resolver: Allocate IDs for named pipeline constants

Keep track of any constant IDs specified in the shader, and then
allocate IDs for the remaining constants when creating the semantic
info.

Bug: tint:755
Change-Id: I6a76b1193cac459b62582cde7469b092dde51d5d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/50841
Commit-Queue: James Price <jrprice@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Auto-Submit: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

src/program_builder.h

@@ -38,6 +38,7 @@
 #include "src/ast/member_accessor_expression.h"
 #include "src/ast/module.h"
 #include "src/ast/multisampled_texture.h"
+#include "src/ast/override_decoration.h"
 #include "src/ast/pointer.h"
 #include "src/ast/return_statement.h"
 #include "src/ast/sampled_texture.h"
@@ -1786,6 +1787,32 @@ class ProgramBuilder {
     return create<ast::LocationDecoration>(source_, location);
   }
 
+  /// Creates an ast::OverrideDecoration with a specific constant ID
+  /// @param source the source information
+  /// @param id the id value
+  /// @returns the override decoration pointer
+  ast::OverrideDecoration* Override(const Source& source, uint32_t id) {
+    return create<ast::OverrideDecoration>(source, id);
+  }
+
+  /// Creates an ast::OverrideDecoration with a specific constant ID
+  /// @param id the optional id value
+  /// @returns the override decoration pointer
+  ast::OverrideDecoration* Override(uint32_t id) {
+    return Override(source_, id);
+  }
+
+  /// Creates an ast::OverrideDecoration without a constant ID
+  /// @param source the source information
+  /// @returns the override decoration pointer
+  ast::OverrideDecoration* Override(const Source& source) {
+    return create<ast::OverrideDecoration>(source);
+  }
+
+  /// Creates an ast::OverrideDecoration without a constant ID
+  /// @returns the override decoration pointer
+  ast::OverrideDecoration* Override() { return Override(source_); }
+
   /// Creates an ast::StageDecoration
   /// @param source the source information
   /// @param stage the pipeline stage