glsl: Track UBO block names in the symbol table.

The GLSL 1.40 spec says:

    "Uniform block names and variable names declared within uniform
    blocks are scoped at the program level."

Track the block name in the symbol table and emit errors when conflicts
exist.

Fixes es3conform's uniform_buffer_object_block_name_conflict test, and
fixes the piglit block-name-clashes-with-{variable,function,struct}.vert
tests.

NOTE: This is a candidate for the 9.0 branch.

v2: Fix bad constructor initialization.  Noticed by Topi Pohjolainen.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/glsl/ast_to_hir.cpp

@@ -4132,6 +4132,12 @@ ast_uniform_block::hir(exec_list *instructions,
    struct gl_uniform_block *ubo = get_next_uniform_block(state);
    ubo->Name = ralloc_strdup(state->uniform_blocks, this->block_name);
 
+   if (!state->symbols->add_uniform_block(ubo)) {
+      YYLTYPE loc = this->get_location();
+      _mesa_glsl_error(&loc, state, "Uniform block name `%s' already taken in "
+                       "the current scope.\n", ubo->Name);
+   }
+
    unsigned int num_variables = 0;
    foreach_list_typed(ast_declarator_list, decl_list, link, &declarations) {
       foreach_list_const(node, &decl_list->declarations) {

src/glsl/glsl_symbol_table.cpp

@@ -41,13 +41,15 @@ public:
       ralloc_free(entry);
    }
 
-   symbol_table_entry(ir_variable *v)                     : v(v), f(0), t(0) {}
-   symbol_table_entry(ir_function *f)                     : v(0), f(f), t(0) {}
-   symbol_table_entry(const glsl_type *t)                 : v(0), f(0), t(t) {}
+   symbol_table_entry(ir_variable *v)               : v(v), f(0), t(0), u(0) {}
+   symbol_table_entry(ir_function *f)               : v(0), f(f), t(0), u(0) {}
+   symbol_table_entry(const glsl_type *t)           : v(0), f(0), t(t), u(0) {}
+   symbol_table_entry(struct gl_uniform_block *u)   : v(0), f(0), t(0), u(u) {}
 
    ir_variable *v;
    ir_function *f;
    const glsl_type *t;
+   struct gl_uniform_block *u;
 };
 
 glsl_symbol_table::glsl_symbol_table()
@@ -132,6 +134,12 @@ bool glsl_symbol_table::add_function(ir_function *f)
    return _mesa_symbol_table_add_symbol(table, -1, f->name, entry) == 0;
 }
 
+bool glsl_symbol_table::add_uniform_block(struct gl_uniform_block *u)
+{
+   symbol_table_entry *entry = new(mem_ctx) symbol_table_entry(u);
+   return _mesa_symbol_table_add_symbol(table, -1, u->Name, entry) == 0;
+}
+
 void glsl_symbol_table::add_global_function(ir_function *f)
 {
    symbol_table_entry *entry = new(mem_ctx) symbol_table_entry(f);

src/glsl/glsl_symbol_table.h

@@ -99,6 +99,7 @@ public:
    bool add_variable(ir_variable *v);
    bool add_type(const char *name, const glsl_type *t);
    bool add_function(ir_function *f);
+   bool add_uniform_block(struct gl_uniform_block *u);
    /*@}*/
 
    /**