Use updated IDownstreamCompiler::CompileOptions (#63)

* Upgrade slang.
Use the new IDownstreamCompiler interface.
Handle different CompileOptions versions.
Attempt to support __chkstk.

* Small fix around _chkstk.

* Use __ prefix.

* Change name based on processor target for chkstk.

* Update slang submodule.

* Fix __chkstk lookup name.

premake5.lua

@@ -217,6 +217,8 @@ workspace "slang-llvm"
         platforms {"aarch64" }
     end
 
+    flags "MultiProcessorCompile"
+
     -- 
     -- Make slang-test the startup project.
     --

source/slang-llvm/slang-llvm.cpp

@@ -91,6 +91,23 @@
 #   include <string.h>
 #endif
 
+#if SLANG_WINDOWS_FAMILY
+
+/*
+It's not clear if this function is needed for ARM WIN targets, but we'll assume it does for now.
+
+https://learn.microsoft.com/en-us/windows/win32/devnotes/-win32-chkstk
+https://www.betaarchive.com/wiki/index.php/Microsoft_KB_Archive/100775 
+https://codywu2010.wordpress.com/2010/10/04/__chkstk-and-stack-overflow/
+*/
+
+#   if SLANG_PROCESSOR_X86
+extern "C" void /* __declspec(naked)*/ __cdecl _chkstk();
+#   else
+extern "C" void /* __declspec(naked)*/ __cdecl __chkstk();
+#   endif
+#endif
+
 // Predeclare. We'll use this symbol to lookup timestamp, if we don't have a hash.
 extern "C" SLANG_DLL_EXPORT SlangResult createLLVMDownstreamCompiler_V3(const SlangUUID& intfGuid, Slang::IDownstreamCompiler** out);
 
@@ -463,6 +480,16 @@ static uint64_t __stdcall _aulldiv(uint64_t a, uint64_t b)
     x(__bzero, OSXSpecific::bzero, void, (void*, size_t))
 #endif
 
+#if SLANG_WINDOWS_FAMILY 
+#   if SLANG_PROCESSOR_X86
+#       define SLANG_PLATFORM_FUNCS(x) \
+            x(_chkstk, _chkstk, void, ()) 
+#   else
+#       define SLANG_PLATFORM_FUNCS(x) \
+            x(__chkstk, __chkstk, void, ()) 
+#   endif
+#endif
+
 #ifndef SLANG_PLATFORM_FUNCS
 #   define SLANG_PLATFORM_FUNCS(x)
 #endif
@@ -562,8 +589,16 @@ void* LLVMDownstreamCompiler::getObject(const Guid& guid)
     return nullptr;
 }
 
-SlangResult LLVMDownstreamCompiler::compile(const CompileOptions& options, IArtifact** outArtifact)
+SlangResult LLVMDownstreamCompiler::compile(const CompileOptions& inOptions, IArtifact** outArtifact)
 {
+    if (!isVersionCompatible(inOptions))
+    {
+        // Not possible to compile with this version of the interface.
+        return SLANG_E_NOT_IMPLEMENTED;
+    }
+
+    CompileOptions options = getCompatibleVersion(&inOptions);
+
     // Currently supports single source file
     if (options.sourceArtifacts.count != 1)
     {