[Bug middle-end/15147] New: A REG rtx can be smaller if register renaming is rewritten such that ORIGIAN_REGNO can go away

[steven at gcc dot gnu dot org]

We only need ORIGINAL_REGNO for register renaming, so that a REG rtx is now of
format "i00" where it could be "i0" if the ORIGINAL_REGNO would go away.

If there is a smarter way to achieve the same thing (e.g. mark regs that have
been renamed and use a side lookup table), this may save us a pointer per reg,
which may be a significant amount of memory.

Given that register renaming as-is is known to be both buggy and slow, perhaps
we should just throw away the existing code for now and rewrite the pass...

-- 
           Summary: A REG rtx can be smaller if register renaming is
                    rewritten such that ORIGIAN_REGNO can go away
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Keywords: memory-hog
          Severity: enhancement
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: steven at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15147