Implement TypedArray#copyWithin (#830)

examples/n-body/package.json

@@ -10,7 +10,7 @@
     "tsbuild": "tsc -p assembly -t ES2017 -m commonjs --outDir build",
     "build": "npm run asbuild && npm run tsbuild",
     "server": "http-server . -o -c-1",
-    "test": "node --noliftoff --nowasm-tier-up --wasm-lazy-compilation --wasm-no-bounds-checks --expose-gc tests"
+    "test": "node --wasm-lazy-compilation --wasm-no-bounds-checks --expose-gc tests"
   },
   "devDependencies": {
     "http-server": "^0.11.1",

std/assembly/index.d.ts

@@ -1141,6 +1141,8 @@ declare abstract class TypedArray<T> implements ArrayBufferView<T> {
   slice(begin?: i32, end?: i32): TypedArray<T>;
   /** Returns a new TypedArray of this type on the same ArrayBuffer from begin inclusive to end exclusive. */
   subarray(begin?: i32, end?: i32): TypedArray<T>;
+  /** The copyWithin() method copies the sequence of array elements within the array to the position starting at target. The copy is taken from the index positions of the second and third arguments start and end. The end argument is optional and defaults to the length of the array. */
+  copyWithin(target: i32, start: i32, end?: i32): this;
   /**  The reduce() method applies a function against an accumulator and each value of the typed array (from left-to-right) has to reduce it to a single value. This method has the same algorithm as Array.prototype.reduce(). */
   reduce<U>(callbackfn: (accumulator: U, value: T, index: i32, self: this) => U, initialValue: U): U;
   /**  The reduceRight() method applies a function against an accumulator and each value of the typed array (from left-to-right) has to reduce it to a single value, starting from the end of the array. This method has the same algorithm as Array.prototype.reduceRight(). */

std/assembly/typedarray.ts

@@ -72,6 +72,10 @@ export class Int8Array extends ArrayBufferView {
     return SUBARRAY<Int8Array, i8>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Int8Array {
+    return COPY_WITHIN<Int8Array, i8>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: i8, index: i32, array: Int8Array) => T,
     initialValue: T,
@@ -188,6 +192,10 @@ export class Uint8Array extends ArrayBufferView {
     return SUBARRAY<Uint8Array, u8>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Uint8Array {
+    return COPY_WITHIN<Uint8Array, u8>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: u8, index: i32, array: Uint8Array) => T,
     initialValue: T,
@@ -304,6 +312,10 @@ export class Uint8ClampedArray extends ArrayBufferView {
     return SUBARRAY<Uint8ClampedArray, u8>(this, start, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Uint8ClampedArray {
+    return COPY_WITHIN<Uint8ClampedArray, u8>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: u8, index: i32, array: Uint8ClampedArray) => T,
     initialValue: T,
@@ -420,6 +432,10 @@ export class Int16Array extends ArrayBufferView {
     return SUBARRAY<Int16Array, i16>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Int16Array {
+    return COPY_WITHIN<Int16Array, i16>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: i16, index: i32, array: Int16Array) => T,
     initialValue: T,
@@ -536,6 +552,10 @@ export class Uint16Array extends ArrayBufferView {
     return SUBARRAY<Uint16Array, u16>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Uint16Array {
+    return COPY_WITHIN<Uint16Array, u16>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: u16, index: i32, array: Uint16Array) => T,
     initialValue: T,
@@ -652,6 +672,10 @@ export class Int32Array extends ArrayBufferView {
     return SUBARRAY<Int32Array, i32>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Int32Array {
+    return COPY_WITHIN<Int32Array, i32>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: i32, index: i32, array: Int32Array) => T,
     initialValue: T,
@@ -768,6 +792,10 @@ export class Uint32Array extends ArrayBufferView {
     return SUBARRAY<Uint32Array, u32>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Uint32Array {
+    return COPY_WITHIN<Uint32Array, u32>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: u32, index: i32, array: Uint32Array) => T,
     initialValue: T,
@@ -884,6 +912,10 @@ export class Int64Array extends ArrayBufferView {
     return SUBARRAY<Int64Array, i64>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Int64Array {
+    return COPY_WITHIN<Int64Array, i64>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: i64, index: i32, array: Int64Array) => T,
     initialValue: T,
@@ -1000,6 +1032,10 @@ export class Uint64Array extends ArrayBufferView {
     return SUBARRAY<Uint64Array, u64>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Uint64Array {
+    return COPY_WITHIN<Uint64Array, u64>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: u64, index: i32, array: Uint64Array) => T,
     initialValue: T,
@@ -1116,6 +1152,10 @@ export class Float32Array extends ArrayBufferView {
     return SUBARRAY<Float32Array, f32>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Float32Array {
+    return COPY_WITHIN<Float32Array, f32>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: f32, index: i32, array: Float32Array) => T,
     initialValue: T,
@@ -1232,6 +1272,10 @@ export class Float64Array extends ArrayBufferView {
     return SUBARRAY<Float64Array, f64>(this, begin, end);
   }
 
+  copyWithin(target: i32, start: i32, end: i32 = i32.MAX_VALUE): Float64Array {
+    return COPY_WITHIN<Float64Array, f64>(this, target, start, end);
+  }
+
   reduce<T>(
     fn: (accumulator: T, value: f64, index: i32, array: Float64Array) => T,
     initialValue: T,
@@ -1361,6 +1405,31 @@ function SUBARRAY<TArray extends ArrayBufferView, T>(
   return out;
 }
 
+// @ts-ignore: decorator
+@inline
+function COPY_WITHIN<TArray extends ArrayBufferView, T>(
+  array: TArray,
+  target: i32,
+  start: i32,
+  end: i32
+): TArray {
+  var len = array.length;
+  var dataStart = array.dataStart;
+
+      end   = min<i32>(end, len);
+  var to    = target < 0 ? max(len + target, 0) : min(target, len);
+  var from  = start < 0 ? max(len + start, 0) : min(start, len);
+  var last  = end < 0 ? max(len + end, 0) : min(end, len);
+  var count = min(last - from, len - to);
+
+  memory.copy(
+    dataStart + (<usize>to << alignof<T>()),
+    dataStart + (<usize>from << alignof<T>()),
+    <usize>count << alignof<T>()
+  );
+  return array;
+}
+
 // @ts-ignore: decorator
 @inline
 function REDUCE<TArray extends ArrayBufferView, T, TRet>(

tests/compiler/std/dataview.optimized.wat

@@ -1634,7 +1634,7 @@
   if
    i32.const 280
    i32.const 376
-   i32.const 154
+   i32.const 158
    i32.const 44
    call $~lib/builtins/abort
    unreachable

tests/compiler/std/dataview.untouched.wat

@@ -3327,7 +3327,7 @@
   if
    i32.const 280
    i32.const 376
-   i32.const 154
+   i32.const 158
    i32.const 44
    call $~lib/builtins/abort
    unreachable