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Re: [patch] fix PR65048: check that jump-thread paths are still valid


On 02/13/15 16:50, Sebastian Pop wrote:
Hi,

the attached patch fixes PR65048 by checking before jump-threading that a path
to be threaded is still valid: as the testcase shows, there may be paths that
are not connected anymore because the cfg has changed in a previous jump-thread.

         PR tree-optimization/65048
         * tree-ssa-threadupdate.c (valid_jump_thread_path): New.
         (thread_through_all_blocks): Call valid_jump_thread_path.
         Remove invalid FSM jump-thread paths.

         * gcc.dg/tree-ssa/ssa-dom-thread-9.c: New.

The patch passed bootstrap and regression tests on x86_64-linux.
Ok for trunk?
These kinds of situations are normally pruned out in mark_threaded_blocks.

The dumps for the FSM threads are a bit sparse -- they don't show the entire path. That makes it much harder to see what's going on.

It also appears that FSM is  registering lots of duplicate paths.

grep Registering j*.dom1 | grep -v PHI | sort
  Registering FSM jump thread: (10, 12) incoming edge;  (15, 3) nocopy;
  Registering FSM jump thread: (11, 12) incoming edge;  (15, 16) nocopy;
  Registering FSM jump thread: (16, 3) incoming edge;  (15, 16) nocopy;
  Registering FSM jump thread: (5, 10) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (5, 10) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (5, 11) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (5, 11) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (6, 14) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (6, 14) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (6, 3) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (6, 3) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (7, 10) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (7, 10) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (7, 11) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (7, 11) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (8, 14) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (8, 14) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (8, 3) incoming edge;  (13, 14) nocopy;
  Registering FSM jump thread: (8, 3) incoming edge;  (13, 14) nocopy;


Something seems wrong there.


Anyway, so what node precisely is not connected? Is that happening as a result of the duplicated jump threads or is it something else?

Jeff


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