glsl: Prohibit illegal mixing of redeclarations inside/outside gl_PerVertex.

From section 7.1 (Built-In Language Variables) of the GLSL 4.10
spec:

    Also, if a built-in interface block is redeclared, no member of
    the built-in declaration can be redeclared outside the block
    redeclaration.

We have been regarding this text as a clarification to the behaviour
established for gl_PerVertex by GLSL 1.50, so we apply it regardless
of GLSL version.

This patch enforces the rule by adding an enum to ir_variable to track
how the variable was declared: implicitly, normally, or in an
interface block.

Fixes piglit tests:
- gs-redeclares-pervertex-out-after-global-redeclaration.geom
- vs-redeclares-pervertex-out-after-global-redeclaration.vert
- gs-redeclares-pervertex-out-after-other-global-redeclaration.geom
- vs-redeclares-pervertex-out-after-other-global-redeclaration.vert
- gs-redeclares-pervertex-out-before-global-redeclaration
- vs-redeclares-pervertex-out-before-global-redeclaration

Cc: "10.0" <[email protected]>

v2: Don't set "how_declared" redundantly in builtin_variables.cpp.
Properly clone "how_declared".

Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 36 insertions, 0 deletions

diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index 7859702ed01..4f775da4bd1 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -294,6 +294,34 @@ enum ir_variable_mode {
 };
 
 /**
+ * Enum keeping track of how a variable was declared.  For error checking of
+ * the gl_PerVertex redeclaration rules.
+ */
+enum ir_var_declaration_type {
+   /**
+    * Normal declaration (for most variables, this means an explicit
+    * declaration.  Exception: temporaries are always implicitly declared, but
+    * they still use ir_var_declared_normally).
+    *
+    * Note: an ir_variable that represents a named interface block uses
+    * ir_var_declared_normally.
+    */
+   ir_var_declared_normally = 0,
+
+   /**
+    * Variable was explicitly declared (or re-declared) in an unnamed
+    * interface block.
+    */
+   ir_var_declared_in_block,
+
+   /**
+    * Variable is an implicitly declared built-in that has not been explicitly
+    * re-declared by the shader.
+    */
+   ir_var_declared_implicitly,
+};
+
+/**
  * \brief Layout qualifiers for gl_FragDepth.
  *
  * The AMD/ARB_conservative_depth extensions allow gl_FragDepth to be redeclared
@@ -526,6 +554,14 @@ public:
    unsigned assigned:1;
 
    /**
+    * Enum indicating how the variable was declared.  See
+    * ir_var_declaration_type.
+    *
+    * This is used to detect certain kinds of illegal variable redeclarations.
+    */
+   unsigned how_declared:2;
+
+   /**
     * Storage class of the variable.
     *
     * \sa ir_variable_mode