glsl: Add a variable context to constant_expression_value().

Signed-off-by: Olivier Galibert <galibert@pobox.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net> [v1]

src/glsl/ast_function.cpp

@@ -278,7 +278,7 @@ generate_call(exec_list *instructions, ir_function_signature *sig,
     * Function calls were first allowed to be constant expressions in GLSL 1.20.
     */
    if (state->language_version >= 120) {
-      ir_constant *value = sig->constant_expression_value(actual_parameters);
+      ir_constant *value = sig->constant_expression_value(actual_parameters, NULL);
       if (value != NULL) {
 	 return value;
       }

src/glsl/ir.h

@@ -146,7 +146,7 @@ public:
 
    virtual ir_visitor_status accept(ir_hierarchical_visitor *);
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual ir_rvalue * as_rvalue()
    {
@@ -502,10 +502,11 @@ public:
    virtual ir_visitor_status accept(ir_hierarchical_visitor *);
 
    /**
-    * Attempt to evaluate this function as a constant expression, given
-    * a list of the actual parameters.  Returns NULL for non-built-ins.
+    * Attempt to evaluate this function as a constant expression,
+    * given a list of the actual parameters and the variable context.
+    * Returns NULL for non-built-ins.
     */
-   ir_constant *constant_expression_value(exec_list *actual_parameters);
+   ir_constant *constant_expression_value(exec_list *actual_parameters, struct hash_table *variable_context);
 
    /**
     * Get the name of the function for which this is a signature
@@ -763,7 +764,7 @@ public:
 
    virtual ir_assignment *clone(void *mem_ctx, struct hash_table *ht) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual void accept(ir_visitor *v)
    {
@@ -999,10 +1000,14 @@ public:
    /**
     * Attempt to constant-fold the expression
     *
+    * The "variable_context" hash table links ir_variable * to ir_constant *
+    * that represent the variables' values.  \c NULL represents an empty
+    * context.
+    *
     * If the expression cannot be constant folded, this method will return
     * \c NULL.
     */
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    /**
     * Determine the number of operands used by an expression
@@ -1065,7 +1070,7 @@ public:
 
    virtual ir_call *clone(void *mem_ctx, struct hash_table *ht) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual ir_call *as_call()
    {
@@ -1297,7 +1302,7 @@ public:
 
    virtual ir_texture *clone(void *mem_ctx, struct hash_table *) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual void accept(ir_visitor *v)
    {
@@ -1389,7 +1394,7 @@ public:
 
    virtual ir_swizzle *clone(void *mem_ctx, struct hash_table *) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual ir_swizzle *as_swizzle()
    {
@@ -1456,7 +1461,7 @@ public:
    virtual ir_dereference_variable *clone(void *mem_ctx,
 					  struct hash_table *) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual ir_dereference_variable *as_dereference_variable()
    {
@@ -1505,7 +1510,7 @@ public:
    virtual ir_dereference_array *clone(void *mem_ctx,
 				       struct hash_table *) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual ir_dereference_array *as_dereference_array()
    {
@@ -1544,7 +1549,7 @@ public:
    virtual ir_dereference_record *clone(void *mem_ctx,
 					struct hash_table *) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    /**
     * Get the variable that is ultimately referenced by an r-value
@@ -1609,7 +1614,7 @@ public:
 
    virtual ir_constant *clone(void *mem_ctx, struct hash_table *) const;
 
-   virtual ir_constant *constant_expression_value();
+   virtual ir_constant *constant_expression_value(struct hash_table *variable_context = NULL);
 
    virtual ir_constant *as_constant()
    {

src/glsl/ir_constant_expression.cpp

@@ -38,6 +38,7 @@
 #include "ir.h"
 #include "ir_visitor.h"
 #include "glsl_types.h"
+#include "program/hash_table.h"
 
 /* Using C99 rounding functions for roundToEven() implementation is
  * difficult, because round(), rint, and nearbyint() are affected by
@@ -71,14 +72,14 @@ dot(ir_constant *op0, ir_constant *op1)
 }
 
 ir_constant *
-ir_rvalue::constant_expression_value()
+ir_rvalue::constant_expression_value(struct hash_table *variable_context)
 {
    assert(this->type->is_error());
    return NULL;
 }
 
 ir_constant *
-ir_expression::constant_expression_value()
+ir_expression::constant_expression_value(struct hash_table *variable_context)
 {
    if (this->type->is_error())
       return NULL;
@@ -89,7 +90,7 @@ ir_expression::constant_expression_value()
    memset(&data, 0, sizeof(data));
 
    for (unsigned operand = 0; operand < this->get_num_operands(); operand++) {
-      op[operand] = this->operands[operand]->constant_expression_value();
+      op[operand] = this->operands[operand]->constant_expression_value(variable_context);
       if (!op[operand])
 	 return NULL;
    }
@@ -886,7 +887,7 @@ ir_expression::constant_expression_value()
 
 
 ir_constant *
-ir_texture::constant_expression_value()
+ir_texture::constant_expression_value(struct hash_table *variable_context)
 {
    /* texture lookups aren't constant expressions */
    return NULL;
@@ -894,9 +895,9 @@ ir_texture::constant_expression_value()
 
 
 ir_constant *
-ir_swizzle::constant_expression_value()
+ir_swizzle::constant_expression_value(struct hash_table *variable_context)
 {
-   ir_constant *v = this->val->constant_expression_value();
+   ir_constant *v = this->val->constant_expression_value(variable_context);
 
    if (v != NULL) {
       ir_constant_data data = { { 0 } };
@@ -923,12 +924,19 @@ ir_swizzle::constant_expression_value()
 
 
 ir_constant *
-ir_dereference_variable::constant_expression_value()
+ir_dereference_variable::constant_expression_value(struct hash_table *variable_context)
 {
    /* This may occur during compile and var->type is glsl_type::error_type */
    if (!var)
       return NULL;
 
+   /* Give priority to the context hashtable, if it exists */
+   if (variable_context) {
+      ir_constant *value = (ir_constant *)hash_table_find(variable_context, var);
+      if(value)
+	 return value;
+   }
+
    /* The constant_value of a uniform variable is its initializer,
     * not the lifetime constant value of the uniform.
     */
@@ -943,10 +951,10 @@ ir_dereference_variable::constant_expression_value()
 
 
 ir_constant *
-ir_dereference_array::constant_expression_value()
+ir_dereference_array::constant_expression_value(struct hash_table *variable_context)
 {
-   ir_constant *array = this->array->constant_expression_value();
-   ir_constant *idx = this->array_index->constant_expression_value();
+   ir_constant *array = this->array->constant_expression_value(variable_context);
+   ir_constant *idx = this->array_index->constant_expression_value(variable_context);
 
    if ((array != NULL) && (idx != NULL)) {
       void *ctx = ralloc_parent(this);
@@ -998,7 +1006,7 @@ ir_dereference_array::constant_expression_value()
 
 
 ir_constant *
-ir_dereference_record::constant_expression_value()
+ir_dereference_record::constant_expression_value(struct hash_table *variable_context)
 {
    ir_constant *v = this->record->constant_expression_value();
 
@@ -1007,7 +1015,7 @@ ir_dereference_record::constant_expression_value()
 
 
 ir_constant *
-ir_assignment::constant_expression_value()
+ir_assignment::constant_expression_value(struct hash_table *variable_context)
 {
    /* FINISHME: Handle CEs involving assignment (return RHS) */
    return NULL;
@@ -1015,21 +1023,21 @@ ir_assignment::constant_expression_value()
 
 
 ir_constant *
-ir_constant::constant_expression_value()
+ir_constant::constant_expression_value(struct hash_table *variable_context)
 {
    return this;
 }
 
 
 ir_constant *
-ir_call::constant_expression_value()
+ir_call::constant_expression_value(struct hash_table *variable_context)
 {
-   return this->callee->constant_expression_value(&this->actual_parameters);
+   return this->callee->constant_expression_value(&this->actual_parameters, variable_context);
 }
 
 
 ir_constant *
-ir_function_signature::constant_expression_value(exec_list *actual_parameters)
+ir_function_signature::constant_expression_value(exec_list *actual_parameters, struct hash_table *variable_context)
 {
    const glsl_type *type = this->return_type;
    if (type == glsl_type::void_type)
@@ -1047,7 +1055,7 @@ ir_function_signature::constant_expression_value(exec_list *actual_parameters)
    /* Check if all parameters are constant */
    ir_constant *op[3];
    foreach_list(n, actual_parameters) {
-      ir_constant *constant = ((ir_rvalue *) n)->constant_expression_value();
+      ir_constant *constant = ((ir_rvalue *) n)->constant_expression_value(variable_context);
       if (constant == NULL)
 	 return NULL;