birthpoints in rtl.

[Alexandre Oliva]

On Feb 27, 2008, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:

> The appeal for birthpoints is that unlike the abortive attempt in
> the past to add SSA to RTL, adding a noop moves does not really mess
> up anything.

IIRC, when people tried to do RTL SSA, the problem was with match_dups
in IN/OUT operands.

I think there's a relatively simple way to deal with this: an RTL form
that takes two operands, one for input, one for output, that would
represent the SSA names for input and output that must be coalesced to
the same variable when going out of SSA, say, during register
allocation.

Has something like this been considered before?

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
FSF Latin America Board Member         http://www.fsfla.org/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}