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

[Joe Buck]

On Thu, May 15, 2003 at 12:49:23AM +0200, Gabriel Dos Reis wrote:
> | > Would that loss of performance be related to ABI issues (in single
> | > element case)? 
> | 
> | No, it has to do with premature commitment of structs to memory.
> 
> Aha, thanks.  I thought that since some ABIs seem to require that every
> structure ought to be returned in memory, GCC (on those targets)
> cannot optimize away the abstraction penatly in the case a structure
> contains a single or two scalar(s). 

ABI rules don't affect what can be done with local (after inlining) structs
and classes, and that's where GCC is getting killed by, say, KAI's compiler.