Re: [tree-ssa] Speedup alias analysis [patch]

[law at redhat dot com]

In message <1056475283.21707.214.camel@p4>, Andrew MacLeod writes:
 >On Tue, 2003-06-24 at 11:52, law@redhat.com wrote:
 >> In message <1056462218.4062.79.camel@frodo.toronto.redhat.com>, Diego Novil
 >lo 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_EX
 >PR,
 >> 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.
I wasn't sure.  If indeed this is how things work, then we should be in
good shape.

jeff