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glsl: look for multiple variables simultaneously with find_assignment_visitor 

Save some passes over the IR.

v2: redesign to make the users of find_assignments more readable
v3:
- fix missing !
- add some comments and make the num_found check more explicit (Timothy)

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com> (v1)
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
This commit is contained in:
Nicolai Hähnle 2017-06-22 12:12:44 +02:00
parent a2b02c4948
commit 727e8ba133
1 changed files with 83 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

126
src/compiler/glsl/linker.cpp
View File

@ -90,27 +90,31 @@
namespace {
struct find_variable {
const char *name;
bool found;
find_variable(const char *name) : name(name), found(false) {}
};
/**
* Visitor that determines whether or not a variable is ever written.
*
* Use \ref find_assignments for convenience.
*/
class find_assignment_visitor : public ir_hierarchical_visitor {
public:
find_assignment_visitor(const char *name)
: name(name), found(false)
find_assignment_visitor(unsigned num_vars,
find_variable * const *vars)
: num_variables(num_vars), num_found(0), variables(vars)
{
/* 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;
return check_variable_name(var->name);
}
virtual ir_visitor_status visit_enter(ir_call *ir)
@ -123,35 +127,71 @@ public:
if (sig_param->data.mode == ir_var_function_out ||
sig_param->data.mode == ir_var_function_inout) {
ir_variable *var = param_rval->variable_referenced();
if (var && strcmp(name, var->name) == 0) {
found = true;
if (var && check_variable_name(var->name) == visit_stop)
return visit_stop;
}
}
}
if (ir->return_deref != NULL) {
ir_variable *const var = ir->return_deref->variable_referenced();
if (strcmp(name, var->name) == 0) {
found = true;
if (check_variable_name(var->name) == visit_stop)
return visit_stop;
}
return visit_continue_with_parent;
}
private:
ir_visitor_status check_variable_name(const char *name)
{
for (unsigned i = 0; i < num_variables; ++i) {
if (strcmp(variables[i]->name, name) == 0) {
if (!variables[i]->found) {
variables[i]->found = true;
assert(num_found < num_variables);
if (++num_found == num_variables)
return visit_stop;
}
break;
}
}
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? */
unsigned num_variables; /**< Number of variables to find */
unsigned num_found; /**< Number of variables already found */
find_variable * const *variables; /**< Variables to find */
};
/**
* Determine whether or not any of NULL-terminated list of variables is ever
* written to.
*/
static void
find_assignments(exec_list *ir, find_variable * const *vars)
{
unsigned num_variables = 0;
for (find_variable * const *v = vars; *v; ++v)
num_variables++;
find_assignment_visitor visitor(num_variables, vars);
visitor.run(ir);
}
/**
* Determine whether or not the given variable is ever written to.
*/
static void
find_assignments(exec_list *ir, find_variable *var)
{
find_assignment_visitor visitor(1, &var);
visitor.run(ir);
}
/**
* Visitor that determines whether or not a variable is ever read.
@ -567,11 +607,16 @@ analyze_clip_cull_usage(struct gl_shader_program *prog,
* gl_ClipVertex nor gl_ClipDistance. However with
* GL_EXT_clip_cull_distance, this functionality is exposed in ES 3.0.
*/
find_assignment_visitor clip_distance("gl_ClipDistance");
find_assignment_visitor cull_distance("gl_CullDistance");
clip_distance.run(shader->ir);
cull_distance.run(shader->ir);
find_variable gl_ClipDistance("gl_ClipDistance");
find_variable gl_CullDistance("gl_CullDistance");
find_variable gl_ClipVertex("gl_ClipVertex");
find_variable * const variables[] = {
&gl_ClipDistance,
&gl_CullDistance,
!prog->IsES ? &gl_ClipVertex : NULL,
NULL
};
find_assignments(shader->ir, variables);
/* From the ARB_cull_distance spec:
*
@ -583,17 +628,13 @@ analyze_clip_cull_usage(struct gl_shader_program *prog,
* gl_ClipVertex.
*/
if (!prog->IsES) {
find_assignment_visitor clip_vertex("gl_ClipVertex");
clip_vertex.run(shader->ir);
if (clip_vertex.variable_found() && clip_distance.variable_found()) {
if (gl_ClipVertex.found && gl_ClipDistance.found) {
linker_error(prog, "%s shader writes to both `gl_ClipVertex' "
"and `gl_ClipDistance'\n",
_mesa_shader_stage_to_string(shader->Stage));
return;
}
if (clip_vertex.variable_found() && cull_distance.variable_found()) {
if (gl_ClipVertex.found && gl_CullDistance.found) {
linker_error(prog, "%s shader writes to both `gl_ClipVertex' "
"and `gl_CullDistance'\n",
_mesa_shader_stage_to_string(shader->Stage));
@ -601,13 +642,13 @@ analyze_clip_cull_usage(struct gl_shader_program *prog,
}
}
if (clip_distance.variable_found()) {
if (gl_ClipDistance.found) {
ir_variable *clip_distance_var =
shader->symbols->get_variable("gl_ClipDistance");
assert(clip_distance_var);
*clip_distance_array_size = clip_distance_var->type->length;
}
if (cull_distance.variable_found()) {
if (gl_CullDistance.found) {
ir_variable *cull_distance_var =
shader->symbols->get_variable("gl_CullDistance");
assert(cull_distance_var);
@ -676,9 +717,9 @@ validate_vertex_shader_executable(struct gl_shader_program *prog,
* gl_Position is not an error.
*/
if (prog->data->Version < (prog->IsES ? 300 : 140)) {
find_assignment_visitor find("gl_Position");
find.run(shader->ir);
if (!find.variable_found()) {
find_variable gl_Position("gl_Position");
find_assignments(shader->ir, &gl_Position);
if (!gl_Position.found) {
if (prog->IsES) {
linker_warning(prog,
"vertex shader does not write to `gl_Position'. "
@ -722,13 +763,12 @@ validate_fragment_shader_executable(struct gl_shader_program *prog,
if (shader == NULL)
return;
find_assignment_visitor frag_color("gl_FragColor");
find_assignment_visitor frag_data("gl_FragData");
find_variable gl_FragColor("gl_FragColor");
find_variable gl_FragData("gl_FragData");
find_variable * const variables[] = { &gl_FragColor, &gl_FragData, NULL };
find_assignments(shader->ir, variables);
frag_color.run(shader->ir);
frag_data.run(shader->ir);
if (frag_color.variable_found() && frag_data.variable_found()) {
if (gl_FragColor.found && gl_FragData.found) {
linker_error(prog, "fragment shader writes to both "
"`gl_FragColor' and `gl_FragData'\n");
}