[Mesa-dev] [PATCH 11/19] glsl: Track explicitly set location independent from the actual location

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

Almost all of the time the location set by layout(location=...) is the
location that will be used for the variable.  Vertex shader inputs and
fragment shader outputs, for example, are visible to the API.  We just
use those actual settings.

Locations set for varyings, however, are a different story.  In those
cases, the locations set in the shader are just used to facilitate
matching outputs to inputs.  We need to track the value so that we can
ensure that

   layout(location=2) out float foo;

will be assigned the same resource as

   layout(location=2) in float bar;

but we probably don't want to use 2 as the actual location in the set of
varyings.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/glsl/ast_to_hir.cpp | 2 ++
 src/glsl/ir.cpp         | 1 +
 src/glsl/ir.h           | 8 ++++++++
 3 files changed, 11 insertions(+)

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 8f6e901..965b866 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -2225,6 +2225,8 @@ validate_explicit_location(const struct ast_type_qualifier *qual,
             assert(!"Unexpected shader type");
             break;
          }
+
+         var->data.user_location = var->data.location;
       } else {
          var->data.location = qual->location;
       }
diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index a41eddf..77d02e1 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -1536,6 +1536,7 @@ ir_variable::ir_variable(const struct glsl_type *type, const char *name,
    this->data.explicit_location = false;
    this->data.has_initializer = false;
    this->data.location = -1;
+   this->data.user_location = -1;
    this->data.location_frac = 0;
    this->warn_extension = NULL;
    this->constant_value = NULL;
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index 8fa3b9e..6c77e83 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -672,6 +672,14 @@ public:
       int location;
 
       /**
+       * Location explicitly set in the shader using a layout qualifier.
+       *
+       * \note
+       * This may not be the location actually uses for this variable.
+       */
+      int user_location;
+
+      /**
        * output index for dual source blending.
        */
       int index;
-- 
1.8.1.4