expr->get_num_operands(); i++) {
- if (!expr->operands[i]->as_constant())
- return false;
- }
- }
-
- /* Ditto for swizzles. */
- ir_swizzle *swiz = (*rvalue)->as_swizzle();
- if (swiz && !swiz->val->as_constant())
- return false;
-
- /* Ditto for array dereferences */
- ir_dereference_array *array_ref = (*rvalue)->as_dereference_array();
- if (array_ref && (!array_ref->array->as_constant() ||
- !array_ref->array_index->as_constant()))
- return false;
-
- /* No constant folding can be performed on variable dereferences. We need
- * to explicitly avoid them, as calling constant_expression_value() on a
- * variable dereference will return a clone of var->constant_value. This
- * would make us propagate the value into the tree, which isn't our job.
- */
- ir_dereference_variable *var_ref = (*rvalue)->as_dereference_variable();
- if (var_ref)
- return false;
-
- ir_constant *constant = (*rvalue)->constant_expression_value();
- if (constant) {
- *rvalue = constant;
- return true;
- }
- return false;
-}
-
-void
-ir_constant_folding_visitor::handle_rvalue(ir_rvalue **rvalue)
-{
- if (ir_constant_fold(rvalue))
- this->progress = true;
-}
-
-ir_visitor_status
-ir_constant_folding_visitor::visit_enter(ir_discard *ir)
-{
- if (ir->condition) {
- ir->condition->accept(this);
- handle_rvalue(&ir->condition);
-
- ir_constant *const_val = ir->condition->as_constant();
- /* If the condition is constant, either remove the condition or
- * remove the never-executed assignment.
- */
- if (const_val) {
- if (const_val->value.b[0])
- ir->condition = NULL;
- else
- ir->remove();
- this->progress = true;
- }
- }
-
- return visit_continue_with_parent;
-}
-
-ir_visitor_status
-ir_constant_folding_visitor::visit_enter(ir_assignment *ir)
-{
- ir->rhs->accept(this);
- handle_rvalue(&ir->rhs);
-
- if (ir->condition) {
- ir->condition->accept(this);
- handle_rvalue(&ir->condition);
-
- ir_constant *const_val = ir->condition->as_constant();
- /* If the condition is constant, either remove the condition or
- * remove the never-executed assignment.
- */
- if (const_val) {
- if (const_val->value.b[0])
- ir->condition = NULL;
- else
- ir->remove();
- this->progress = true;
- }
- }
-
- /* Don't descend into the LHS because we want it to stay as a
- * variable dereference. FINISHME: We probably should to get array
- * indices though.
- */
- return visit_continue_with_parent;
-}
-
-ir_visitor_status
-ir_constant_folding_visitor::visit_enter(ir_call *ir)
-{
- /* Attempt to constant fold parameters */
- foreach_two_lists(formal_node, &ir->callee->parameters,
- actual_node, &ir->actual_parameters) {
- ir_rvalue *param_rval = (ir_rvalue *) actual_node;
- ir_variable *sig_param = (ir_variable *) formal_node;
-
- if (sig_param->data.mode == ir_var_function_in
- || sig_param->data.mode == ir_var_const_in) {
- ir_rvalue *new_param = param_rval;
-
- handle_rvalue(&new_param);
- if (new_param != param_rval) {
- param_rval->replace_with(new_param);
- }
- }
- }
-
- /* Next, see if the call can be replaced with an assignment of a constant */
- ir_constant *const_val = ir->constant_expression_value();
-
- if (const_val != NULL) {
- ir_assignment *assignment =
- new(ralloc_parent(ir)) ir_assignment(ir->return_deref, const_val);
- ir->replace_with(assignment);
- }
-
- return visit_continue_with_parent;
-}
-
-bool
-do_constant_folding(exec_list *instructions)
-{
- ir_constant_folding_visitor constant_folding;
-
- visit_list_elements(&constant_folding, instructions);
-
- return constant_folding.progress;
-}
diff --git a/src/compiler/glsl/opt_constant_propagation.cpp b/src/compiler/glsl/opt_constant_propagation.cpp
index 4039512097..055587f7e1 100644
--- a/src/compiler/glsl/opt_constant_propagation.cpp
+++ b/src/compiler/glsl/opt_constant_propagation.cpp
@@ -115,6 +115,7 @@ public:
virtual ir_visitor_status visit_enter(class ir_function_signature *);
virtual ir_visitor_status visit_enter(class ir_function *);
virtual ir_visitor_status visit_leave(class ir_assignment *);
+ virtual ir_visitor_status visit_enter(ir_discard *ir);
virtual ir_visitor_status visit_enter(class ir_call *);
virtual ir_visitor_status visit_enter(class ir_if *);
@@ -142,6 +143,52 @@ public:
void *lin_ctx;
};
+bool
+ir_constant_fold(ir_rvalue **rvalue)
+{
+ if (*rvalue == NULL || (*rvalue)->ir_type == ir_type_constant)
+ return false;
+
+ /* Note that we do rvalue visitoring on leaving. So if an
+ * expression has a non-constant operand, no need to go looking
+ * down it to find if it's constant. This cuts the time of this
+ * pass down drastically.
+ */
+ ir_expression *expr = (*rvalue)->as_expression();
+ if (expr) {
+ for (unsigned int i = 0; i < expr->get_num_operands(); i++) {
+ if (!expr->operands[i]->as_constant())
+ return false;
+ }
+ }
+
+ /* Ditto for swizzles. */
+ ir_swizzle *swiz = (*rvalue)->as_swizzle();
+ if (swiz && !swiz->val->as_constant())
+ return false;
+
+ /* Ditto for array dereferences */
+ ir_dereference_array *array_ref = (*rvalue)->as_dereference_array();
+ if (array_ref && (!array_ref->array->as_constant() ||
+ !array_ref->array_index->as_constant()))
+ return false;
+
+ /* No constant folding can be performed on variable dereferences. We need
+ * to explicitly avoid them, as calling constant_expression_value() on a
+ * variable dereference will return a clone of var->constant_value. This
+ * would make us propagate the value into the tree, which isn't our job.
+ */
+ ir_dereference_variable *var_ref = (*rvalue)->as_dereference_variable();
+ if (var_ref)
+ return false;
+
+ ir_constant *constant = (*rvalue)->constant_expression_value();
+ if (constant) {
+ *rvalue = constant;
+ return true;
+ }
+ return false;
+}
void
ir_constant_propagation_visitor::constant_folding(ir_rvalue **rvalue)
@@ -284,6 +331,24 @@ ir_constant_propagation_visitor::visit_leave(ir_assignment *ir)
{
constant_folding(&ir->rhs);
+ if (ir->condition) {
+ ir->condition->accept(this);
+ constant_folding(&ir->condition);
+
+ ir_constant *const_val = ir->condition->as_constant();
+ /* If the condition is constant, either remove the condition or
+ * remove the never-executed assignment.
+ */
+ if (const_val) {
+ if (const_val->value.b[0])
+ ir->condition = NULL;
+ else
+ ir->remove();
+ this->progress = true;
+ return visit_continue;
+ }
+ }
+
if (this->in_assignee)
return visit_continue;
@@ -339,6 +404,15 @@ ir_constant_propagation_visitor::visit_enter(ir_call *ir)
}
}
+ /* Next, see if the call can be replaced with an assignment of a constant */
+ ir_constant *const_val = ir->constant_expression_value();
+
+ if (const_val != NULL) {
+ ir_assignment *assignment =
+ new(ralloc_parent(ir)) ir_assignment(ir->return_deref, const_val);
+ ir->replace_with(assignment);
+ }
+
/* Since we're unlinked, we don't (necssarily) know the side effects of
* this call. So kill all copies.
*/
@@ -465,6 +539,29 @@ ir_constant_propagation_visitor::kill(ir_variable *var, unsigned write_mask)
new(this->lin_ctx) kill_entry(var, write_mask));
}
+ir_visitor_status
+ir_constant_propagation_visitor::visit_enter(ir_discard *ir)
+{
+ if (ir->condition) {
+ ir->condition->accept(this);
+ handle_rvalue(&ir->condition);
+
+ ir_constant *const_val = ir->condition->as_constant();
+ /* If the condition is constant, either remove the condition or
+ * remove the never-executed assignment.
+ */
+ if (const_val) {
+ if (const_val->value.b[0])
+ ir->condition = NULL;
+ else
+ ir->remove();
+ this->progress = true;
+ }
+ }
+
+ return visit_continue_with_parent;
+}
+
/**
* Adds an entry to the available constant list if it's a plain assignment
* of a variable to a variable.
--
2.11.1
More information about the mesa-dev
mailing list