Merge pull request #4408 from swiftwasm/katei/wip-silgen-once

Handle `swift_once` workaround in a proper way

Author: kateinoigakukun

include/swift/AST/Builtins.def

@@ -699,7 +699,7 @@ BUILTIN_MISC_OPERATION(IntToFPWithOverflow, "itofp_with_overflow", "n", Special)
 /// zeroInitializer has type <T> () -> T
 BUILTIN_MISC_OPERATION(ZeroInitializer, "zeroInitializer", "n", Special)
 
-/// once has type (Builtin.RawPointer, () -> ())
+/// once has type (Builtin.RawPointer, (Builtin.RawPointer) -> ())
 BUILTIN_MISC_OPERATION(Once, "once", "", Special)
 /// onceWithContext has type (Builtin.RawPointer, (Builtin.RawPointer) -> (), Builtin.RawPointer)
 BUILTIN_MISC_OPERATION(OnceWithContext, "onceWithContext", "", Special)

lib/SILGen/SILGen.cpp

@@ -1650,21 +1650,7 @@ SILFunction *SILGenModule::emitLazyGlobalInitializer(StringRef funcName,
   auto *onceBuiltin =
       cast<FuncDecl>(getBuiltinValueDecl(C, C.getIdentifier("once")));
   auto blockParam = onceBuiltin->getParameters()->get(1);
-  auto *type = blockParam->getType()->castTo<FunctionType>();
-  SmallVector<AnyFunctionType::Param, 1> params;
-  // wasm: Lazy global init is used with swift_once which passes a context
-  // pointer parameter. If lazy global init doesn't take a context argument,
-  // caller and callee signatures are mismatched and it causes runtime
-  // exception on WebAssembly runtime. So we need to add dummy argument
-  // to consume the context pointer.
-  // See also: emitLazyGlobalInitializer
-  if (C.LangOpts.Target.isOSBinFormatWasm()) {
-    auto dummyParam = AnyFunctionType::Param(C.getUnsafeRawPointerDecl()->getDeclaredInterfaceType()
-                                             ->getCanonicalType());
-    params.push_back(dummyParam);
-  }
-  Type initType = FunctionType::get(params, TupleType::getEmpty(C),
-                                    type->getExtInfo());
+  auto *initType = blockParam->getType()->castTo<FunctionType>();
   auto initSILType = cast<SILFunctionType>(
       Types.getLoweredRValueType(TypeExpansionContext::minimal(), initType));
 

lib/SILGen/SILGenGlobalVariable.cpp

@@ -228,18 +228,11 @@ void SILGenFunction::emitLazyGlobalInitializer(PatternBindingDecl *binding,
                                                unsigned pbdEntry) {
   MagicFunctionName = SILGenModule::getMagicFunctionName(binding->getDeclContext());
 
-  ASTContext &C = getASTContext();
-  // wasm: Lazy global init is used with swift_once which passes a context
-  // pointer parameter. If lazy global init doesn't take a context argument,
-  // caller and callee signatures are mismatched and it causes runtime
-  // exception on WebAssembly runtime. So we need to add dummy argument
-  // to consume the context pointer.
-  // See also: emitLazyGlobalInitializer
-  if (C.LangOpts.Target.isOSBinFormatWasm()) {
-    auto UnsafeRawPointer = C.getUnsafeRawPointerDecl();
-    auto UnsafeRawPtrTy = getLoweredType(UnsafeRawPointer->getDeclaredInterfaceType());
-    F.front().createFunctionArgument(UnsafeRawPtrTy);
-  }
+  // Add context pointer argument required to pass to `Builtin.once`
+  SILBasicBlock &entry = *F.begin();
+  SILType rawPointerSILTy
+    = getLoweredLoadableType(getASTContext().TheRawPointerType);
+  entry.createFunctionArgument(rawPointerSILTy);
 
   {
     Scope scope(Cleanups, binding);