From fe04ea894b93f4126bc2853269c2064ca59f843e Mon Sep 17 00:00:00 2001
From: Syrus Akbary <me@syrusakbary.com>
Date: Thu, 15 Jul 2021 23:57:07 -0700
Subject: [PATCH] Added WebAssembly Module converter

---
 lib/js-api/Cargo.toml      |  2 +-
 lib/js-api/src/module.rs   | 11 +++++++++++
 lib/js-api/src/ptr.rs      | 19 +++++--------------
 lib/js-api/tests/module.rs | 11 +++++++++++
 4 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/lib/js-api/Cargo.toml b/lib/js-api/Cargo.toml
index 35688464484..9cc65398e86 100644
--- a/lib/js-api/Cargo.toml
+++ b/lib/js-api/Cargo.toml
@@ -40,7 +40,7 @@ wasm-bindgen-test = "0.3.0"
 maintenance = { status = "actively-developed" }
 
 [features]
-default = ["std", "wasm-types-polyfill"]
+default = ["std", "wasm-types-polyfill", "wat"]
 wasm-types-polyfill = ["wasmparser"]
 std = []
 core = []
diff --git a/lib/js-api/src/module.rs b/lib/js-api/src/module.rs
index 1735348ff11..a976d337153 100644
--- a/lib/js-api/src/module.rs
+++ b/lib/js-api/src/module.rs
@@ -506,3 +506,14 @@ impl fmt::Debug for Module {
             .finish()
     }
 }
+
+impl From<WebAssembly::Module> for Module {
+    fn from(module: WebAssembly::Module) -> Module {
+        Module {
+            store: Store::default(),
+            module,
+            name: None,
+            type_hints: None,
+        }
+    }
+}
diff --git a/lib/js-api/src/ptr.rs b/lib/js-api/src/ptr.rs
index 449851489d5..e64aab94d25 100644
--- a/lib/js-api/src/ptr.rs
+++ b/lib/js-api/src/ptr.rs
@@ -86,13 +86,6 @@ impl<T: Copy, Ty> WasmPtr<T, Ty> {
     }
 }
 
-#[inline(always)]
-fn align_pointer(ptr: usize, align: usize) -> usize {
-    // clears bits below aligment amount (assumes power of 2) to align pointer
-    debug_assert!(align.count_ones() == 1);
-    ptr & !(align - 1)
-}
-
 /// Methods for `WasmPtr`s to data that can be dereferenced, namely to types
 /// that implement [`ValueType`], meaning that they're valid for all possible
 /// bit patterns.
@@ -109,8 +102,7 @@ impl<T: Copy + ValueType> WasmPtr<T, Item> {
         if total_len > memory.size().bytes().0 || mem::size_of::<T>() == 0 {
             return None;
         }
-        let offset = align_pointer(self.offset as usize, mem::align_of::<T>()) as u32;
-        let subarray = memory.uint8view().subarray(offset, total_len as u32);
+        let subarray = memory.uint8view().subarray(self.offset, total_len as u32);
         Some(WasmCell::new(subarray))
     }
 }
@@ -140,14 +132,13 @@ impl<T: Copy + ValueType> WasmPtr<T, Array> {
             return None;
         }
 
-        let offset = align_pointer(self.offset as usize, mem::align_of::<T>()) as u32;
-
         Some(
             (0..length)
                 .map(|i| {
-                    let subarray = memory
-                        .uint8view()
-                        .subarray(offset + i * item_size, offset + (i + 1) * item_size);
+                    let subarray = memory.uint8view().subarray(
+                        self.offset + i * item_size,
+                        self.offset + (i + 1) * item_size,
+                    );
                     WasmCell::new(subarray)
                 })
                 .collect::<Vec<_>>(),
diff --git a/lib/js-api/tests/module.rs b/lib/js-api/tests/module.rs
index f254f909754..5698e8e9d71 100644
--- a/lib/js-api/tests/module.rs
+++ b/lib/js-api/tests/module.rs
@@ -1,3 +1,4 @@
+use js_sys::{Uint8Array, WebAssembly};
 use wasm_bindgen_test::*;
 use wasmer_js::*;
 
@@ -22,6 +23,16 @@ fn module_set_name() {
     assert_eq!(module.name(), Some("new_name"));
 }
 
+#[wasm_bindgen_test]
+fn module_from_jsmodule() {
+    let wat = br#"(module $name)"#;
+    let binary = wat2wasm(wat).unwrap();
+    let js_bytes = unsafe { Uint8Array::view(&binary) };
+    let js_module = WebAssembly::Module::new(&js_bytes.into()).unwrap();
+    let module: Module = js_module.into();
+    assert_eq!(module.store(), &Store::default());
+}
+
 #[wasm_bindgen_test]
 fn imports() {
     let store = Store::default();