spirv-reader: add option to use HLSL-style pipeline IO

This is currently unused.

Bug: tint:508
Change-Id: I9027d468496014123a41b9941cf9df35868b6e1a
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/49000
Commit-Queue: David Neto <dneto@google.com>
Auto-Submit: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

src/reader/spirv/parser_impl.h

@@ -102,6 +102,14 @@ class ParserImpl : Reader {
   /// @returns the accumulated error string
   const std::string error() { return errors_.str(); }
 
+  /// Changes pipeline IO to be HLSL-style: as entry point parameters and
+  /// return.
+  /// TODO(crbug.com/tint/508): Once all this support has landed, switch
+  /// over to that, and remove the old support.
+  void SetHLSLStylePipelineIO() { hlsl_style_pipeline_io_ = true; }
+  /// @returns true if HLSL-style IO should be used.
+  bool UseHLSLStylePipelineIO() const { return hlsl_style_pipeline_io_; }
+
   /// Builds an internal representation of the SPIR-V binary,
   /// and parses it into a Tint AST module.  Diagnostics are emitted
   /// to the error stream.
@@ -672,6 +680,10 @@ class ParserImpl : Reader {
   /// See also BuiltInPositionInfo which is a separate mechanism for a more
   /// complex case of replacing an entire structure.
   BuiltInsMap special_builtins_;
+
+  /// This is temporary while this module is converted to use the new style
+  /// of pipeline IO.
+  bool hlsl_style_pipeline_io_ = false;
 };
 
 }  // namespace spirv