src/mesa/main/shader_query.cpp - platform/external/mesa3d - Git at Google

 /*
  * Copyright © 2011 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 shader_query.cpp
  * C-to-C++ bridge functions to query GLSL shader data
  *
  * \author Ian Romanick <ian.d.romanick@intel.com>
  */

 #include "main/core.h"
 #include "glsl_symbol_table.h"
 #include "ir.h"
 #include "shaderobj.h"
 #include "program/hash_table.h"
 #include "../glsl/program.h"

 extern "C" {
 #include "shaderapi.h"
 }

 void GLAPIENTRY
 _mesa_BindAttribLocationARB(GLhandleARB program, GLuint index,
                             const GLcharARB *name)
 {
    GET_CURRENT_CONTEXT(ctx);

    struct gl_shader_program *const shProg =
       _mesa_lookup_shader_program_err(ctx, program, "glBindAttribLocation");
    if (!shProg)
       return;

    if (!name)
       return;

    if (strncmp(name, "gl_", 3) == 0) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glBindAttribLocation(illegal name)");
       return;
    }

    if (index >= ctx->Const.VertexProgram.MaxAttribs) {
       _mesa_error(ctx, GL_INVALID_VALUE, "glBindAttribLocation(index)");
       return;
    }

    /* Replace the current value if it's already in the list.  Add
     * VERT_ATTRIB_GENERIC0 because that's how the linker differentiates
     * between built-in attributes and user-defined attributes.
     */
    shProg->AttributeBindings->put(index + VERT_ATTRIB_GENERIC0, name);

    /*
     * Note that this attribute binding won't go into effect until
     * glLinkProgram is called again.
     */
 }

 void GLAPIENTRY
 _mesa_GetActiveAttribARB(GLhandleARB program, GLuint desired_index,
                          GLsizei maxLength, GLsizei * length, GLint * size,
                          GLenum * type, GLcharARB * name)
 {
    GET_CURRENT_CONTEXT(ctx);
    struct gl_shader_program *shProg;

    shProg = _mesa_lookup_shader_program_err(ctx, program, "glGetActiveAttrib");
    if (!shProg)
       return;

    if (!shProg->LinkStatus) {
       _mesa_error(ctx, GL_INVALID_VALUE,
                   "glGetActiveAttrib(program not linked)");
       return;
    }

    if (shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
       _mesa_error(ctx, GL_INVALID_VALUE, "glGetActiveAttrib(no vertex shader)");
       return;
    }

    exec_list *const ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
    unsigned current_index = 0;

    foreach_list(node, ir) {
       const ir_variable *const var = ((ir_instruction *) node)->as_variable();

       if (var == NULL
 	  || var->mode != ir_var_in
 	  || var->location == -1)
 	 continue;

       if (current_index == desired_index) {
 	 _mesa_copy_string(name, maxLength, length, var->name);

 	 if (size)
 	    *size = (var->type->is_array()) ? var->type->length : 1;

 	 if (type)
 	    *type = var->type->gl_type;

 	 return;
       }

       current_index++;
    }

    /* If the loop did not return early, the caller must have asked for
     * an index that did not exit.  Set an error.
     */
    _mesa_error(ctx, GL_INVALID_VALUE, "glGetActiveAttrib(index)");
 }

 GLint GLAPIENTRY
 _mesa_GetAttribLocationARB(GLhandleARB program, const GLcharARB * name)
 {
    GET_CURRENT_CONTEXT(ctx);
    struct gl_shader_program *const shProg =
       _mesa_lookup_shader_program_err(ctx, program, "glGetAttribLocation");

    if (!shProg) {
       return -1;
    }

    if (!shProg->LinkStatus) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glGetAttribLocation(program not linked)");
       return -1;
    }

    if (!name)
       return -1;

    /* Not having a vertex shader is not an error.
     */
    if (shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL)
       return -1;

    exec_list *ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
    foreach_list(node, ir) {
       const ir_variable *const var = ((ir_instruction *) node)->as_variable();

       /* The extra check against VERT_ATTRIB_GENERIC0 is because
        * glGetAttribLocation cannot be used on "conventional" attributes.
        *
        * From page 95 of the OpenGL 3.0 spec:
        *
        *     "If name is not an active attribute, if name is a conventional
        *     attribute, or if an error occurs, -1 will be returned."
        */
       if (var == NULL
 	  || var->mode != ir_var_in
 	  || var->location == -1
 	  || var->location < VERT_ATTRIB_GENERIC0)
 	 continue;

       if (strcmp(var->name, name) == 0)
 	 return var->location - VERT_ATTRIB_GENERIC0;
    }

    return -1;
 }


 unsigned
 _mesa_count_active_attribs(struct gl_shader_program *shProg)
 {
    if (!shProg->LinkStatus
        || shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
       return 0;
    }

    exec_list *const ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
    unsigned i = 0;

    foreach_list(node, ir) {
       const ir_variable *const var = ((ir_instruction *) node)->as_variable();

       if (var == NULL
 	  || var->mode != ir_var_in
 	  || var->location == -1)
 	 continue;

       i++;
    }

    return i;
 }


 size_t
 _mesa_longest_attribute_name_length(struct gl_shader_program *shProg)
 {
    if (!shProg->LinkStatus
        || shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
       return 0;
    }

    exec_list *const ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
    size_t longest = 0;

    foreach_list(node, ir) {
       const ir_variable *const var = ((ir_instruction *) node)->as_variable();

       if (var == NULL
 	  || var->mode != ir_var_in
 	  || var->location == -1)
 	 continue;

       const size_t len = strlen(var->name);
       if (len >= longest)
 	 longest = len + 1;
    }

    return longest;
 }

 void GLAPIENTRY
 _mesa_BindFragDataLocation(GLuint program, GLuint colorNumber,
 			   const GLchar *name)
 {
    _mesa_BindFragDataLocationIndexed(program, colorNumber, 0, name);
 }

 void GLAPIENTRY
 _mesa_BindFragDataLocationIndexed(GLuint program, GLuint colorNumber,
                                   GLuint index, const GLchar *name)
 {
    GET_CURRENT_CONTEXT(ctx);

    struct gl_shader_program *const shProg =
       _mesa_lookup_shader_program_err(ctx, program, "glBindFragDataLocationIndexed");
    if (!shProg)
       return;

    if (!name)
       return;

    if (strncmp(name, "gl_", 3) == 0) {
       _mesa_error(ctx, GL_INVALID_OPERATION, "glBindFragDataLocationIndexed(illegal name)");
       return;
    }

    if (index > 1) {
       _mesa_error(ctx, GL_INVALID_VALUE, "glBindFragDataLocationIndexed(index)");
       return;
    }

    if (index == 0 && colorNumber >= ctx->Const.MaxDrawBuffers) {
       _mesa_error(ctx, GL_INVALID_VALUE, "glBindFragDataLocationIndexed(colorNumber)");
       return;
    }

    if (index == 1 && colorNumber >= ctx->Const.MaxDualSourceDrawBuffers) {
       _mesa_error(ctx, GL_INVALID_VALUE, "glBindFragDataLocationIndexed(colorNumber)");
       return;
    }

    /* Replace the current value if it's already in the list.  Add
     * FRAG_RESULT_DATA0 because that's how the linker differentiates
     * between built-in attributes and user-defined attributes.
     */
    shProg->FragDataBindings->put(colorNumber + FRAG_RESULT_DATA0, name);
    shProg->FragDataIndexBindings->put(index, name);
    /*
     * Note that this binding won't go into effect until
     * glLinkProgram is called again.
     */

 }

 GLint GLAPIENTRY
 _mesa_GetFragDataIndex(GLuint program, const GLchar *name)
 {
    GET_CURRENT_CONTEXT(ctx);
    struct gl_shader_program *const shProg =
       _mesa_lookup_shader_program_err(ctx, program, "glGetFragDataIndex");

    if (!shProg) {
       return -1;
    }

    if (!shProg->LinkStatus) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glGetFragDataIndex(program not linked)");
       return -1;
    }

    if (!name)
       return -1;

    if (strncmp(name, "gl_", 3) == 0) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glGetFragDataIndex(illegal name)");
       return -1;
    }

    /* Not having a fragment shader is not an error.
     */
    if (shProg->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL)
       return -1;

    exec_list *ir = shProg->_LinkedShaders[MESA_SHADER_FRAGMENT]->ir;
    foreach_list(node, ir) {
       const ir_variable *const var = ((ir_instruction *) node)->as_variable();

       /* The extra check against FRAG_RESULT_DATA0 is because
        * glGetFragDataLocation cannot be used on "conventional" attributes.
        *
        * From page 95 of the OpenGL 3.0 spec:
        *
        *     "If name is not an active attribute, if name is a conventional
        *     attribute, or if an error occurs, -1 will be returned."
        */
       if (var == NULL
           || var->mode != ir_var_out
           || var->location == -1
           || var->location < FRAG_RESULT_DATA0)
          continue;

       if (strcmp(var->name, name) == 0)
          return var->index;
    }

    return -1;
 }

 GLint GLAPIENTRY
 _mesa_GetFragDataLocation(GLuint program, const GLchar *name)
 {
    GET_CURRENT_CONTEXT(ctx);
    struct gl_shader_program *const shProg =
       _mesa_lookup_shader_program_err(ctx, program, "glGetFragDataLocation");

    if (!shProg) {
       return -1;
    }

    if (!shProg->LinkStatus) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glGetFragDataLocation(program not linked)");
       return -1;
    }

    if (!name)
       return -1;

    if (strncmp(name, "gl_", 3) == 0) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glGetFragDataLocation(illegal name)");
       return -1;
    }

    /* Not having a fragment shader is not an error.
     */
    if (shProg->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL)
       return -1;

    exec_list *ir = shProg->_LinkedShaders[MESA_SHADER_FRAGMENT]->ir;
    foreach_list(node, ir) {
       const ir_variable *const var = ((ir_instruction *) node)->as_variable();

       /* The extra check against FRAG_RESULT_DATA0 is because
        * glGetFragDataLocation cannot be used on "conventional" attributes.
        *
        * From page 95 of the OpenGL 3.0 spec:
        *
        *     "If name is not an active attribute, if name is a conventional
        *     attribute, or if an error occurs, -1 will be returned."
        */
       if (var == NULL
 	  || var->mode != ir_var_out
 	  || var->location == -1
 	  || var->location < FRAG_RESULT_DATA0)
 	 continue;

       if (strcmp(var->name, name) == 0)
 	 return var->location - FRAG_RESULT_DATA0;
    }

    return -1;
 }
	/*
	* Copyright © 2011 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 shader_query.cpp
	* C-to-C++ bridge functions to query GLSL shader data
	*
	* \author Ian Romanick <ian.d.romanick@intel.com>
	*/

	#include "main/core.h"
	#include "glsl_symbol_table.h"
	#include "ir.h"
	#include "shaderobj.h"
	#include "program/hash_table.h"
	#include "../glsl/program.h"

	extern "C" {
	#include "shaderapi.h"
	}

	void GLAPIENTRY
	_mesa_BindAttribLocationARB(GLhandleARB program, GLuint index,
	const GLcharARB *name)
	{
	GET_CURRENT_CONTEXT(ctx);

	struct gl_shader_program *const shProg =
	_mesa_lookup_shader_program_err(ctx, program, "glBindAttribLocation");
	if (!shProg)
	return;

	if (!name)
	return;

	if (strncmp(name, "gl_", 3) == 0) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glBindAttribLocation(illegal name)");
	return;
	}

	if (index >= ctx->Const.VertexProgram.MaxAttribs) {
	_mesa_error(ctx, GL_INVALID_VALUE, "glBindAttribLocation(index)");
	return;
	}

	/* Replace the current value if it's already in the list. Add
	* VERT_ATTRIB_GENERIC0 because that's how the linker differentiates
	* between built-in attributes and user-defined attributes.
	*/
	shProg->AttributeBindings->put(index + VERT_ATTRIB_GENERIC0, name);

	/*
	* Note that this attribute binding won't go into effect until
	* glLinkProgram is called again.
	*/
	}

	void GLAPIENTRY
	_mesa_GetActiveAttribARB(GLhandleARB program, GLuint desired_index,
	GLsizei maxLength, GLsizei * length, GLint * size,
	GLenum * type, GLcharARB * name)
	{
	GET_CURRENT_CONTEXT(ctx);
	struct gl_shader_program *shProg;

	shProg = _mesa_lookup_shader_program_err(ctx, program, "glGetActiveAttrib");
	if (!shProg)
	return;

	if (!shProg->LinkStatus) {
	_mesa_error(ctx, GL_INVALID_VALUE,
	"glGetActiveAttrib(program not linked)");
	return;
	}

	if (shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
	_mesa_error(ctx, GL_INVALID_VALUE, "glGetActiveAttrib(no vertex shader)");
	return;
	}

	exec_list *const ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
	unsigned current_index = 0;

	foreach_list(node, ir) {
	const ir_variable const var = ((ir_instruction ) node)->as_variable();

	if (var == NULL
	\|\| var->mode != ir_var_in
	\|\| var->location == -1)
	continue;

	if (current_index == desired_index) {
	_mesa_copy_string(name, maxLength, length, var->name);

	if (size)
	*size = (var->type->is_array()) ? var->type->length : 1;

	if (type)
	*type = var->type->gl_type;

	return;
	}

	current_index++;
	}

	/* If the loop did not return early, the caller must have asked for
	* an index that did not exit. Set an error.
	*/
	_mesa_error(ctx, GL_INVALID_VALUE, "glGetActiveAttrib(index)");
	}

	GLint GLAPIENTRY
	_mesa_GetAttribLocationARB(GLhandleARB program, const GLcharARB * name)
	{
	GET_CURRENT_CONTEXT(ctx);
	struct gl_shader_program *const shProg =
	_mesa_lookup_shader_program_err(ctx, program, "glGetAttribLocation");

	if (!shProg) {
	return -1;
	}

	if (!shProg->LinkStatus) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glGetAttribLocation(program not linked)");
	return -1;
	}

	if (!name)
	return -1;

	/* Not having a vertex shader is not an error.
	*/
	if (shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL)
	return -1;

	exec_list *ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
	foreach_list(node, ir) {
	const ir_variable const var = ((ir_instruction ) node)->as_variable();

	/* The extra check against VERT_ATTRIB_GENERIC0 is because
	* glGetAttribLocation cannot be used on "conventional" attributes.
	*
	* From page 95 of the OpenGL 3.0 spec:
	*
	* "If name is not an active attribute, if name is a conventional
	* attribute, or if an error occurs, -1 will be returned."
	*/
	if (var == NULL
	\|\| var->mode != ir_var_in
	\|\| var->location == -1
	\|\| var->location < VERT_ATTRIB_GENERIC0)
	continue;

	if (strcmp(var->name, name) == 0)
	return var->location - VERT_ATTRIB_GENERIC0;
	}

	return -1;
	}


	unsigned
	_mesa_count_active_attribs(struct gl_shader_program *shProg)
	{
	if (!shProg->LinkStatus
	\|\| shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
	return 0;
	}

	exec_list *const ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
	unsigned i = 0;

	foreach_list(node, ir) {
	const ir_variable const var = ((ir_instruction ) node)->as_variable();

	if (var == NULL
	\|\| var->mode != ir_var_in
	\|\| var->location == -1)
	continue;

	i++;
	}

	return i;
	}


	size_t
	_mesa_longest_attribute_name_length(struct gl_shader_program *shProg)
	{
	if (!shProg->LinkStatus
	\|\| shProg->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
	return 0;
	}

	exec_list *const ir = shProg->_LinkedShaders[MESA_SHADER_VERTEX]->ir;
	size_t longest = 0;

	foreach_list(node, ir) {
	const ir_variable const var = ((ir_instruction ) node)->as_variable();

	if (var == NULL
	\|\| var->mode != ir_var_in
	\|\| var->location == -1)
	continue;

	const size_t len = strlen(var->name);
	if (len >= longest)
	longest = len + 1;
	}

	return longest;
	}

	void GLAPIENTRY
	_mesa_BindFragDataLocation(GLuint program, GLuint colorNumber,
	const GLchar *name)
	{
	_mesa_BindFragDataLocationIndexed(program, colorNumber, 0, name);
	}

	void GLAPIENTRY
	_mesa_BindFragDataLocationIndexed(GLuint program, GLuint colorNumber,
	GLuint index, const GLchar *name)
	{
	GET_CURRENT_CONTEXT(ctx);

	struct gl_shader_program *const shProg =
	_mesa_lookup_shader_program_err(ctx, program, "glBindFragDataLocationIndexed");
	if (!shProg)
	return;

	if (!name)
	return;

	if (strncmp(name, "gl_", 3) == 0) {
	_mesa_error(ctx, GL_INVALID_OPERATION, "glBindFragDataLocationIndexed(illegal name)");
	return;
	}

	if (index > 1) {
	_mesa_error(ctx, GL_INVALID_VALUE, "glBindFragDataLocationIndexed(index)");
	return;
	}

	if (index == 0 && colorNumber >= ctx->Const.MaxDrawBuffers) {
	_mesa_error(ctx, GL_INVALID_VALUE, "glBindFragDataLocationIndexed(colorNumber)");
	return;
	}

	if (index == 1 && colorNumber >= ctx->Const.MaxDualSourceDrawBuffers) {
	_mesa_error(ctx, GL_INVALID_VALUE, "glBindFragDataLocationIndexed(colorNumber)");
	return;
	}

	/* Replace the current value if it's already in the list. Add
	* FRAG_RESULT_DATA0 because that's how the linker differentiates
	* between built-in attributes and user-defined attributes.
	*/
	shProg->FragDataBindings->put(colorNumber + FRAG_RESULT_DATA0, name);
	shProg->FragDataIndexBindings->put(index, name);
	/*
	* Note that this binding won't go into effect until
	* glLinkProgram is called again.
	*/

	}

	GLint GLAPIENTRY
	_mesa_GetFragDataIndex(GLuint program, const GLchar *name)
	{
	GET_CURRENT_CONTEXT(ctx);
	struct gl_shader_program *const shProg =
	_mesa_lookup_shader_program_err(ctx, program, "glGetFragDataIndex");

	if (!shProg) {
	return -1;
	}

	if (!shProg->LinkStatus) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glGetFragDataIndex(program not linked)");
	return -1;
	}

	if (!name)
	return -1;

	if (strncmp(name, "gl_", 3) == 0) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glGetFragDataIndex(illegal name)");
	return -1;
	}

	/* Not having a fragment shader is not an error.
	*/
	if (shProg->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL)
	return -1;

	exec_list *ir = shProg->_LinkedShaders[MESA_SHADER_FRAGMENT]->ir;
	foreach_list(node, ir) {
	const ir_variable const var = ((ir_instruction ) node)->as_variable();

	/* The extra check against FRAG_RESULT_DATA0 is because
	* glGetFragDataLocation cannot be used on "conventional" attributes.
	*
	* From page 95 of the OpenGL 3.0 spec:
	*
	* "If name is not an active attribute, if name is a conventional
	* attribute, or if an error occurs, -1 will be returned."
	*/
	if (var == NULL
	\|\| var->mode != ir_var_out
	\|\| var->location == -1
	\|\| var->location < FRAG_RESULT_DATA0)
	continue;

	if (strcmp(var->name, name) == 0)
	return var->index;
	}

	return -1;
	}

	GLint GLAPIENTRY
	_mesa_GetFragDataLocation(GLuint program, const GLchar *name)
	{
	GET_CURRENT_CONTEXT(ctx);
	struct gl_shader_program *const shProg =
	_mesa_lookup_shader_program_err(ctx, program, "glGetFragDataLocation");

	if (!shProg) {
	return -1;
	}

	if (!shProg->LinkStatus) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glGetFragDataLocation(program not linked)");
	return -1;
	}

	if (!name)
	return -1;

	if (strncmp(name, "gl_", 3) == 0) {
	_mesa_error(ctx, GL_INVALID_OPERATION,
	"glGetFragDataLocation(illegal name)");
	return -1;
	}

	/* Not having a fragment shader is not an error.
	*/
	if (shProg->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL)
	return -1;

	exec_list *ir = shProg->_LinkedShaders[MESA_SHADER_FRAGMENT]->ir;
	foreach_list(node, ir) {
	const ir_variable const var = ((ir_instruction ) node)->as_variable();

	/* The extra check against FRAG_RESULT_DATA0 is because
	* glGetFragDataLocation cannot be used on "conventional" attributes.
	*
	* From page 95 of the OpenGL 3.0 spec:
	*
	* "If name is not an active attribute, if name is a conventional
	* attribute, or if an error occurs, -1 will be returned."
	*/
	if (var == NULL
	\|\| var->mode != ir_var_out
	\|\| var->location == -1
	\|\| var->location < FRAG_RESULT_DATA0)
	continue;

	if (strcmp(var->name, name) == 0)
	return var->location - FRAG_RESULT_DATA0;
	}

	return -1;
	}