[tree-ssa] Speedup alias analysis [patch]

[Andrew MacLeod]

On Tue, 2003-06-24 at 11:52, law@redhat.com wrote:
> In message <1056462218.4062.79.camel@frodo.toronto.redhat.com>, Diego Novillo w
> rites:
>  >The only unaliased virtual ops are non-scalar data references.  Or you
>  >mean a must-alias pass?  In the first case we need a scalarizer of some
>  >kind.  In the second one, we'd prove that 'p' always points to 'a' and
>  >replace every reference to '*p' with 'a' directly.
> BTW, I was pondering this a little recently.  One of the issues that we'll
> have to deal with is that if we replace *p with a on the LHS of a MODIFY_EXPR,
> then we'll need to call back into the SSA builder as we've just added a
> definition of "a".  Nothing terrible, but it's worth remembering.
> 
Isn't there already an 'a' that is a virtual DEF tho? We can just
replace the LHS with the virtual def version. 

#  a_4 = VDEF <a_2>
*p_3 = 10;

becomes
  a_4 = 10;

and all the VUSEs of a_4 becomes real uses.

Andrew

Andrew