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, 4 insertions, 24 deletions

diff --git a/source/slang/syntax-base-defs.h b/source/slang/syntax-base-defs.h
index 03d4b749a..eda554988 100644
--- a/source/slang/syntax-base-defs.h
+++ b/source/slang/syntax-base-defs.h
@@ -62,29 +62,9 @@ ABSTRACT_SYNTAX_CLASS(ExpressionType, Val)
 
 RAW(
 public:
-    static RefPtr<ExpressionType> Error;
-    static RefPtr<ExpressionType> initializerListType;
-    static RefPtr<ExpressionType> Overloaded;
+    Session* getSession() { return this->session; }
+    void setSession(Session* s) { this->session = s; }
 
-    static Dictionary<int, RefPtr<ExpressionType>> sBuiltinTypes;
-    static Dictionary<String, Decl*> sMagicDecls;
-
-    // Note: just exists to make sure we can clean up
-    // canonical types we create along the way
-    static List<RefPtr<ExpressionType>> sCanonicalTypes;
-
-
-
-    static ExpressionType* GetBool();
-    static ExpressionType* GetFloat();
-    static ExpressionType* getDoubleType();
-    static ExpressionType* GetInt();
-    static ExpressionType* GetUInt();
-    static ExpressionType* GetVoid();
-    static ExpressionType* getInitializerListType();
-    static ExpressionType* GetError();
-
-public:
     virtual String ToString() = 0;
 
     bool Equals(ExpressionType * type);
@@ -115,8 +95,6 @@ public:
     bool IsSampler() { return As<SamplerStateType>() != nullptr; }
     bool IsStruct();
     bool IsClass();
-    static void Init();
-    static void Finalize();
     ExpressionType* GetCanonicalType();
 
     virtual RefPtr<Val> SubstituteImpl(Substitutions* subst, int* ioDiff) override;
@@ -127,6 +105,8 @@ protected:
 
     virtual ExpressionType* CreateCanonicalType() = 0;
     ExpressionType* canonicalType = nullptr;
+
+    Session* session = nullptr;
     )
 END_SYNTAX_CLASS()