Don't always give shared linkage to spl functions

private functions on specialization were being given shared linkage.
Use swift::getSpecializeLinkage to correctly get the linkage for the
specialized function based on the linkage of the original function.

Author: meg-gupta

lib/SILOptimizer/Transforms/AllocBoxToStack.cpp

@@ -19,6 +19,7 @@
 #include "swift/SIL/SILCloner.h"
 #include "swift/SILOptimizer/PassManager/Passes.h"
 #include "swift/SILOptimizer/PassManager/Transforms.h"
+#include "swift/SILOptimizer/Utils/InstOptUtils.h"
 #include "swift/SILOptimizer/Utils/SILOptFunctionBuilder.h"
 #include "swift/SILOptimizer/Utils/SpecializationMangler.h"
 #include "swift/SILOptimizer/Utils/StackNesting.h"
@@ -633,11 +634,12 @@ SILFunction *PromotedParamCloner::initCloned(SILOptFunctionBuilder &FuncBuilder,
          && "SILFunction missing DebugScope");
   assert(!Orig->isGlobalInit() && "Global initializer cannot be cloned");
   auto *Fn = FuncBuilder.createFunction(
-      SILLinkage::Shared, ClonedName, ClonedTy, Orig->getGenericEnvironment(),
-      Orig->getLocation(), Orig->isBare(), Orig->isTransparent(), Serialized,
-      IsNotDynamic, Orig->getEntryCount(), Orig->isThunk(),
-      Orig->getClassSubclassScope(), Orig->getInlineStrategy(),
-      Orig->getEffectsKind(), Orig, Orig->getDebugScope());
+      swift::getSpecializedLinkage(Orig, Orig->getLinkage()), ClonedName,
+      ClonedTy, Orig->getGenericEnvironment(), Orig->getLocation(),
+      Orig->isBare(), Orig->isTransparent(), Serialized, IsNotDynamic,
+      Orig->getEntryCount(), Orig->isThunk(), Orig->getClassSubclassScope(),
+      Orig->getInlineStrategy(), Orig->getEffectsKind(), Orig,
+      Orig->getDebugScope());
   for (auto &Attr : Orig->getSemanticsAttrs()) {
     Fn->addSemanticsAttr(Attr);
   }