[Llvm-bgq-discuss] Issues with inlining

[Schlottke, Michael]

P.P.S: the described behavior with the “-fno-inline” flag occurred with r220548 and r217688 (I didn’t check any older version).

On 23 Feb 2015, at 15:50 , Schlottke, Michael <m.schlottke at fz-juelich.de<mailto:m.schlottke at fz-juelich.de>> wrote:

Dear Clang/BGQ folks,

We encounter a problem with certain parts of our C++ code when using higher-level optimizations (-On with n>1) with clang on JUQUEEN. I was able to boil down the problem to being apparently linked to the “-inline” optimization pass. When I compile with “-O3” or “-O2” and also use the “-fno-inline” option afterwards, execution works as expected.

The problem only seems to occur on the BG/Q machine as we use the same flags everywhere and it does work on e.g. our institute’s cluster. Therefore my questions are

a) Have you encountered a similar problem on BG/Q? If yes, how did you manage to resolve it?
b) What would be the best way to identify and fix the offending lines in our code (assuming that it can be fixed/reduced to a handful of locations)?

Thanks a lot!

Michael

P.S.: Since I have a good idea in which file the error is located, I tried to fix the location by just specifying

#pragma clang optimize off

at the beginning of a source file. This, however, led to a compiler crash (see http://llvm.org/bugs/show_bug.cgi?id=22664), so I could not investigate this issue further.


--
Michael Schlottke

SimLab Highly Scalable Fluids & Solids Engineering
Jülich Supercomputing Centre (JSC)
Forschungszentrum Jülich GmbH
52425 Jülich
Germany

Phone: +49 (2461) 61 2326
Mail: m.schlottke at fz-juelich.de<mailto:m.schlottke at fz-juelich.de>
Web: http://www.fz-juelich.de/jsc




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