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, 9 insertions, 4 deletions

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 5a59674f5..d2f932ebf 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -375,6 +375,11 @@ struct EmitVisitor
         : context(context)
     {}
 
+    Session* getSession()
+    {
+        return context->shared->entryPoint->compileRequest->mSession;
+    }
+
     // Low-level emit logic
 
     void emitRawTextSpan(char const* textBegin, char const* textEnd)
@@ -2308,9 +2313,9 @@ struct EmitVisitor
                 emitTokenWithLocation(litExpr->token);
                 break;
             }
-            if(type->Equals(ExpressionType::GetInt()))
+            if(type->Equals(getSession()->getIntType()))
             {}
-            else if(type->Equals(ExpressionType::GetUInt()))
+            else if(type->Equals(getSession()->getUIntType()))
             {
                 suffix = "u";
             }
@@ -2330,9 +2335,9 @@ struct EmitVisitor
                 emitTokenWithLocation(litExpr->token);
                 break;
             }
-            if(type->Equals(ExpressionType::GetFloat()))
+            if(type->Equals(getSession()->getFloatType()))
             {}
-            else if(type->Equals(ExpressionType::getDoubleType()))
+            else if(type->Equals(getSession()->getDoubleType()))
             {
                 suffix = "l";
             }