[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #19 from gcc at abeckmann dot de 2009-10-16 13:13 --- some cases where this warning still occurs in 4.4 are documented in #40146 -- gcc at abeckmann dot de changed: What|Removed |Added CC||gcc at abeckmann dot de http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #17 from jason at gcc dot gnu dot org 2009-03-05 14:10 --- Subject: Bug 38908 Author: jason Date: Thu Mar 5 14:10:07 2009 New Revision: 144643 URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=144643 Log: PR c++/38908 * class.c (is_really_empty_class): New fn. * cp-tree.h: Declare it. * cp-objcp-common.c (cp_expr_size): Use it. Added: trunk/gcc/testsuite/g++.dg/warn/Wuninitialized-3.C Modified: trunk/gcc/cp/ChangeLog trunk/gcc/cp/class.c trunk/gcc/cp/cp-objcp-common.c trunk/gcc/cp/cp-tree.h trunk/gcc/testsuite/ChangeLog -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #18 from jason at gcc dot gnu dot org 2009-03-05 14:32 --- 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=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
-- 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|2009-01-27 16:11:53 |2009-03-05 03:54:13 date|| http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #16 from mark at codesourcery dot com 2009-02-02 07:15 ---
Subject: Re: [4.4 regression] Unexplained 'anonymous' is
used uninitialized in this function warning in cc1plus -m64
rguenther at suse dot de wrote:
Ok. But, as opposed to inheritance, inserting empty members seems to
make a class non-empty:
struct A {};
struct B { A x; };
I'm surprised by that too, but the ABI definition is:
empty class
A class with no non-static data members other than zero-width
bitfields, no virtual functions, no virtual base classes, and no
non-empty non-virtual proper base classes.
Here, we do have a non-static data member that is not a zero-width
bitfield, so I guess this isn't an empty class.
So, CLASSTYPE_EMPTY_P would be a conservative approximation at present,
but we need a new bit to capture the broader thing that is desired here.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #14 from rguenther at suse dot de 2009-01-29 09:19 ---
Subject: Re: [4.4 regression] Unexplained 'anonymous' is
used uninitialized in this function warning in cc1plus -m64
On Wed, 28 Jan 2009, mmitchel at gcc dot gnu dot org wrote:
--- Comment #13 from mmitchel at gcc dot gnu dot org 2009-01-28 23:56
---
Actually, CLASSTYPE_EMPTY_P is probably a fine thing to use for C++. (It's of
course C++ specific; you'd either need to access it via a hook, or promote to
a
language-independent bit.) CLASSTYPE_EMPTY_P will not capture an array of
empty objects, but that's an extreme corner-case.
Note that CLASSTYPE_EMPTY_P classes may have arbitrary size. That's because
of
things like:
struct A{};
struct B : public A {};
struct C : public A, public B {};
In C, you cannot put the B sub-object at the same address as the A sub-object
since that would end up with two A sub-objects (the A-in-B-in-C subobject and
A-in-C subobject) at the same address. So, C will be a two-byte structure.
Obviously, you can generalize this to make arbitrarily huge empty classes.
Ok. But, as opposed to inheritance, inserting empty members seems to
make a class non-empty:
struct A {};
struct B { A x; };
even if in the single-member case I would have expected it to behave
like the single-inheritance case really. Note that cp_expr_size boils
down to checking CLASSTYPE_EMPTY_P already, but in the member case
doesn't seem to map to does not need initialization.
Richard.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #15 from hjl at gcc dot gnu dot org 2009-01-29 17:43 --- Subject: Bug 38908 Author: hjl Date: Thu Jan 29 17:43:14 2009 New Revision: 143765 URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=143765 Log: 2009-01-29 H.J. Lu hongjiu...@intel.com 2009-01-28 Richard Guenther rguent...@suse.de PR middle-end/38908 * g++.dg/warn/Wuninitialized-2.C: New testcase. 2009-01-27 Daniel Kraft d...@domob.eu PR fortran/38883 * gfortran.dg/mvbits_6.f90: New test. * gfortran.dg/mvbits_7.f90: New test. * gfortran.dg/mvbits_8.f90: New test. 2009-01-21 Daniel Kraft d...@domob.eu PR fortran/38887 * gfortran.dg/mvbits_5.f90: New test. Added: branches/gcc-4_3-branch/gcc/testsuite/g++.dg/warn/Wuninitialized-2.C - copied unchanged from r143764, trunk/gcc/testsuite/g++.dg/warn/Wuninitialized-2.C branches/gcc-4_3-branch/gcc/testsuite/gfortran.dg/mvbits_5.f90 - copied unchanged from r143764, trunk/gcc/testsuite/gfortran.dg/mvbits_5.f90 branches/gcc-4_3-branch/gcc/testsuite/gfortran.dg/mvbits_6.f90 - copied unchanged from r143764, trunk/gcc/testsuite/gfortran.dg/mvbits_6.f90 branches/gcc-4_3-branch/gcc/testsuite/gfortran.dg/mvbits_7.f90 - copied unchanged from r143764, trunk/gcc/testsuite/gfortran.dg/mvbits_7.f90 branches/gcc-4_3-branch/gcc/testsuite/gfortran.dg/mvbits_8.f90 - copied unchanged from r143764, trunk/gcc/testsuite/gfortran.dg/mvbits_8.f90 Modified: branches/gcc-4_3-branch/gcc/testsuite/ChangeLog -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #7 from rguenth at gcc dot gnu dot org 2009-01-28 09:36 --- Fixed. -- rguenth at gcc dot gnu dot org changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution||FIXED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #7 from rguenth at gcc dot gnu dot org 2009-01-28 09:36 --- Fixed. --- Comment #8 from rguenth at gcc dot gnu dot org 2009-01-28 09:36 --- Subject: Bug 38908 Author: rguenth Date: Wed Jan 28 09:36:41 2009 New Revision: 143722 URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=143722 Log: 2009-01-28 Richard Guenther rguent...@suse.de PR middle-end/38908 * tree-ssa.c (warn_uninitialized_var): Do not warn for seemingly uninitialized aggregate uses in call arguments. * g++.dg/warn/Wuninitialized-2.C: New testcase. Added: trunk/gcc/testsuite/g++.dg/warn/Wuninitialized-2.C Modified: trunk/gcc/ChangeLog trunk/gcc/testsuite/ChangeLog trunk/gcc/tree-ssa.c -- rguenth at gcc dot gnu dot org changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution||FIXED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #9 from bangerth at gmail dot com 2009-01-28 17:27 ---
Created an attachment (id=17203)
-- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17203action=view)
Failing testcase
Richard,
I hate to break the news to you but there are even more cases. Attached
is a file that produces this warning:
dof_renumbering.ii:51892: warning: 'anonymous' may be used uninitialized in
this function
dof_renumbering.ii:51892: note: 'anonymous' was declared here
The warning comes from using the unnamed object 'dfs_visitor()', which is
of this type:
struct empty
{};
struct dfs_visitor {
dfs_visitor() { }
dfs_visitor(empty vis) : m_vis(vis) { }
empty m_vis;
};
---
I wished I could come up with a smaller testcase, this one is fairly
lengthy, though everything of importance happens in the last 20 or so lines.
Best
Wolfgang
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #10 from bangerth at gmail dot com 2009-01-28 17:28 --- Re-open -- bangerth at gmail dot com changed: What|Removed |Added Status|RESOLVED|REOPENED Resolution|FIXED | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #11 from rguenth at gcc dot gnu dot org 2009-01-28 20:49
---
# VUSE D.86121_223(D) { D.86121 }
# vis_224 = VDEF vis_91 { vis }
vis = D.86121;
cp_expr_size returns 1 for the objects.
var_decl 0xb5eb5c08 D.86121
type record_type 0xb62bfbc8 dfs_visitor needs-constructing type_1 type_5
type_6 QI
size integer_cst 0xb7cef6c8 constant 8
unit size integer_cst 0xb7cef6e4 constant 1
align 8 symtab 0 alias set 80 canonical type 0xb62bfbc8
fields field_decl 0xb6bc4c38 m_vis type record_type 0xb62bf9c0 empty
used nonlocal decl_3 QI file t.ii line 51866 col 11 size
integer_cst 0xb7cef6c8 8 unit size integer_cst 0xb7cef6e4 1
align 8 offset_align 128
offset integer_cst 0xb7cef658 constant 0
bit offset integer_cst 0xb7cefdc8 constant 0 context record_type
0xb62bfbc8 dfs_visitor chain type_decl 0xb62bfc98 dfs_visitor context
namespace_decl 0xb7c2cea0 boost
needs-constructor X() X(constX) this=(X) n_parents=0 use_template=0
interface-unknown
pointer_to_this pointer_type 0xb62bfe38 reference_to_this
reference_type 0xb629a7b8 chain type_decl 0xb62bfc30 dfs_visitor
used ignored QI file t.ii line 51892 col 9 size integer_cst 0xb7cef6c8 8
unit size integer_cst 0xb7cef6e4 1
align 8 context function_decl 0xb62c2300 foo abstract_origin var_decl
0xb6268528 D.75386
calling it on the m_vis member yields zero.
We change dfs_visitors empty flag to false in check_field_decls.
Short testcase:
struct empty {};
struct dfs_visitor {
dfs_visitor() { }
empty m_vis;
};
void bar(const dfs_visitor);
void foo(void)
{
dfs_visitor vis;
dfs_visitor vis2 = vis;
bar (vis2);
}
Note that we also end up generating code for the copy.
--
rguenth at gcc dot gnu dot org changed:
What|Removed |Added
Keywords||diagnostic, missed-
||optimization
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #12 from rguenth at gcc dot gnu dot org 2009-01-28 20:54
---
This needs to be dealt from within the frontend, possibly like Mark suggested
by inventing another predicate (I assume that CLASSTYPE_EMPTY_P is used for
some C++ standard stuff so we cannot just change that). It may still be ok
for the expr_size langhook to return true for this kind of type:
struct empty {};
struct still_empty { empty x; };
--
rguenth at gcc dot gnu dot org changed:
What|Removed |Added
AssignedTo|rguenth at gcc dot gnu dot |unassigned at gcc dot gnu
|org |dot org
Status|REOPENED|NEW
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #13 from mmitchel at gcc dot gnu dot org 2009-01-28 23:56
---
Actually, CLASSTYPE_EMPTY_P is probably a fine thing to use for C++. (It's of
course C++ specific; you'd either need to access it via a hook, or promote to a
language-independent bit.) CLASSTYPE_EMPTY_P will not capture an array of
empty objects, but that's an extreme corner-case.
Note that CLASSTYPE_EMPTY_P classes may have arbitrary size. That's because of
things like:
struct A{};
struct B : public A {};
struct C : public A, public B {};
In C, you cannot put the B sub-object at the same address as the A sub-object
since that would end up with two A sub-objects (the A-in-B-in-C subobject and
A-in-C subobject) at the same address. So, C will be a two-byte structure.
Obviously, you can generalize this to make arbitrarily huge empty classes.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #5 from bangerth at gmail dot com 2009-01-27 16:00 --- Richard, this isn't a duplicate of PR 38851: while the testcase there indeed now passes, the one in the current PR still fails. Best Wolfgang -- bangerth at gmail dot com changed: What|Removed |Added Status|RESOLVED|REOPENED Resolution|DUPLICATE | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
-- bangerth at gmail dot com changed: What|Removed |Added Priority|P3 |P2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #6 from rguenth at gcc dot gnu dot org 2009-01-27 16:11 --- Well, it is a duplicate really, just this testcase involves one more case: # VUSE D.2044_1(D) # retval_3 = VDEF retval_2(D) __comp_ctor (retval, D.2044); where the uninitialized aggregate use appears as a function argument. While I would like to have registers for these, simply disabling the warning for calls looks easier. I am testing a patch. -- rguenth at gcc dot gnu dot org changed: What|Removed |Added AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot |dot org |org Status|REOPENED|ASSIGNED Last reconfirmed|2009-01-21 22:24:03 |2009-01-27 16:11:53 date|| http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #4 from rguenth at gcc dot gnu dot org 2009-01-25 18:02 --- struct S8 D.2460; struct S8 D.2470; bb 2: # VUSE D.2460_1(D) # D.2470_3 = VDEF D.2470_2(D) D.2470 = D.2460; and struct S8 is empty. This is a dup of PR38851 which has a smaller testcase. *** This bug has been marked as a duplicate of 38851 *** -- rguenth at gcc dot gnu dot org changed: What|Removed |Added Status|NEW |RESOLVED Resolution||DUPLICATE http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #3 from bangerth at dealii dot org 2009-01-23 19:26 --- I see this as well. It triggers a ton of time in boost::graph code. I think it should have higher priority than P3. W. -- bangerth at dealii dot org changed: What|Removed |Added CC||bangerth at dealii dot org, ||mmitchel at gcc dot gnu dot ||org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
--- Comment #2 from bkoz at gcc dot gnu dot org 2009-01-21 22:41 --- fix summary -- bkoz at gcc dot gnu dot org changed: What|Removed |Added Summary|[4.3 regression] Unexplained|[4.4 regression] Unexplained |'anonymous' is used |'anonymous' is used |uninitialized in this |uninitialized in this |function warning in cc1plus|function warning in cc1plus |-m64|-m64 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
[Bug c++/38908] [4.4 regression] Unexplained 'anonymous' is used uninitialized in this function warning in cc1plus -m64
-- rguenth at gcc dot gnu dot org changed: What|Removed |Added Target Milestone|--- |4.4.0 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38908
