![]() Therefore both alternatives are reasonable choices for any devices. Regarding the two ARM instruction sets, neither of them is absolutely faster than the other, although Thumb-2 has a slight advantage in general. This is not surprising since the execution speed on the V8 benchmark was in focus of recent JavaScriptCore developments. ![]() The highest jump can be seen on the V8 benchmark set, where the last two modes are almost 10 times faster than the reference. Instead of absolute execution times, the relative speedups are shown compared to ARM version of CLoop of course the higher values mark better results.Īs we can see on these figures, enabling more sophisticated optimizations improves the execution on all benchmark sets, although the speedup is quite different. We measured these execution modes on three well known benchmark sets: SunSpider, V8, and WindScorpion. ![]() All the rest are mixed modes which combines LLInt, JIT and DFG-JIT. CLoop and LLInt are pure interpreted modes, while JIT represents a mode where all JavaScript source are compiled to native code. The following figures show the comparison of these execution mode combinations. During the last couple of months we finished the support of LLInt and DFG-JIT on the ARM instruction set, and below we present a comparison of them on both ARM and Thumb2 instruction sets. We have been deeply involved in the development of this port and we are responsible for the ARM-Linux support of JavaScriptCore. This compiler performs aggressive optimizations based on the profiling data collected during the previous executions of the function.Īll of these execution modes are supported by the ARM port of JavaScriptCore. When a given function is executed a large number of times, the function is recompiled by the DFG-JIT (Data Flow Graph JIT) compiler. This machine code will be executed next time that the function is invoked. When the invocation of a JavaScript function reaches a certain threshold, the function is translated to machine code by the JIT compiler. This mode is only recommended as a last resort, since it is not compatible with the further execution modes. If a backend is not available, it falls back to a C++ based implementation called CLoop. However, LLInt requires CPU-specific backends for each architecture (such as ARM). This new approach provides better interaction between the interpreter and the native code in a mixed environment. LLInt replaced the old C++ interpreter in February of 2012. The last execution mode also employs a JIT compiler, but it performs costly optimizations on the JavaScript source code before it is translated to native code. The next level is translating the JavaScript source code into native code by the JIT (Just-in-time) compiler. The basic execution mode is the interpreted execution model provided by the LLInt (Low Level Interpreter) component. At the moment JavaScriptCore has three execution modes. Each optimization level corresponds to an execution mode. A higher optimization level offers better runtime performance, but its trade-off is longer compilation time. ![]() It is a profiling virtual machine which supports various optimization levels. The JavaScript execution engine of WebKit is called JavaScriptCore. In this blog post we show the different execution modes of the JavaScript engine and compare their performance. We have worked on quite a few areas of WebKit including the JavaScript engine, multicore support, graphics and the building and testing environment. We, at the Department of Software Engineering, University of Szeged, Hungary, are long time contributors of a well-known browser engine called WebKit. The heart of all browsers is a browser engine. You can find them being used everywhere on devices ranging from phones and tablets to personal computers. Nowadays web browsers are among the most widely used software tools. To that end it's usually considered good practice to specify the vendor-prefixed version first and then the non-prefixed version, in order that the non-prefixed property will override the vendor-prefixed property-settings once it's implemented for example. The prefixes will, over time, be removed (at least in theory) as the unprefixed, the final version, of the property is implemented in that browser. This allows properties to be set specific to each individual browser/rendering engine in order for inconsistencies between implementations to be safely accounted for. Typically they're used to implement new, or proprietary CSS features, prior to final clarification/definition by the W3. These are the vendor-prefixed properties offered by the relevant rendering engines ( -webkit for Chrome, Safari -moz for Firefox, -o for Opera, -ms for Internet Explorer).
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |