Remove uses of global variables

There were two main places where global variables were used in the Slang implementation:

1. The "standard library" code was generated as a string at run-time, and stored in a global variable so that it could be amortized across compiles.

2. The representation of types uses some globals (well, class `static` members) to store common types (e.g., `void`) and to deal with memory lifetime for things like canonicalized types.

In each case the "simple" fix is to move the relevant state into the `Session` type that controlled their lifetime already (the `Session` destructor was already cleaning up these globals to avoid leaks).

For the standard library stuff this really was easy, but for the types it required threading through the `Session` a bit carefully.

One more case that I found: there was a function-`static` variable used to generate a unique ID for files output when dumping of intermediates is enabled (this is almost strictly a debugging option).
Rather than make this counter per-session (which would lead to different sessions on different threads clobbering the same few files), I went ahead and used an atomic in this case.

Note that the remaining case I had been worried about was any function-`static` counter that might be used in generating unique names.
It  turns out that right now the parser doesn't use such a counter (even in cases where it probably should), and the lowering pass already uses a counter local to the pass (again, whether or not this is a good idea).

This change should be a major step toward allowing an application to use Slang in multiple threads, so long as each thread uses a distinct `SlangSession`. The case of using a single session across multiple threads is harder to support, and will require more careful implementation work.

1 files changed, 5 insertions, 27 deletions

diff --git a/source/slang/slang-stdlib.cpp b/source/slang/slang-stdlib.cpp
index 2a0d2abb2..71e8a6621 100644
--- a/source/slang/slang-stdlib.cpp
+++ b/source/slang/slang-stdlib.cpp
@@ -1,6 +1,6 @@
 // slang-stdlib.cpp
 
-#include "slang-stdlib.h"
+#include "compiler.h"
 #include "syntax.h"
 
 #define STRINGIZE(x) STRINGIZE2(x)
@@ -1042,9 +1042,7 @@ typedef Texture2D texture2D;
 
 namespace Slang
 {
-    static String stdlibPath;
-
-    String getStdlibPath()
+    String Session::getStdlibPath()
     {
         if(stdlibPath.Length() != 0)
             return stdlibPath;
@@ -1068,12 +1066,6 @@ namespace Slang
         return stdlibPath;
     }
 
-    // Cached code for the various libraries
-    String coreLibraryCode;
-    String slangLibraryCode;
-    String hlslLibraryCode;
-    String glslLibraryCode;
-
     enum
     {
         SINT_MASK   = 1 << 0,
@@ -1156,7 +1148,7 @@ namespace Slang
     };
 
 
-    String getCoreLibraryCode()
+    String Session::getCoreLibraryCode()
     {
         if (coreLibraryCode.Length() > 0)
             return coreLibraryCode;
@@ -1974,7 +1966,7 @@ namespace Slang
         return coreLibraryCode;
     }
 
-    String getHLSLLibraryCode()
+    String Session::getHLSLLibraryCode()
     {
         if (hlslLibraryCode.Length() > 0)
             return hlslLibraryCode;
@@ -2073,7 +2065,7 @@ namespace Slang
 
     // GLSL-specific library code
 
-    String getGLSLLibraryCode()
+    String Session::getGLSLLibraryCode()
     {
         if(glslLibraryCode.Length() != 0)
             return glslLibraryCode;
@@ -2283,18 +2275,4 @@ namespace Slang
         glslLibraryCode = sb.ProduceString();
         return glslLibraryCode;
     }
-
-
-
-    //
-
-    void finalizeShaderLibrary()
-    {
-        stdlibPath = String();
-
-        coreLibraryCode = String();
-        hlslLibraryCode = String();
-        glslLibraryCode = String();
-    }
-
 }