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, 1 insertions, 1 deletions

diff --git a/source/slang/parameter-binding.cpp b/source/slang/parameter-binding.cpp
index 6128261c7..9b1036d02 100644
--- a/source/slang/parameter-binding.cpp
+++ b/source/slang/parameter-binding.cpp
@@ -1689,7 +1689,7 @@ void generateParameterBindings(
 
         RefPtr<Variable> var = new Variable();
         var->Name.Content = "SLANG_hack_samplerForTexelFetch";
-        var->Type.type = new SamplerStateType();
+        var->Type.type = getSamplerStateType(request->mSession);
 
         auto typeLayout = new TypeLayout();
         typeLayout->type = var->Type.type;