[Bug optimization/13985] [3.4/3.5 regression] ICE in gcc.c-torture/compile/930621-1.c

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

------- Additional Comments From ebotcazou at gcc dot gnu dot org  2004-04-20 09:24 -------
> I don't understand?  The comment as I formulated it assumes very little
> knowledge about our implementation (basically just that loop->father is
> superloop of the loop).  It only refers to the well-known definition of
> the natural loop.

That loop->father is a superloop of the loop is hardly problematic indeed :-)

But "all paths from the LOOP to LOOP->FATHER's latch" implicitly assumes that
you know the criterion based on which the loop are sorted and, given the lack of
 hurry to approve the patch :-), I don't think everyone is as familiar as you
with this stuff.

> I was sort of thinking about extending the comments at the
> fix_{bb,loop}_placement in a similar way (i.e. to explain not only what
> they are doing, but also why it is so).

IMHO such a general comment would rather belong in the class of file-scope
comments (that cfgloopmanip.c lacks btw).  As I said, the comment of
fix_bb_placement is nice because it matches the level of abstraction of the
function itself (which doesn't deal with latches).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13985