Bad codegen for ARM (and maybe others) when optimizing

[Kai Nacke via digitalmars-d-ldc]

Hi Dan!

On Friday, 6 February 2015 at 15:03:11 UTC, Dan Olson wrote:
> I think an ARM specific abi class is the right solution.  On a 
> whim, I tried one small change in abi.cpp
>
>     bool passByVal(Type* t)
>     {
>         // was
>         // return t->toBasetype()->ty == Tstruct;
>         return false;
>     }
>
> This gets rid of LLVM byval attribute and fixes this codegen 
> problem.  The generated instructions are similar to clang.  The 
> parameter is not an array like clang, it is the IR struct type 
> as a value, but it works.
>
> "%badopt.A"  instead of "%badopt.A* byval"
>
> Another thing I noticed about clang is that structs that fit in 
> 32-bits are returned directly in r0 instead of an sret 
> parameter.  There may be more, I need to study clang.

We can add an ARM specific abi class. Could you just provide your 
change as a pull request?
(I tried similar things in the past with the PPC backend. But at 
some point it was easier to fix LLVM. :-)

Regards,
Kai