[Mesa-dev] [PATCH] glsl/linker: produce error when invalid explicit locations are used

[Iago Toral Quiroga]

We only need to add a check to validate output locations here. For
inputs with invalid locations we will fail to link when we can't
find a matching output in the same (invalid) location.

Fixes:
KHR-GL45.enhanced_layouts.varying_location_limit
---
 src/compiler/glsl/link_varyings.cpp | 12 +++++++++++-
 src/compiler/glsl/link_varyings.h   |  3 ++-
 src/compiler/glsl/linker.cpp        |  2 +-
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp
index 29842ecacd..bdb70edf47 100644
--- a/src/compiler/glsl/link_varyings.cpp
+++ b/src/compiler/glsl/link_varyings.cpp
@@ -381,7 +381,8 @@ cross_validate_front_and_back_color(struct gl_shader_program *prog,
  * Validate that outputs from one stage match inputs of another
  */
 void
-cross_validate_outputs_to_inputs(struct gl_shader_program *prog,
+cross_validate_outputs_to_inputs(struct gl_context *ctx,
+                                 struct gl_shader_program *prog,
                                  gl_linked_shader *producer,
                                  gl_linked_shader *consumer)
 {
@@ -410,6 +411,15 @@ cross_validate_outputs_to_inputs(struct gl_shader_program *prog,
          unsigned slot_limit = idx + num_elements;
          unsigned last_comp;
 
+         unsigned slot_max =
+            ctx->Const.Program[producer->Stage].MaxOutputComponents / 4;
+         if (slot_limit > slot_max) {
+            linker_error(prog,
+                         "Invalid location %u in %s shader\n",
+                         idx, _mesa_shader_stage_to_string(producer->Stage));
+            return;
+         }
+
          if (type->without_array()->is_record()) {
             /* The component qualifier can't be used on structs so just treat
              * all component slots as used.
diff --git a/src/compiler/glsl/link_varyings.h b/src/compiler/glsl/link_varyings.h
index 4e1f6d2e42..081b04ea38 100644
--- a/src/compiler/glsl/link_varyings.h
+++ b/src/compiler/glsl/link_varyings.h
@@ -300,7 +300,8 @@ link_varyings(struct gl_shader_program *prog, unsigned first, unsigned last,
               struct gl_context *ctx, void *mem_ctx);
 
 void
-cross_validate_outputs_to_inputs(struct gl_shader_program *prog,
+cross_validate_outputs_to_inputs(struct gl_context *ctx,
+                                 struct gl_shader_program *prog,
                                  gl_linked_shader *producer,
                                  gl_linked_shader *consumer);
 
diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
index 03eb05bf63..3798309678 100644
--- a/src/compiler/glsl/linker.cpp
+++ b/src/compiler/glsl/linker.cpp
@@ -4929,7 +4929,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       if (!prog->data->LinkStatus)
          goto done;
 
-      cross_validate_outputs_to_inputs(prog,
+      cross_validate_outputs_to_inputs(ctx, prog,
                                        prog->_LinkedShaders[prev],
                                        prog->_LinkedShaders[i]);
       if (!prog->data->LinkStatus)
-- 
2.11.0