Wasm translator multi-value bugfix: handle branch to loop with loop params.

cranelift/wasm/src/code_translator.rs

@@ -361,7 +361,7 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
                 // We signal that all the code that follows until the next End is unreachable
                 frame.set_branched_to_exit();
                 let return_count = if frame.is_loop() {
-                    0
+                    frame.num_param_values()
                 } else {
                     frame.num_return_values()
                 };

tests/wasm/loop-params.wat

@@ -0,0 +1,13 @@
+  (module
+    (func (export "run") (result i32)
+      (local $i i32)
+      (i32.const 0) ;; sum
+      (i32.const 10) ;; i
+      (loop $loop (param i32 i32) (result i32)
+        (local.tee $i)
+        (i32.add) ;; sum = i + sum
+        (i32.sub (local.get $i) (i32.const 1))
+        (i32.eqz (local.tee $i))
+        (if (param i32) (result i32)
+            (then)
+            (else (local.get $i) (br $loop))))))