LLVM stands for Low Level Virtual Machine which is a compiler infrastructure, written in C++. The LLVM project started in 2000 at the University of Illinois at Urbana-Champaign, under the direction of Vikram Adve and Chris Lattner. In late 2000, Lattner joined the University of Illinois at Urbana-Champaign as a research assistant and M.Sc. student. Lattner was hired by Apple in 2005.
LLVM Compiler in Xcode 3.2.3 does not support C++. You have to use LLVM-GCC for C++ in Xcode 3.2.3. Now LLVM Compiler 2.0 in Xcode 4 supports C++. That is why the default compiler of Xcode 4 is LLVM Compiler. GCC 4.2 is not recommended because Apple will not fix bugs any more.
1. Fast compile times - Almost 3x faster debug builds
2. Great user features
3. Beautiful error messages
4. compatible with GCC
Clang Frontend is a parser for C family of languages including C, Objective-C, C++.Clang is part of many great new tools: LLVM Compiler, Xcode Static Analyzer, Xcode 4, LLDB Debugger, OpenCL. Clang is integrated into Xcode 4 for source code indexing, syntax highlighting, code completion, live warnings and Fix-its.
Xcode Static Analyzer
Automatically find bugs by analyzing your code.
Benefits of LLVM Compiler 2 C++
1. Faster compilation
2. Greatly improved warnings and errors
3. Complete binary compatibility
4. Better C++ standards conformance
5. Objective-C++ supportPerformanceC++ compile-time performance: 25% fasterC++ memory usage: 33% smaller
Upcoming C++ '0x Standard
libc++ introduced for new C++ standard.
I think every developer using Xcode 4 should move onto LLVM compiler.
WWDC2010 Session312 What's New in the LLVM Compiler
Author: Chris Lattner - LLVM Chief Architect