2011/11/30 Ian Lance Taylor <iant@xxxxxxxxxx>: > Aurelien Buhrig <aurelien.buhrig.gcc@xxxxxxxxx> writes: > >> I'm trying to optimize our target ABI, and I'm wondering what is the >> best strategy to define it. >> Is there a paper, or any hint, dealing with this topic ? >> For instance, >> - which ratio between call-used-reg vs "static regs" >> - which ratio between arg regs vs call-used-reg >> - what should be return regs >> - ... >> I guess this problem is very target dependent, but there are maybe >> general ideas about this. > > I don't know of any papers on this topic. > > There are several things that feed into this, including: > > * The relative cost of saving registers on the stack. > > * How orthogonal your register set is--e.g., are there any registers > with special purposes in the ISA? Are there different register > classes that hold different types of values? Are there any > restrictions on which registers can be used in a memory address? > > * How many registers you have overall. > > * What kind of code you are most interested in optimizing. E.g., image > processing code tends to lead to functions with lots of loops with > lots of loop local variables that benefit from being in registers. > > Ian This pb is indeed highly hardware and application dependent. I will experiment to see what is the best... Thanks for your help, Aurélien
