Fwd: [Lto-team] Fwd: [tuples] reduced testcase of the libjava build failure

[Doug Kwan (關振德)]

---------- Forwarded message ----------
From: Doug Kwan (關振德) <dougkwan@google.com>
Date: 2008/5/1
Subject: Re: [Lto-team] Fwd: [tuples] reduced testcase of the libjava
build failure
To: Rafael Espindola <espindola@google.com>
副本： lto-team <lto-team@google.com>


The test case fails because we find a basic block with 3 out-going
 edges in gimple_verify_flow_info:

            if (!true_edge
                || !false_edge
                || !(true_edge->flags & EDGE_TRUE_VALUE)
                || !(false_edge->flags & EDGE_FALSE_VALUE)
                || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
                || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
                || EDGE_COUNT (bb->succs) >= 3)
              {
                error ("wrong outgoing edge flags at end of bb %d",
                       bb->index);
                err = 1;
              }

 The offend bb ends with a statement like

    if (a <= b) ...

 where a & b are floating point values.  With -fnon-call-exceptions,
 floating point comparison is considered trapping so it make sense for
 the bb to have a third exception edge.

 The test-case does not fail with TOT compiled with --enable-checking.
 I looked at that and found that tree_could_trap_p is broken in two
 levels.  First, it does not handle COND_EXPR specially. It just looked
 at the TREE_TYPE for COND_EXPR (void_type_node) to compute
 fp_operation.  I added a code to recurse with the condition in
 COND_EXPR and it was still broken.  The reason is that it uses the
 type of a comparison tree (boolean_type_node) to compute the flag
 fp_operation.  Finally I fixed that and I got the same ICE as in the
 tuple branch.

 I guess --enable-checking=yes and -fnon-call-exceptions do not got
 together to make the bugs detectable.  I will try relaxing the test in
 gimple_verify_flow_info to allow for a third exception edge and see
 how things goes.

 -Doug



 2008/5/1 Rafael Espindola <espindola@google.com>:


> ---------- Forwarded message ----------
 >  From: Rafael Espindola <espindola@google.com>
 >  Date: 2008/5/1
 >  Subject: [tuples] reduced testcase of the libjava build failure
 >  To: gcc-patches <gcc-patches@gcc.gnu.org>
 >
 >
 >  I will try to fix it tomorrow, but it would be great if someone could
 >   to give it a try today :-)
 >
 >   To reproduce:
 >
 >   ./cc1plus testcase.ii -O1   -fnon-call-exceptions -quiet
 >
 >   testcase.ii: In function 'void run()':
 >   testcase.ii:8: error: wrong outgoing edge flags at end of bb 2
 >   testcase.ii:8: internal compiler error: verify_flow_info failed
 >
 >   Cheers,
 >   --
 >   Rafael Avila de Espindola
 >
 >   Google Ireland Ltd.
 >   Gordon House
 >   Barrow Street
 >   Dublin 4
 >   Ireland
 >
 >   Registered in Dublin, Ireland
 >   Registration Number: 368047
 >
 >
 >
 >  --
 >  Rafael Avila de Espindola
 >
 >  Google Ireland Ltd.
 >  Gordon House
 >  Barrow Street
 >  Dublin 4
 >  Ireland
 >
 >  Registered in Dublin, Ireland
 >  Registration Number: 368047
 >


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