summaryrefslogtreecommitdiffstats
path: root/src/compiler/glsl/opt_constant_folding.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/compiler/glsl/opt_constant_folding.cpp')
-rw-r--r--src/compiler/glsl/opt_constant_folding.cpp190
1 files changed, 190 insertions, 0 deletions
diff --git a/src/compiler/glsl/opt_constant_folding.cpp b/src/compiler/glsl/opt_constant_folding.cpp
new file mode 100644
index 0000000..150a17b
--- /dev/null
+++ b/src/compiler/glsl/opt_constant_folding.cpp
@@ -0,0 +1,190 @@
+/*
+ * 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 */
+
+void
+ir_constant_folding_visitor::handle_rvalue(ir_rvalue **rvalue)
+{
+ if (*rvalue == NULL || (*rvalue)->ir_type == ir_type_constant)
+ return;
+
+ /* 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;
+ }
+ }
+
+ /* Ditto for swizzles. */
+ ir_swizzle *swiz = (*rvalue)->as_swizzle();
+ if (swiz && !swiz->val->as_constant())
+ return;
+
+ ir_constant *constant = (*rvalue)->constant_expression_value();
+ if (constant) {
+ *rvalue = constant;
+ this->progress = true;
+ } else {
+ (*rvalue)->accept(this);
+ }
+}
+
+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;
+}