Issue #1442 - Part 1: Change ArrayBufferCopyData self-hosting intrinsic to take a start offset for the destination.

This will be needed to manage stream chunks.
https://bugzilla.mozilla.org/show_bug.cgi?id=1272697

1 files changed, 5 insertions, 4 deletions

diff --git a/js/src/vm/SharedArrayObject.cpp b/js/src/vm/SharedArrayObject.cpp
index 8e55001d13..44fe3b790d 100644
--- a/js/src/vm/SharedArrayObject.cpp
+++ b/js/src/vm/SharedArrayObject.cpp
@@ -331,15 +331,16 @@ SharedArrayBufferObject::addSizeOfExcludingThis(JSObject* obj, mozilla::MallocSi
 }
 
 /* static */ void
-SharedArrayBufferObject::copyData(Handle<SharedArrayBufferObject*> toBuffer,
-                                  Handle<SharedArrayBufferObject*> fromBuffer,
-                                  uint32_t fromIndex, uint32_t count)
+SharedArrayBufferObject::copyData(Handle<SharedArrayBufferObject*> toBuffer, uint32_t toIndex,
+                                  Handle<SharedArrayBufferObject*> fromBuffer, uint32_t fromIndex,
+                                  uint32_t count)
 {
     MOZ_ASSERT(toBuffer->byteLength() >= count);
+    MOZ_ASSERT(toBuffer->byteLength() >= toIndex + count);
     MOZ_ASSERT(fromBuffer->byteLength() >= fromIndex);
     MOZ_ASSERT(fromBuffer->byteLength() >= fromIndex + count);
 
-    jit::AtomicOperations::memcpySafeWhenRacy(toBuffer->dataPointerShared(),
+    jit::AtomicOperations::memcpySafeWhenRacy(toBuffer->dataPointerShared() + toIndex,
                                               fromBuffer->dataPointerShared() + fromIndex,
                                               count);
 }