glsl2: Add and use new variable mode ir_var_temporary

[mesa.git] / src / glsl / ast_function.cpp

/*
 * 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.
 */

#include "glsl_symbol_table.h"
#include "ast.h"
#include "glsl_types.h"
#include "ir.h"

inline unsigned min(unsigned a, unsigned b)
{
   return (a < b) ? a : b;
}

static ir_rvalue *
convert_component(ir_rvalue *src, const glsl_type *desired_type);

static unsigned
process_parameters(exec_list *instructions, exec_list *actual_parameters,
                   exec_list *parameters,
                   struct _mesa_glsl_parse_state *state)
{
   unsigned count = 0;

   foreach_list (n, parameters) {
      ast_node *const ast = exec_node_data(ast_node, n, link);
      ir_rvalue *result = ast->hir(instructions, state);

      ir_constant *const constant = result->constant_expression_value();
      if (constant != NULL)
         result = constant;

      actual_parameters->push_tail(result);
      count++;
   }

   return count;
}


static ir_rvalue *
process_call(exec_list *instructions, ir_function *f,
             YYLTYPE *loc, exec_list *actual_parameters,
             struct _mesa_glsl_parse_state *state)
{
   void *ctx = state;

   ir_function_signature *sig = f->matching_signature(actual_parameters);

   /* The instructions param will be used when the FINISHMEs below are done */
   (void) instructions;

   if (sig != NULL) {
      /* Verify that 'out' and 'inout' actual parameters are lvalues.  This
       * isn't done in ir_function::matching_signature because that function
       * cannot generate the necessary diagnostics.
       */
      exec_list_iterator actual_iter = actual_parameters->iterator();
      exec_list_iterator formal_iter = sig->parameters.iterator();

      while (actual_iter.has_next()) {
         ir_rvalue *actual = (ir_rvalue *) actual_iter.get();
         ir_variable *formal = (ir_variable *) formal_iter.get();

         assert(actual != NULL);
         assert(formal != NULL);

         if ((formal->mode == ir_var_out)
             || (formal->mode == ir_var_inout)) {
            if (! actual->is_lvalue()) {
               /* FINISHME: Log a better diagnostic here.  There is no way
                * FINISHME: to tell the user which parameter is invalid.
                */
               _mesa_glsl_error(loc, state, "`%s' parameter is not lvalue",
                                (formal->mode == ir_var_out) ? "out" : "inout");
            }
         }

         if (formal->type->is_numeric() || formal->type->is_boolean()) {
            ir_rvalue *converted = convert_component(actual, formal->type);
            actual->replace_with(converted);
         }

         actual_iter.next();
         formal_iter.next();
      }

      /* Always insert the call in the instruction stream, and return a deref
       * of its return val if it returns a value, since we don't know if
       * the rvalue is going to be assigned to anything or not.
       */
      ir_call *call = new(ctx) ir_call(sig, actual_parameters);
      if (!sig->return_type->is_void()) {
         ir_variable *var;
         ir_dereference_variable *deref;

         var = new(ctx) ir_variable(sig->return_type,
                                    talloc_asprintf(ctx, "%s_retval",
                                                    sig->function_name()),
                                    ir_var_temporary);
         instructions->push_tail(var);

         deref = new(ctx) ir_dereference_variable(var);
         ir_assignment *assign = new(ctx) ir_assignment(deref, call, NULL);
         instructions->push_tail(assign);

         deref = new(ctx) ir_dereference_variable(var);
         return deref;
      } else {
         instructions->push_tail(call);
         return NULL;
      }
   } else {
      /* FINISHME: Log a better error message here.  G++ will show the types
       * FINISHME: of the actual parameters and the set of candidate
       * FINISHME: functions.  A different error should also be logged when
       * FINISHME: multiple functions match.
       */
      _mesa_glsl_error(loc, state, "no matching function for call to `%s'",
                       f->name);
      return ir_call::get_error_instruction(ctx);
   }
}


static ir_rvalue *
match_function_by_name(exec_list *instructions, const char *name,
                       YYLTYPE *loc, exec_list *actual_parameters,
                       struct _mesa_glsl_parse_state *state)
{
   void *ctx = state;
   ir_function *f = state->symbols->get_function(name);

   if (f == NULL) {
      _mesa_glsl_error(loc, state, "function `%s' undeclared", name);
      return ir_call::get_error_instruction(ctx);
   }

   /* Once we've determined that the function being called might exist, try
    * to find an overload of the function that matches the parameters.
    */
   return process_call(instructions, f, loc, actual_parameters, state);
}


/**
 * Perform automatic type conversion of constructor parameters
 */
static ir_rvalue *
convert_component(ir_rvalue *src, const glsl_type *desired_type)
{
   void *ctx = talloc_parent(src);
   const unsigned a = desired_type->base_type;
   const unsigned b = src->type->base_type;
   ir_expression *result = NULL;

   if (src->type->is_error())
      return src;

   assert(a <= GLSL_TYPE_BOOL);
   assert(b <= GLSL_TYPE_BOOL);

   if ((a == b) || (src->type->is_integer() && desired_type->is_integer()))
      return src;

   switch (a) {
   case GLSL_TYPE_UINT:
   case GLSL_TYPE_INT:
      if (b == GLSL_TYPE_FLOAT)
         result = new(ctx) ir_expression(ir_unop_f2i, desired_type, src, NULL);
      else {
         assert(b == GLSL_TYPE_BOOL);
         result = new(ctx) ir_expression(ir_unop_b2i, desired_type, src, NULL);
      }
      break;
   case GLSL_TYPE_FLOAT:
      switch (b) {
      case GLSL_TYPE_UINT:
         result = new(ctx) ir_expression(ir_unop_u2f, desired_type, src, NULL);
         break;
      case GLSL_TYPE_INT:
         result = new(ctx) ir_expression(ir_unop_i2f, desired_type, src, NULL);
         break;
      case GLSL_TYPE_BOOL:
         result = new(ctx) ir_expression(ir_unop_b2f, desired_type, src, NULL);
         break;
      }
      break;
   case GLSL_TYPE_BOOL:
      switch (b) {
      case GLSL_TYPE_UINT:
      case GLSL_TYPE_INT:
         result = new(ctx) ir_expression(ir_unop_i2b, desired_type, src, NULL);
         break;
      case GLSL_TYPE_FLOAT:
         result = new(ctx) ir_expression(ir_unop_f2b, desired_type, src, NULL);
         break;
      }
      break;
   }

   assert(result != NULL);

   ir_constant *const constant = result->constant_expression_value();
   return (constant != NULL) ? (ir_rvalue *) constant : (ir_rvalue *) result;
}


/**
 * Dereference a specific component from a scalar, vector, or matrix
 */
static ir_rvalue *
dereference_component(ir_rvalue *src, unsigned component)
{
   void *ctx = talloc_parent(src);
   assert(component < src->type->components());

   /* If the source is a constant, just create a new constant instead of a
    * dereference of the existing constant.
    */
   ir_constant *constant = src->as_constant();
   if (constant)
      return new(ctx) ir_constant(constant, component);

   if (src->type->is_scalar()) {
      return src;
   } else if (src->type->is_vector()) {
      return new(ctx) ir_swizzle(src, component, 0, 0, 0, 1);
   } else {
      assert(src->type->is_matrix());

      /* Dereference a row of the matrix, then call this function again to get
       * a specific element from that row.
       */
      const int c = component / src->type->column_type()->vector_elements;
      const int r = component % src->type->column_type()->vector_elements;
      ir_constant *const col_index = new(ctx) ir_constant(c);
      ir_dereference *const col = new(ctx) ir_dereference_array(src, col_index);

      col->type = src->type->column_type();

      return dereference_component(col, r);
   }

   assert(!"Should not get here.");
   return NULL;
}


static ir_rvalue *
process_array_constructor(exec_list *instructions,
                          const glsl_type *constructor_type,
                          YYLTYPE *loc, exec_list *parameters,
                          struct _mesa_glsl_parse_state *state)
{
   void *ctx = state;
   /* Array constructors come in two forms: sized and unsized.  Sized array
    * constructors look like 'vec4[2](a, b)', where 'a' and 'b' are vec4
    * variables.  In this case the number of parameters must exactly match the
    * specified size of the array.
    *
    * Unsized array constructors look like 'vec4[](a, b)', where 'a' and 'b'
    * are vec4 variables.  In this case the size of the array being constructed
    * is determined by the number of parameters.
    *
    * From page 52 (page 58 of the PDF) of the GLSL 1.50 spec:
    *
    *    "There must be exactly the same number of arguments as the size of
    *    the array being constructed. If no size is present in the
    *    constructor, then the array is explicitly sized to the number of
    *    arguments provided. The arguments are assigned in order, starting at
    *    element 0, to the elements of the constructed array. Each argument
    *    must be the same type as the element type of the array, or be a type
    *    that can be converted to the element type of the array according to
    *    Section 4.1.10 "Implicit Conversions.""
    */
   exec_list actual_parameters;
   const unsigned parameter_count =
      process_parameters(instructions, &actual_parameters, parameters, state);

   if ((parameter_count == 0)
       || ((constructor_type->length != 0)
           && (constructor_type->length != parameter_count))) {
      const unsigned min_param = (constructor_type->length == 0)
         ? 1 : constructor_type->length;

      _mesa_glsl_error(loc, state, "array constructor must have %s %u "
                       "parameter%s",
                       (constructor_type->length != 0) ? "at least" : "exactly",
                       min_param, (min_param <= 1) ? "" : "s");
      return ir_call::get_error_instruction(ctx);
   }

   if (constructor_type->length == 0) {
      constructor_type =
         glsl_type::get_array_instance(state,
                                       constructor_type->element_type(),
                                       parameter_count);
      assert(constructor_type != NULL);
      assert(constructor_type->length == parameter_count);
   }

   ir_function *f = state->symbols->get_function(constructor_type->name);

   /* If the constructor for this type of array does not exist, generate the
    * prototype and add it to the symbol table.
    */
   if (f == NULL) {
      f = constructor_type->generate_constructor(state->symbols);
   }

   ir_rvalue *const r =
      process_call(instructions, f, loc, &actual_parameters, state);

   assert(r != NULL);
   assert(r->type->is_error() || (r->type == constructor_type));

   return r;
}


/**
 * Try to convert a record constructor to a constant expression
 */
static ir_constant *
constant_record_constructor(const glsl_type *constructor_type,
                            YYLTYPE *loc, exec_list *parameters,
                            struct _mesa_glsl_parse_state *state)
{
   void *ctx = state;
   bool all_parameters_are_constant = true;

   exec_node *node = parameters->head;
   for (unsigned i = 0; i < constructor_type->length; i++) {
      ir_instruction *ir = (ir_instruction *) node;

      if (node->is_tail_sentinal()) {
         _mesa_glsl_error(loc, state,
                          "insufficient parameters to constructor for `%s'",
                          constructor_type->name);
         return NULL;
      }

      if (ir->type != constructor_type->fields.structure[i].type) {
         _mesa_glsl_error(loc, state,
                          "parameter type mismatch in constructor for `%s' "
                          " (%s vs %s)",
                          constructor_type->name,
                          ir->type->name,
                          constructor_type->fields.structure[i].type->name);
         return NULL;
      }

      if (ir->as_constant() == NULL)
         all_parameters_are_constant = false;

      node = node->next;
   }

   if (!all_parameters_are_constant)
      return NULL;

   return new(ctx) ir_constant(constructor_type, parameters);
}


/**
 * Generate data for a constant matrix constructor w/a single scalar parameter
 *
 * Matrix constructors in GLSL can be passed a single scalar of the
 * approriate type.  In these cases, the resulting matrix is the identity
 * matrix multipled by the specified scalar.  This function generates data for
 * that matrix.
 *
 * \param type         Type of the desired matrix.
 * \param initializer  Scalar value used to initialize the matrix diagonal.
 * \param data         Location to store the resulting matrix.
 */
void
generate_constructor_matrix(const glsl_type *type, ir_constant *initializer,
                            ir_constant_data *data)
{
   switch (type->base_type) {
   case GLSL_TYPE_UINT:
   case GLSL_TYPE_INT:
      for (unsigned i = 0; i < type->components(); i++)
         data->u[i] = 0;

      for (unsigned i = 0; i < type->matrix_columns; i++) {
         /* The array offset of the ith row and column of the matrix.
          */
         const unsigned idx = (i * type->vector_elements) + i;

         data->u[idx] = initializer->value.u[0];
      }
      break;

   case GLSL_TYPE_FLOAT:
      for (unsigned i = 0; i < type->components(); i++)
         data->f[i] = 0;

      for (unsigned i = 0; i < type->matrix_columns; i++) {
         /* The array offset of the ith row and column of the matrix.
          */
         const unsigned idx = (i * type->vector_elements) + i;

         data->f[idx] = initializer->value.f[0];
      }

      break;

   default:
      assert(!"Should not get here.");
      break;
   }
}


/**
 * Generate data for a constant vector constructor w/a single scalar parameter
 *
 * Vector constructors in GLSL can be passed a single scalar of the
 * approriate type.  In these cases, the resulting vector contains the specified
 * value in all components.  This function generates data for that vector.
 *
 * \param type         Type of the desired vector.
 * \param initializer  Scalar value used to initialize the vector.
 * \param data         Location to store the resulting vector data.
 */
void
generate_constructor_vector(const glsl_type *type, ir_constant *initializer,
                            ir_constant_data *data)
{
   switch (type->base_type) {
   case GLSL_TYPE_UINT:
   case GLSL_TYPE_INT:
      for (unsigned i = 0; i < type->components(); i++)
         data->u[i] = initializer->value.u[0];

      break;

   case GLSL_TYPE_FLOAT:
      for (unsigned i = 0; i < type->components(); i++)
         data->f[i] = initializer->value.f[0];

      break;

   case GLSL_TYPE_BOOL:
      for (unsigned i = 0; i < type->components(); i++)
         data->b[i] = initializer->value.b[0];

      break;

   default:
      assert(!"Should not get here.");
      break;
   }
}


/**
 * Determine if a list consists of a single scalar r-value
 */
bool
single_scalar_parameter(exec_list *parameters)
{
   const ir_rvalue *const p = (ir_rvalue *) parameters->head;
   assert(((ir_rvalue *)p)->as_rvalue() != NULL);

   return (p->type->is_scalar() && p->next->is_tail_sentinal());
}


/**
 * Generate inline code for a vector constructor
 *
 * The generated constructor code will consist of a temporary variable
 * declaration of the same type as the constructor.  A sequence of assignments
 * from constructor parameters to the temporary will follow.
 *
 * \return
 * An \c ir_dereference_variable of the temprorary generated in the constructor
 * body.
 */
ir_rvalue *
emit_inline_vector_constructor(const glsl_type *type,
                               exec_list *instructions,
                               exec_list *parameters,
                               void *ctx)
{
   assert(!parameters->is_empty());

   ir_variable *var = new(ctx) ir_variable(type,
                                           talloc_strdup(ctx, "vec_ctor"),
                                           ir_var_temporary);
   instructions->push_tail(var);

   /* There are two kinds of vector constructors.
    *
    *  - Construct a vector from a single scalar by replicating that scalar to
    *    all components of the vector.
    *
    *  - Construct a vector from an arbirary combination of vectors and
    *    scalars.  The components of the constructor parameters are assigned
    *    to the vector in order until the vector is full.
    */
   const unsigned lhs_components = type->components();
   if (single_scalar_parameter(parameters)) {
      ir_rvalue *first_param = (ir_rvalue *)parameters->head;
      ir_rvalue *rhs = new(ctx) ir_swizzle(first_param, 0, 0, 0, 0,
                                           lhs_components);
      ir_dereference_variable *lhs = new(ctx) ir_dereference_variable(var);

      assert(rhs->type == lhs->type);

      ir_instruction *inst = new(ctx) ir_assignment(lhs, rhs, NULL);
      instructions->push_tail(inst);
   } else {
      unsigned base_component = 0;
      foreach_list(node, parameters) {
         ir_rvalue *rhs = (ir_rvalue *) node;
         unsigned rhs_components = rhs->type->components();

         /* Do not try to assign more components to the vector than it has!
          */
         if ((rhs_components + base_component) > lhs_components) {
            rhs_components = lhs_components - base_component;
         }

         /* Emit an assignment of the constructor parameter to the next set of
          * components in the temporary variable.
          */
         unsigned mask[4] = { 0, 0, 0, 0 };
         for (unsigned i = 0; i < rhs_components; i++) {
            mask[i] = i + base_component;
         }


         ir_rvalue *lhs_ref = new(ctx) ir_dereference_variable(var);
         ir_swizzle *lhs = new(ctx) ir_swizzle(lhs_ref, mask, rhs_components);

         ir_instruction *inst = new(ctx) ir_assignment(lhs, rhs, NULL);
         instructions->push_tail(inst);

         /* Advance the component index by the number of components that were
          * just assigned.
          */
         base_component += rhs_components;
      }
   }
   return new(ctx) ir_dereference_variable(var);
}


/**
 * Generate assignment of a portion of a vector to a portion of a matrix column
 *
 * \param src_base  First component of the source to be used in assignment
 * \param column    Column of destination to be assiged
 * \param row_base  First component of the destination column to be assigned
 * \param count     Number of components to be assigned
 *
 * \note
 * \c src_base + \c count must be less than or equal to the number of components
 * in the source vector.
 */
ir_instruction *
assign_to_matrix_column(ir_variable *var, unsigned column, unsigned row_base,
                        ir_rvalue *src, unsigned src_base, unsigned count,
                        TALLOC_CTX *ctx)
{
   const unsigned mask[8] = { 0, 1, 2, 3, 0, 0, 0, 0 };

   ir_constant *col_idx = new(ctx) ir_constant(column);
   ir_rvalue *column_ref = new(ctx) ir_dereference_array(var, col_idx);

   assert(column_ref->type->components() >= (row_base + count));
   ir_rvalue *lhs = new(ctx) ir_swizzle(column_ref, &mask[row_base], count);

   assert(src->type->components() >= (src_base + count));
   ir_rvalue *rhs = new(ctx) ir_swizzle(src, &mask[src_base], count);

   return new(ctx) ir_assignment(lhs, rhs, NULL);
}


/**
 * Generate inline code for a matrix constructor
 *
 * The generated constructor code will consist of a temporary variable
 * declaration of the same type as the constructor.  A sequence of assignments
 * from constructor parameters to the temporary will follow.
 *
 * \return
 * An \c ir_dereference_variable of the temprorary generated in the constructor
 * body.
 */
ir_rvalue *
emit_inline_matrix_constructor(const glsl_type *type,
                               exec_list *instructions,
                               exec_list *parameters,
                               void *ctx)
{
   assert(!parameters->is_empty());

   ir_variable *var = new(ctx) ir_variable(type,
                                           talloc_strdup(ctx, "mat_ctor"),
                                           ir_var_temporary);
   instructions->push_tail(var);

   /* There are three kinds of matrix constructors.
    *
    *  - Construct a matrix from a single scalar by replicating that scalar to
    *    along the diagonal of the matrix and setting all other components to
    *    zero.
    *
    *  - Construct a matrix from an arbirary combination of vectors and
    *    scalars.  The components of the constructor parameters are assigned
    *    to the matrix in colum-major order until the matrix is full.
    *
    *  - Construct a matrix from a single matrix.  The source matrix is copied
    *    to the upper left portion of the constructed matrix, and the remaining
    *    elements take values from the identity matrix.
    */
   ir_rvalue *const first_param = (ir_rvalue *) parameters->head;
   if (single_scalar_parameter(parameters)) {
      /* Assign the scalar to the X component of a vec4, and fill the remaining
       * components with zero.
       */
      ir_variable *rhs_var =
         new(ctx) ir_variable(glsl_type::vec4_type,
                              talloc_strdup(ctx, "mat_ctor_vec"),
                              ir_var_temporary);
      instructions->push_tail(rhs_var);

      ir_constant_data zero;
      zero.f[0] = 0.0;
      zero.f[1] = 0.0;
      zero.f[2] = 0.0;
      zero.f[3] = 0.0;

      ir_instruction *inst =
         new(ctx) ir_assignment(new(ctx) ir_dereference_variable(rhs_var),
                                new(ctx) ir_constant(rhs_var->type, &zero),
                                NULL);
      instructions->push_tail(inst);

      ir_rvalue *const rhs_ref = new(ctx) ir_dereference_variable(rhs_var);
      ir_rvalue *const x_of_rhs = new(ctx) ir_swizzle(rhs_ref, 0, 0, 0, 0, 1);

      inst = new(ctx) ir_assignment(x_of_rhs, first_param, NULL);
      instructions->push_tail(inst);

      /* Assign the temporary vector to each column of the destination matrix
       * with a swizzle that puts the X component on the diagonal of the
       * matrix.  In some cases this may mean that the X component does not
       * get assigned into the column at all (i.e., when the matrix has more
       * columns than rows).
       */
      static const unsigned rhs_swiz[4][4] = {
         { 0, 1, 1, 1 },
         { 1, 0, 1, 1 },
         { 1, 1, 0, 1 },
         { 1, 1, 1, 0 }
      };

      const unsigned cols_to_init = min(type->matrix_columns,
                                        type->vector_elements);
      for (unsigned i = 0; i < cols_to_init; i++) {
         ir_constant *const col_idx = new(ctx) ir_constant(i);
         ir_rvalue *const col_ref = new(ctx) ir_dereference_array(var, col_idx);

         ir_rvalue *const rhs_ref = new(ctx) ir_dereference_variable(rhs_var);
         ir_rvalue *const rhs = new(ctx) ir_swizzle(rhs_ref, rhs_swiz[i],
                                                    type->vector_elements);

         inst = new(ctx) ir_assignment(col_ref, rhs, NULL);
         instructions->push_tail(inst);
      }

      for (unsigned i = cols_to_init; i < type->matrix_columns; i++) {
         ir_constant *const col_idx = new(ctx) ir_constant(i);
         ir_rvalue *const col_ref = new(ctx) ir_dereference_array(var, col_idx);

         ir_rvalue *const rhs_ref = new(ctx) ir_dereference_variable(rhs_var);
         ir_rvalue *const rhs = new(ctx) ir_swizzle(rhs_ref, 1, 1, 1, 1,
                                                    type->vector_elements);

         inst = new(ctx) ir_assignment(col_ref, rhs, NULL);
         instructions->push_tail(inst);
      }
   } else if (first_param->type->is_matrix()) {
      /* From page 50 (56 of the PDF) of the GLSL 1.50 spec:
       *
       *     "If a matrix is constructed from a matrix, then each component
       *     (column i, row j) in the result that has a corresponding
       *     component (column i, row j) in the argument will be initialized
       *     from there. All other components will be initialized to the
       *     identity matrix. If a matrix argument is given to a matrix
       *     constructor, it is an error to have any other arguments."
       */
      assert(first_param->next->is_tail_sentinal());
      ir_rvalue *const src_matrix = first_param;

      /* If the source matrix is smaller, pre-initialize the relavent parts of
       * the destination matrix to the identity matrix.
       */
      if ((src_matrix->type->matrix_columns < var->type->matrix_columns)
          || (src_matrix->type->vector_elements < var->type->vector_elements)) {

         /* If the source matrix has fewer rows, every column of the destination
          * must be initialized.  Otherwise only the columns in the destination
          * that do not exist in the source must be initialized.
          */
         unsigned col =
            (src_matrix->type->vector_elements < var->type->vector_elements)
            ? 0 : src_matrix->type->matrix_columns;

         const glsl_type *const col_type = var->type->column_type();
         for (/* empty */; col < var->type->matrix_columns; col++) {
            ir_constant_data ident;

            ident.f[0] = 0.0;
            ident.f[1] = 0.0;
            ident.f[2] = 0.0;
            ident.f[3] = 0.0;

            ident.f[col] = 1.0;

            ir_rvalue *const rhs = new(ctx) ir_constant(col_type, &ident);

            ir_rvalue *const lhs =
               new(ctx) ir_dereference_array(var, new(ctx) ir_constant(col));

            ir_instruction *inst = new(ctx) ir_assignment(lhs, rhs, NULL);
            instructions->push_tail(inst);
         }
      }

      /* Assign columns from the source matrix to the destination matrix.
       *
       * Since the parameter will be used in the RHS of multiple assignments,
       * generate a temporary and copy the paramter there.
       */
      ir_variable *const rhs_var =
         new(ctx) ir_variable(first_param->type,
                              talloc_strdup(ctx, "mat_ctor_mat"),
                              ir_var_temporary);
      instructions->push_tail(rhs_var);

      ir_dereference *const rhs_var_ref =
         new(ctx) ir_dereference_variable(rhs_var);
      ir_instruction *const inst =
         new(ctx) ir_assignment(rhs_var_ref, first_param, NULL);
      instructions->push_tail(inst);


      const unsigned swiz[4] = { 0, 1, 2, 3 };
      const unsigned last_col = min(src_matrix->type->matrix_columns,
                                    var->type->matrix_columns);
      for (unsigned i = 0; i < last_col; i++) {
         ir_rvalue *const lhs_col =
            new(ctx) ir_dereference_array(var, new(ctx) ir_constant(i));
         ir_rvalue *const rhs_col =
            new(ctx) ir_dereference_array(rhs_var, new(ctx) ir_constant(i));

         /* If one matrix has columns that are smaller than the columns of the
          * other matrix, wrap the column access of the larger with a swizzle
          * so that the LHS and RHS of the assignment have the same size (and
          * therefore have the same type).
          *
          * It would be perfectly valid to unconditionally generate the
          * swizzles, this this will typically result in a more compact IR tree.
          */
         ir_rvalue *lhs;
         ir_rvalue *rhs;
         if (lhs_col->type->vector_elements < rhs_col->type->vector_elements) {
            lhs = lhs_col;

            rhs = new(ctx) ir_swizzle(rhs_col, swiz,
                                      lhs_col->type->vector_elements);
         } else if (lhs_col->type->vector_elements
                    > rhs_col->type->vector_elements) {
            lhs = new(ctx) ir_swizzle(lhs_col, swiz,
                                      rhs_col->type->vector_elements);
            rhs = rhs_col;
         } else {
            lhs = lhs_col;
            rhs = rhs_col;
         }

         assert(lhs->type == rhs->type);

         ir_instruction *inst = new(ctx) ir_assignment(lhs, rhs, NULL);
         instructions->push_tail(inst);
      }
   } else {
      const unsigned rows = type->matrix_columns;
      const unsigned cols = type->vector_elements;
      unsigned col_idx = 0;
      unsigned row_idx = 0;

      foreach_list (node, parameters) {
         ir_rvalue *const rhs = (ir_rvalue *) node;
         const unsigned components_remaining_this_column = rows - row_idx;
         unsigned rhs_components = rhs->type->components();
         unsigned rhs_base = 0;

         /* Since the parameter might be used in the RHS of two assignments,
          * generate a temporary and copy the paramter there.
          */
         ir_variable *rhs_var =
            new(ctx) ir_variable(rhs->type,
                                 talloc_strdup(ctx, "mat_ctor_vec"),
                                 ir_var_temporary);
         instructions->push_tail(rhs_var);

         ir_dereference *rhs_var_ref =
            new(ctx) ir_dereference_variable(rhs_var);
         ir_instruction *inst = new(ctx) ir_assignment(rhs_var_ref, rhs, NULL);
         instructions->push_tail(inst);

         /* Assign the current parameter to as many components of the matrix
          * as it will fill.
          *
          * NOTE: A single vector parameter can span two matrix columns.  A
          * single vec4, for example, can completely fill a mat2.
          */
         if (rhs_components >= components_remaining_this_column) {
            const unsigned count = min(rhs_components,
                                       components_remaining_this_column);

            rhs_var_ref = new(ctx) ir_dereference_variable(rhs_var);

            ir_instruction *inst = assign_to_matrix_column(var, col_idx,
                                                           row_idx,
                                                           rhs_var_ref, 0,
                                                           count, ctx);
            instructions->push_tail(inst);

            rhs_base = count;

            col_idx++;
            row_idx = 0;
         }

         /* If there is data left in the parameter and components left to be
          * set in the destination, emit another assignment.  It is possible
          * that the assignment could be of a vec4 to the last element of the
          * matrix.  In this case col_idx==cols, but there is still data
          * left in the source parameter.  Obviously, don't emit an assignment
          * to data outside the destination matrix.
          */
         if ((col_idx < cols) && (rhs_base < rhs_components)) {
            const unsigned count = rhs_components - rhs_base;

            rhs_var_ref = new(ctx) ir_dereference_variable(rhs_var);

            ir_instruction *inst = assign_to_matrix_column(var, col_idx,
                                                           row_idx,
                                                           rhs_var_ref,
                                                           rhs_base,
                                                           count, ctx);
            instructions->push_tail(inst);

            row_idx += count;
         }
      }
   }

   return new(ctx) ir_dereference_variable(var);
}


ir_rvalue *
ast_function_expression::hir(exec_list *instructions,
                             struct _mesa_glsl_parse_state *state)
{
   void *ctx = state;
   /* There are three sorts of function calls.
    *
    * 1. constructors - The first subexpression is an ast_type_specifier.
    * 2. methods - Only the .length() method of array types.
    * 3. functions - Calls to regular old functions.
    *
    * Method calls are actually detected when the ast_field_selection
    * expression is handled.
    */
   if (is_constructor()) {
      const ast_type_specifier *type = (ast_type_specifier *) subexpressions[0];
      YYLTYPE loc = type->get_location();
      const char *name;

      const glsl_type *const constructor_type = type->glsl_type(& name, state);


      /* Constructors for samplers are illegal.
       */
      if (constructor_type->is_sampler()) {
         _mesa_glsl_error(& loc, state, "cannot construct sampler type `%s'",
                          constructor_type->name);
         return ir_call::get_error_instruction(ctx);
      }

      if (constructor_type->is_array()) {
         if (state->language_version <= 110) {
            _mesa_glsl_error(& loc, state,
                             "array constructors forbidden in GLSL 1.10");
            return ir_call::get_error_instruction(ctx);
         }

         return process_array_constructor(instructions, constructor_type,
                                          & loc, &this->expressions, state);
      }

      /* There are two kinds of constructor call.  Constructors for built-in
       * language types, such as mat4 and vec2, are free form.  The only
       * requirement is that the parameters must provide enough values of the
       * correct scalar type.  Constructors for arrays and structures must
       * have the exact number of parameters with matching types in the
       * correct order.  These constructors follow essentially the same type
       * matching rules as functions.
       */
      if (!constructor_type->is_numeric() && !constructor_type->is_boolean())
         return ir_call::get_error_instruction(ctx);

      /* Total number of components of the type being constructed. */
      const unsigned type_components = constructor_type->components();

      /* Number of components from parameters that have actually been
       * consumed.  This is used to perform several kinds of error checking.
       */
      unsigned components_used = 0;

      unsigned matrix_parameters = 0;
      unsigned nonmatrix_parameters = 0;
      exec_list actual_parameters;

      foreach_list (n, &this->expressions) {
         ast_node *ast = exec_node_data(ast_node, n, link);
         ir_rvalue *result = ast->hir(instructions, state)->as_rvalue();

         /* From page 50 (page 56 of the PDF) of the GLSL 1.50 spec:
          *
          *    "It is an error to provide extra arguments beyond this
          *    last used argument."
          */
         if (components_used >= type_components) {
            _mesa_glsl_error(& loc, state, "too many parameters to `%s' "
                             "constructor",
                             constructor_type->name);
            return ir_call::get_error_instruction(ctx);
         }

         if (!result->type->is_numeric() && !result->type->is_boolean()) {
            _mesa_glsl_error(& loc, state, "cannot construct `%s' from a "
                             "non-numeric data type",
                             constructor_type->name);
            return ir_call::get_error_instruction(ctx);
         }

         /* Count the number of matrix and nonmatrix parameters.  This
          * is used below to enforce some of the constructor rules.
          */
         if (result->type->is_matrix())
            matrix_parameters++;
         else
            nonmatrix_parameters++;

         actual_parameters.push_tail(result);
         components_used += result->type->components();
      }

      /* From page 28 (page 34 of the PDF) of the GLSL 1.10 spec:
       *
       *    "It is an error to construct matrices from other matrices. This
       *    is reserved for future use."
       */
      if ((state->language_version <= 110) && (matrix_parameters > 0)
          && constructor_type->is_matrix()) {
         _mesa_glsl_error(& loc, state, "cannot construct `%s' from a "
                          "matrix in GLSL 1.10",
                          constructor_type->name);
         return ir_call::get_error_instruction(ctx);
      }

      /* From page 50 (page 56 of the PDF) of the GLSL 1.50 spec:
       *
       *    "If a matrix argument is given to a matrix constructor, it is
       *    an error to have any other arguments."
       */
      if ((matrix_parameters > 0)
          && ((matrix_parameters + nonmatrix_parameters) > 1)
          && constructor_type->is_matrix()) {
         _mesa_glsl_error(& loc, state, "for matrix `%s' constructor, "
                          "matrix must be only parameter",
                          constructor_type->name);
         return ir_call::get_error_instruction(ctx);
      }

      /* From page 28 (page 34 of the PDF) of the GLSL 1.10 spec:
       *
       *    "In these cases, there must be enough components provided in the
       *    arguments to provide an initializer for every component in the
       *    constructed value."
       */
      if ((components_used < type_components) && (components_used != 1)) {
         _mesa_glsl_error(& loc, state, "too few components to construct "
                          "`%s'",
                          constructor_type->name);
         return ir_call::get_error_instruction(ctx);
      }

      /* Later, we cast each parameter to the same base type as the
       * constructor.  Since there are no non-floating point matrices, we
       * need to break them up into a series of column vectors.
       */
      if (constructor_type->base_type != GLSL_TYPE_FLOAT) {
         foreach_list_safe(n, &actual_parameters) {
            ir_rvalue *matrix = (ir_rvalue *) n;

            if (!matrix->type->is_matrix())
               continue;

            /* Create a temporary containing the matrix. */
            ir_variable *var = new(ctx) ir_variable(matrix->type, "matrix_tmp",
                                                    ir_var_temporary);
            instructions->push_tail(var);
            instructions->push_tail(new(ctx) ir_assignment(new(ctx)
               ir_dereference_variable(var), matrix, NULL));
            var->constant_value = matrix->constant_expression_value();

            /* Replace the matrix with dereferences of its columns. */
            for (int i = 0; i < matrix->type->matrix_columns; i++) {
               matrix->insert_before(new (ctx) ir_dereference_array(var,
                  new(ctx) ir_constant(i)));
            }
            matrix->remove();
         }
      }

      bool all_parameters_are_constant = true;

      /* Type cast each parameter and, if possible, fold constants.*/
      foreach_list_safe(n, &actual_parameters) {
         ir_rvalue *ir = (ir_rvalue *) n;

         const glsl_type *desired_type =
            glsl_type::get_instance(constructor_type->base_type,
                                    ir->type->vector_elements,
                                    ir->type->matrix_columns);
         ir_rvalue *result = convert_component(ir, desired_type);

         /* Attempt to convert the parameter to a constant valued expression.
          * After doing so, track whether or not all the parameters to the
          * constructor are trivially constant valued expressions.
          */
         ir_rvalue *const constant = result->constant_expression_value();

         if (constant != NULL)
            result = constant;
         else
            all_parameters_are_constant = false;

         if (result != ir) {
            ir->insert_before(result);
            ir->remove();
         }
      }

      /* If all of the parameters are trivially constant, create a
       * constant representing the complete collection of parameters.
       */
      if (all_parameters_are_constant) {
         if (components_used >= type_components)
            return new(ctx) ir_constant(constructor_type,
                                        & actual_parameters);

         /* The above case must handle all scalar constructors.
          */
         assert(constructor_type->is_vector()
                || constructor_type->is_matrix());

         /* Constructors with exactly one component are special for
          * vectors and matrices.  For vectors it causes all elements of
          * the vector to be filled with the value.  For matrices it
          * causes the matrix to be filled with 0 and the diagonal to be
          * filled with the value.
          */
         ir_constant_data data;
         ir_constant *const initializer =
            (ir_constant *) actual_parameters.head;
         if (constructor_type->is_matrix())
            generate_constructor_matrix(constructor_type, initializer,
                                        &data);
         else
            generate_constructor_vector(constructor_type, initializer,
                                        &data);

         return new(ctx) ir_constant(constructor_type, &data);
      } else if (constructor_type->is_scalar()) {
         return dereference_component((ir_rvalue *) actual_parameters.head,
                                      0);
      } else if (constructor_type->is_vector()) {
         return emit_inline_vector_constructor(constructor_type,
                                               instructions,
                                               &actual_parameters,
                                               ctx);
      } else {
         assert(constructor_type->is_matrix());
         return emit_inline_matrix_constructor(constructor_type,
                                               instructions,
                                               &actual_parameters,
                                               ctx);
      }
   } else {
      const ast_expression *id = subexpressions[0];
      YYLTYPE loc = id->get_location();
      exec_list actual_parameters;

      process_parameters(instructions, &actual_parameters, &this->expressions,
                         state);

      const glsl_type *const type =
         state->symbols->get_type(id->primary_expression.identifier);

      if ((type != NULL) && type->is_record()) {
         ir_constant *constant =
            constant_record_constructor(type, &loc, &actual_parameters, state);

         if (constant != NULL)
            return constant;
      }

      return match_function_by_name(instructions, 
                                    id->primary_expression.identifier, & loc,
                                    &actual_parameters, state);
   }

   return ir_call::get_error_instruction(ctx);
}