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.

4 files changed, 115 insertions, 10 deletions

diff --git a/source/core/core.vcxproj b/source/core/core.vcxproj
index ec6195940..d1ed4715f 100644
--- a/source/core/core.vcxproj
+++ b/source/core/core.vcxproj
@@ -183,11 +183,13 @@
     <ClInclude Include="platform.h" />
     <ClInclude Include="secure-crt.h" />
     <ClInclude Include="slang-byte-encode-util.h" />
+    <ClInclude Include="slang-cpu-defines.h" />
     <ClInclude Include="slang-free-list.h" />
     <ClInclude Include="slang-io.h" />
     <ClInclude Include="slang-math.h" />
     <ClInclude Include="slang-memory-arena.h" />
     <ClInclude Include="slang-random-generator.h" />
+    <ClInclude Include="slang-string-slice-pool.h" />
     <ClInclude Include="slang-string-util.h" />
     <ClInclude Include="slang-string.h" />
     <ClInclude Include="smart-pointer.h" />
@@ -203,6 +205,7 @@
     <ClCompile Include="slang-io.cpp" />
     <ClCompile Include="slang-memory-arena.cpp" />
     <ClCompile Include="slang-random-generator.cpp" />
+    <ClCompile Include="slang-string-slice-pool.cpp" />
     <ClCompile Include="slang-string-util.cpp" />
     <ClCompile Include="slang-string.cpp" />
     <ClCompile Include="stream.cpp" />
@@ -210,7 +213,7 @@
     <ClCompile Include="token-reader.cpp" />
   </ItemGroup>
   <ItemGroup>
-    <None Include="core.natvis" />
+    <Natvis Include="core.natvis" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
diff --git a/source/core/core.vcxproj.filters b/source/core/core.vcxproj.filters
index f9eeef43a..7936ca11b 100644
--- a/source/core/core.vcxproj.filters
+++ b/source/core/core.vcxproj.filters
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup>
     <Filter Include="Header Files">
@@ -45,6 +45,12 @@
     <ClInclude Include="secure-crt.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="slang-byte-encode-util.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="slang-cpu-defines.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="slang-free-list.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -60,6 +66,9 @@
     <ClInclude Include="slang-random-generator.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="slang-string-slice-pool.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="slang-string-util.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -81,14 +90,14 @@
     <ClInclude Include="type-traits.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="slang-byte-encode-util.h">
-      <Filter>Header Files</Filter>
-    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="platform.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="slang-byte-encode-util.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="slang-free-list.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -101,6 +110,9 @@
     <ClCompile Include="slang-random-generator.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="slang-string-slice-pool.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="slang-string-util.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -116,13 +128,10 @@
     <ClCompile Include="token-reader.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="slang-byte-encode-util.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
   </ItemGroup>
   <ItemGroup>
-    <None Include="core.natvis">
+    <Natvis Include="core.natvis">
       <Filter>Source Files</Filter>
-    </None>
+    </Natvis>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/source/core/slang-string-slice-pool.cpp b/source/core/slang-string-slice-pool.cpp
new file mode 100644
index 000000000..88963d68f
--- /dev/null
+++ b/source/core/slang-string-slice-pool.cpp
@@ -0,0 +1,43 @@
+#include "slang-string-slice-pool.h"
+
+namespace Slang {
+
+StringSlicePool::StringSlicePool() :
+    m_arena(1024)
+{
+    clear();
+}
+
+void StringSlicePool::clear()
+{
+    m_slices.SetSize(1);
+    m_slices[0] = UnownedStringSlice::fromLiteral("");
+
+    m_map.Clear();
+}
+
+StringSlicePool::Handle StringSlicePool::add(const Slice& slice)
+{
+    const int* indexPtr = m_map.TryGetValue(slice);
+    if (indexPtr)
+    {
+        return Handle(*indexPtr);
+    }
+
+    // Create a scoped copy
+    UnownedStringSlice scopePath(m_arena.allocateString(slice.begin(), slice.size()), slice.size());
+
+    const int index = int(m_slices.Count());
+
+    m_slices.Add(scopePath);
+    m_map.Add(scopePath, index);
+    return Handle(index);
+}
+
+int StringSlicePool::findIndex(const Slice& slice) const
+{
+    const int* index = m_map.TryGetValue(slice);
+    return index ? *index : -1;
+
+}
+} // namespace Slang
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