birthpoints in rtl.

[Alexandre Oliva]

On Mar  4, 2008, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:

> Richard Sandiford wrote:
>> If we went for an explicit move, I assume we would either have to
>> (a) discount hard regs that can't be moved, (b) force backends to
>> allow all no-op moves or (c) circumvent the backend somehow.

> From my point of view, this is a killer argument that if we want to
> build fuds/birthpoints for all regs, the info must be on the side.

Nah.  It can't be too hard to implicitly insert a

(set (match_operand 0 "anything_goes_p" "X") (match_dup 0))

pattern in every back end, even behind the scenes.

We might as well do this for USEs, CLOBBERs, ASMs (and DEBUG_INSNs),
and phase out some of the special treatment they get at various places
for not being recognizable.

-- 
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}