Hi, That is good solution, thanks.
But what if I want to compile e.o and d.o with cross-module inlining (but also with fixed regs and so, without lto, as you are suggesting)? On gcc-4.3.3, I had "combine" option for such cases. Is it completely impossible in gcc 4.6.2? --- With best regards, Konstantin On Tue, Feb 7, 2012 at 4:37 PM, Richard Guenther <richard.guent...@gmail.com> wrote: > On Tue, Feb 7, 2012 at 1:26 PM, Konstantin Vladimirov > <konstantin.vladimi...@gmail.com> wrote: >> Hi, >> >> Consider some project, consisting of files: a.c, b.c, d.c and e.c >> >> Compiler is gcc 4.6.2 >> >> Files a.c and b.c are performance bottlenecks and requires heavy >> cross-module inline, so must be compiled with -flto option >> Files d.c and e.c is preffered to be compiled with lto option too, but >> they are of special usage, and requires some registers (say r9 and >> r10) to be fixed (with -ffixed-<reg> option) during compilation. >> >> All these files forms single binary. >> >> Now the problem is: if I compiling >> >> gcc $OPTIONS -flto a.c -o a.o >> gcc $OPTIONS -flto b.c -o b.o >> gcc $OPTIONS -ffixed-r9 -ffixed-r10 -flto d.c -o d.o >> gcc $OPTIONS -ffixed-r9 -ffixed-r10 -flto e.c -o d.o >> >> and then >> >> gcc $OPTIONS -flto a.o b.o d.o e.o -o a.out >> >> Then registers inside d.o and e.o are being reallocated at link time, >> and r9, r10 are used in the d.o and e.o parts in the resulted binary. >> Also I can not specify fixed regs to final link, because this will fix >> registers in a.o and b.o parts, that will affect performance. >> >> The best way for me seems to somehow separately link pseudo-object >> files a.o and b.o with -flto to simple object (say x.o), and then link >> e.o and d.o to single, say, y.o, and then call linker to finally link >> binary without cross-module optimizations. But I can not find >> possibility to do it, and I doubt if this at all conforms with lto >> ideology. > > That's indeed the way to go, but you don't need anything fancy like > partial linking. > > gcc $OPTIONS -flto a.c -o a.o > gcc $OPTIONS -flto b.c -o b.o > gcc $OPTIONS -ffixed-r9 -ffixed-r10 d.c -o d.o > gcc $OPTIONS -ffixed-r9 -ffixed-r10 e.c -o e.o > gcc $OPTIONS -flto a.o b.o d.o e.o > > should do it automatically. Just make sure to not compile d.o and e.o > with -flto. > > Richard. > >> So, I want to perform link-time optimizations between a.o and b.o, and >> don't want them between (a.o or b.o) and (d.o or e.o) >> >> How can I approach this? >> >> Thanks in advance for everyone, who will help. >> >> --- >> With best regards, Konstantin
