[WASM] Fix KeyPath optimization bug around signature match

For wasm, KeyPath getter always take indices parameter to match callee
and caller signature. So need to pass stub pointer.

Author: kateinoigakukun

lib/IRGen/GenKeyPath.cpp

@@ -250,6 +250,10 @@ getAccessorForComputedComponent(IRGenModule &IGM,
                                forwardingSubs,
                                &ignoreWitnessMetadata,
                                forwardedArgs);
+    } else if (IGM.Triple.isOSBinFormatWasm()) {
+      // wasm: Add null swift.type pointer to match signature even when there is
+      // no generic environment.
+      forwardedArgs.add(llvm::ConstantPointerNull::get(IGM.TypeMetadataPtrTy));
     }
     auto fnPtr = FunctionPointer::forDirect(IGM, accessorFn,
                                           accessor->getLoweredFunctionType());

lib/SILOptimizer/Utils/KeyPathProjector.cpp

@@ -237,7 +237,22 @@ class GettablePropertyProjector : public ComponentProjector {
       assert(getter->getArguments().size() == 2 + target.isOSBinFormatWasm());
 
       auto ref = builder.createFunctionRef(loc, getter);
-      builder.createApply(loc, ref, subs, {addr, parentValue});
+
+      std::vector<SILValue> args{addr, parentValue};
+      // FIXME(wasm): For wasm, KeyPath getter always take indices parameter
+      // to match callee and caller signature. So need to pass stub pointer.
+      // See also: getOrCreateKeyPathSetter and getOrCreateKeyPathGetter
+      if (builder.getASTContext().LangOpts.Target.isOSBinFormatWasm()) {
+        auto IntTy = SILType::getBuiltinIntegerType(32, builder.getASTContext());
+        auto UnsafeRawPointerTy = SILType::getRawPointerType(builder.getASTContext());
+        auto zeroVal = SILValue(builder.createIntegerLiteral(loc, IntTy, 0));
+        auto stackBuffer = SILValue(builder.createAllocStack(loc, IntTy));
+        builder.createStore(loc, zeroVal, stackBuffer, StoreOwnershipQualifier::Unqualified);
+        auto nonePointer = builder.createUncheckedAddrCast(loc, stackBuffer, UnsafeRawPointerTy);
+        args.push_back(SILValue(nonePointer));
+      }
+
+      builder.createApply(loc, ref, subs, args);
 
       // If we were previously accessing a class member, we're done now.
       insertEndAccess(beginAccess, builder);