Mesa (master): glsl: Mark whole variable used for ClipDistance and TessLevel*.
Kenneth Graunke
kwg at kemper.freedesktop.org
Sat Jan 7 00:25:37 UTC 2017
Module: Mesa
Branch: master
Commit: 5c580e64cc206ab160e1767c42e4d6c81f67da4d
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=5c580e64cc206ab160e1767c42e4d6c81f67da4d
Author: Kenneth Graunke <kenneth at whitecape.org>
Date: Sun Nov 15 04:22:10 2015 -0800
glsl: Mark whole variable used for ClipDistance and TessLevel*.
There's no point in trying to mark partial array access for
gl_ClipDistance, gl_TessLevelOuter, or gl_TessLevelInner - they're
special built-in variables that control fixed function hardware,
and will likely be used in an all-or-nothing fashion.
Since these arrays only occupy 1-2 varying slots, we have to avoid
our normal processing which increments the slot value by the array
index.
(I wrote this code before i965 switched from ir_set_program_inouts
to nir_shader_gather_info. It's not used by anyone today, and I'm
not sure how valuable it is...the alternative to GLSL IR lowering
is NIR compact arrays, at which point you should use nir_gather_info.)
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
Reviewed-by: Timothy Arceri <timothy.arceri at collabora.com>
---
src/compiler/glsl/ir_set_program_inouts.cpp | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/src/compiler/glsl/ir_set_program_inouts.cpp b/src/compiler/glsl/ir_set_program_inouts.cpp
index 66f0c1e..376d9c6 100644
--- a/src/compiler/glsl/ir_set_program_inouts.cpp
+++ b/src/compiler/glsl/ir_set_program_inouts.cpp
@@ -330,6 +330,23 @@ is_multiple_vertices(gl_shader_stage stage, ir_variable *var)
return false;
}
+/**
+ * Return true if \p var is a GLSL built-in array that controls fixed-function
+ * aspects of the pipeline. These have to be used as a whole.
+ */
+static bool
+is_fixed_function_array(ir_variable *var)
+{
+ switch (var->data.location) {
+ case VARYING_SLOT_TESS_LEVEL_OUTER:
+ case VARYING_SLOT_TESS_LEVEL_INNER:
+ case VARYING_SLOT_CLIP_DIST0:
+ return true;
+ default:
+ return false;
+ }
+}
+
ir_visitor_status
ir_set_program_inouts_visitor::visit_enter(ir_dereference_array *ir)
{
@@ -362,9 +379,12 @@ ir_set_program_inouts_visitor::visit_enter(ir_dereference_array *ir)
} else if (ir_dereference_variable * const deref_var =
ir->array->as_dereference_variable()) {
/* ir => foo[i], where foo is a variable. */
- if (is_multiple_vertices(this->shader_stage, deref_var->var)) {
- /* foo is a geometry or tessellation shader input, so i is
- * the vertex, and we're accessing the entire input.
+ if (is_multiple_vertices(this->shader_stage, deref_var->var) ||
+ is_fixed_function_array(deref_var->var)) {
+ /* In the first case, foo is a geometry or tessellation shader input,
+ * so i is the vertex, and we're accessing the entire input. In the
+ * second case, foo is a GLSL built-in array that controls
+ * fixed-function hardware, which is consumed as a whole.
*/
mark_whole_variable(deref_var->var);
/* We've now taken care of foo, but i might contain a subexpression
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