[PATCH] Simplify builtins when result ignored (take 2)

[Jan Hubicka]

> 
> The following patch implements Zack's suggestion that the tests
> to avoid expanding "pure" and "const" built-in functions when
> the result is ignored should be done generically rather than on
> a builtin-by-builtin basis.
> 
> The following patch also catches the case where expand_builtin
> was being called with ignore=1 and target=0, but we weren't
> passing target=const0_rtx to the low-level expand_builtin_foo
> functions.
> 
> This revised patch has been tested on i686-pc-linux-gnu with a
> complete "make bootstrap", all languages except Ada and treelang,
> and regression checked with a top-level "make -k check" with no
> new regressions.
> 
> Ok for mainline?

Can't this be done for the calls in general (ie in expand_call)?

Honza