[R-pkg-devel] Compiling 32-bit on Windows using 64-bit gcc and -m32

[Tomas Kalibera]

On 9/7/20 7:07 PM, bill using denney.ws wrote:
> Hello,
>
>   
>
> My question is:
>
> Can I use the 64-bit gcc to build a 32-bit package with the -m32 command
> line option with Rtools?  And, can that work for CRAN?  Or more generally,
> is there a work-around for needing lots of RAM during compilation with the
> 32-bit compiler?
>
> The background is:
>
> I'm trying to compile a the development version of RxODE
> (https://github.com/nlmixrdevelopment/RxODE/issues/278), but I'm hitting
> 32-bit memory limits (using >3GB and possibly >4GB RAM during compilation)
> using the 32-bit version of gcc.  Specifically,

I think this is too much memory to be used for compilation. I think it 
would be best to simplify the code, possibly split it, or just reduce 
the optimization level, as I read you have done already anyway. Maybe it 
doesn't have to be -O0, maybe you can enable some. In the past I've seen 
similar cases when inlining too aggressively in large files, maybe you 
could just reduce that a bit. It may very well be that reducing the 
optimization level just a little bit will provide about the same 
performance, but require far less memory at compile time (in the past 
there have been cases when -O3 did not produce faster code than -O2 on a 
set of standard benchmarks, of course that may be different in today's 
compilers).

Spending much more time for optimizing of the 32-bit builds may not be 
worth the effort (and neither on the R/CRAN side).

Best
Tomas


>
>   
>
> "C:/rtools40/mingw32/bin/"gcc [etc., see the link above for the full command
> line]
>
>   
>
> yields the error
>
>   
>
> cc1.exe: out of memory allocating 65536 bytes
>
>   
>
> There is no problem building with mingw64, and I played around to confirm
> that by using:
>
>   
>
> Sys.setenv(BINPREF="c:/rtools40/mingw64/bin/")
>
>   
>
> And compilation completed successfully (though installation failed as
> expected because the compiled .dll couldn't load on 32-bit R).
>
>   
>
> Thanks,
>
>   
>
> Bill
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-package-devel using r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-package-devel