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glsl: Update lower_packed_varyings to handle varying structs. 

This patch adds code to lower_packed_varyings to handle varyings of
type struct.  Varying structs are currently packed in the most naive
possible way (in declaration order, with no gaps), so there is a
potential loss of runtime efficiency.  In a later patch it would be
nice to replace this with a "flattening" approach (wherein a varying
struct is flattened to individual varyings corresponding to each of
its structure elements), so that the linker can align each structure
element independently.  However, that would require a significantly
more complex implementation.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Paul Berry 2013-01-11 12:56:03 -08:00
parent 88e4bfde26
commit 1ecd23dea9
1 changed files with 18 additions and 4 deletions
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22
src/glsl/lower_packed_varyings.cpp
View File

@ -70,6 +70,10 @@
* This lowering pass also packs flat floats, ints, and uints together, by
* using ivec4 as the base type of flat "varyings", and using appropriate
* casts to convert floats and uints into ints.
*
* This lowering pass also handles varyings whose type is a struct or an array
* of struct. Structs are packed in order and with no gaps, so there may be a
* performance penalty due to structure elements being double-parked.
*/
#include "glsl_symbol_table.h"
@ -274,10 +278,20 @@ lower_packed_varyings_visitor::lower_rvalue(ir_rvalue *rvalue,
ir_variable *unpacked_var,
const char *name)
{
/* FINISHME: Support for "varying" records in GLSL 1.50. */
assert(!rvalue->type->is_record());
if (rvalue->type->is_array()) {
if (rvalue->type->is_record()) {
for (unsigned i = 0; i < rvalue->type->length; i++) {
if (i != 0)
rvalue = rvalue->clone(this->mem_ctx, NULL);
const char *field_name = rvalue->type->fields.structure[i].name;
ir_dereference_record *dereference_record = new(this->mem_ctx)
ir_dereference_record(rvalue, field_name);
char *deref_name
= ralloc_asprintf(this->mem_ctx, "%s.%s", name, field_name);
fine_location = this->lower_rvalue(dereference_record, fine_location,
unpacked_var, deref_name);
}
return fine_location;
} else if (rvalue->type->is_array()) {
/* Arrays are packed/unpacked by considering each array element in
* sequence.
*/