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Poor performance on software cross-compiled for MinGW


I just discovered that the output from my Linux-hosted MinGW gcc cross compiler has some performance issues. That is, I have some code that runs 4-5 times faster on Linux (Red Hat Enterprise 4) when built using the standard compiler there, and using the same options as for the MinGW build, than the cross-compiled code does on Windows. The hardware is identical, and the job consists mainly of raw processing, so I'm inclined to blame it on the compiler rather than OS differences or similar. I'm not using any -O... flags at this time.

Cross compiler version is 3.4.2, with http://surfnet.dl.sourceforge.net/sourceforge/mingw/gcc-3.4.2-20040916-1-src.diff.gz applied and otherwise built using the standard procedure, if there is such a thing. I'll probably write up all the gory details later, but thought I might send a quick post first just to ask for ideas about where to start looking for the cause of the performance gap.

So, can anyone help me out here? Again, I don't expect you to pin-point the cause of the problem without getting a much more detailed description, but if you can suggest things to check in the compiler build config, know about specific things not to do to get an efficient binary etc, your input would be most welcome.

One idea I had was that the code would be built without support for newer processors and/or the FPU, so I tried

-march=i686 -mhard-float -msse -mfpmath=sse

but this did not make a lot of difference.

- Toralf



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