[Bug c++/19634] New: Infinite memory usage on Alpha

[Bug c++/19634] New: Infinite memory usage on Alpha

[falk at debian dot org]

This makes 27_io/basic_istream/extractors_character/char/9826.cc fail
(see e.g. http://gcc.gnu.org/ml/gcc-testresults/2005-01/msg01098.html). I'll
attach a semi-reduced test case. Doesn't seem to happen on other platforms.

Profiling shows prominently "alpha_sa_mask" and "reload". Adding -da makes the
problem go away...

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           Summary: Infinite memory usage on Alpha
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: memory-hog
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: falk at debian dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: alphaev68-unknown-linux-gnu
  GCC host triplet: alphaev68-unknown-linux-gnu
GCC target triplet: alphaev68-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] Infinite memory usage on Alpha

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2005-01-26 01:43 -------
Created an attachment (id=8072)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=8072&action=view)
Test case. Compile with no options


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug middle-end/19634] Infinite memory usage on Alpha

[pinskia at gcc dot gnu dot org]

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           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |middle-end


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug target/19634] Infinite memory usage on Alpha

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2005-01-26 10:30 -------
Is this a regression?

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           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |target


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug target/19634] [4.0 regression] Infinite memory usage on Alpha

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2005-01-26 11:03 -------
(In reply to comment #2)
> Is this a regression?

Yes, g++ 3.4 compiles this fine , and 3.3 too if I s/class/struct/.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.0.0
      Known to work|                            |3.3.3 3.4.3
            Summary|Infinite memory usage on    |[4.0 regression] Infinite
                   |Alpha                       |memory usage on Alpha
            Version|4.0.0                       |3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug target/19634] [4.0 regression] Infinite memory usage on Alpha

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2005-01-26 11:17 -------
Whoops.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|3.0                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug target/19634] [4.0 regression] Infinite memory usage on Alpha

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-01-26 11:16 -------
Is this a recent problem, ie. any idea when this started to FAIL?

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug target/19634] [4.0 regression] Infinite memory usage on Alpha

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2005-01-26 11:23 -------
(In reply to comment #4)
> Is this a recent problem, ie. any idea when this started to FAIL?

With 20041209, I get a segfault. With 20050116 or 20050120, I get the infinite
loop. I don't have any other old versions around. Seems to indicate memory
corruption...


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug target/19634] [4.0 regression] Infinite memory usage on Alpha

[pinskia at gcc dot gnu dot org]

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug target/19634] [4.0 regression] Infinite memory usage on Alpha

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-02-10 01:07 -------
Some sort of reload bug.  We keep allocating new spill slots.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rth at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-02-10 01:07:14
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-02-10 01:59 -------
Not a reload bug.  RTL state gets mangled by pop_function_context_from 
called underneath mangle_decl_string.  We may be able to work around this
problem like so, but I'm still not certain that we're not borking something.
This can only be truely fixed by not doing such gross push/pop state 
changes within the c++ front end.



Index: passes.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/passes.c,v
retrieving revision 2.65
diff -u -p -d -r2.65 passes.c
--- passes.c    1 Feb 2005 10:03:09 -0000       2.65
+++ passes.c    10 Feb 2005 01:57:18 -0000
@@ -1530,6 +1530,12 @@ rest_of_compilation (void)
   if (rtl_dump_and_exit || flag_syntax_only || errorcount || sorrycount)
     goto exit_rest_of_compilation;

+  /* Make sure rtl for the current function is set at this point.  This
+     may recurse in "interesting" ways for c++, which can hork passes.
+     It is 100% certain that we'll need this rtl, so this does not cause
+     extra work.  */
+  (void) DECL_RTL (current_function_decl);
+
   rest_of_handle_jump ();

   rest_of_handle_eh ();


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rth at gcc dot gnu dot org
         AssignedTo|rth at gcc dot gnu dot org  |unassigned at gcc dot gnu
                   |                            |dot org
             Status|ASSIGNED                    |NEW
          Component|target                      |c++


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-10 02:05 -------
This is related PR 18683 which is a related problem.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-10 02:15 -------
RTH, you added the wrong mark before.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-02-10 02:20 -------
True enough, and one could indeed "fix" this problem on Alpha by adding a
similar check to samegp_function_operand.  However, I don't think this is
the right approach to this problem.  How many other places in other targets
need to be changed?  I'd very much prefer a solution that fixes all such 
potential problems all at once.

It *is* 100% certain that once we've started generating rtl for a function,
that we'll need the DECL_ASSEMBLER_NAME in order to emit it.  We might as 
well do this in one place, rather than having to recurse in some random place
later during code generation.

And for the record, the problem here has to do with reseting 
virtuals_instantiated instead of reg_renumber.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2005-02-10 04:35 -------
I agree that the C++ recursion is very ugly.  The last time I looked at this, I
concluded it would be hard to fix, but now I'm not entirely certain that's true.
The problem comes from the call to push_access_scope in
get_mostly_instantiated_function_type.  There's certainly no need to do access
control in this context; we could just save and restore flag_access_control. 
The comment says "make sure that we can see identifiers" -- but I don't think
that makes any sense.

If that doesn't work, I think that rth's proposed fix is a reasonable
work-around.  I'd be worried, though, that in the process of compiling the
function, after this point, we might need to mangle some other function (say,
one called from this one), and run into the same problem because of that.  

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-02-11 04:29 -------
patch: http://gcc.gnu.org/ml/gcc-patches/2005-02/msg00490.html

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rth at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
           Keywords|                            |patch
   Last reconfirmed|2005-02-10 01:07:14         |2005-02-11 04:29:45
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-02-11 21:10 -------
Fixed.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634

[Bug c++/19634] [4.0 regression] Infinite memory usage on Alpha

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19634