D on lm32-CPU: string argument on stack instead of register
j at j.nl
Fri Jul 31 15:30:10 UTC 2020
On Friday, 31 July 2020 at 10:22:20 UTC, Michael Reese wrote:
> My question: Is there a way I can tell the D compiler to use
> registers instead of stack for string arguments, or any other
> trick to reduce code size while maintaining an ideomatic D
A D string is a "slice", which is a struct (pointer + length).
Depending on the function call ABI, structs are passed in
registers or on the stack.
On x86, the D calling convention is to put small POD structs in
registers, similar to the C++ calling convention.
I don't know whether GDC has attributes to change the calling
convention of functions (besides extern(C/C++/Windows/etc.)), but
that's where you'd need to look.
Otherwise, file a bug with GDC. Slice arguments are common enough
to require enregistering them in the D calling convention on your
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