IBM Releases XL compilers for Mac OS X

Visigothe writes "IBM released their XL Fortran Compiler and XL C/C++ Compiler for OS X. The compiler is binary compatible with GCC 3.3, and has multiple levels of optimization, creating binaries that are much faster than their GCC-compiled counterparts." No prices are noted, and the planned availability date is January 16.

Comments

Benchmarks

[melquiades]

Has anybody seen any useful benchmarks of compiler output comparing XL and GCC on PowerPC?

That would be interesting to see.

Supports G4 and G5, but not G3

[Laplace]

It's great that IBMs compiler produces faster code that is compatible with gcc, however it appears that it won't generate code that runs on G3 machines. This means if you want to build apps with it you either need to write code that builds with two compilers or not support any G3 machines.

As a very happy G3 user I will be sad when I'm forced to upgrade.

Setting up a karma whore...

[Troy]

Pardon my ignorance, I was 31337 for only 37 seconds in 1997.

What do they mean when they say that two compilers are "binary compatible" Does it mean that XL produces identical machine code? Does it take identical switches so makefiles don't have to be rewritten? Does it simply mean that XL has the same foibles as gcc, so code written to gcc's foibles doesn't need tinkering? Use of the term doesn't quite fit with my current understanding of compilers.

-Troy

FASTER OS X?

[zulux]

What does Apple use to compile OS X - and if IBM get the Objective C sections woking properly, could Apple use the IBM comiper to get OS X to run faster?

Re:FASTER OS X?

[addaon]

OS X and all Apple software for OS X that I know of (maybe not including some high-end stuff, I just don't know for sure) is indeed built with GCC.

Porting an operating system to a different compiler is a pain in the neck, and most OS's use compiler-specific tricks to deal with low-level details. Also, most of Apple's higher-level software is in Objective C, and as of now only GCC really supports Obj C well on the mac.

Re:FASTER OS X?

[Visigothe]

Apple currently uses GCC to build Panther. As XL is much faster in 95% of the situations, I would imagine that Apple would transition to XL once the Obj-C portions of the compiler were a bit more mature. [The public beta of XLC didn't have any Obj-C support]

Re:FASTER OS X?

[rmlane]

As mentioned by others, the majority of OS X is compiled by GCC.

The exception is Quicktime, which uses (and has used since well before OS X) a older, custom version of the IBM compilers. I believe, but am not 100% sure, that Quicktime has always used the IBM compilers on PowerPC CPUs.

This is very good news for Apple's science users, one of the real problems pushing Mac boxes into some markets has been the lack of a really good Fortran compiler. The performance boost for C/C++ code will also be appreciated.

As for a wholesale transition of OS X to the IBM compilers: next to no chance. QA of the transition would take far too long and absorb resources that could be better used on other improvements. It would also cause problems with the Open Source versions of Darwin, so expect the vast majority of OS X to remain GCC compiled.

That being said, I would expect that certain chunks will be transitioned, where it makes sense. The output of the IBM compilers is binary compatible with GCC, so you can recompile (and re-QA) chunks of the OS where you'll get a major improvment.

Quartz Extreme, CoreFoundation and AppKit spring to mind, but don't expect this to happen in 10.3 or 10.4, more like 10.5 or 11.0.

Re:FASTER OS X?

[gerardrj]

You mean it would consume more resources than a complete re-write of the OS from Pascal to C as happened with System 6 to System 7 transition?

I expect that once IBM completes the ObjC compiler that most of the OS will be migrated to that compiler, as will much of the high performance commercial software out there. The developer tools will still come with the free GCC compiler, and Apple will still maintain it, but without changes to the core of GCC (which are being resisted by the maintainers), it will never make the G5 shine.

I have yet to see pricing from IBM on these compilers, so I don't know yet how viable they will be for smaller developers. It might be that developers offer two versions of their software: standard for the regular cost, and the 15%-40% better performance version from the IBM compiler for like 20% higher cost, just so they can recoup their added costs.

Autovectorisation ?

[Jesrad]

Weren't these compilers supposed to bring automatic conversion of multiple 32bits arithmetic operations into Altivec-accelerated code ?

Fortran Motives

[fm6]

From what I've heard, software companies hate selling Fortran compilers. You'll notice that Microsoft no longer has one. Not enough people use the language to make it worth the development and support costs.

So why are you still able to buy Fortran compilers? Because the people who use the language tend to be engineers (the physical kind) and scientists, and thus spend a lot of money on high-end computers. No Fortran compiler, not fat contracts for your Starfire and Origin boxes. Which is why Sun and SGI both sell Fortran. And whose the leading vendor of Fortran for the Itanium? Good guess.

So is IBM trying to help Apple sell more Macs? Probably not. They'd make a little money from the extra CPU sales, but not enough to justify something like this. More likely they have this compiler to help them sell more high-performance PPC systems. As long as they have it, not that much extra effort to port it to the Mac.

Re:Fortran Motives

[jabberjaw]

Yes indeed Fortran is still alive and kicking. Although I have heard that some of the physics libraries are being converted to C/C++.
As an aside, has anyone else noticed the lack of Fortran texts in brick & motor bookstores? I know Numerical Recepies in Fortran is online, anyone care to mention a good intro. text for a "n00b" like me?

Re:Fortran Motives

[fm6]

I used to work with a guy who had just finished a Physics PhD. He hated Fortran, and had insisted on using C++ all through school. But he admitted to being the only person in his program who did so. Proof that programming languages are as about the community they serve as the technology they encompass.

Re:Fortran Motives

[Anonymous Coward]

Fortran is part of the SPEC benchmark, so every vendor will continue to produce Fortran compilers and write them off as marketing cost.

objective-c support

[sethdelackner]

So has anyone got better pointers towards the state of their objective-c support? I know they say it is there as a technical preview with no guarantees until they finish, but does it basically work and is slow, or is it unable to compile even modestly complex stuff?

Don't forget x86!

[MarcQuadra]

don't forget x86, there's nothing STOPPING the *.app files from holding code for any architecture. If Apple ever does have to jump ship to x86 I'm sure there'll be a lot of apps that are distributed with PPC and x86 (and probably x86-64) executables inside them.

One Application Icon to Rule Them All.