[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

--- Comment #5 from Matt Hargett <matt at use dot net> 2010-11-17 21:43:13 UTC ---
GCC 4.6.0.20101116 still shows this problem, but also introduces new problems
on top of it. Let me know if I should file a new bug for the regressions.
Either way, is there any update on this enhancement getting into 4.6? Thanks!

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[hubicka at ucw dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

--- Comment #6 from Jan Hubicka <hubicka at ucw dot cz> 2010-11-17 23:01:58 UTC ---
The problem with not recomputing address taken flag is solved. The testcase
still
failed to iling because of type mismatch (i.e. one() instead of one(void)).
You probably could fix your sources there to work around this.

Whether this will be fixed is Richard's call (we need to make constant
propagation to take
away the cast I guess).  Technically this is regression to 4.3.

Yes, please go ahead and report the new problems so there is enough time to fix
them.

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

--- Comment #7 from Matt Hargett <matt at use dot net> 2011-01-11 23:44:22 UTC ---
Is the last remaining issue with this test case fixed by the patch for PR46076?

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[hubicka at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

Jan Hubicka <hubicka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|hubicka at gcc dot gnu.org  |mjambor at suse dot cz

--- Comment #8 from Jan Hubicka <hubicka at gcc dot gnu.org> 2011-01-12 10:43:13 UTC ---
Hi,
the last problem was solved, sadly it is not last.  We still keep the functions
around because we don't see that indirect inlining effectively removes the
reference.  
Martin probably should look into this for 4.7.

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

--- Comment #9 from Matt Hargett <matt at use dot net> 2011-03-16 21:43:56 UTC ---
Now that 4.7 stage 1 is open, let me know if there's anything else I can
reasonably provide to provide examples, testing, etc. Thanks!

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

Matt Hargett <matt at use dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #10 from Matt Hargett <matt at use dot net> 2011-04-12 18:29:28 UTC ---
I just tested and it looks like this is actually fixed in 4.6 for this specific
example and another one I had.

I'm still seeing remnants with C++, but I'll file a separate bug for that.

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

Matt Hargett <matt at use dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |

--- Comment #11 from Matt Hargett <matt at use dot net> 2013-01-17 00:09:32 UTC ---
Still a problem in latest 4.7, google/4.7, and trunk (4.8).

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[hubicka at ucw dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

--- Comment #12 from Jan Hubicka <hubicka at ucw dot cz> 2013-01-17 10:27:10 UTC ---
> Still a problem in latest 4.7, google/4.7, and trunk (4.8).
So 4.6 was working but 4.7 isn't?

Re: [Bug middle-end/42371] dead code not eliminated during folding with whole-program

[Jan Hubicka]

> Still a problem in latest 4.7, google/4.7, and trunk (4.8).
So 4.6 was working but 4.7 isn't?

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

--- Comment #13 from Matt Hargett <matt at use dot net> 2013-01-17 18:28:18 UTC ---
No. 

4.6 doesn't devirt (at -O2 or -O3) and therefore the DCE isn't relevant.

At both -O2 and -O3, with and without -fwhole-program, both with and without
adjustin declarations one()/two() to one(void)/two(void):

4.7 and google/4.7 both devirt correctly but the DCE on the function bodies
doesn't happen.

4.8 also devirts correctly, but the DCE on the function bodies doesn't happen.

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |NEW

--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-18 10:25:04 UTC ---
Clearing of address-taken does not work:

two/1 (two) @0x7fafc0e29818
  Type: function
  Visibility: prevailing_def_ironly
  Address is taken.
  References:
  Referring: main/3 (addr)
  Availability: available
  Function flags: analyzed body finalized
  Called by:
  Calls:

that is, we do not re-compute address-taken after IPA inline transform stage
and thus do not reclaim indirectly inlined functions that we no longer need.

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[hubicka at ucw dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

--- Comment #15 from Jan Hubicka <hubicka at ucw dot cz> 2013-01-19 21:48:12 UTC ---
> Clearing of address-taken does not work:
> 
> two/1 (two) @0x7fafc0e29818
>   Type: function
>   Visibility: prevailing_def_ironly
>   Address is taken.
>   References:
>   Referring: main/3 (addr)
>   Availability: available
>   Function flags: analyzed body finalized
>   Called by:
>   Calls:
> 
> that is, we do not re-compute address-taken after IPA inline transform stage
> and thus do not reclaim indirectly inlined functions that we no longer need.

We can't recompute here because inlining transform happens during the final
compilation stage, so the functions are already beging output to the assembly.

IPA-prop needs to realize that indirect inlining is going to optimize out the
address operation and remove the reference.  I assume this is not too hard to
implement - we only need to record when the function parameter is used _only_
of the stuff represented by jump functions and indirect edges. I was trying
to convince Martin to implement this for a while :)

Virtual functions are ven harder than indirect calls since we need to figure
out
the vtable will become unreachable at the IPA stage.

Honza

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[jamborm at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |http://gcc.gnu.org/ml/gcc-p
                   |                            |atches/2013-04/msg01032.htm
                   |                            |l
                 CC|                            |jamborm at gcc dot gnu.org

--- Comment #16 from Martin Jambor <jamborm at gcc dot gnu.org> 2013-04-17 15:58:17 UTC ---
I have submitted a patch to address this issue:

http://gcc.gnu.org/ml/gcc-patches/2013-04/msg01032.html

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[jamborm at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #17 from Martin Jambor <jamborm at gcc dot gnu.org> ---
Author: jamborm
Date: Mon May 13 10:16:09 2013
New Revision: 198821

URL: http://gcc.gnu.org/viewcvs?rev=198821&root=gcc&view=rev
Log:
2013-05-13  Martin Jambor  <mjambor@suse.cz>

    PR middle-end/42371
    * ipa-prop.h (IPA_UNDESCRIBED_USE): New macro.
    (ipa_constant_data): New type.
    (ipa_jump_func): Use ipa_constant_data to hold information about
    constant jump functions.
    (ipa_get_jf_constant): Adjust to jump function type changes.
    (ipa_get_jf_constant_rdesc): New function.
    (ipa_param_descriptor): New field controlled_uses.
    (ipa_get_controlled_uses): New function.
    (ipa_set_controlled_uses): Likewise.
    * ipa-ref.h (ipa_find_reference): Declare.
    * ipa-prop.c (ipa_cst_ref_desc): New type.
    (ipa_print_node_jump_functions_for_edge): Adjust for jump function type
    changes.
    (ipa_set_jf_constant): Likewise.  Also create reference descriptions.
    New parameter cs.  Adjust all callers.
    (ipa_analyze_params_uses): Detect uncontrolled and controlled uses.
    (remove_described_reference): New function.
    (jfunc_rdesc_usable): Likewise.
    (try_make_edge_direct_simple_call): Decrement controlled use count,
    attempt to remove reference if it hits zero.
    (combine_controlled_uses_counters): New function.
    (propagate_controlled_uses): Likewise.
    (ipa_propagate_indirect_call_infos): Call propagate_controlled_uses.
    (ipa_edge_duplication_hook): Duplicate reference descriptions.
    (ipa_print_node_params): Print described use counter.
    (ipa_write_jump_function): Adjust to jump function type changes.
    (ipa_read_jump_function): New parameter CS, pass it to
    ipa_set_jf_constant.  Adjust caller.
    (ipa_write_node_info): Stream controlled use count
    (ipa_read_node_info): Likewise.
    * cgraph.c (cgraph_mark_address_taken_node): Bail out instead of
    asserting.
    * ipa-cp.c (ipcp_discover_new_direct_edges): Decrement controlled use
    count.  Remove cloning-added reference if it reaches zero.
    * ipa-ref.c (ipa_find_reference): New function.

testsuite/
    * gcc.dg/ipa/remref-0.c: New test.
    * gcc.dg/ipa/remref-1a.c: Likewise.
    * gcc.dg/ipa/remref-1b.c: Likewise.
    * gcc.dg/ipa/remref-2a.c: Likewise.
    * gcc.dg/ipa/remref-2b.c: Likewise.


Added:
    trunk/gcc/testsuite/gcc.dg/ipa/remref-0.c
    trunk/gcc/testsuite/gcc.dg/ipa/remref-1a.c
    trunk/gcc/testsuite/gcc.dg/ipa/remref-1b.c
    trunk/gcc/testsuite/gcc.dg/ipa/remref-2a.c
    trunk/gcc/testsuite/gcc.dg/ipa/remref-2b.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cgraph.c
    trunk/gcc/ipa-cp.c
    trunk/gcc/ipa-prop.c
    trunk/gcc/ipa-prop.h
    trunk/gcc/ipa-ref.c
    trunk/gcc/ipa-ref.h
    trunk/gcc/testsuite/ChangeLog

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[matt at use dot net]

------- Comment #4 from matt at use dot net  2010-06-07 19:46 -------
Let me know when this is implemented on trunk (preferrably by marking this
report as resolved) and I'll test my proprietary test cases here.

Thanks!


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[hubicka at gcc dot gnu dot org]

------- Comment #3 from hubicka at gcc dot gnu dot org  2010-01-22 19:11 -------
really an enhancement rather than bug.


-- 

hubicka at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
   Last reconfirmed|2010-01-22 19:09:51         |2010-01-22 19:11:10
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[hubicka at gcc dot gnu dot org]

------- Comment #2 from hubicka at gcc dot gnu dot org  2010-01-22 19:09 -------
Note that testcase mises "static" in front of one/two.  This is something I
plan to implement for next release. Last release has some preparation work for
it, but at the moment we don't really build may edges nor other datastructures
related with indirect calls.

Honza


-- 

hubicka at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |hubicka at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-12-15 13:38:42         |2010-01-22 19:09:51
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371

[Bug middle-end/42371] dead code not eliminated during folding with whole-program

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2009-12-15 13:38 -------
This is because we never re-compute the address-taken flag of functions.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |missed-optimization
   Last reconfirmed|0000-00-00 00:00:00         |2009-12-15 13:38:42
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42371