[Bug middle-end/36177] [4.4 Regression] g++.dg/opt/pr23714.C ICEs with 135041 -> 135057

["steven at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #4 from steven at gcc dot gnu dot org  2008-05-08 22:27 -------
So I was looking at an older revision of dce.c.  There is this new check before
the !NONJUMP_INSN_P check now:

  /* We can delete dead const or pure calls as long as they do not
     infinite loop and are not sibling calls.  The problem with
     sibling calls is that it is hard to see the result.  */
  if (CALL_P (insn) 
      && (!SIBLING_CALL_P (insn))
      && (RTL_CONST_OR_PURE_CALL_P (insn)
          && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)))
    return true;

CALL_P is obviously true for this insn, and so is !SIBLING_CALL_P (there is no
call_insn/j).  The "/u" flag means that RTL_CONST_OR_PURE_CALL_P is true for
the insn.  The "/c" flag is clear, so RTL_LOOPING_CONST_OR_PURE_CALL_P is
false.

I don't know where RTL_CONST_OR_PURE_CALL_P is set.  But that's where I would
look.

[ I see that RTL_LOOPING_CONST_OR_PURE_CALL_P is not documented.  Kenny, can
you please take care of that (and probably other necessary document updates
following your patch)? ]


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36177