[llvm] [SPIRV] Add support for pointers to functions with aggregate args/returns as global variables / constant initialisers (PR #169595)

[Alex Voicu via llvm-commits]

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@@ -518,22 +539,17 @@ SPIRVPrepareFunctions::removeAggregateTypesFromSignature(Function *F) {
                     Returns);
   NewF->takeName(F);
 
-  NamedMDNode *FuncMD =
-      F->getParent()->getOrInsertNamedMetadata("spv.cloned_funcs");
-  SmallVector<Metadata *, 2> MDArgs;
-  MDArgs.push_back(MDString::get(B.getContext(), NewF->getName()));
-  for (auto &ChangedTyP : ChangedTypes)
-    MDArgs.push_back(MDNode::get(
-        B.getContext(),
-        {ConstantAsMetadata::get(B.getInt32(ChangedTyP.first)),
-         ValueAsMetadata::get(Constant::getNullValue(ChangedTyP.second))}));
-  MDNode *ThisFuncMD = MDNode::get(B.getContext(), MDArgs);
-  FuncMD->addOperand(ThisFuncMD);
+  addFunctionTypeMutation(
+      NewF->getParent()->getOrInsertNamedMetadata("spv.cloned_funcs"),
+      std::move(ChangedTypes), NewF->getName());
 
   for (auto *U : make_early_inc_range(F->users())) {
     if (auto *CI = dyn_cast<CallInst>(U))
       CI->mutateFunctionType(NewF->getFunctionType());
-    U->replaceUsesOfWith(F, NewF);
+    if (auto *C = dyn_cast<Constant>(U))
+      C->handleOperandChange(F, NewF);
+    else
+      U->replaceUsesOfWith(F, NewF);
   }
----------------
AlexVlx wrote:

I'm not entirely sure what you mean by the first bullet. This has to handle indirect call cases as well, where there'd be no called function, but rather a called operand; what we are interested in is mutating the call site itself. Could you say more about your concern?

As for using RAUW, I don't quite think we can do that, since it does `assert(New->getType() == getType() && "replaceAllUses of value with new value of different type!");`. Otherwise stated, it expects the type of the new value to match the type of the old, which is not quite what is happening here, I don' think. We are using the riskier forms because we're using a value with new, aggregate free type.

https://github.com/llvm/llvm-project/pull/169595