[Wasm] Disable use of returnaddress in exclusivity diagnostics

Function calls and returns in Wasm are protected by Wasm runtime
and there is no way to get or control return address.

Author: kateinoigakukun

lib/IRGen/IRGenSIL.cpp

@@ -5765,7 +5765,9 @@ void IRGenSILFunction::visitBeginUnpairedAccessInst(
     // in which case we should use the caller, which is generally ok because
     // materializeForSet can't usually be thunked.
     llvm::Value *pc;
-    if (hasBeenInlined(access)) {
+    // Wasm doesn't have returnaddress because it can't access call frame
+    // for security purposes
+    if (IGM.Triple.isWasm() || hasBeenInlined(access)) {
       pc = llvm::ConstantPointerNull::get(IGM.Int8PtrTy);
     } else {
       auto retAddrFn =

stdlib/public/runtime/Exclusivity.cpp

@@ -42,6 +42,9 @@
 #elif _MSC_VER
 #include <intrin.h>
 #define get_return_address() _ReturnAddress()
+#elif defined(__wasm__)
+// Wasm can't access call frame for security purposes
+#define get_return_address() ((void*) 0)
 #else
 #error missing implementation for get_return_address
 #define get_return_address() ((void*) 0)