two-element struct performance (was: strict-aliasing and typedefs)

[Richard Henderson]

On Thu, Feb 19, 2004 at 04:16:59PM -0700, law@redhat.com wrote:
> Doing better would require that the tree-ssa optimizers know about ABI
> details for passing parameters and return values -- if it had that knowledge
> then it would know that the caller will provide a suitable memory location
> for the return value and we could use it directly instead of first building
> the return value in T.6.

I don't know that tree-ssa knowledge of ABI details is quite necessary.

I think if we'd performed the computation into a RESULT_DECL rather than
into a VAR_DECL temporary, that would effectively do the job since we
can arrange for the RESULT_DECL to have rtl appropriate for a caller
provided memory location.


r~