Re: hppa-linux regressions and 3.2.2 release

["John David Anglin" <dave at hiauly1 dot hia dot nrc dot ca>]

> > I recall Eric Botcazou's patch were being reviewed this week but my
> > impression was that the discussion got stalled after Joe Buck asked
> > whether the patch was just papering over a fundamental problem.  I'll
> > recheck what the final answer is and incorporate the patch if
> > appropriate.
> 
> Jan thinks that the patch might be valid.

Jan wrote:
> No, I guess the fix is correct - it is merely looking for loop preheader
> and should crash when there is empty block at the end of insn stream.

I note that in my examination of the problem I found an empty block at
the end of the insn stream.  Thus, I can confirm that this is the problem
that Eric's patch addresses.

As the prior loop terminates if insn is null, it is obvious that a null
check of some kind is needed in the following instruction which will cause a
crash if insn is null.  The testcase is simply an example of a situation
where a null value can occur.

As to Joe's point, this doesn't happen on 3.3 because there isn't an
empty block at the end of the insn stream.  There is always a code_label
in the insn stream.  As a result, the preceding loop doesn't ever reach
the end of the insn stream.  If the presence of a code label is guaranteed,
then the null check in the preceeding for loop can probably be removed.
I don't know why 3.2 and 3.3 differ in this respect but I seem to
recall problems with label usage counts at one time.

The PA-RISC assembly output with the patch ok.

I have completed a bootstrap on hppa2.0w-hp-hpux11.11 with Eric's patch.
The results are posted here

<http://gcc.gnu.org/ml/gcc-testresults/2003-02/msg00117.html>.

There are no regressions.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)

PS: Eric, your analysis of PR9492 was awesome.