[Wasm R2R] Retype integer constant struct returns to the native return type

src/coreclr/jit/lower.cpp

@@ -5859,6 +5859,17 @@ void Lowering::LowerRetStruct(GenTreeUnOp* ret)
             else
             {
                 assert(varTypeUsesIntReg(nativeReturnType));
+                // ZeroObj assertion propagation can create an INT zero for a wider
+                // (e.g. LONG) integer struct return. Retype it to the native return type
+                // so that targets with a typed value stack (Wasm) emit e.g. an i64.const
+                // rather than an i32.const. Mirrors the float/double case above.
+#if defined(TARGET_WASM)
+                if (genActualType(retVal) != genActualType(nativeReturnType))
+                {
+                    assert(retVal->IsIntegralConst(0));
+                    retVal->BashToZeroConst(nativeReturnType);
+                }
+#endif // defined(TARGET_WASM)
             }
             break;
         }