[llvm-commits] [ARM] Extra frame for non-VA byval parameter

[Stepan Dyatkovskiy]

> I think it makes sense to unify the two stack objects, but should we increase the size of the first FixedStack to the entire parameter?
I think we should allocate size for entire parameter even if its 
contents was splitted onto regs and mem. Main point here is to set SP 
offset properly.
ARMTargetLowering::LowerFormalArguments should be fixed in severl place 
to make it working properly. I'll present a new patch tomorrow, I hope.

Try to run next example with command
llc example.ll -mtriple=armv7-none-linux-gnueabi explode-stack.ll -o -

%struct_t = type { double, double, double }

declare void @f(i32);

define void @explode(i32 %n0, %struct_t* byval %s0, %struct_t* byval 
%s1, %struct_t* byval %s2, %struct_t* byval %sN ) {
entry:
   call void (i32)* @f(i32 %n0)
   ret void
}

You can see a lot of spam then ) Since byval regs are not reserved 
actually for fixed byval params. So stack frame for these regs allocated 
again and again, with the same offset though :-)

-Stepan







> Also I am not sure whether it will affect the varargs since varargs and byval share the same code.