1 files changed, 259 insertions, 0 deletions
diff --git a/src/compiler/glsl/loop_analysis.h b/src/compiler/glsl/loop_analysis.h
new file mode 100644
index 00000000000..3b1971d7edc
--- /dev/null
+++ b/src/compiler/glsl/loop_analysis.h
@@ -0,0 +1,259 @@
+/* -*- c++ -*- */
+/*
+ * 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.
+ */
+
+#pragma once
+#ifndef LOOP_ANALYSIS_H
+#define LOOP_ANALYSIS_H
+
+#include "ir.h"
+#include "program/hash_table.h"
+
+/**
+ * Analyze and classify all variables used in all loops in the instruction list
+ */
+extern class loop_state *
+analyze_loop_variables(exec_list *instructions);
+
+
+/**
+ * Fill in loop control fields
+ *
+ * Based on analysis of loop variables, this function tries to remove
+ * redundant sequences in the loop of the form
+ *
+ *  (if (expression bool ...) (break))
+ *
+ * For example, if it is provable that one loop exit condition will
+ * always be satisfied before another, the unnecessary exit condition will be
+ * removed.
+ */
+extern bool
+set_loop_controls(exec_list *instructions, loop_state *ls);
+
+
+extern bool
+unroll_loops(exec_list *instructions, loop_state *ls,
+             const struct gl_shader_compiler_options *options);
+
+ir_rvalue *
+find_initial_value(ir_loop *loop, ir_variable *var);
+
+int
+calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment,
+		     enum ir_expression_operation op);
+
+
+/**
+ * Tracking for all variables used in a loop
+ */
+class loop_variable_state : public exec_node {
+public:
+   class loop_variable *get(const ir_variable *);
+   class loop_variable *insert(ir_variable *);
+   class loop_variable *get_or_insert(ir_variable *, bool in_assignee);
+   class loop_terminator *insert(ir_if *);
+
+
+   /**
+    * Variables that have not yet been classified
+    */
+   exec_list variables;
+
+   /**
+    * Variables whose values are constant within the body of the loop
+    *
+    * This list contains \c loop_variable objects.
+    */
+   exec_list constants;
+
+   /**
+    * Induction variables for this loop
+    *
+    * This list contains \c loop_variable objects.
+    */
+   exec_list induction_variables;
+
+   /**
+    * Simple if-statements that lead to the termination of the loop
+    *
+    * This list contains \c loop_terminator objects.
+    *
+    * \sa is_loop_terminator
+    */
+   exec_list terminators;
+
+   /**
+    * If any of the terminators in \c terminators leads to termination of the
+    * loop after a constant number of iterations, this is the terminator that
+    * leads to termination after the smallest number of iterations.  Otherwise
+    * NULL.
+    */
+   loop_terminator *limiting_terminator;
+
+   /**
+    * Hash table containing all variables accessed in this loop
+    */
+   hash_table *var_hash;
+
+   /**
+    * Number of ir_loop_jump instructions that operate on this loop
+    */
+   unsigned num_loop_jumps;
+
+   /**
+    * Whether this loop contains any function calls.
+    */
+   bool contains_calls;
+
+   loop_variable_state()
+   {
+      this->num_loop_jumps = 0;
+      this->contains_calls = false;
+      this->var_hash = hash_table_ctor(0, hash_table_pointer_hash,
+				       hash_table_pointer_compare);
+      this->limiting_terminator = NULL;
+   }
+
+   ~loop_variable_state()
+   {
+      hash_table_dtor(this->var_hash);
+   }
+
+   DECLARE_RALLOC_CXX_OPERATORS(loop_variable_state)
+};
+
+
+class loop_variable : public exec_node {
+public:
+   /** The variable in question. */
+   ir_variable *var;
+
+   /** Is the variable read in the loop before it is written? */
+   bool read_before_write;
+
+   /** Are all variables in the RHS of the assignment loop constants? */
+   bool rhs_clean;
+
+   /**
+    * Is there an assignment to the variable that is conditional, or inside a
+    * nested loop?
+    */
+   bool conditional_or_nested_assignment;
+
+   /** Reference to the first assignment to the variable in the loop body. */
+   ir_assignment *first_assignment;
+
+   /** Number of assignments to the variable in the loop body. */
+   unsigned num_assignments;
+
+   /**
+    * Increment value for a loop induction variable
+    *
+    * If this is a loop induction variable, the amount by which the variable
+    * is incremented on each iteration through the loop.
+    *
+    * If this is not a loop induction variable, NULL.
+    */
+   ir_rvalue *increment;
+
+
+   inline bool is_induction_var() const
+   {
+      /* Induction variables always have a non-null increment, and vice
+       * versa.
+       */
+      return this->increment != NULL;
+   }
+
+
+   inline bool is_loop_constant() const
+   {
+      const bool is_const = (this->num_assignments == 0)
+         || (((this->num_assignments == 1)
+	     && !this->conditional_or_nested_assignment
+	     && !this->read_before_write
+             && this->rhs_clean) || this->var->data.read_only);
+
+      /* If the RHS of *the* assignment is clean, then there must be exactly
+       * one assignment of the variable.
+       */
+      assert((this->rhs_clean && (this->num_assignments == 1))
+	     || !this->rhs_clean);
+
+      return is_const;
+   }
+
+   void record_reference(bool in_assignee,
+                         bool in_conditional_code_or_nested_loop,
+                         ir_assignment *current_assignment);
+};
+
+
+class loop_terminator : public exec_node {
+public:
+   loop_terminator()
+      : ir(NULL), iterations(-1)
+   {
+   }
+
+   /**
+    * Statement which terminates the loop.
+    */
+   ir_if *ir;
+
+   /**
+    * The number of iterations after which the terminator is known to
+    * terminate the loop (if that is a fixed value).  Otherwise -1.
+    */
+   int iterations;
+};
+
+
+class loop_state {
+public:
+   ~loop_state();
+
+   /**
+    * Get the loop variable state data for a particular loop
+    */
+   loop_variable_state *get(const ir_loop *);
+
+   loop_variable_state *insert(ir_loop *ir);
+
+   bool loop_found;
+
+private:
+   loop_state();
+
+   /**
+    * Hash table containing all loops that have been analyzed.
+    */
+   hash_table *ht;
+
+   void *mem_ctx;
+
+   friend loop_state *analyze_loop_variables(exec_list *instructions);
+};
+
+#endif /* LOOP_ANALYSIS_H */