[Bug target/15718] [3.3 regression][alpha] ICE in subreg_hard_regno, at emit-rtl.c:928

["gdr at integrable-solutions dot net" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From gdr at integrable-solutions dot net  2004-05-29 06:39 -------
Subject: Re:  [3.3 regression][alpha] ICE in subreg_hard_regno, at emit-rtl.c:928

"jbuck at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes:

| Sorry, WONTFIX is not acceptable for a bug that was not present in 3.3.3 and is
| present in 3.3.4.  This is an ICE-on-valid-code regression that affects two
| rather simple cases already in our testsuite.  The apparent effect would be that
| Alpha users would have to avoid the use of complex numbers in Fortran programs.

I think that is too far an excessive statement.  As I pointed out in
another message, this coerner case is pretty much a known issue.
We've been around this in V3 by special casing.  What is happening, I
remember correctly, is that passing/returning complex numbers in
register is pretty much broken on alpha and can be fixed only by
changing the ABI. They cn still be used -- one just has to pas them 
by reference.  (The way we got around that in C++, was to make the
resulting complex<> class a non-trivial POD so that the compiler was
forced to  put them always in stack)

    http://gcc.gnu.org/ml/gcc-bugs/2000-03/msg01215.html
    http://sources.redhat.com/ml/libc-alpha/2004-01/msg00121.html

The problem has been there for long time awaiting (some) complex
programs to hit it.

|  To be fair, I can't assess what proportion of programs would be affected.
| 
| WONTFIX is basically saying "Alpha Fortran users should consider 3.3.4 unusable".
| 
| I appreciate that the fix that you were considering would require an ABI change
| and therefore can't be backported.  But this bug was not present before, so it

>From my understanding, the bug was there, just hidden, awaiting to be hit.

-- Gaby


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15718