Implement TypedArray.set function.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 873 matching lines @@
     return typed_array->accessor();                                           \
   }
 
 TYPED_ARRAY_GETTER(Buffer, buffer)
 TYPED_ARRAY_GETTER(ByteLength, byte_length)
 TYPED_ARRAY_GETTER(ByteOffset, byte_offset)
 TYPED_ARRAY_GETTER(Length, length)
 
 #undef TYPED_ARRAY_GETTER
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_TypedArraySetSpecialCases) {

[rossberg, 2013/05/07 13:53:23]

Nit: I'd change the name, since it's the normal cases, right? How about
TypedArraySetFastCases?

[Dmitry Lomov (no reviews), 2013/05/07 14:20:00]

Done.

+  HandleScope scope(isolate);
+  CONVERT_ARG_HANDLE_CHECKED(Object, target_obj, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Object, source_obj, 1);
+  CONVERT_ARG_HANDLE_CHECKED(Object, offset_obj, 2);
+  if (!target_obj->IsJSTypedArray() || !source_obj->IsJSTypedArray())
+    return isolate->heap()->false_value();
+
+  Handle<JSTypedArray> target(JSTypedArray::cast(*target_obj));
+  Handle<JSTypedArray> source(JSTypedArray::cast(*source_obj));
+  size_t offset = NumberToSize(isolate, *offset_obj);
+  size_t target_length = NumberToSize(isolate, target->length());
+  size_t source_length = NumberToSize(isolate, source->length());
+  size_t target_byte_length = NumberToSize(isolate, target->byte_length());
+  size_t source_byte_length = NumberToSize(isolate, source->byte_length());
+  if (offset > target_length ||
+      offset + source_length > target_length ||
+      offset + source_length < offset)  // overflow
+    return isolate->Throw(*isolate->factory()->NewRangeError(
+          "typed_array_set_source_too_long", HandleVector<Object>(NULL, 0)));
+
+  Handle<JSArrayBuffer> target_buffer(JSArrayBuffer::cast(target->buffer()));
+  Handle<JSArrayBuffer> source_buffer(JSArrayBuffer::cast(source->buffer()));
+  size_t target_offset = NumberToSize(isolate, target->byte_offset());
+  size_t source_offset = NumberToSize(isolate, source->byte_offset());
+  uint8_t* target_base =
+      static_cast<uint8_t*>(target_buffer->backing_store()) + target_offset;
+  uint8_t* source_base =
+      static_cast<uint8_t*>(source_buffer->backing_store()) + source_offset;
+
+  // Typed arrays of the same type: use memmove.
+  if (target->type() == source->type()) {
+    memmove(target_base + offset * target->element_size(),
+        source_base, source_byte_length);
+    return isolate->heap()->true_value();
+  }
+
+  // Typed arrays of different types over the same backing store
+  if ((source_base <= target_base &&
+        source_base + source_byte_length >  target_base) ||

[rossberg, 2013/05/07 13:53:23]

Style nit: spurious space

[Dmitry Lomov (no reviews), 2013/05/07 14:20:00]

Done.

+      (target_base <= source_base &&
+        target_base + target_byte_length > source_base)) {
+    size_t target_element_size = target->element_size();
+    size_t source_element_size = source->element_size();
+
+    size_t source_length = NumberToSize(isolate, source->length());
+
+    // Copy left part
+    size_t left_index;
+    {
+      // First un-mutated byte after the next write
+      uint8_t* target_ptr = target_base + (offset + 1) * target_element_size;
+      // Next read at source_ptr. We do not care for memory changing before
+      // source_ptr - we have already copied it.
+      uint8_t* source_ptr = source_base;
+      for (left_index = 0;
+           left_index < source_length && target_ptr <= source_ptr;
+           left_index++) {
+        Handle<Object> v = Object::GetElement(
+            source, static_cast<uint32_t>(left_index));
+        JSObject::SetElement(
+            target, static_cast<uint32_t>(offset + left_index), v,
+            NONE, kNonStrictMode);
+        target_ptr += target_element_size;
+        source_ptr += source_element_size;
+      }
+    }
+    // Copy right part
+    size_t right_index;
+    {
+      // First unmutated byte before the next write
+      uint8_t* target_ptr =
+        target_base + (offset + source_length - 1) * target_element_size;
+      // Next read before source_ptr. We do not care for memory changing after
+      // source_ptr - we have already copied it.
+      uint8_t* source_ptr =
+        source_base + source_length * source_element_size;
+      for (right_index = source_length - 1;
+           right_index >= left_index && target_ptr >= source_ptr;
+           right_index--) {
+        Handle<Object> v = Object::GetElement(
+            source, static_cast<uint32_t>(right_index));
+        JSObject::SetElement(
+            target, static_cast<uint32_t>(offset + right_index), v,
+            NONE, kNonStrictMode);
+        target_ptr -= target_element_size;
+        source_ptr -= source_element_size;
+      }
+    }
+    ASSERT((right_index + 1) - left_index <= 8);

[rossberg, 2013/05/07 13:53:23]

I'd keep a comment similar to the one I had in d8 to explain this assertion.

[Dmitry Lomov (no reviews), 2013/05/07 14:20:00]

Done.

+    Handle<Object> temp[8];
+    size_t idx;
+    for (idx = left_index; idx <= right_index; idx++) {
+      temp[idx - left_index] = Object::GetElement(
+          source, static_cast<uint32_t>(idx));
+    }
+    for (idx = left_index; idx <= right_index; idx++) {
+      JSObject::SetElement(
+          target, static_cast<uint32_t>(offset + idx), temp[idx-left_index],
+          NONE, kNonStrictMode);
+    }
+  } else {  // Non-overlapping typed arrays

[rossberg, 2013/05/07 13:53:23]

Perhaps negate the conditional to put the common and simple case first.

[Dmitry Lomov (no reviews), 2013/05/07 14:20:00]

Can I please not? :))
On 2013/05/07 13:53:23, rossberg wrote:

+    for (size_t idx = 0; idx < source_length; idx++) {
+      Handle<Object> value = Object::GetElement(
+          source, static_cast<uint32_t>(idx));
+      JSObject::SetElement(
+          target, static_cast<uint32_t>(offset + idx), value,
+          NONE, kNonStrictMode);
+    }
+  }
+
+  return isolate->heap()->true_value();
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_SetInitialize) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSSet, holder, 0);
   Handle<ObjectHashSet> table = isolate->factory()->NewObjectHashSet(0);
   holder->set_table(*table);
   return *holder;
 }
 
 
@@ skipping 12490 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal