Improve reallocateUnsafe and properly free unmanaged objects (#368)

Author: MaxGraey

std/assembly/internal/arraybuffer.ts

@@ -40,25 +40,23 @@ export function reallocateUnsafe(buffer: ArrayBuffer, newByteLength: i32): Array
     assert(newByteLength <= MAX_BLENGTH);
     if (newByteLength <= <i32>(computeSize(oldByteLength) - HEADER_SIZE)) { // fast path: zero out additional space
       store<i32>(changetype<usize>(buffer), newByteLength, offsetof<ArrayBuffer>("byteLength"));
-      memory.fill(
-        changetype<usize>(buffer) + HEADER_SIZE + <usize>oldByteLength,
-        0,
-        <usize>(newByteLength - oldByteLength)
-      );
     } else { // slow path: copy to new buffer
       let newBuffer = allocateUnsafe(newByteLength);
       memory.copy(
         changetype<usize>(newBuffer) + HEADER_SIZE,
         changetype<usize>(buffer) + HEADER_SIZE,
         <usize>oldByteLength
       );
-      memory.fill(
-        changetype<usize>(newBuffer) + HEADER_SIZE + <usize>oldByteLength,
-        0,
-        <usize>(newByteLength - oldByteLength)
-      );
-      return newBuffer;
+      if (!isManaged<ArrayBuffer>()) {
+        memory.free(changetype<usize>(buffer));
+      }
+      buffer = newBuffer;
     }
+    memory.fill(
+      changetype<usize>(buffer) + HEADER_SIZE + <usize>oldByteLength,
+      0,
+      <usize>(newByteLength - oldByteLength)
+    );
   } else if (newByteLength < oldByteLength) { // fast path: override size
     // TBD: worth to copy and release if size is significantly less than before?
     assert(newByteLength >= 0);

tests/compiler/std/array.optimized.wat

@@ -5,12 +5,12 @@
  (type $iiiv (func (param i32 i32 i32)))
  (type $iiiii (func (param i32 i32 i32 i32) (result i32)))
  (type $iiii (func (param i32 i32 i32) (result i32)))
+ (type $iv (func (param i32)))
  (type $iiv (func (param i32 i32)))
  (type $iiif (func (param i32 i32 i32) (result f32)))
  (type $F (func (result f64)))
  (type $Iv (func (param i64)))
  (type $ffi (func (param f32 f32) (result i32)))
- (type $iv (func (param i32)))
  (type $FFi (func (param f64 f64) (result i32)))
  (type $Fi (func (param f64) (result i32)))
  (type $iiiiiv (func (param i32 i32 i32 i32 i32)))
@@ -2229,7 +2229,6 @@
  (func $~lib/internal/arraybuffer/reallocateUnsafe (; 14 ;) (type $iii) (param $0 i32) (param $1 i32) (result i32)
   (local $2 i32)
   (local $3 i32)
-  (local $4 i32)
   get_local $1
   get_local $0
   i32.load
@@ -2263,39 +2262,30 @@
     get_local $0
     get_local $1
     i32.store
-    get_local $0
-    i32.const 8
-    i32.add
-    get_local $2
-    i32.add
-    i32.const 0
-    get_local $1
-    get_local $2
-    i32.sub
-    call $~lib/internal/memory/memset
    else    
     get_local $1
     call $~lib/internal/arraybuffer/allocateUnsafe
     tee_local $3
     i32.const 8
     i32.add
-    tee_local $4
     get_local $0
     i32.const 8
     i32.add
     get_local $2
     call $~lib/internal/memory/memmove
-    get_local $2
-    get_local $4
-    i32.add
-    i32.const 0
-    get_local $1
-    get_local $2
-    i32.sub
-    call $~lib/internal/memory/memset
     get_local $3
-    return
+    set_local $0
    end
+   get_local $0
+   i32.const 8
+   i32.add
+   get_local $2
+   i32.add
+   i32.const 0
+   get_local $1
+   get_local $2
+   i32.sub
+   call $~lib/internal/memory/memset
   else   
    get_local $1
    get_local $2
@@ -2307,7 +2297,7 @@
     if
      i32.const 0
      i32.const 40
-     i32.const 64
+     i32.const 62
      i32.const 4
      call $~lib/env/abort
      unreachable