Fix zero initialization of locals causing garbage values (#331)

* Fix zero initialization of locals stackvalues

* Add get zero initialized local tests with stack garbage

Author: abelstuker

src/Interpreter/interpreter.cpp

@@ -104,8 +104,8 @@ void Interpreter::setup_call(Module *m, uint32_t fidx) {
                   m->sp, STACK_SIZE);
         }
 #endif
+        memset(&m->stack[m->sp], 0, sizeof(StackValue));
         m->stack[m->sp].value_type = func->local_value_type[lidx];
-        m->stack[m->sp].value = {0};  // Initialize whole union to 0
     }
 
     // Set program counter to start of function

tests/latch/core/local_get_0.asserts.wast

@@ -2,6 +2,8 @@
        (assert_return (invoke "type-local-i64") (i64.const 0))
        (assert_return (invoke "type-local-f32") (f32.const 0))
        (assert_return (invoke "type-local-f64") (f64.const 0))
+       (assert_return (invoke "zero-init-f64") (f64.const 0))
+       (assert_return (invoke "zero-init-i64") (i64.const 0))
        (assert_return (invoke "type-param-i32" (i32.const 2)) (i32.const 2))
        (assert_return (invoke "type-param-i64" (i64.const 3)) (i64.const 3))
        (assert_return (invoke "as-block-value" (i32.const 6)) (i32.const 6))

tests/latch/core/local_get_0.wast

@@ -2,15 +2,15 @@
 (module
   ;; Typing
 
-  (func (export "type-local-i32") (result i32) (local i32) (local.get 0))
-  (func (export "type-local-i64") (result i64) (local i64) (local.get 0))
-  (func (export "type-local-f32") (result f32) (local f32) (local.get 0))
-  (func (export "type-local-f64") (result f64) (local f64) (local.get 0))
+  (func $type-local-i32 (export "type-local-i32") (result i32) (local i32) (local.get 0))
+  (func $type-local-i64 (export "type-local-i64") (result i64) (local i64) (local.get 0))
+  (func $type-local-f32 (export "type-local-f32") (result f32) (local f32) (local.get 0))
+  (func $type-local-f64 (export "type-local-f64") (result f64) (local f64) (local.get 0))
 
-  (func (export "type-param-i32") (param i32) (result i32) (local.get 0))
-  (func (export "type-param-i64") (param i64) (result i64) (local.get 0))
-  (func (export "type-param-f32") (param f32) (result f32) (local.get 0))
-  (func (export "type-param-f64") (param f64) (result f64) (local.get 0))
+  (func $type-param-i32 (export "type-param-i32") (param i32) (result i32) (local.get 0))
+  (func $type-param-i64 (export "type-param-i64") (param i64) (result i64) (local.get 0))
+  (func $type-param-f32 (export "type-param-f32") (param f32) (result f32) (local.get 0))
+  (func $type-param-f64 (export "type-param-f64") (param f64) (result f64) (local.get 0))
 
   (func (export "type-mixed") (param i64 f32 f64 i32 i32)
     (local f32 i64 i64 f64)
@@ -25,6 +25,19 @@
     (drop (f64.neg (local.get 8)))
   )
 
+  ;; ensure the full 64-bit local value is 0-initialized
+  ;; (similar to type-local-<x>64 but with added stack garbage)
+  (func (export "zero-init-f64") (result f64)
+    (f64.const 0xAAAAAAAAAAAAAAAA)
+    (drop)
+    (call $type-local-f64)
+  )
+  (func (export "zero-init-i64") (result i64)
+    (i64.const 0xAAAAAAAAAAAAAAAA)
+    (drop)
+    (call $type-local-i64)
+  )
+
   ;; Reading
 
   (func (export "read") (param i64 f32 f64 i32 i32) (result f64)