Reviewed-by: Tapani Pälli <tapani.pa...@intel.com>
On 11/25/2015 11:54 AM, Timothy Arceri wrote:
From: Gregory Hainaut <gregory.hain...@gmail.com>
This fixes an issue where the addition of the FLAT qualifier in
varying_matches::record() can break the expected varying order.
It also avoids a future issue with the relaxing of interpolation
qualifier matching constraints in GLSL 4.50.
V2: (by Timothy Arceri)
* reworked comment slightly
Signed-off-by: Gregory Hainaut <gregory.hain...@gmail.com>
Reviewed-by: Timothy Arceri <timothy.arc...@collabora.com>
---
src/glsl/link_varyings.cpp | 38 ++++++++++++++++++++++++++++++++------
1 file changed, 32 insertions(+), 6 deletions(-)
diff --git a/src/glsl/link_varyings.cpp b/src/glsl/link_varyings.cpp
index ac2755f..71750d1 100644
--- a/src/glsl/link_varyings.cpp
+++ b/src/glsl/link_varyings.cpp
@@ -766,7 +766,7 @@ public:
gl_shader_stage consumer_stage);
~varying_matches();
void record(ir_variable *producer_var, ir_variable *consumer_var);
- unsigned assign_locations(uint64_t reserved_slots);
+ unsigned assign_locations(uint64_t reserved_slots, bool separate_shader);
void store_locations() const;
private:
@@ -988,11 +988,36 @@ varying_matches::record(ir_variable *producer_var,
ir_variable *consumer_var)
* passed to varying_matches::record().
*/
unsigned
-varying_matches::assign_locations(uint64_t reserved_slots)
+varying_matches::assign_locations(uint64_t reserved_slots, bool
separate_shader)
{
- /* Sort varying matches into an order that makes them easy to pack. */
- qsort(this->matches, this->num_matches, sizeof(*this->matches),
- &varying_matches::match_comparator);
+ /* We disable varying sorting for separate shader programs for the
+ * following reasons:
+ *
+ * 1/ All programs must sort the code in the same order to guarantee the
+ * interface matching. However varying_matches::record() will change the
+ * interpolation qualifier of some stages.
+ *
+ * 2/ GLSL version 4.50 removes the matching constrain on the interpolation
+ * qualifier.
+ *
+ * From Section 4.5 (Interpolation Qualifiers) of the GLSL 4.40 spec:
+ *
+ * "The type and presence of interpolation qualifiers of variables with
+ * the same name declared in all linked shaders for the same cross-stage
+ * interface must match, otherwise the link command will fail.
+ *
+ * When comparing an output from one stage to an input of a subsequent
+ * stage, the input and output don't match if their interpolation
+ * qualifiers (or lack thereof) are not the same."
+ *
+ * "It is a link-time error if, within the same stage, the interpolation
+ * qualifiers of variables of the same name do not match."
+ */
+ if (!separate_shader) {
+ /* Sort varying matches into an order that makes them easy to pack. */
+ qsort(this->matches, this->num_matches, sizeof(*this->matches),
+ &varying_matches::match_comparator);
+ }
unsigned generic_location = 0;
unsigned generic_patch_location = MAX_VARYING*4;
@@ -1592,7 +1617,8 @@ assign_varying_locations(struct gl_context *ctx,
reserved_varying_slot(producer, ir_var_shader_out) |
reserved_varying_slot(consumer, ir_var_shader_in);
- const unsigned slots_used = matches.assign_locations(reserved_slots);
+ const unsigned slots_used = matches.assign_locations(reserved_slots,
+ prog->SeparateShader);
matches.store_locations();
for (unsigned i = 0; i < num_tfeedback_decls; ++i) {
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