[Bug debug/39086] New: Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[Bug debug/39086] New: Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[jamborm at gcc dot gnu dot org]

When compiling test 27_io/basic_istream/requirements/explicit_instantiation.cc
from the libstc++ testsuite and adding the -fno-tree-sra flag, I get
the following error:

----------------------------------------------------------------------
user@host:~/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/testsuite$
$HOME/gcc/svn/obj/./gcc/g++ -shared-libgcc -B$HOME/gcc/svn/obj/./gcc
-nostdinc++ -L$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/src
-L$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/src/.libs
-B$HOME/gcc/inst/svn//i686-pc-linux-gnu/bin/
-B$HOME/gcc/inst/svn//i686-pc-linux-gnu/lib/ -isystem
$HOME/gcc/inst/svn//i686-pc-linux-gnu/include -isystem
$HOME/gcc/inst/svn//i686-pc-linux-gnu/sys-include -g -O2 -D_GLIBCXX_ASSERT
-fmessage-length=0 -ffunction-sections -fdata-sections -g -O2 -D_GNU_SOURCE -g
-O2   -D_GNU_SOURCE   -DLOCALEDIR="." -nostdinc++
-I$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/include/i686-pc-linux-gnu
-I$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/include
-I$HOME/gcc/svn/libstdc++-v3/libsupc++
-I$HOME/gcc/svn/libstdc++-v3/include/backward
-I$HOME/gcc/svn/libstdc++-v3/testsuite/util
$HOME/gcc/svn/libstdc++-v3/testsuite/27_io/basic_istream/requirements/explicit_instantiation.cc
   -include bits/stdc++.h -S  -o explicit_instantiation.s -fno-tree-sra
In file included from
$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/include/istream:833,
                 from
$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/include/sstream:44,
                 from
$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/include/complex:52,
                 from
$HOME/gcc/svn/libstdc++-v3/include/precompiled/stdc++.h:69:
$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/include/bits/istream.tcc: In
member function 'typename std::basic_istream<_CharT, _Traits>::int_type
std::basic_istream<_CharT, _Traits>::get() [with _CharT =
__gnu_cxx::character<unsigned char, __gnu_test::pod_int,
__gnu_test::pod_state>, _Traits =
std::char_traits<__gnu_cxx::character<unsigned char, __gnu_test::pod_int,
__gnu_test::pod_state> >]':
$HOME/gcc/svn/obj/i686-pc-linux-gnu/libstdc++-v3/include/bits/istream.tcc:222:
internal compiler error: in decl_ultimate_origin, at dwarf2out.c:5770
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
----------------------------------------------------------------------

This is with trunk revision 143890, compiled on i686-pc-linux without
bootstrap.  I will attach preprocessed source shortly.


-- 
           Summary: Failing assert in dwarf2out.c:5770 when compiling with -
                    fno-tree-sra
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jamborm at gcc dot gnu dot org
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[jamborm at gcc dot gnu dot org]

------- Comment #1 from jamborm at gcc dot gnu dot org  2009-02-03 15:09 -------
Created an attachment (id=17232)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17232&action=view)
Preprocessed source

Enough to compile with -O2 -g -fno-tree-sra explicit_instantiation.ii


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2009-02-03 15:30 -------
Not too useful, that preprocessed source includes PCHs.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[jamborm at gcc dot gnu dot org]

------- Comment #3 from jamborm at gcc dot gnu dot org  2009-02-03 16:56 -------
Created an attachment (id=17236)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17236&action=view)
Preprocessed source

OK, this one is hopefully without any precompiled headers. 


-- 

jamborm at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #17232|0                           |1
        is obsolete|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2009-02-04 21:14 -------
It fails with 
gcc version 4.4.0 20090116 (experimental) [trunk revision 143440] (GCC) 
But I don't have anything older to try it with on that machine.

It did work with gcc version 4.4.0 20081229 (experimental) [trunk revision
142951] (GCC)  on i386-darwin8.11.

I don't have time right now to figure out if this is really a regression or not
or a reduced testcase but I am going to mark it as a regression so at least
someone will look at it.  I really think it is a regression.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   GCC host triplet|i686-pc-linux-gnu           |
 GCC target triplet|                            |i686-pc-linux-gnu
           Keywords|                            |ice-on-valid-code
            Summary|Failing assert in           |[4.4 Regression] Failing
                   |dwarf2out.c:5770 when       |assert in dwarf2out.c:5770
                   |compiling with -fno-tree-sra|when compiling with -fno-
                   |                            |tree-sra
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[hjl dot tools at gmail dot com]

------- Comment #5 from hjl dot tools at gmail dot com  2009-02-04 23:54 -------
It is a regression introduced between revision 139502 and revision 139996.
I am doing a binary search on it.


-- 

hjl dot tools at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-02-04 23:54:13
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[hjl dot tools at gmail dot com]

------- Comment #6 from hjl dot tools at gmail dot com  2009-02-05 01:27 -------
It is caused by revision 139755:

http://gcc.gnu.org/ml/gcc-cvs/2008-08/msg01320.html


-- 

hjl dot tools at gmail dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2009-02-05 22:06 -------
Reducing.


-- 

rguenth at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] Failing assert in dwarf2out.c:5770 when compiling with -fno-tree-sra

[rguenth at gcc dot gnu dot org]

------- Comment #8 from rguenth at gcc dot gnu dot org  2009-02-05 22:44 -------
Created an attachment (id=17254)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17254&action=view)
reduced testcase

ICEs with -O2 -fno-tree-sra -g [-m32]


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[rguenth at gcc dot gnu dot org]

------- Comment #9 from rguenth at gcc dot gnu dot org  2009-02-05 22:48 -------
4.3 rejects the reduced testcase, the original works though.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.4.0
      Known to work|                            |4.3.3
            Summary|[4.4 Regression] Failing    |[4.4 Regression] ICE in
                   |assert in dwarf2out.c:5770  |decl_ultimate_origin, at
                   |when compiling with -fno-   |dwarf2out.c:5770 when
                   |tree-sra                    |compiling with -fno-tree-sra


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jakub at gcc dot gnu dot org]

------- Comment #10 from jakub at gcc dot gnu dot org  2009-02-05 23:39 -------
Just s/class ios_base/struct ios_base/ if you don't want 4.3 to reject it.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jakub at gcc dot gnu dot org]

------- Comment #11 from jakub at gcc dot gnu dot org  2009-02-06 09:35 -------
Created an attachment (id=17261)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17261&action=view)
pr39086.C

Slightly more reduced testcase.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jakub at gcc dot gnu dot org]

------- Comment #12 from jakub at gcc dot gnu dot org  2009-02-06 10:54 -------
Seems that 2008-08-29 patch effect on this testcase is that __builtin_expect is
removed later and it apparently isn't considered as zero cost.  This is
strange, as gimple_reg = gimple_reg2 is considered to have 0 cost.  I think
__builtin_expect shouldn't count the cost of the second argument and for the
first argument if lhs of the call is_gimple_reg and so is the first call
argument, it should also return 0 cost.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jakub at gcc dot gnu dot org]

------- Comment #13 from jakub at gcc dot gnu dot org  2009-02-06 16:23 -------
Created an attachment (id=17262)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17262&action=view)
pr39086.C

Even more reduced testcase on which g++ -O2 -W -Wall is quiet (no missing
returns in functions returning non-void etc.).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jakub at gcc dot gnu dot org]

------- Comment #14 from jakub at gcc dot gnu dot org  2009-02-06 16:37 -------
The problem is with f4 RESULT_DECL.  First during save_inline_function_body
remap_decl creates a copy of that RESULT_DECL and sets copy's
DECL_ABSTRACT_ORIGIN to the original f4's RESULT_DECL.  Then during
optimization of the original f4 tree_nrv sets the original f4 RESULT_DECL's
DECL_ABSTRACT_ORIGIN to found's DECL_ABSTRACT_ORIGIN (where found is a VAR_DECL
originally from f1).  But at this point decl_ultimate_origin will already ICE
on the inlined f4's RESULT_DECL, as its DECL_ABSTRACT_ORIGIN has another
DECL_ABSTRACT_ORIGIN, so it is not ultimate anymore.

I have no idea how to prevent this though.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jakub at gcc dot gnu dot org]

------- Comment #15 from jakub at gcc dot gnu dot org  2009-02-09 12:54 -------
And, even if decl_ultimate_origin checking is weakened and it actually looks
for ultimate origin for RESULT_DECLs, I'm not sure the generated debug info is
correct.  The problem is that the tree NRV optimization is an optimization in
the current function only, it shouldn't affect inlined copies of that function.
When foo is inlined into bar, in bar there is some VAR_DECL with abstract
origin in foo's RESULT_DECL.  In foo, if tree NRV kicks in, RESULT_DECL has
abstract origin some VAR_DECL.  But that was a result of a local optimization
of foo, it doesn't mean that the VAR_DECL in bar with foo's RESULT_DECL as
abstract origin
should have that other var in foo as origin.  Perhaps we'd need to emit a
virtual foo's info and then emit real out-of-line foo as "inlined instance" of
that virtual foo or something to get proper debug info.


-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jason at gcc dot gnu dot org]

-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jason at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-02-04 23:54:13         |2009-03-07 16:48:47
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jason at gcc dot gnu dot org]

------- Comment #16 from jason at gcc dot gnu dot org  2009-03-07 20:16 -------
So here's what happens:

1) The front end chooses 'x' as the NRV for f4 and rewrites the assignments.
2) inlining creates a temporary variable for the return value of f1.  So we
have

<bb 3>:
  D.1204 = ax;
  <retval> = D.1204;
  goto <bb 5>;

<bb 4>:
  <retval> = OBJ_TYPE_REF(*this->_vptr.C;this->0) (this);

3) tree-nrv looks at this, sees <retval> = D.1204, doesn't see the other
assignment to retval because it's a GIMPLE_CALL rather than a GIMPLE_ASSIGN,
and decides to make D.1204 the NRV.

4) tree-nrv copies the debugging information for D.1204 over the debugging
information for the f4 return value, which already had the info for 'x'.

5) The f4 retval now has DECL_ABSTRACT_ORIGIN referring to f1, which causes
chaos.

It seems that there are several bugs here:

* tree-nrv shouldn't do NRV after the front end already did, as it might miss
modifications that aren't of the form it expects.  Specifically, it doesn't
seem to check whether anything takes the address of the RESULT_DECL.

* tree-nrv needs to notice GIMPLE_CALL modifications.

* tree-nrv shouldn't clobber the debug information on the RESULT_DECL in favor
of another artificial variable.

* tree-nrv shouldn't copy DECL_ABSTRACT_ORIGIN that refers to another function.

I'm working on a patch for all these issues.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jason at gcc dot gnu dot org]

------- Comment #18 from jason at gcc dot gnu dot org  2009-03-11 05:02 -------
Fixed.


-- 

jason at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086

[Bug debug/39086] [4.4 Regression] ICE in decl_ultimate_origin, at dwarf2out.c:5770 when compiling with -fno-tree-sra

[jason at gcc dot gnu dot org]

------- Comment #17 from jason at gcc dot gnu dot org  2009-03-11 05:01 -------
Subject: Bug 39086

Author: jason
Date: Wed Mar 11 05:01:30 2009
New Revision: 144772

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=144772
Log:
        PR debug/39086
        * tree-nrv.c (tree_nrv): Don't do this optimization if the front
        end already did.  Notice GIMPLE_CALL modifications of the result.
        Don't copy debug information from an ignored decl or a decl from
        another function.

Added:
    trunk/gcc/testsuite/g++.dg/opt/nrv15.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-nrv.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39086