lto pseudo-object files and fixed registers

[Konstantin Vladimirov <konstantin dot vladimirov at gmail dot com>]

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.

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