Heads up, g++ in Xcode 5 points to Clang

[David Nadlinger]

On Monday, 28 October 2013 at 21:07:07 UTC, Iain Buclaw wrote:
> From what I've read and gathered from David over a period of 
> some
> conversations.  Clang infrastructure-wise is much like 
> gcc-3.3/gcc-4.0
> was - they have a well defined AST that is capable of 
> representing
> everything you'd expect in a typical C-family language, with a
> backdoor to lower level register/assembly representations for
> target-specific implementations.

If you are referring to LLVM here: Yes and no.

It's true that the LLVM IR is mostly target-independent (except 
for data type sizes and so on) with a number of backdoors in the 
form of inline assembly, special intrinsics and so on.

But at the same time, the LLVM IR is also of a very different 
quality than GCC GENERIC, being strictly in SSA form. I have not 
looked into the current GCC architecture in any detail, but I'd 
guess that LLVM itself starts approximately at the point where 
the middle-end does in GCC.

Clang itself is obviously on a higher layer, but unlike GENERIC, 
its data structures are not designed to be reused for 
non-C-family languages. So, the questions of whether its AST can 
represent every concept from another language or if it needs 
contains backdoors to a lower level are somewhat moot.

David