XXX SIL Optimizer: Set the [thunk] attribute on specializations XXX

The original SILFunction may be [fragile] because it came from
an imported module, or maybe it was [fragile] because it was
declared @_transparent by the user.

Furthermore, the devirtualizer can devirtualize calls inside
[fragile] functions, pointing them at  non-fragile functions.

FIXME: For resilience, we cannot devirtualize this stuff anyway.
Instead, try to not set [fragile] on clones unless needed.

Author: slavapestov

lib/SILOptimizer/Transforms/AllocBoxToStack.cpp

@@ -565,7 +565,7 @@ PromotedParamCloner::initCloned(SILFunction *Orig,
   auto *Fn = M.getOrCreateFunction(
       SILLinkage::Shared, ClonedName, ClonedTy, Orig->getContextGenericParams(),
       Orig->getLocation(), Orig->isBare(), IsNotTransparent, Orig->isFragile(),
-      Orig->isThunk(), Orig->getClassVisibility(), Orig->getInlineStrategy(),
+      IsThunk, Orig->getClassVisibility(), Orig->getInlineStrategy(),
       Orig->getEffectsKind(), Orig, Orig->getDebugScope());
   for (auto &Attr : Orig->getSemanticsAttrs()) {
     Fn->addSemanticsAttr(Attr);

lib/SILOptimizer/Transforms/FunctionSignatureOptCloner.cpp

@@ -353,7 +353,7 @@ createEmptyFunctionWithOptimizedSig(const std::string &NewFName) {
   // Create the new function.
   auto *NewF = M.getOrCreateFunction(
       F->getLinkage(), NewFName, NewFTy, nullptr, F->getLocation(), F->isBare(),
-      F->isTransparent(), F->isFragile(), F->isThunk(), F->getClassVisibility(),
+      F->isTransparent(), F->isFragile(), IsThunk, F->getClassVisibility(),
       F->getInlineStrategy(), F->getEffectsKind(), 0, F->getDebugScope(),
       F->getDeclContext());
 

lib/SILOptimizer/Utils/GenericCloner.cpp

@@ -39,7 +39,7 @@ SILFunction *GenericCloner::initCloned(SILFunction *Orig,
       getSpecializedLinkage(Orig, Orig->getLinkage()), NewName,
       ReInfo.getSpecializedType(), nullptr,
       Orig->getLocation(), Orig->isBare(), Orig->isTransparent(),
-      Orig->isFragile(), Orig->isThunk(), Orig->getClassVisibility(),
+      Orig->isFragile(), IsThunk, Orig->getClassVisibility(),
       Orig->getInlineStrategy(), Orig->getEffectsKind(), Orig,
       Orig->getDebugScope(), Orig->getDeclContext());
   NewF->setDeclCtx(Orig->getDeclContext());