[Cython] OS X 10.7 Lion: GCC __builtin_expect unrecognized inside OpenMP blocks

Stefan Behnel stefan_ml at behnel.de
Sat Mar 10 14:00:33 CET 2012

Lisandro Dalcin, 10.03.2012 10:51:
> On 10 March 2012 03:41, mark florisson wrote:
>> On 9 March 2012 14:22, Lisandro Dalcin wrote:
>>> I'm basically experiencing the issues here:
>>> http://www.cocoabuilder.com/archive/xcode/310299-error-calling-builtin-expect-inside-omp-parallel-for.html
>>> Can you imagine any way to workaround it?
>> What a lovely C compiler bug... Did you file a bug report with gcc or
>> xcode? What version of gcc does Lion ship with?
> I'm using a Mac just by accident, no idea (nor motivation) to report
> bugs to Apple.
> $ gcc --version
> i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 (Based on Apple Inc.
> build 5658) (LLVM build 2336.9.00)
> Could that be the the bug is actually in the LLVM backend?
>> I suppose the macro would have to be disabled for OS X Lion inside
>> parallel sections (there seems to be __APPLE__ and __OSX__, I don't
>> know about detecting the OS X version), that's easy to do (undef and
>> redefine to no-ops before parallel section and redefine it again after
>> the section). I'll try fixing it during the sprints next week.
> Perhaps switching to use a "omp_likely"/"omp_unlikely" macros inside
> OpenMP blocks would be nicer than defining/undefining?

Could that be coded into the macro or would it require to change the
generated code? But at least it sounds like it would not impact code in
functions that are being called from within the OpenMP blocks, would it?
Just the code straight inside the block. A work-around could still have a
substantial impact if it requires changes to the generated code.


More information about the cython-devel mailing list