Actual global support (#2262)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Use TerminatedUnownedStringSlice for literals in output C++.

* Remove Escape/Unescape functions used in slang-token-reader.cpp
Add target type of 'host-cpp' etc to map to the target types.

* Fix some corner cases around string encoding.

* Added unit test for string escaping.
Fixed some assorted escaping bugs.

* Updated test output.

* Added decode test.

* Stop using hex output, to get around 'greedy' aspect. Use octal instead.

* Added HostHostCallable
Small changes to use ArtifactDesc/Info instead of large switches.

* Fix C++ emit to handle arbitrary function export.

* Add options handling for callable without an output being specified.

* Can compile with COM interface. Added example using com interface.

* Use the IR Ptr type instead of hack in C++ emit for interfaces.

* Fix issue with outputting the COM call when ptr is used.

* Fix crash issue on compilation failure.

* Add support for __global.

* Added `ActualGlobalRate`
Added special handling around globals and COM interfaces.
Tested out in cpu-com-example.

* Fix typo in NodeBase.

* Support for accessing globals by name working.

* Check that actual global initialization is working.

* Refactor the com replacement such that it doesn't need a cache or do anything special with GlobalVar.

* Remove context.
Only create replacement if needed.

* Split out COM host-callable into a unit-test.

* host-callable com testing on C++and llvm.

* Comment around the COM ptr replacement.

* Disable com test on vs 32 bit.
Fix C++ prelude

* Disable 32 bit targets testing com host-callable.

* Use JSON parsing to locate VS version.

* Need platform detection in C++prelude.

* Fix com host callable test for LLVM.

* Work around for not being able to include "targetConditionals.h"

1 files changed, 50 insertions, 2 deletions

diff --git a/source/slang/slang-emit-cpp.cpp b/source/slang/slang-emit-cpp.cpp
index ddc8b24ed..c23135c70 100644
--- a/source/slang/slang-emit-cpp.cpp
+++ b/source/slang/slang-emit-cpp.cpp
@@ -2547,7 +2547,50 @@ void CPPSourceEmitter::emitPreModuleImpl()
     }
 }
 
-/* virtual */void CPPSourceEmitter::emitFuncDecorationsImpl(IRFunc* func)
+
+void CPPSourceEmitter::emitGlobalInstImpl(IRInst* inst)
+{
+    if (as<IRGlobalVar>(inst) && inst->findDecoration<IRExternCppDecoration>())
+    {
+        // JS:
+        // Turns out just doing extern "C" means something different on a variable
+        // So we need to wrap in extern "C" { }
+        m_writer->emit("extern \"C\" {\n");
+        Super::emitGlobalInstImpl(inst);
+        m_writer->emit("\n}\n");
+    }
+    else
+    {
+        Super::emitGlobalInstImpl(inst);
+    }
+}
+
+static bool _isExported(IRInst* inst)
+{
+    for (auto decoration : inst->getDecorations())
+    {
+        const auto op = decoration->getOp();
+        if (op == kIROp_PublicDecoration ||
+            op == kIROp_HLSLExportDecoration)
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+void CPPSourceEmitter::emitVarDecorationsImpl(IRInst* inst)
+{
+    if (as<IRGlobalVar>(inst) && _isExported(inst))
+    {
+        m_writer->emit("SLANG_PRELUDE_SHARED_LIB_EXPORT\n");
+    }
+
+    Super::emitVarDecorationsImpl(inst);
+}
+
+
+void CPPSourceEmitter::_maybeEmitExportLike(IRInst* inst)
 {
     // Specially handle export, as we don't want to emit it multiple times
     if (getTargetReq()->isWholeProgramRequest())
@@ -2556,7 +2599,7 @@ void CPPSourceEmitter::emitPreModuleImpl()
         bool isExported = false;
 
         // If public/export made it externally visible
-        for (auto decoration : func->getDecorations())
+        for (auto decoration : inst->getDecorations())
         {
             const auto op = decoration->getOp();
             if (op == kIROp_ExternCppDecoration)
@@ -2581,6 +2624,11 @@ void CPPSourceEmitter::emitPreModuleImpl()
             m_writer->emit("extern \"C\"\n");
         }
     }
+}
+
+/* virtual */void CPPSourceEmitter::emitFuncDecorationsImpl(IRFunc* func)
+{
+    _maybeEmitExportLike(func);
 
     // Use the default for others
     Super::emitFuncDecorationsImpl(func);