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glsl: store read vector in a temp in vec_index_to_cond 

Vector indexing on matrixes generates several copy of the
constant matrix, for instance vec=mat4[i][j] generates :
vec=mat4[i].x;
vec=(j==1)?mat4[i].y;
vec=(j==2)?mat4[i].z;
vec=(j==3)?mat4[i].w;
In the case of constant matrixes, the mat4[i] expression generates
copy of the 16 elements of the matrix 4 times ; indirect addressing
also prevents some conservative CSE algorithms (like the one in LLVM)
from factoring the mat4[i] expression.
This patch will make the vec_index_to_cond pass generates :
temp = mat4[i];
vec=temp.x;
vec=(j==1)?temp.y;
vec=(j==2)?temp.z;
vec=(j==3)?temp.w;

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Vincent Lejeune 2012-11-04 23:04:30 +01:00
parent 05a2f66cde
commit 557d4918ad
1 changed files with 12 additions and 4 deletions
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16
src/glsl/lower_vec_index_to_cond_assign.cpp
View File

@ -68,9 +68,9 @@ ir_rvalue *
ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(ir_rvalue *ir)
{
ir_dereference_array *orig_deref = ir->as_dereference_array();
ir_assignment *assign;
ir_variable *index, *var;
ir_dereference *deref;
ir_assignment *assign, *value_assign;
ir_variable *index, *var, *value;
ir_dereference *deref, *deref_value;
unsigned i;
if (!orig_deref)
@ -95,6 +95,14 @@ ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(ir_rvalue
assign = new(base_ir) ir_assignment(deref, orig_deref->array_index, NULL);
list.push_tail(assign);
/* Store the value inside a temp, thus avoiding matrixes duplication */
value = new(base_ir) ir_variable(orig_deref->array->type, "vec_value_tmp",
ir_var_temporary);
list.push_tail(value);
deref_value = new(base_ir) ir_dereference_variable(value);
value_assign = new(base_ir) ir_assignment(deref_value, orig_deref->array);
list.push_tail(value_assign);
/* Temporary where we store whichever value we swizzle out. */
var = new(base_ir) ir_variable(ir->type, "vec_index_tmp_v",
ir_var_temporary);
@ -117,7 +125,7 @@ ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(ir_rvalue
* underlying variable.
*/
ir_rvalue *swizzle =
new(base_ir) ir_swizzle(orig_deref->array->clone(mem_ctx, NULL),
new(base_ir) ir_swizzle(deref_value->clone(mem_ctx, NULL),
i, 0, 0, 0, 1);
deref = new(base_ir) ir_dereference_variable(var);