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, 35 insertions, 3 deletions

diff --git a/source/slang/syntax.h b/source/slang/syntax.h
index 3f1c47fb9..56b5624b5 100644
--- a/source/slang/syntax.h
+++ b/source/slang/syntax.h
@@ -11,6 +11,7 @@
 
 namespace Slang
 {
+    class Session;
     class Substitutions;
     class SyntaxVisitor;
     class FunctionSyntaxNode;
@@ -1074,16 +1075,19 @@ namespace Slang
     //
     // TODO(tfoley): These should really belong to the compilation context!
     //
-    void RegisterBuiltinDecl(
+    void registerBuiltinDecl(
+        Session*                    session,
         RefPtr<Decl>                decl,
         RefPtr<BuiltinTypeModifier> modifier);
-    void RegisterMagicDecl(
+    void registerMagicDecl(
+        Session*                    session,
         RefPtr<Decl>                decl,
         RefPtr<MagicTypeModifier>   modifier);
 
     // Look up a magic declaration by its name
     RefPtr<Decl> findMagicDecl(
-        String const& name);
+        Session*        session,
+        String const&   name);
 
     // Create an instance of a syntax class by name
     SyntaxNodeBase* createInstanceOfSyntaxClassByName(
@@ -1171,6 +1175,34 @@ namespace Slang
         return declRef.getDecl()->inner.Ptr();
     }
 
+
+    //
+
+    RefPtr<ArrayExpressionType> getArrayType(
+        ExpressionType* elementType,
+        IntVal*         elementCount);
+
+    RefPtr<ArrayExpressionType> getArrayType(
+        ExpressionType* elementType);
+
+    RefPtr<NamedExpressionType> getNamedType(
+        Session*                    session,
+        DeclRef<TypeDefDecl> const& declRef);
+
+    RefPtr<TypeType> getTypeType(
+        ExpressionType* type);
+
+    RefPtr<FuncType> getFuncType(
+        Session*                        session,
+        DeclRef<CallableDecl> const&    declRef);
+
+    RefPtr<GenericDeclRefType> getGenericDeclRefType(
+        Session*                    session,
+        DeclRef<GenericDecl> const& declRef);
+
+    RefPtr<SamplerStateType> getSamplerStateType(
+        Session*        session);
+
 } // namespace Slang
 
 #endif
\ No newline at end of file