Feature/source loc refactor (#668)

* * Remove the need for IRHighLevelDecoration in Emit
* Use the IRLayoutDecoration for GeometryShaderPrimitiveTypeModifier

* Initial look at at variable byte encoding, and simple unit test.

* Fixing problems with comparison due to naming differences with slang/fxc.

* * More tests and perf improvements for byte encoding.
* Mechanism to detect processor and processor features in main slang header.

* Split out cpu based defines into slang-cpu-defines.h so do not polute slang.h

* Support for variable byte encoding on serialization.

* Removed unused flag.

* Fix warning.

* Fix calcMsByte32 for 0 values without using intrinsic.

* Fix a mistake in calculating maximum instruction size.

* Introduced the idea of SourceUnit.

* Small improvements around naming.
Add more functionality - including getting the HumaneLoc.

* Add support for #line default

* Compiling with new SourceLoc handling.

* Fix off by one on #line directives.

* Can use 32bits for SourceLoc. Fix serialize to use that.

* Small fixes and comment on usage.

* Premake run.

* Fix signed warning.

* Fix typo on StringSlicePool::has found in review.

1 files changed, 7 insertions, 12 deletions

diff --git a/source/slang/lexer.h b/source/slang/lexer.h
index 1f2954d27..46d2aa227 100644
--- a/source/slang/lexer.h
+++ b/source/slang/lexer.h
@@ -73,7 +73,7 @@ namespace Slang
     struct Lexer
     {
         void initialize(
-            SourceFile*     sourceFile,
+            SourceUnit*     sourceUnit,
             DiagnosticSink* sink,
             NamePool*       namePool);
 
@@ -83,15 +83,7 @@ namespace Slang
 
         TokenList lexAllTokens();
 
-        // Begin overriding the reported locations of tokens,
-        // based on a `#line` directives
-        void startOverridingSourceLocations(SourceLoc loc);
-
-        // Stop overriding source locations, and go back
-        // to reporting source locations in the original file
-        void stopOverridingSourceLocations();
-
-        SourceFile*     sourceFile;
+        SourceUnit*     sourceUnit;
         DiagnosticSink* sink;
         NamePool*       namePool;
 
@@ -100,13 +92,16 @@ namespace Slang
         char const*     begin;
         char const*     end;
 
+        /// The starting sourceLoc (same as first location of SourceUnit)
+        SourceLoc       startLoc;           
+
         // The starting source location for the code as written,
         // which cannot be overridden.
-        SourceLoc       spellingStartLoc;
+        //SourceLoc       spellingStartLoc;
 
         // The nominal starting location for the file, taking
         // any active `#line` directive into account.
-        SourceLoc       presumedStartLoc;
+        //SourceLoc       presumedStartLoc;
 
         TokenFlags      tokenFlags;
         LexerFlags      lexerFlags;