[LLVMdev] Any reason why fastcc on x86 shouldn't use ECX as a return register?

Duncan Sands baldrick at free.fr
Mon Jan 4 23:22:22 PST 2010

Hi Kenneth,

> Now that we can safely return arbitrarily large structs on x86, it
> seems to me that fastcc, which doesn't have to conform to any
> preexisting ABI, should use ECX as well as EAX and EDX for returning
> {i32,i32,i32} rather than use sret-demotion.

the x86 trampoline lowering code would need tweaking to check that the ECX
register was available for it.



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