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Christopher Bahns wrote: > Hello, > > I am converting a program (based on the MC68306) from the Microtec > Research (MRI) compiler to the GNU compiler. Things in general are going > pretty well, but I'm having a problem: The size of the code generated by > GNU is too big to fit in my flash memory, whereas the code generated by > MRI does fit. > > I have 96k of flash available. The MRI-built program uses all but the > last 2572 bytes, so it is rather close to reaching the limit. However, > the GNU-built program is 11080 bytes over limit, causing my link to > fail. The total difference in sizes between the two compilers is 13652 > bytes, or an increase of 14.3% when going from MRI to GNU. These numbers > just apply to the executable code, which is the ".text" section with > GNU, and with MRI it is the combination of the "code", "const", > "literals", "strings", "??INITDATA", and "ioports" sections. The others > sections are ok, but the general trend seems to be that if two > corresponding sections are not the same size, the GNU version is always > bigger. In this particular case it is too big for my program to work. > > My configuration: Windows 98SE, Cygnus Cygwin 1.0, binutils-2.9.1 > (patched), gcc-2.95.2, newlib-1.8.2, target=m68k-coff. > > I built the compiler myself without modifying the default configuration > for this target. When building my program I use the "-O2" option, which > makes the program quite small in comparison to other optimization > settings ("-O3" is larger, and "-Os" is only slightly smaller). I'm not > sure whether it's the difference in the sizes of the project's > functions, or those of the MRI and GNU run-time libraries that are > linked in. But, I suspect that it's the run-time libraries since the > project's functions are built from essentially the same source. The > differences in the compilers may account for a small difference here, > but I assume that if the source code is identical, that the size of code > generated by GNU (with level 2 optimizations) should be very near the > size of code generated by MRI. > > So, I'll assume that it's the difference in the implementation of the > run-time libraries. But, how do I proceed? You might use the size command to figure out if the gcc is larger than the MRI compiled version of your function (e.g. >>size my_func.o). This might answer the question if the standard libraries or your object file is the cause of the over size. > Has anyone else had this > problem, or been at all concerned about the sizes of the executables > generated by the GNU compiler (particularly for m68k targets)? I think > I'll try to rebuild the compiler with the "-O2" option and see if that > makes a difference. Has anyone done this, or have any insight into > whether the resulting libraries will work, or whether the optimizations > will make a significant difference? > > Thanks a lot for any help. The help that I've gotten here so far has > been very helpful. > Chris > > ------------------------------------------------------------------------ > ------ > Want more information? See the CrossGCC FAQ, http://www.objsw.com/CrossGCC/ > Want to unsubscribe? Send a note to crossgcc-unsubscribe@sourceware.cygnus.com ------ Want more information? See the CrossGCC FAQ, http://www.objsw.com/CrossGCC/ Want to unsubscribe? Send a note to crossgcc-unsubscribe@sourceware.cygnus.com
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