[Mesa-dev] [PATCH] glsl: break the gl_FragData array into separate gl_FragData[i] variables
Marek Olšák
maraeo at gmail.com
Sun Oct 20 18:20:59 CEST 2013
From: Marek Olšák <marek.olsak at amd.com>
This avoids a defect in lower_output_reads.
The problem is lower_output_reads treats the gl_FragData array as a single
variable. It first redirects all output writes to a temporary variable (array)
and then writes the whole temporary variable to the output, generating
assignments to all elements of gl_FragData.
BTW this pass can be modified to lower all arrays, not just inputs and outputs.
The question is whether it is worth it.
---
src/glsl/opt_dead_builtin_varyings.cpp | 163 ++++++++++++++++++++++++++-------
1 file changed, 132 insertions(+), 31 deletions(-)
diff --git a/src/glsl/opt_dead_builtin_varyings.cpp b/src/glsl/opt_dead_builtin_varyings.cpp
index 7e8cd43..72ff9df 100644
--- a/src/glsl/opt_dead_builtin_varyings.cpp
+++ b/src/glsl/opt_dead_builtin_varyings.cpp
@@ -42,9 +42,11 @@
* If any texture coordinate slots can be eliminated, the gl_TexCoord array is
* broken down into separate vec4 variables with locations equal to
* VARYING_SLOT_TEX0 + i.
+ *
+ * The same is done for the gl_FragData fragment shader output.
*/
-#include "main/imports.h" /* for snprintf */
+#include "main/core.h" /* for snprintf and ARRAY_SIZE */
#include "ir.h"
#include "ir_rvalue_visitor.h"
#include "ir_optimization.h"
@@ -60,10 +62,14 @@ namespace {
class varying_info_visitor : public ir_hierarchical_visitor {
public:
/* "mode" can be either ir_var_shader_in or ir_var_shader_out */
- varying_info_visitor(ir_variable_mode mode)
+ varying_info_visitor(ir_variable_mode mode, bool find_frag_outputs = false)
: lower_texcoord_array(true),
texcoord_array(NULL),
texcoord_usage(0),
+ find_frag_outputs(find_frag_outputs),
+ lower_fragdata_array(true),
+ fragdata_array(NULL),
+ fragdata_usage(0),
color_usage(0),
tfeedback_color_usage(0),
fog(NULL),
@@ -79,8 +85,27 @@ public:
{
ir_variable *var = ir->variable_referenced();
- if (var && var->mode == this->mode &&
- var->location == VARYING_SLOT_TEX0) {
+ if (!var || var->mode != this->mode)
+ return visit_continue;
+
+ if (this->find_frag_outputs && var->location == FRAG_RESULT_DATA0) {
+ this->fragdata_array = var;
+
+ ir_constant *index = ir->array_index->as_constant();
+ if (index == NULL) {
+ /* This is variable indexing. */
+ this->fragdata_usage |= (1 << var->type->array_size()) - 1;
+ this->lower_fragdata_array = false;
+ }
+ else {
+ this->fragdata_usage |= 1 << index->get_uint_component(0);
+ }
+
+ /* Don't visit the leaves of ir_dereference_array. */
+ return visit_continue_with_parent;
+ }
+
+ if (!this->find_frag_outputs && var->location == VARYING_SLOT_TEX0) {
this->texcoord_array = var;
ir_constant *index = ir->array_index->as_constant();
@@ -105,8 +130,17 @@ public:
{
ir_variable *var = ir->variable_referenced();
- if (var->mode == this->mode && var->type->is_array() &&
- var->location == VARYING_SLOT_TEX0) {
+ if (var->mode != this->mode || !var->type->is_array())
+ return visit_continue;
+
+ if (this->find_frag_outputs && var->location == FRAG_RESULT_DATA0) {
+ /* This is a whole array dereference. */
+ this->fragdata_usage |= (1 << var->type->array_size()) - 1;
+ this->lower_fragdata_array = false;
+ return visit_continue;
+ }
+
+ if (!this->find_frag_outputs && var->location == VARYING_SLOT_TEX0) {
/* This is a whole array dereference like "gl_TexCoord = x;",
* there's probably no point in lowering that.
*/
@@ -121,6 +155,10 @@ public:
if (var->mode != this->mode)
return visit_continue;
+ /* Nothing to do here for fragment outputs. */
+ if (this->find_frag_outputs)
+ return visit_continue;
+
/* Handle colors and fog. */
switch (var->location) {
case VARYING_SLOT_COL0:
@@ -185,12 +223,20 @@ public:
if (!this->texcoord_array) {
this->lower_texcoord_array = false;
}
+ if (!this->fragdata_array) {
+ this->lower_fragdata_array = false;
+ }
}
bool lower_texcoord_array;
ir_variable *texcoord_array;
unsigned texcoord_usage; /* bitmask */
+ bool find_frag_outputs; /* false if it's looking for varyings */
+ bool lower_fragdata_array;
+ ir_variable *fragdata_array;
+ unsigned fragdata_usage; /* bitmask */
+
ir_variable *color[2];
ir_variable *backcolor[2];
unsigned color_usage; /* bitmask */
@@ -222,6 +268,7 @@ public:
{
void *const ctx = ir;
+ memset(this->new_fragdata, 0, sizeof(this->new_fragdata));
memset(this->new_texcoord, 0, sizeof(this->new_texcoord));
memset(this->new_color, 0, sizeof(this->new_color));
memset(this->new_backcolor, 0, sizeof(this->new_backcolor));
@@ -236,31 +283,16 @@ public:
* occurences of gl_TexCoord will be replaced with.
*/
if (info->lower_texcoord_array) {
- for (int i = MAX_TEXTURE_COORD_UNITS-1; i >= 0; i--) {
- if (info->texcoord_usage & (1 << i)) {
- char name[32];
-
- if (!(external_texcoord_usage & (1 << i))) {
- /* This varying is unused in the next stage. Declare
- * a temporary instead of an output. */
- snprintf(name, 32, "gl_%s_TexCoord%i_dummy", mode_str, i);
- this->new_texcoord[i] =
- new (ctx) ir_variable(glsl_type::vec4_type, name,
- ir_var_temporary);
- }
- else {
- snprintf(name, 32, "gl_%s_TexCoord%i", mode_str, i);
- this->new_texcoord[i] =
- new(ctx) ir_variable(glsl_type::vec4_type, name,
- info->mode);
- this->new_texcoord[i]->location = VARYING_SLOT_TEX0 + i;
- this->new_texcoord[i]->explicit_location = true;
- this->new_texcoord[i]->explicit_index = 0;
- }
-
- ir->head->insert_before(new_texcoord[i]);
- }
- }
+ prepare_array(ir, this->new_texcoord, ARRAY_SIZE(this->new_texcoord),
+ VARYING_SLOT_TEX0, "TexCoord", mode_str,
+ info->texcoord_usage, external_texcoord_usage);
+ }
+
+ /* Handle gl_FragData in the same way like gl_TexCoord. */
+ if (info->lower_fragdata_array) {
+ prepare_array(ir, this->new_fragdata, ARRAY_SIZE(this->new_fragdata),
+ FRAG_RESULT_DATA0, "FragData", mode_str,
+ info->fragdata_usage, (1 << MAX_DRAW_BUFFERS) - 1);
}
/* Create dummy variables which will replace set-but-unused color and
@@ -301,6 +333,41 @@ public:
visit_list_elements(this, ir);
}
+ void prepare_array(exec_list *ir,
+ struct ir_variable **new_var,
+ int max_elements, unsigned start_location,
+ const char *var_name, const char *mode_str,
+ unsigned usage, unsigned external_usage)
+ {
+ void *const ctx = ir;
+
+ for (int i = max_elements-1; i >= 0; i--) {
+ if (usage & (1 << i)) {
+ char name[32];
+
+ if (!(external_usage & (1 << i))) {
+ /* This varying is unused in the next stage. Declare
+ * a temporary instead of an output. */
+ snprintf(name, 32, "gl_%s_%s%i_dummy", mode_str, var_name, i);
+ new_var[i] =
+ new (ctx) ir_variable(glsl_type::vec4_type, name,
+ ir_var_temporary);
+ }
+ else {
+ snprintf(name, 32, "gl_%s_%s%i", mode_str, var_name, i);
+ new_var[i] =
+ new(ctx) ir_variable(glsl_type::vec4_type, name,
+ this->info->mode);
+ new_var[i]->location = start_location + i;
+ new_var[i]->explicit_location = true;
+ new_var[i]->explicit_index = 0;
+ }
+
+ ir->head->insert_before(new_var[i]);
+ }
+ }
+ }
+
virtual ir_visitor_status visit(ir_variable *var)
{
/* Remove the gl_TexCoord array. */
@@ -309,6 +376,12 @@ public:
var->remove();
}
+ /* Remove the gl_FragData array. */
+ if (this->info->lower_fragdata_array &&
+ var == this->info->fragdata_array) {
+ var->remove();
+ }
+
/* Replace set-but-unused color and fog outputs with dummy variables. */
for (int i = 0; i < 2; i++) {
if (var == this->info->color[i] && this->new_color[i]) {
@@ -350,6 +423,19 @@ public:
}
}
+ /* Same for gl_FragData. */
+ if (this->info->lower_fragdata_array) {
+ /* gl_TexCoord[i] occurence */
+ ir_dereference_array *const da = (*rvalue)->as_dereference_array();
+
+ if (da && da->variable_referenced() == this->info->fragdata_array) {
+ unsigned i = da->array_index->as_constant()->get_uint_component(0);
+
+ *rvalue = new(ctx) ir_dereference_variable(this->new_fragdata[i]);
+ return;
+ }
+ }
+
/* Replace set-but-unused color and fog outputs with dummy variables. */
ir_dereference_variable *const dv = (*rvalue)->as_dereference_variable();
if (!dv)
@@ -392,6 +478,7 @@ public:
private:
const varying_info_visitor *info;
+ ir_variable *new_fragdata[MAX_DRAW_BUFFERS];
ir_variable *new_texcoord[MAX_TEXTURE_COORD_UNITS];
ir_variable *new_color[2];
ir_variable *new_backcolor[2];
@@ -408,6 +495,15 @@ lower_texcoord_array(exec_list *ir, const varying_info_visitor *info)
1 | 2, true);
}
+static void
+lower_fragdata_array(exec_list *ir)
+{
+ varying_info_visitor info(ir_var_shader_out, true);
+ info.get(ir, 0, NULL);
+
+ replace_varyings_visitor(ir, &info, 0, 0, 0);
+}
+
void
do_dead_builtin_varyings(struct gl_context *ctx,
@@ -487,4 +583,9 @@ do_dead_builtin_varyings(struct gl_context *ctx,
producer_info.color_usage,
producer_info.has_fog);
}
+
+ /* Finally, lower the gl_FragData array to separate variables. */
+ if (consumer->Type == GL_FRAGMENT_SHADER) {
+ lower_fragdata_array(consumer->ir);
+ }
}
--
1.8.1.2
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