[Bug tree-optimization/30604] New: Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[Bug tree-optimization/30604] New: Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[mark at gcc dot gnu dot org]

Compiling the attached class file with -O results is:

$ gcj -findirect-dispatch -O -c CppTreeParser.class 

Unable to coalesce ssa_names 7  and 8642  which are marked as MUST COALESCE.
_t_7(ab) and  _t_8642(ab)
frysk/expr/CppTreeParser.java: In class 'frysk.expr.CppTreeParser':
frysk/expr/CppTreeParser.java: In method
'frysk.expr.CppTreeParser.expr(antlr.collections.AST)':
frysk/expr/CppTreeParser.java:0: internal compiler error: SSA corruption

This only happens with -O. It compiles fine with 4.1.1.


-- 
           Summary: Unable to coalesce ssa_names <x>  and <y>  which are
                    marked as MUST COALESCE
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: mark at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[mark at gcc dot gnu dot org]

------- Comment #1 from mark at gcc dot gnu dot org  2007-01-26 20:35 -------
Created an attachment (id=12965)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12965&action=view)
Generated .class byte code file

This is a generated .class file. It has been generated by gcj -C
CppTreeParser.java (which uses ecj). The original .java source file was
generated by antlr (and a little sed script) from cpp.g. Original available
from the frysk project
http://sourceware.org/cgi-bin/cvsweb.cgi/frysk-core/frysk/expr/cpp.g?cvsroot=frysk

Other intermediary files available on request of course.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2007-01-28 19:26 -------
I can reproduce this ICE but it is very hard to see where the problem is with
such a long testcase.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[aph at gcc dot gnu dot org]

-- 

aph at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |aph at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-02-01 15:01:36
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[mark at gcc dot gnu dot org]

------- Comment #3 from mark at gcc dot gnu dot org  2007-02-01 15:22 -------
Created an attachment (id=12994)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12994&action=view)
Generated .java source file


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[tbm at cyrius dot com]

------- Comment #4 from tbm at cyrius dot com  2007-03-08 09:03 -------
I have a fairly small C++ testcase for what appears to be the same issue:

(sid)3604:tbm@em64t: ~] g++ -c firebird2-nav.cc
(sid)3605:tbm@em64t: ~] g++ -c -O firebird2-nav.cc

Unable to coalesce ssa_names 27  and 10  which are marked as MUST COALESCE.
result_27(ab) and  result_10(ab)
firebird2-nav.cc: In function 'BOOLEAN NAV_get_record(Rsb*, mfb*, RPB*,
RSE_GET_MODE)':
firebird2-nav.cc:235: internal compiler error: SSA corruption
Please submit a full bug report,


-- 

tbm at cyrius dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tbm at cyrius dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[tbm at cyrius dot com]

------- Comment #5 from tbm at cyrius dot com  2007-03-08 09:05 -------
Created an attachment (id=13167)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13167&action=view)
testcase


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[pinskia at gcc dot gnu dot org]

------- Comment #6 from pinskia at gcc dot gnu dot org  2007-03-08 12:34 -------
> I have a fairly small C++ testcase for what appears to be the same issue:

I think that issue is actually different as the SSA inliner came in after this
bug was filed so I filed this with a reduced testcase as PR 31081.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[amacleod at redhat dot com]

------- Comment #7 from amacleod at redhat dot com  2007-03-08 20:12 -------
Looking at the original testcase, the complaint is that _t_8232 and _t_3 are
both used in the PHI definition of _t_7.  (using mainline from march 5th)

ie,  _t_7(ab) = PHI <...., _t_8232, ... , _t_3, ...>

That definition occurs in BB2509.

Because its an abnormal edge, all three must be coalescable.

_t_8232 is defined in BB 2315, but _t_3 is live on entry and through this
block, meaning they have different values and are live at the same time, so
they cannot be coalesced

The listing looks OK after ccp2, but in the listing after the FRE pass _t_3
becomes live on entry to this block, and it wasn't before.

I can't really read the detailed output from FRE, but it does seem to have
replaced a bunch of expressions with _t_3, so that would appear to be the
culprit.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

Re: [Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[Daniel Berlin]

On 8 Mar 2007 20:12:16 -0000, amacleod at redhat dot com
<gcc-bugzilla@gcc.gnu.org> wrote:
>
>
> ------- Comment #7 from amacleod at redhat dot com  2007-03-08 20:12 -------
> Looking at the original testcase, the complaint is that _t_8232 and _t_3 are
> both used in the PHI definition of _t_7.  (using mainline from march 5th)
>
> ie,  _t_7(ab) = PHI <...., _t_8232, ... , _t_3, ...>
>

Uh, did you not put the (ab) next to the arguments, or do they really
not have SSA_NAME_OCCURS_IN_ABNORMAL_PHI set on them? (They should)

> I can't really read the detailed output from FRE, but it does seem to have
> replaced a bunch of expressions with _t_3, so that would appear to be the
> culprit.

It won't value number things with SSA_NAME_OCCURS_IN_ABNORMAL_PHI set,
so it should never eliminate anything with them.

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[amacleod at redhat dot com]

------- Comment #8 from amacleod at redhat dot com  2007-03-08 20:20 -------
-fno-tree-fre makes the test case compile, which is further indication FRE is
the problem.


-- 

amacleod at redhat dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dnovillo at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[dberlin at dberlin dot org]

------- Comment #9 from dberlin at gcc dot gnu dot org  2007-03-10 00:01 -------
Subject: Re:  Unable to coalesce ssa_names <x> and <y> which are marked as MUST
COALESCE

On 8 Mar 2007 20:12:16 -0000, amacleod at redhat dot com
<gcc-bugzilla@gcc.gnu.org> wrote:
>
>
> ------- Comment #7 from amacleod at redhat dot com  2007-03-08 20:12 -------
> Looking at the original testcase, the complaint is that _t_8232 and _t_3 are
> both used in the PHI definition of _t_7.  (using mainline from march 5th)
>
> ie,  _t_7(ab) = PHI <...., _t_8232, ... , _t_3, ...>
>

Uh, did you not put the (ab) next to the arguments, or do they really
not have SSA_NAME_OCCURS_IN_ABNORMAL_PHI set on them? (They should)

> I can't really read the detailed output from FRE, but it does seem to have
> replaced a bunch of expressions with _t_3, so that would appear to be the
> culprit.

It won't value number things with SSA_NAME_OCCURS_IN_ABNORMAL_PHI set,
so it should never eliminate anything with them.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[amacleod at redhat dot com]

------- Comment #10 from amacleod at redhat dot com  2007-03-12 13:33 -------
They do all have the (ab) next to them, I was just indicating that they all
occurred in a PHI together, and hence needed to be coalesced. I should have
been more precise.

Well, _t_3 definately does have the (ab) flag, and I don't know what all it
does do, but it does introduce the situation where we have overlapping abnormal
ssa-names which have to be coalesced.  

I see it does a bunch of replacements which include _t_3(ab), lines such as:
Replaced (struct  *) #ref#17#7_8338 with _t_3(ab) in #ref#17#7.2741_8343 =
(struct  *) #ref#17#7_8338;

(Just an example, not meant to be the erroneous replacement). So it is clearly
doing something with it.


-- 

amacleod at redhat dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |amacleod at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[amacleod at redhat dot com]

------- Comment #11 from amacleod at redhat dot com  2007-11-09 15:37 -------
OK, new investigation show that using the smaller testcase firebird2-nav.cc
shows the inliner is misbehaving. 

before inlining  (*041t.profile):

  # BLOCK 2 freq:10000
  # PRED: ENTRY [100.0%]  (fallthru,exec)
  D.2709_4 = request_3(D)->req_pool;
  D.2710_5 = (struct blk *) D.2709_4;
  D.2711_6 = request_3(D)->req_transaction;
  D.2712_10 = VIO_get (tdbb_7(D), rpb_8(D), rsb_9(D), D.2711_6, D.2710_5);
  # SUCC: 4 (ab,eh,exec) 3 [100.0%]  (fallthru,exec)

  # BLOCK 3 freq:10000
  # PRED: 2 [100.0%]  (fallthru,exec)
  result_12(ab) = (BOOLEAN) D.2712_10;
<...>
  BTR_key (tdbb_7(D), D.2719_20, D.2718_19, D.2717_18, &value, 0B);
  goto <bb 5>;
  # SUCC: 4 (ab,eh,exec) 5 [100.0%]  (fallthru,exec)

  # BLOCK 4
  # PRED: 2 (ab,eh,exec) 3 (ab,eh,exec)
  # result_1(ab) = PHI <result_11(ab)(2), result_12(ab)(3)>
<L0>:;
  <...>

 # BLOCK 5 freq:10000
  # PRED: 3 [100.0%]  (fallthru,exec) 4 [100.0%]  (fallthru,exec)
  # result_2 = PHI <result_12(ab)(3), result_1(ab)(4)>
  return result_2;
  # SUCC: EXIT [100.0%]



and after inlining (*046i.inline) we see:



<bb 2>:

<bb 7>:
  D.2882_11 = request_9(D)->req_pool;
  D.2883_12 = (struct blk *) D.2882_11;
  D.2884_13 = request_9(D)->req_transaction;
  D.2885_14 = VIO_get (tdbb_8(D), rpb_3(D), rsb_1(D), D.2884_13, D.2883_12);

<bb 3>:
  result_15(ab) = (BOOLEAN) D.2885_14;
<...>
  BTR_key (tdbb_8(D), D.2892_22, D.2891_21, D.2890_20, &value, 0B);
  goto <bb 5>;

  # result_24(ab) = PHI <result_10(ab)(7), result_15(ab)(3)>
<L4>:;
<...>

<bb 5>:
  # result_23 = PHI <result_15(ab)(3), result_24(ab)(4)>
  if (result_23 != 0)
    goto <bb 6>;
  else
    goto <bb 7>;

<bb 6>:
  return 1;



Basic block 7 is missing a PHI node which should merge result_23 and result_10.
 The result of this missing PHI should then be used in block 5 instead of
result_10.

The way it currently sits, result 10 is live through basic block 3, which makes
it conflict with result_15, and makes the abnormal edges uncoalescable.

Someone familiar with the inliner can probably fix this quickly. I took a quick
look but its a different world in there :-)


-- 

amacleod at redhat dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jh at suse dot cz


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[pinskia at gcc dot gnu dot org]

------- Comment #12 from pinskia at gcc dot gnu dot org  2007-11-09 18:27 -------
(In reply to comment #11)
> OK, new investigation show that using the smaller testcase firebird2-nav.cc
> shows the inliner is misbehaving. 

That smaller testcase is a different issue as explained in comment #6 and has
been filed under PR 31081 already.  


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[amacleod at redhat dot com]

------- Comment #13 from amacleod at redhat dot com  2007-11-09 18:40 -------
Then perhaps we should remove the attachment from this PR if it isn't
relevant...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[rguenth at gcc dot gnu dot org]

------- Comment #14 from rguenth at gcc dot gnu dot org  2008-02-15 12:55 -------
Eventually this is related to PR35164, so please re-check here once that is
fixed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |35164


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[dcb314 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

David Binderman <dcb314 at hotmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dcb314 at hotmail dot com

--- Comment #15 from David Binderman <dcb314 at hotmail dot com> ---
I've got a testcase from gcc trunk dated 20130605 that
can generate the same "Unable to coalesce" message.

Testcase available on request.

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[rguenther at suse dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

--- Comment #16 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 6 Jun 2013, dcb314 at hotmail dot com wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604
> 
> David Binderman <dcb314 at hotmail dot com> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                            |dcb314 at hotmail dot com
> 
> --- Comment #15 from David Binderman <dcb314 at hotmail dot com> ---
> I've got a testcase from gcc trunk dated 20130605 that
> can generate the same "Unable to coalesce" message.
> 
> Testcase available on request.

Can you open a new bugreport please?  It's very likely a different
reason than this one.

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

Arseny Solokha <asolokha at gmx dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |asolokha at gmx dot com

--- Comment #18 from Arseny Solokha <asolokha at gmx dot com> ---
Is this PR still relevant?

[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604

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

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

--- Comment #19 from Richard Biener <rguenth at gcc dot gnu.org> ---
no

*** This bug has been marked as a duplicate of bug 35164 ***