================
@@ -2839,6 +2840,43 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
return CGF.authPointerToPointerCast(Result, E->getType(), DestTy);
}
case CK_AddressSpaceConversion: {
+ llvm::Type *DestLTy = ConvertType(DestTy);
+ // WebAssembly reference types are opaque target extension types so an
+ // "address space conversion" involving them is not a real pointer cast.
+ auto IsWasmFuncref = [](llvm::Type *T) {
+ auto *TET = dyn_cast<llvm::TargetExtType>(T);
+ return TET && TET->getName() == "wasm.funcref";
+ };
+ bool SrcIsFuncref = IsWasmFuncref(ConvertType(E->getType()));
+ bool DestIsFuncref = IsWasmFuncref(DestLTy);
+ if (SrcIsFuncref && DestIsFuncref) {
+ // funcref -> funcref (e.g. between differently-typed funcrefs) is the
+ // identity on the opaque reference value.
+ return Visit(E);
+ }
+ if (SrcIsFuncref && !DestIsFuncref) {
+ // funcref -> pointer: use wasm_funcref_to_ptr. This will probably crash
+ // later in codegen since we haven't implemented a way to actually get a
+ // function pointer from a funcref.
+ llvm::Function *ToPtr =
+ CGF.CGM.getIntrinsic(llvm::Intrinsic::wasm_funcref_to_ptr);
+ return CGF.Builder.CreateCall(ToPtr, {Visit(E)});
+ }
+ if (!SrcIsFuncref && DestIsFuncref) {
+ // A null function pointer converts to a null funcref (ref.null func),
----------------
hoodmane wrote:
Yeah it's always null:
> // The table offset at which to place function addresses. We reserve zero
> // for the null function pointer.
https://github.com/llvm/llvm-project/blob/main/lld/wasm/Config.h?plain=1#L99
but it would work fine to emit a table.get 0 for this too since that will just
return null. Would allow us to delete this special case.
https://github.com/llvm/llvm-project/pull/203165
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