[Bug tree-optimization/26197] New: [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[Bug tree-optimization/26197] New: [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[reichelt at gcc dot gnu dot org]

The following testcase triggers an ICE when compiled with
"-O2 -ftree-vectorize" on x86_64-unknown-linux-gnu (mainline):

=====================================================
struct A
{
  int* x[2];
  A() { for (int** p=x; p<x+2; ++p) *p = 0; }
};

struct B
{
  char c;
  A a0, a1, a2, a3, *p;

  B() {}
  B(const B& b) : c(), a0(b.a0), p(b.p) {}
  ~B() { delete p; }
};

inline void foo(const B& b) { new B(b); }

void bar()
{
  foo(B());
  foo(B());
}
=====================================================

bug.cc: In function 'void bar()':
bug.cc:19: internal compiler error: tree check: expected ssa_name, have
struct_field_tag in is_old_name, at tree-into-ssa.c:466
Please submit a full bug report, [etc.]

This is similar to PR 26169, but hasn't been fixed yet.


-- 
           Summary: [4.2 regression] ICE in is_old_name, at tree-into-
                    ssa.c:466
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code, monitored
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: reichelt at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-02-09 15:10 -------
Confirmed.  (there is a missed optimization here also which Richard G. and I am
looking at right now).

Anyways,
Before:
  # p_247 = PHI <&D.2477.a0.x[0](2)>;
<L183>:;
  #   TMT.32_246 = V_MAY_DEF <TMT.32_255>;
  *p_247 = 0B;

After:
#   SFT.12 = V_MAY_DEF <SFT.12>;
#   TMT.32_246 = V_MAY_DEF <TMT.32_255>;
D.2477.a0.x[0] = 0B;

We forgot to rename SFT.12.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2006-02-09 15:10:13
               date|                            |
   Target Milestone|---                         |4.2.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-02-09 15:45 -------
(In reply to comment #1)
> Confirmed.  (there is a missed optimization here also which Richard G. and I am
> looking at right now).

This missed optimization is filed as PR 26198.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[law at redhat dot com]

------- Comment #3 from law at redhat dot com  2006-02-09 16:03 -------
Subject: Re:  [4.2 regression] ICE in
        is_old_name, at tree-into-ssa.c:466

On Thu, 2006-02-09 at 15:10 +0000, pinskia at gcc dot gnu dot org wrote:
> 
> ------- Comment #1 from pinskia at gcc dot gnu dot org  2006-02-09 15:10 -------
> Confirmed.  (there is a missed optimization here also which Richard G. and I am
> looking at right now).
> 
> Anyways,
> Before:
>   # p_247 = PHI <&D.2477.a0.x[0](2)>;
> <L183>:;
>   #   TMT.32_246 = V_MAY_DEF <TMT.32_255>;
>   *p_247 = 0B;
> 
> After:
> #   SFT.12 = V_MAY_DEF <SFT.12>;
> #   TMT.32_246 = V_MAY_DEF <TMT.32_255>;
> D.2477.a0.x[0] = 0B;
> 
> We forgot to rename SFT.12.
When does the unnamed SFT.12 first appear?

jeff


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[law at redhat dot com]

------- Comment #4 from law at redhat dot com  2006-02-10 20:24 -------
This is a bug in the vectorizer and has absolutely nothing to do with PR26169.

The vectorizer is twiddling things such that the set of virtual operands
changes
for the statement in question.  ie, if you look at the statement before and
after the vectorizer runs it has the form:
#   TMT.32D.2670_172 = V_MAY_DEF <TMT.32D.2670_17>;
D.2524_41->a0D.2385 = D.2477.a0D.2385;

However, if you were to call update_stmt on the statement immediately after
the vectorizer is complete, then dumped the statement again, you'd have:
#   TMT.32D.2670_172 = V_MAY_DEF <TMT.32D.2670_17>;
#   VUSE <SFT.11D.2649>;
#   VUSE <SFT.12D.2650>;
D.2524_41->a0D.2385 = D.2477.a0D.2385;

That's a clear indication that this bug is actually in the vectorizer.  Not
VRP or the SSA updating code.

When a pass twiddles aliasing information such that the set of virtual operands
would change on a statement that is a bug if the statement is not properly
updated.

Jeff


-- 

law at redhat dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|law at gcc dot gnu dot org  |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[rakdver at gcc dot gnu dot org]

------- Comment #5 from rakdver at gcc dot gnu dot org  2006-02-12 19:24 -------
Probably related to

http://gcc.gnu.org/ml/gcc-patches/2006-01/msg00446.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[dorit at il dot ibm dot com]

------- Comment #6 from dorit at il dot ibm dot com  2006-02-13 16:23 -------
(In reply to comment #5)
> Probably related to
> http://gcc.gnu.org/ml/gcc-patches/2006-01/msg00446.html

Would you expect then that calling mark_new_vars_to_rename, like you did in
your patch, will fix this problem?

I wasn't able to reproduce this error on powerpc-linux and i686-pc-linux-gnu. I
do realize that there's a problem with the setting of virtual operands in the
vectorizer. The over conservativeness in the vectorizer with respect to setting
aliasing information for vector pointers when accessing struct fields may be
responssible for this. I will try to look into this issue. In the meantime,
could someone that can reproduce this problem try out the
mark_new_vars_to_rename patch that Zdenek suggested in the link?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[rakdver at gcc dot gnu dot org]

------- Comment #7 from rakdver at gcc dot gnu dot org  2006-02-16 12:52 -------
No, that patch does not fix the problem.  It is however the same type of
problem -- vectorizer not updating virtual operands properly (I had tried to
find all places in vectorizer where this could happen in that patch, but I
obviously missed some).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[rakdver at gcc dot gnu dot org]

------- Comment #8 from rakdver at gcc dot gnu dot org  2006-02-16 17:53 -------
This seems somewhat more complicated than I thought -- vectorizer actually does
not touch the statement with changed vops, it just clobbers alias info somehow
so that we are adding vops for it we did not before. I will have a look why
this happens.


-- 

rakdver at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rakdver at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2006-02-09 15:10:13         |2006-02-16 17:53:48
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[rakdver at gcc dot gnu dot org]

------- Comment #9 from rakdver at gcc dot gnu dot org  2006-02-17 19:54 -------
SFT for D.2477.a is SFT.12. Before vectorizer is run, SFT.12 has is_alias_tag
== false and may_aliases = {TMT.32}; thus, we would only add a vuse for TMT.32
to the statement, and this is subsumed by the VDEF.

Vectorizer calls new_type_alias for D.2477.  This causes SFT.12 to be added to
the alias set of this new tag, and SFT.12->is_alias_tag is set to true (by
add_may_alias).  This however means that since that moment on,
add_virtual_operand will be also adding vuses for SFT.12; i.e., although we
haven't touched the statement at all, its virtual operands will change.

I haven't any idea how this might be fixed (the more I learn about the way
alias info translates to virtual operands, the less I understand it :-( ). I am
CCing someone who might know.


-- 

rakdver at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dberlin at gcc dot gnu dot
                   |                            |org, dnovillo at gcc dot gnu
                   |                            |dot org
         AssignedTo|rakdver at gcc dot gnu dot  |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name, at tree-into-ssa.c:466

[dorit at il dot ibm dot com]

------- Comment #10 from dorit at il dot ibm dot com  2006-02-19 16:10 -------
so maybe if an SFT has may-aliases then new_type_alias should add the
may-aliases of the SFT as may-aliases of the new tag, instead of adding the SFT
as a may-alias of the new tag. ?

There's a comment in new_type_alias that's quite worrying:
"/* The following is based on code in add_stmt_operand to ensure that the
         same defs/uses/vdefs/vuses will be found...."
So this code depends on code in add_stmt_operand, that may have changed by
now... 

Related or not, there's another bug in new_type_alias in PR26359.


-- 

dorit at il dot ibm dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |victork at il dot ibm dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[dorit at il dot ibm dot com]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 3092 bytes --]



------- Comment #11 from dorit at il dot ibm dot com  2006-02-28 08:26 -------
Created an attachment (id=10935)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10935&action=view)
tentative patch

I get a similar error message when trying to bootstrap mainline with
vectorization enabled:

/home/dorit/mainline_svn/build2/./prev-gcc/xgcc
-B/home/dorit/mainline_svn/build2/./prev-gcc/
-B/home/dorit/mainline_svn2/ppc64-yellowdog-linux/bin/ -c   -g -O2
-ftree-vectorize -maltivec -DIN_GCC   -W -Wall -Wwrite-strings
-Wstrict-prototypes -Wmissing-prototypes -pedantic -Wno-long-long
-Wno-variadic-macros -Wno-overlength-strings -Wold-style-definition
-Wmissing-format-attribute -Werror -fno-common   -DHAVE_CONFIG_H -I. -I.
-I../../gcc/gcc -I../../gcc/gcc/. -I../../gcc/gcc/../include
-I../../gcc/gcc/../libcpp/include  -I../../gcc/gcc/../libdecnumber
-I../libdecnumber    ../../gcc/gcc/recog.c -o recog.o
../../gcc/gcc/recog.c: In function âconstrain_operandsâ:
../../gcc/gcc/recog.c:2270: internal compiler error: tree check: expected
ssa_name, have struct_field_tag in verify_ssa, at tree-ssa.c:735
make[3]: *** [recog.o] Error 1
make[3]: Leaving directory `/home/dorit/mainline_svn/build2/gcc'
make[2]: *** [all-stage2-gcc] Error 2
make[2]: Leaving directory `/home/dorit/mainline_svn/build2'
make[1]: *** [stage2-bubble] Error 2
make[1]: Leaving directory `/home/dorit/mainline_svn/build2'
make: *** [bootstrap] Error 2

Following Zdenek's observations, I tried the attached patch. It solves this
failure above in recog.c, but it fails bootstrap with vectorization enabled
later on. (It does pass regular bootstrap on ppc-linux). So this patch needs to
be further examined, but I wonder if it fixes this PR (I can't reproduce it)?

About the patch: 

new_type_alias() originally looked like this:

TAG <- new tag for ptr;
if (var has subvars){
   foreach subvar
        add the subvar as may-alias of TAG.
}
else{
   get the may-aliases of var;
   if (|may-aliases| == 1)
        set the (single) may-alias of var as the new tag of ptr;
   else if (|may-aliases| == 0)
        add var as may-alias of the TAG;
   else /* |may-aliases| > 1 */
        add the may-aliases of var as may-aliases of TAG;
}

What I did is basically factored out the 'else' part into a separate function,
and called that function also in the 'if' part, for each subvar; this way, we
don't add the subvar as may-alias of TAG if the subvar itself has may-aliases,
but add its may-aliases instead:

new version of new_type_alias():

TAG <- new tag for ptr;
if (var has subvars){
   foreach subvar
     add_may_aliases_for_new_tag (TAG, subvar)
}
else{
   add_may_aliases_for_new_tag (TAG, var)
}

add_may_aliases_for_new_tag (TAG, var)
{
   get the may-aliases of var;
   if (|may-aliases| == 1)
        set the (single) may-alias of var as the new tag of ptr;
   else if (|may-aliases| == 0)
        add var as may-alias of the TAG;
   else /* |may-aliases| > 1 */
        add the may-aliases of var as may-aliases of TAG;
}

Makes sense to anyone?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[dnovillo at gcc dot gnu dot org]

------- Comment #12 from dnovillo at gcc dot gnu dot org  2006-02-28 14:38 -------
(In reply to comment #11)

> Makes sense to anyone?
> 
Unfortunately yes.  I am hoping that we will soon be able to get rid of all
this nonsense.  The vectorizer is running against a very recalcitrant alias
pass.  In particular, the alias grouping heuristic is getting in your way,
turning around the roles of memory tag and aliased symbols.

The approach you outline is fine.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[dorit at il dot ibm dot com]

------- Comment #13 from dorit at il dot ibm dot com  2006-03-01 12:35 -------
So I'll submit the patch to gcc-patches for approval. Can someone please check
if this patch actually solves this PR?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[pinskia at gcc dot gnu dot org]

------- Comment #14 from pinskia at gcc dot gnu dot org  2006-03-02 04:44 -------
here is an ever more reduced testcase:
void g(const void*);
struct B
{
  int* x[2];
  int *p;
  B()
  {
     for (int** p=x; p<x+2; ++p)
      *p = 0;
  }
  ~B()
   {
      g(p);
   }
};
void bar()
{
  const B &b = B();
  g(&b);
}
--------
Compile with "-O2 -ftree-vectorize --param max-aliased-vops=0 "
--param max-aliased-vops=0 is needed so that aliaing grouping is done always.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[pinskia at gcc dot gnu dot org]

------- Comment #15 from pinskia at gcc dot gnu dot org  2006-03-03 18:00 -------
*** Bug 26518 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |marcus at jet dot franken
                   |                            |dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[pinskia at gcc dot gnu dot org]

------- Comment #16 from pinskia at gcc dot gnu dot org  2006-04-05 18:38 -------
*** Bug 26948 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |micis at gmx dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[mmitchel at gcc dot gnu dot org]

------- Comment #17 from mmitchel at gcc dot gnu dot org  2006-06-04 17:40 -------
Has anyone tested Dorit's patch?  (IIUC, Dorit is on maternity leave.)


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[patchapp at dberlin dot org]

------- Comment #18 from patchapp at dberlin dot org  2006-07-24 19:50 -------
Subject: Bug number PR26197

A patch for this bug has been added to the patch tracker.
The mailing list url for the patch is
http://gcc.gnu.org/ml/gcc-patches/2006-07/msg01043.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[dorit at gcc dot gnu dot org]

------- Comment #19 from dorit at gcc dot gnu dot org  2006-08-10 12:07 -------
Subject: Bug 26197

Author: dorit
Date: Thu Aug 10 12:07:22 2006
New Revision: 116060

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=116060
Log:
        PR tree-optimization/26197
        * tree-ssa-alias.c (new_type_alias): Takes additional argument. Calls
        get_ref_base_and_extent and overlap_subvar to add only relevant
        subvars as may-aliases.
        (add_may_alias_for_new_tag): New function, factored out of
        new_type_alias.
        * tree-vect-transform.c (vect_create_data_ref_ptr): Call new_type_alias
        with additional argument.
        * tree-flow.h (new_type_alias): Takes additional argument.


Added:
    trunk/gcc/testsuite/g++.dg/vect/param-max-aliased-pr26197.cc
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/vect/vect.exp
    trunk/gcc/tree-flow.h
    trunk/gcc/tree-ssa-alias.c
    trunk/gcc/tree-vect-transform.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[reichelt at gcc dot gnu dot org]

------- Comment #20 from reichelt at gcc dot gnu dot org  2006-08-11 14:53 -------
Fixed on mainline.


-- 

reichelt at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197

[Bug tree-optimization/26197] [4.2 regression] ICE in is_old_name with vectorizer

[pinskia at gcc dot gnu dot org]

------- Comment #21 from pinskia at gcc dot gnu dot org  2006-08-29 17:04 -------
*** Bug 27474 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |uros at kss-loka dot si


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26197