On 05/03/2013 04:07 PM, Ian Romanick wrote:
From: Ian Romanick <ian.d.roman...@intel.com>
Lower ir_binop_vector_extract with a constant index to a swizzle. This
is exactly like ir_dereference_array of a vector with a constant index.
v2: Convert tabs to spaces. Suggested by Eric.
v3: Correctly call convert_vector_extract_to_swizzle in
ir_vec_index_to_swizzle_visitor::visit_enter(ir_call *ir). Suggested by
Ken.
Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
Reviewed-by: Eric Anholt <e...@anholt.net>
---
src/glsl/lower_vec_index_to_swizzle.cpp | 47 ++++++++++++++++++++++++++++++++-
1 file changed, 46 insertions(+), 1 deletion(-)
diff --git a/src/glsl/lower_vec_index_to_swizzle.cpp
b/src/glsl/lower_vec_index_to_swizzle.cpp
index 264d6dc..9d0d696 100644
--- a/src/glsl/lower_vec_index_to_swizzle.cpp
+++ b/src/glsl/lower_vec_index_to_swizzle.cpp
@@ -47,6 +47,7 @@ public:
}
ir_rvalue *convert_vec_index_to_swizzle(ir_rvalue *val);
+ ir_rvalue *convert_vector_extract_to_swizzle(ir_rvalue *val);
virtual ir_visitor_status visit_enter(ir_expression *);
virtual ir_visitor_status visit_enter(ir_swizzle *);
@@ -93,11 +94,45 @@
ir_vec_index_to_swizzle_visitor::convert_vec_index_to_swizzle(ir_rvalue *ir)
* large. For simplicity sake, just clamp the index to [0, size-1].
*/
const int i = MIN2(MAX2(ir_constant->value.i[0], 0),
- ((int) deref->array->type->vector_elements - 1));
+ ((int) deref->array->type->vector_elements - 1));
Looks like a spurious hunk (not a big deal though).
return new(ctx) ir_swizzle(deref->array, i, 0, 0, 0, 1);
}
+ir_rvalue *
+ir_vec_index_to_swizzle_visitor::convert_vector_extract_to_swizzle(ir_rvalue
*ir)
+{
+ ir_expression *const expr = ir->as_expression();
+ if (expr == NULL || expr->operation != ir_binop_vector_extract)
+ return ir;
+
+ ir_constant *const idx = expr->operands[1]->constant_expression_value();
+ if (idx == NULL)
+ return ir;
+
+ void *ctx = ralloc_parent(ir);
+ this->progress = true;
+
+ /* Page 40 of the GLSL 1.20 spec says:
+ *
+ * "When indexing with non-constant expressions, behavior is undefined
+ * if the index is negative, or greater than or equal to the size of
+ * the vector."
+ *
+ * The quoted spec text mentions non-constant expressions, but this code
+ * operates on constants. These constants are the result of non-constant
+ * expressions that have been optimized to constants. The common case here
+ * is a loop counter from an unrolled loop that is used to index a vector.
+ *
+ * The ir_swizzle constructor gets angry if the index is negative or too
+ * large. For simplicity sake, just clamp the index to [0, size-1].
+ */
+ const int i = MIN2(MAX2(idx->value.i[0], 0),
+ ((int) expr->operands[0]->type->vector_elements - 1));
Would be easier to read with CLAMP:
const int i = CLAMP(idx->value.i[0], 0,
int(expr->operands[0]->type->vector_elements - 1));
Either way, this patch is:
Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
+ return new(ctx) ir_swizzle(expr->operands[0], i, 0, 0, 0, 1);
+}
+
ir_visitor_status
ir_vec_index_to_swizzle_visitor::visit_enter(ir_expression *ir)
{
@@ -105,6 +140,7 @@ ir_vec_index_to_swizzle_visitor::visit_enter(ir_expression
*ir)
for (i = 0; i < ir->get_num_operands(); i++) {
ir->operands[i] = convert_vec_index_to_swizzle(ir->operands[i]);
+ ir->operands[i] = convert_vector_extract_to_swizzle(ir->operands[i]);
}
return visit_continue;
@@ -127,6 +163,7 @@ ir_vec_index_to_swizzle_visitor::visit_enter(ir_assignment
*ir)
{
ir->set_lhs(convert_vec_index_to_swizzle(ir->lhs));
ir->rhs = convert_vec_index_to_swizzle(ir->rhs);
+ ir->rhs = convert_vector_extract_to_swizzle(ir->rhs);
return visit_continue;
}
@@ -140,6 +177,12 @@ ir_vec_index_to_swizzle_visitor::visit_enter(ir_call *ir)
if (new_param != param) {
param->replace_with(new_param);
+ } else {
+ new_param = convert_vector_extract_to_swizzle(param);
+
+ if (new_param != param) {
+ param->replace_with(new_param);
+ }
}
}
@@ -151,6 +194,7 @@ ir_vec_index_to_swizzle_visitor::visit_enter(ir_return *ir)
{
if (ir->value) {
ir->value = convert_vec_index_to_swizzle(ir->value);
+ ir->value = convert_vector_extract_to_swizzle(ir->value);
}
return visit_continue;
@@ -160,6 +204,7 @@ ir_visitor_status
ir_vec_index_to_swizzle_visitor::visit_enter(ir_if *ir)
{
ir->condition = convert_vec_index_to_swizzle(ir->condition);
+ ir->condition = convert_vector_extract_to_swizzle(ir->condition);
return visit_continue;
}
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