[llvm-commits] [llvm] r111850 - /llvm/trunk/lib/Target/ARM/ARMFastISel.cpp

[Eric Christopher]

On Aug 23, 2010, at 4:05 PM, Jim Grosbach wrote:

> 
> I suspect x86 is doing things like "always push all callee saved regs whether we used them or not" and always referencing from the frame pointer. That way it can always have a fixed offset from EBP and not worry about how many spills there are. I.e., it's doing custom PEI that allows much stronger assumptions about frame layout much earlier in the compilation. ARM could do similar things if the full-force PEI is too much of a performance hit. In which case, you'd want to use a different "get me the reg+offset info" for frame index references, as the current one looks at the frame info populated by PEI to determine that stuff.
> 
> My naive thought is to give the "real" PEI a shot to get things up and running, and then revisit that if it ends up being too much of a compile-time hit.

It's a good thought, I'll see what I can do :)

-eric