/*
* 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 linker.cpp
* GLSL linker implementation
*
* Given a set of shaders that are to be linked to generate a final program,
* there are three distinct stages.
*
* In the first stage shaders are partitioned into groups based on the shader
* type. All shaders of a particular type (e.g., vertex shaders) are linked
* together.
*
* - Undefined references in each shader are resolve to definitions in
* another shader.
* - Types and qualifiers of uniforms, outputs, and global variables defined
* in multiple shaders with the same name are verified to be the same.
* - Initializers for uniforms and global variables defined
* in multiple shaders with the same name are verified to be the same.
*
* The result, in the terminology of the GLSL spec, is a set of shader
* executables for each processing unit.
*
* After the first stage is complete, a series of semantic checks are performed
* on each of the shader executables.
*
* - Each shader executable must define a \c main function.
* - Each vertex shader executable must write to \c gl_Position.
* - Each fragment shader executable must write to either \c gl_FragData or
* \c gl_FragColor.
*
* In the final stage individual shader executables are linked to create a
* complete exectuable.
*
* - Types of uniforms defined in multiple shader stages with the same name
* are verified to be the same.
* - Initializers for uniforms defined in multiple shader stages with the
* same name are verified to be the same.
* - Types and qualifiers of outputs defined in one stage are verified to
* be the same as the types and qualifiers of inputs defined with the same
* name in a later stage.
*
* \author Ian Romanick <ian.d.romanick@intel.com>
*/
#include <cstdlib>
#include <cstdio>
#include <cstdarg>
extern "C" {
#include <talloc.h>
}
#include "main/mtypes.h"
#include "glsl_symbol_table.h"
#include "glsl_parser_extras.h"
#include "ir.h"
#include "ir_optimization.h"
#include "program.h"
#include "hash_table.h"
/**
* Visitor that determines whether or not a variable is ever written.
*/
class find_assignment_visitor : public ir_hierarchical_visitor {
public:
find_assignment_visitor(const char *name)
: name(name), found(false)
{
/* empty */
}
virtual ir_visitor_status visit_enter(ir_assignment *ir)
{
ir_variable *const var = ir->lhs->variable_referenced();
if (strcmp(name, var->name) == 0) {
found = true;
return visit_stop;
}
return visit_continue_with_parent;
}
bool variable_found()
{
return found;
}
private:
const char *name; /**< Find writes to a variable with this name. */
bool found; /**< Was a write to the variable found? */
};
void
linker_error_printf(glsl_program *prog, const char *fmt, ...)
{
va_list ap;
prog->InfoLog = talloc_strdup_append(prog->InfoLog, "error: ");
va_start(ap, fmt);
prog->InfoLog = talloc_vasprintf_append(prog->InfoLog, fmt, ap);
va_end(ap);
}
void
invalidate_variable_locations(glsl_shader *sh, enum ir_variable_mode mode,
int generic_base)
{
foreach_list(node, &sh->ir) {
ir_variable *const var = ((ir_instruction *) node)->as_variable();
if ((var == NULL) || (var->mode != (unsigned) mode))
continue;
/* Only assign locations for generic attributes / varyings / etc.
*/
if (var->location >= generic_base)
var->location = -1;
}
}
/**
* Determine the number of attribute slots required for a particular type
*
* This code is here because it implements the language rules of a specific
* GLSL version. Since it's a property of the language and not a property of
* types in general, it doesn't really belong in glsl_type.
*/
unsigned
count_attribute_slots(const glsl_type *t)
{
/* From page 31 (page 37 of the PDF) of the GLSL 1.50 spec:
*
* "A scalar input counts the same amount against this limit as a vec4,
* so applications may want to consider packing groups of four
* unrelated float inputs together into a vector to better utilize the
* capabilities of the underlying hardware. A matrix input will use up
* multiple locations. The number of locations used will equal the
* number of columns in the matrix."
*
* The spec does not explicitly say how arrays are counted. However, it
* should be safe to assume the total number of slots consumed by an array
* is the number of entries in the array multiplied by the number of slots
* consumed by a single element of the array.
*/
if (t->is_array())
return t->array_size() * count_attribute_slots(t->element_type());
if (t->is_matrix())
return t->matrix_columns;
return 1;
}
/**
* Verify that a vertex shader executable meets all semantic requirements
*
* \param shader Vertex shader executable to be verified
*/
bool
validate_vertex_shader_executable(struct glsl_program *prog,
struct glsl_shader *shader)
{
if (shader == NULL)
return true;
if (!shader->symbols->get_function("main")) {
linker_error_printf(prog, "vertex shader lacks `main'\n");
return false;
}
find_assignment_visitor find("gl_Position");
find.run(&shader->ir);
if (!find.variable_found()) {
linker_error_printf(prog,
"vertex shader does not write to `gl_Position'\n");
return false;
}
return true;
}
/**
* Verify that a fragment shader executable meets all semantic requirements
*
* \param shader Fragment shader executable to be verified
*/
bool
validate_fragment_shader_executable(struct glsl_program *prog,
struct glsl_shader *shader)
{
if (shader == NULL)
return true;
if (!shader->symbols->get_function("main")) {
linker_error_printf(prog, "fragment shader lacks `main'\n");
return false;
}
find_assignment_visitor frag_color("gl_FragColor");
find_assignment_visitor frag_data("gl_FragData");
frag_color.run(&shader->ir);
frag_data.run(&shader->ir);
if (!frag_color.variable_found() && !frag_data.variable_found()) {
linker_error_printf(prog, "fragment shader does not write to "
"`gl_FragColor' or `gl_FragData'\n");
return false;
}
if (frag_color.variable_found() && frag_data.variable_found()) {
linker_error_printf(prog, "fragment shader writes to both "
"`gl_FragColor' and `gl_FragData'\n");
return false;
}
return true;
}
/**
* Perform validation of uniforms used across multiple shader stages
*/
bool
cross_validate_uniforms(struct glsl_program *prog)
{
/* Examine all of the uniforms in all of the shaders and cross validate
* them.
*/
glsl_symbol_table uniforms;
for (unsigned i = 0; i < prog->_NumLinkedShaders; i++) {
foreach_list(node, &prog->_LinkedShaders[i]->ir) {
ir_variable *const var = ((ir_instruction *) node)->as_variable();
if ((var == NULL) || (var->mode != ir_var_uniform))
continue;
/* If a uniform with this name has already been seen, verify that the
* new instance has the same type. In addition, if the uniforms have
* initializers, the values of the initializers must be the same.
*/
ir_variable *const existing = uniforms.get_variable(var->name);
if (existing != NULL) {
if (var->type != existing->type) {
linker_error_printf(prog, "uniform `%s' declared as type "
"`%s' and type `%s'\n",
var->name, var->type->name,
existing->type->name);
return false;
}
if (var->constant_value != NULL) {
if (existing->constant_value != NULL) {
if (!var->constant_value->has_value(existing->constant_value)) {
linker_error_printf(prog, "initializers for uniform "
"`%s' have differing values\n",
var->name);
return false;
}
} else
/* If the first-seen instance of a particular uniform did not
* have an initializer but a later instance does, copy the
* initializer to the version stored in the symbol table.
*/
existing->constant_value =
(ir_constant *)var->constant_value->clone(NULL);
}
} else
uniforms.add_variable(var->name, var);
}
}
return true;
}
/**
* Validate that outputs from one stage match inputs of another
*/
bool
cross_validate_outputs_to_inputs(struct glsl_program *prog,
glsl_shader *producer, glsl_shader *consumer)
{
glsl_symbol_table parameters;
/* FINISHME: Figure these out dynamically. */
const char *const producer_stage = "vertex";
const char *const consumer_stage = "fragment";
/* Find all shader outputs in the "producer" stage.
*/
foreach_list(node, &producer->ir) {
ir_variable *const var = ((ir_instruction *) node)->as_variable();
/* FINISHME: For geometry shaders, this should also look for inout
* FINISHME: variables.
*/
if ((var == NULL) || (var->mode != ir_var_out))
continue;
parameters.add_variable(var->name, var);
}
/* Find all shader inputs in the "consumer" stage. Any variables that have
* matching outputs already in the symbol table must have the same type and
* qualifiers.
*/
foreach_list(node, &consumer->ir) {
ir_variable *const input = ((ir_instruction *) node)->as_variable();
/* FINISHME: For geometry shaders, this should also look for inout
* FINISHME: variables.
*/
if ((input == NULL) || (input->mode != ir_var_in))
continue;
ir_variable *const output = parameters.get_variable(input->name);
if (output != NULL) {
/* Check that the types match between stages.
*/
if (input->type != output->type) {
linker_error_printf(prog,
"%s shader output `%s' delcared as "
"type `%s', but %s shader input declared "
"as type `%s'\n",
producer_stage, output->name,
output->type->name,
consumer_stage, input->type->name);
return false;
}
/* Check that all of the qualifiers match between stages.
*/
if (input->centroid != output->centroid) {
linker_error_printf(prog,
"%s shader output `%s' %s centroid qualifier, "
"but %s shader input %s centroid qualifier\n",
producer_stage,
output->name,
(output->centroid) ? "has" : "lacks",
consumer_stage,
(input->centroid) ? "has" : "lacks");
return false;
}
if (input->invariant != output->invariant) {
linker_error_printf(prog,
"%s shader output `%s' %s invariant qualifier, "
"but %s shader input %s invariant qualifier\n",
producer_stage,
output->name,
(output->invariant) ? "has" : "lacks",
consumer_stage,
(input->invariant) ? "has" : "lacks");
return false;
}
if (input->interpolation != output->interpolation) {
linker_error_printf(prog,
"%s shader output `%s' specifies %s "
"interpolation qualifier, "
"but %s shader input specifies %s "
"interpolation qualifier\n",
producer_stage,
output->name,
output->interpolation_string(),
consumer_stage,
input->interpolation_string());
return false;
}
}
}
return true;
}
struct uniform_node {
exec_node link;
struct gl_uniform *u;
unsigned slots;
};
void
assign_uniform_locations(struct glsl_program *prog)
{
/* */
exec_list uniforms;
unsigned total_uniforms = 0;
hash_table *ht = hash_table_ctor(32, hash_table_string_hash,
hash_table_string_compare);
for (unsigned i = 0; i < prog->_NumLinkedShaders; i++) {
unsigned next_position = 0;
foreach_list(node, &prog->_LinkedShaders[i]->ir) {
ir_variable *const var = ((ir_instruction *) node)->as_variable();
if ((var == NULL) || (var->mode != ir_var_uniform))
continue;
const unsigned vec4_slots = (var->component_slots() + 3) / 4;
assert(vec4_slots != 0);
uniform_node *n = (uniform_node *) hash_table_find(ht, var->name);
if (n == NULL) {
n = (uniform_node *) calloc(1, sizeof(struct uniform_node));
n->u = (gl_uniform *) calloc(vec4_slots, sizeof(struct gl_uniform));
n->slots = vec4_slots;
n->u[0].Name = strdup(var->name);
for (unsigned j = 1; j < vec4_slots; j++)
n->u[j].Name = n->u[0].Name;
hash_table_insert(ht, n, n->u[0].Name);
uniforms.push_tail(& n->link);
total_uniforms += vec4_slots;
}
if (var->constant_value != NULL)
for (unsigned j = 0; j < vec4_slots; j++)
n->u[j].Initialized = true;
var->location = next_position;
for (unsigned j = 0; j < vec4_slots; j++) {
switch (prog->_LinkedShaders[i]->Type) {
case GL_VERTEX_SHADER:
n->u[j].VertPos = next_position;
break;
case GL_FRAGMENT_SHADER:
n->u[j].FragPos = next_position;
break;
case GL_GEOMETRY_SHADER:
/* FINISHME: Support geometry shaders. */
assert(prog->_LinkedShaders[i]->Type != GL_GEOMETRY_SHADER);
break;
}
next_position++;
}
}
}
gl_uniform_list *ul = (gl_uniform_list *)
calloc(1, sizeof(gl_uniform_list));
ul->Size = total_uniforms;
ul->NumUniforms = total_uniforms;
ul->Uniforms = (gl_uniform *) calloc(total_uniforms, sizeof(gl_uniform));
unsigned idx = 0;
uniform_node *next;
for (uniform_node *node = (uniform_node *) uniforms.head
; node->link.next != NULL
; node = next) {
next = (uniform_node *) node->link.next;
node->link.remove();
memcpy(&ul->Uniforms[idx], node->u, sizeof(gl_uniform) * node->slots);
idx += node->slots;
free(node->u);
free(node);
}
hash_table_dtor(ht);
prog->Uniforms = ul;
}
/**
* Find a contiguous set of available bits in a bitmask
*
* \param used_mask Bits representing used (1) and unused (0) locations
* \param needed_count Number of contiguous bits needed.
*
* \return
* Base location of the available bits on success or -1 on failure.
*/
int
find_available_slots(unsigned used_mask, unsigned needed_count)
{
unsigned needed_mask = (1 << needed_count) - 1;
const int max_bit_to_test = (8 * sizeof(used_mask)) - needed_count;
/* The comparison to 32 is redundant, but without it GCC emits "warning:
* cannot optimize possibly infinite loops" for the loop below.
*/
if ((needed_count == 0) || (max_bit_to_test < 0) || (max_bit_to_test > 32))
return -1;
for (int i = 0; i <= max_bit_to_test; i++) {
if ((needed_mask & ~used_mask) == needed_mask)
return i;
needed_mask <<= 1;
}
return -1;
}
bool
assign_attribute_locations(glsl_program *prog, unsigned max_attribute_index)
{
/* Mark invalid attribute locations as being used.
*/
unsigned used_locations = (max_attribute_index >= 32)
? ~0 : ~((1 << max_attribute_index) - 1);
glsl_shader *const sh = prog->_LinkedShaders[0];
assert(sh->Type == GL_VERTEX_SHADER);
/* Operate in a total of four passes.
*
* 1. Invalidate the location assignments for all vertex shader inputs.
*
* 2. Assign locations for inputs that have user-defined (via
* glBindVertexAttribLocation) locatoins.
*
* 3. Sort the attributes without assigned locations by number of slots
* required in decreasing order. Fragmentation caused by attribute
* locations assigned by the application may prevent large attributes
* from having enough contiguous space.
*
* 4. Assign locations to any inputs without assigned locations.
*/
invalidate_variable_locations(sh, ir_var_in, VERT_ATTRIB_GENERIC0);
if (prog->Attributes != NULL) {
for (unsigned i = 0; i < prog->Attributes->NumParameters; i++) {
ir_variable *const var =
sh->symbols->get_variable(prog->Attributes->Parameters[i].Name);
/* Note: attributes that occupy multiple slots, such as arrays or
* matrices, may appear in the attrib array multiple times.
*/
if ((var == NULL) || (var->location != -1))
continue;
/* From page 61 of the OpenGL 4.0 spec:
*
* "LinkProgram will fail if the attribute bindings assigned by
* BindAttribLocation do not leave not enough space to assign a
* location for an active matrix attribute or an active attribute
* array, both of which require multiple contiguous generic
* attributes."
*
* Previous versions of the spec contain similar language but omit the
* bit about attribute arrays.
*
* Page 61 of the OpenGL 4.0 spec also says:
*
* "It is possible for an application to bind more than one
* attribute name to the same location. This is referred to as
* aliasing. This will only work if only one of the aliased
* attributes is active in the executable program, or if no path
* through the shader consumes more than one attribute of a set
* of attributes aliased to the same location. A link error can
* occur if the linker determines that every path through the
* shader consumes multiple aliased attributes, but
* implementations are not required to generate an error in this
* case."
*
* These two paragraphs are either somewhat contradictory, or I don't
* fully understand one or both of them.
*/
/* FINISHME: The code as currently written does not support attribute
* FINISHME: location aliasing (see comment above).
*/
const int attr = prog->Attributes->Parameters[i].StateIndexes[0];
const unsigned slots = count_attribute_slots(var->type);
/* Mask representing the contiguous slots that will be used by this
* attribute.
*/
const unsigned use_mask = (1 << slots) - 1;
/* Generate a link error if the set of bits requested for this
* attribute overlaps any previously allocated bits.
*/
if ((~(use_mask << attr) & used_locations) != used_locations) {
linker_error_printf(prog,
"insufficient contiguous attribute locations "
"available for vertex shader input `%s'",
var->name);
return false;
}
var->location = VERT_ATTRIB_GENERIC0 + attr;
used_locations |= (use_mask << attr);
}
}
/* Temporary storage for the set of attributes that need locations assigned.
*/
struct temp_attr {
unsigned slots;
ir_variable *var;
/* Used below in the call to qsort. */
static int compare(const void *a, const void *b)
{
const temp_attr *const l = (const temp_attr *) a;
const temp_attr *const r = (const temp_attr *) b;
/* Reversed because we want a descending order sort below. */
return r->slots - l->slots;
}
} to_assign[16];
unsigned num_attr = 0;
foreach_list(node, &sh->ir) {
ir_variable *const var = ((ir_instruction *) node)->as_variable();
if ((var == NULL) || (var->mode != ir_var_in))
continue;
/* The location was explicitly assigned, nothing to do here.
*/
if (var->location != -1)
continue;
to_assign[num_attr].slots = count_attribute_slots(var->type);
to_assign[num_attr].var = var;
num_attr++;
}
/* If all of the attributes were assigned locations by the application (or
* are built-in attributes with fixed locations), return early. This should
* be the common case.
*/
if (num_attr == 0)
return true;
qsort(to_assign, num_attr, sizeof(to_assign[0]), temp_attr::compare);
for (unsigned i = 0; i < num_attr; i++) {
/* Mask representing the contiguous slots that will be used by this
* attribute.
*/
const unsigned use_mask = (1 << to_assign[i].slots) - 1;
int location = find_available_slots(used_locations, to_assign[i].slots);
if (location < 0) {
linker_error_printf(prog,
"insufficient contiguous attribute locations "
"available for vertex shader input `%s'",
to_assign[i].var->name);
return false;
}
to_assign[i].var->location = VERT_ATTRIB_GENERIC0 + location;
used_locations |= (use_mask << location);
}
return true;
}
void
assign_varying_locations(glsl_shader *producer, glsl_shader *consumer)
{
/* FINISHME: Set dynamically when geometry shader support is added. */
unsigned output_index = VERT_RESULT_VAR0;
unsigned input_index = FRAG_ATTRIB_VAR0;
/* Operate in a total of three passes.
*
* 1. Assign locations for any matching inputs and outputs.
*
* 2. Mark output variables in the producer that do not have locations as
* not being outputs. This lets the optimizer eliminate them.
*
* 3. Mark input variables in the consumer that do not have locations as
* not being inputs. This lets the optimizer eliminate them.
*/
invalidate_variable_locations(producer, ir_var_out, VERT_RESULT_VAR0);
invalidate_variable_locations(consumer, ir_var_in, FRAG_ATTRIB_VAR0);
foreach_list(node, &producer->ir) {
ir_variable *const output_var = ((ir_instruction *) node)->as_variable();
if ((output_var == NULL) || (output_var->mode != ir_var_out)
|| (output_var->location != -1))
continue;
ir_variable *const input_var =
consumer->symbols->get_variable(output_var->name);
if ((input_var == NULL) || (input_var->mode != ir_var_in))
continue;
assert(input_var->location == -1);
/* FINISHME: Location assignment will need some changes when arrays,
* FINISHME: matrices, and structures are allowed as shader inputs /
* FINISHME: outputs.
*/
output_var->location = output_index;
input_var->location = input_index;
output_index++;
input_index++;
}
foreach_list(node, &producer->ir) {
ir_variable *const var = ((ir_instruction *) node)->as_variable();
if ((var == NULL) || (var->mode != ir_var_out))
continue;
/* An 'out' variable is only really a shader output if its value is read
* by the following stage.
*/
var->shader_out = (var->location != -1);
}
foreach_list(node, &consumer->ir) {
ir_variable *const var = ((ir_instruction *) node)->as_variable();
if ((var == NULL) || (var->mode != ir_var_in))
continue;
/* An 'in' variable is only really a shader input if its value is written
* by the previous stage.
*/
var->shader_in = (var->location != -1);
}
}
void
link_shaders(struct glsl_program *prog)
{
prog->LinkStatus = false;
prog->Validated = false;
prog->_Used = false;
if (prog->InfoLog != NULL)
talloc_free(prog->InfoLog);
prog->InfoLog = talloc_strdup(NULL, "");
/* Separate the shaders into groups based on their type.
*/
struct glsl_shader **vert_shader_list;
unsigned num_vert_shaders = 0;
struct glsl_shader **frag_shader_list;
unsigned num_frag_shaders = 0;
vert_shader_list = (struct glsl_shader **)
calloc(2 * prog->NumShaders, sizeof(struct glsl_shader *));
frag_shader_list = &vert_shader_list[prog->NumShaders];
for (unsigned i = 0; i < prog->NumShaders; i++) {
switch (prog->Shaders[i]->Type) {
case GL_VERTEX_SHADER:
vert_shader_list[num_vert_shaders] = prog->Shaders[i];
num_vert_shaders++;
break;
case GL_FRAGMENT_SHADER:
frag_shader_list[num_frag_shaders] = prog->Shaders[i];
num_frag_shaders++;
break;
case GL_GEOMETRY_SHADER:
/* FINISHME: Support geometry shaders. */
assert(prog->Shaders[i]->Type != GL_GEOMETRY_SHADER);
break;
}
}
/* FINISHME: Implement intra-stage linking. */
assert(num_vert_shaders <= 1);
assert(num_frag_shaders <= 1);
/* Verify that each of the per-target executables is valid.
*/
if (!validate_vertex_shader_executable(prog, vert_shader_list[0])
|| !validate_fragment_shader_executable(prog, frag_shader_list[0]))
goto done;
prog->_LinkedShaders = (struct glsl_shader **)
calloc(2, sizeof(struct glsl_shader *));
prog->_NumLinkedShaders = 0;
if (num_vert_shaders > 0) {
prog->_LinkedShaders[prog->_NumLinkedShaders] = vert_shader_list[0];
prog->_NumLinkedShaders++;
}
if (num_frag_shaders > 0) {
prog->_LinkedShaders[prog->_NumLinkedShaders] = frag_shader_list[0];
prog->_NumLinkedShaders++;
}
/* Here begins the inter-stage linking phase. Some initial validation is
* performed, then locations are assigned for uniforms, attributes, and
* varyings.
*/
if (cross_validate_uniforms(prog)) {
/* Validate the inputs of each stage with the output of the preceeding
* stage.
*/
for (unsigned i = 1; i < prog->_NumLinkedShaders; i++) {
if (!cross_validate_outputs_to_inputs(prog,
prog->_LinkedShaders[i - 1],
prog->_LinkedShaders[i]))
goto done;
}
prog->LinkStatus = true;
}
/* FINISHME: Perform whole-program optimization here. */
assign_uniform_locations(prog);
if (prog->_LinkedShaders[0]->Type == GL_VERTEX_SHADER)
/* FINISHME: The value of the max_attribute_index parameter is
* FINISHME: implementation dependent based on the value of
* FINISHME: GL_MAX_VERTEX_ATTRIBS. GL_MAX_VERTEX_ATTRIBS must be
* FINISHME: at least 16, so hardcode 16 for now.
*/
if (!assign_attribute_locations(prog, 16))
goto done;
for (unsigned i = 1; i < prog->_NumLinkedShaders; i++)
assign_varying_locations(prog->_LinkedShaders[i - 1],
prog->_LinkedShaders[i]);
/* FINISHME: Assign fragment shader output locations. */
done:
free(vert_shader_list);
}