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, 50 insertions, 0 deletions

diff --git a/source/core/slang-string-slice-pool.h b/source/core/slang-string-slice-pool.h
new file mode 100644
index 000000000..e6846b3dd
--- /dev/null
+++ b/source/core/slang-string-slice-pool.h
@@ -0,0 +1,50 @@
+#ifndef SLANG_STRING_SLICE_POOL_H
+#define SLANG_STRING_SLICE_POOL_H
+
+#include "slang-string.h"
+
+#include "list.h"
+#include "slang-memory-arena.h"
+#include "dictionary.h"
+
+namespace Slang {
+
+class StringSlicePool
+{
+public:
+    /// Handle of 0 is null. If accessed will be returned as the empty string
+    enum class Handle : uint32_t;
+    typedef UnownedStringSlice Slice;
+
+        /// Returns the index of a slice, if contained, or -1 if not found
+    int findIndex(const Slice& slice) const;
+
+        /// True if has the slice
+    bool has(const Slice& slice) { return findIndex(slice) >= 0; }
+        /// Add a slice 
+    Handle add(const Slice& slice);
+
+        /// Empty contents
+    void clear();
+
+        /// Get the slice from the handle
+    const UnownedStringSlice& getSlice(Handle handle) const { return m_slices[UInt(handle)]; }
+
+        /// Get all the slices
+    const List<UnownedStringSlice>& getSlices() const { return m_slices; }
+
+        /// Convert a handle to and index. (A handle is just an index!) 
+    static int asIndex(Handle handle) { return int(handle); }
+
+        /// Ctor
+    StringSlicePool();
+
+protected:
+    List<UnownedStringSlice> m_slices;
+    Dictionary<UnownedStringSlice, int> m_map;
+    MemoryArena m_arena;
+};
+
+} // namespace Slang
+
+#endif // SLANG_STRING_SLICE_POOL_H