* [Bug c++/56481] [4.8 Regression] endless loop compiling a C++ file
2013-02-28 10:32 [Bug c++/56481] New: [4.8 Regression] endless loop compiling a C++ file doko at gcc dot gnu.org
@ 2013-02-28 12:00 ` jakub at gcc dot gnu.org
2013-02-28 16:58 ` jason at gcc dot gnu.org
` (5 subsequent siblings)
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From: jakub at gcc dot gnu.org @ 2013-02-28 12:00 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56481
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2013-02-28
CC| |jakub at gcc dot gnu.org,
| |jason at gcc dot gnu.org
Target Milestone|--- |4.8.0
Ever Confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-28 11:59:57 UTC ---
Reduced testcase:
struct S
{
bool foo () const;
#define A(n) , f##n##0, f##n##1, f##n##2, f##n##3
#define B(n) A(n##0) A(n##1) A(n##2) A(n##3)
#define C B(0) B(1) B(2) B(3)
bool f C;
};
bool
S::foo () const
{
#undef A
#define A(n) && f##n##0 && f##n##1 && f##n##2 && f##n##3
const bool ret = f C;
return ret;
}
Started with my http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=192862
It actually isn't endless, just the compile time complexity is bad.
The problem is I think in:
if (!potential_constant_expression_1 (op, rval, flags))
return false;
if (!processing_template_decl)
op = maybe_constant_value (op);
in TRUTH_{AND,OR}*_EXPR handling in potential_constant_expression_1, because
maybe_constant_value calls potential_constant_expression (op) again.
They are called with different second/third argument (false, tf_none inside
maybe_constant_value, or true (== rval), flags above) though, so I think the
fix wouldn't be as easy as inlining maybe_constant_value by hand here and
avoiding the potential_constant_expression there.
Jason, any ideas?
For large && or || expressions perhaps we could just handle the cases where
op is the same code specially, still we wouldn't get rid of the large
complexity if say TRUTH_AND*_EXPR is only in every second code and there is
some other code in between.
^ permalink raw reply [flat|nested] 8+ messages in thread* [Bug c++/56481] [4.8 Regression] endless loop compiling a C++ file
2013-02-28 10:32 [Bug c++/56481] New: [4.8 Regression] endless loop compiling a C++ file doko at gcc dot gnu.org
2013-02-28 12:00 ` [Bug c++/56481] " jakub at gcc dot gnu.org
@ 2013-02-28 16:58 ` jason at gcc dot gnu.org
2013-02-28 17:36 ` jakub at gcc dot gnu.org
` (4 subsequent siblings)
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From: jason at gcc dot gnu.org @ 2013-02-28 16:58 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56481
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
AssignedTo|unassigned at gcc dot |jason at gcc dot gnu.org
|gnu.org |
^ permalink raw reply [flat|nested] 8+ messages in thread* [Bug c++/56481] [4.8 Regression] endless loop compiling a C++ file
2013-02-28 10:32 [Bug c++/56481] New: [4.8 Regression] endless loop compiling a C++ file doko at gcc dot gnu.org
2013-02-28 12:00 ` [Bug c++/56481] " jakub at gcc dot gnu.org
2013-02-28 16:58 ` jason at gcc dot gnu.org
@ 2013-02-28 17:36 ` jakub at gcc dot gnu.org
2013-02-28 20:22 ` jason at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-02-28 17:36 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56481
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-28 17:35:47 UTC ---
With -std=c++11 this actually started already with
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189851
when that code has been introduced in potential_constant_expression_1.
^ permalink raw reply [flat|nested] 8+ messages in thread* [Bug c++/56481] [4.8 Regression] endless loop compiling a C++ file
2013-02-28 10:32 [Bug c++/56481] New: [4.8 Regression] endless loop compiling a C++ file doko at gcc dot gnu.org
` (2 preceding siblings ...)
2013-02-28 17:36 ` jakub at gcc dot gnu.org
@ 2013-02-28 20:22 ` jason at gcc dot gnu.org
2013-02-28 20:37 ` jason at gcc dot gnu.org
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From: jason at gcc dot gnu.org @ 2013-02-28 20:22 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56481
--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> 2013-02-28 20:21:36 UTC ---
Author: jason
Date: Thu Feb 28 20:21:23 2013
New Revision: 196358
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196358
Log:
PR c++/56481
* semantics.c (potential_constant_expression_1): Use
cxx_eval_outermost_constant_expr rather than maybe_constant_value.
Modified:
trunk/gcc/cp/ChangeLog
trunk/gcc/cp/semantics.c
^ permalink raw reply [flat|nested] 8+ messages in thread* [Bug c++/56481] [4.8 Regression] endless loop compiling a C++ file
2013-02-28 10:32 [Bug c++/56481] New: [4.8 Regression] endless loop compiling a C++ file doko at gcc dot gnu.org
` (3 preceding siblings ...)
2013-02-28 20:22 ` jason at gcc dot gnu.org
@ 2013-02-28 20:37 ` jason at gcc dot gnu.org
2013-02-28 20:45 ` jakub at gcc dot gnu.org
2013-03-17 2:38 ` jason at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: jason at gcc dot gnu.org @ 2013-02-28 20:37 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56481
--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> 2013-02-28 20:36:54 UTC ---
Author: jason
Date: Thu Feb 28 20:36:47 2013
New Revision: 196359
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196359
Log:
PR c++/56481
* g++.dg/cpp0x/constexpr-and.C: New.
Added:
trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-and.C
Modified:
trunk/gcc/testsuite/ChangeLog
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2013-02-28 10:32 [Bug c++/56481] New: [4.8 Regression] endless loop compiling a C++ file doko at gcc dot gnu.org
` (4 preceding siblings ...)
2013-02-28 20:37 ` jason at gcc dot gnu.org
@ 2013-02-28 20:45 ` jakub at gcc dot gnu.org
2013-03-17 2:38 ` jason at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-02-28 20:45 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56481
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-28 20:45:26 UTC ---
Fixed, thanks.
^ permalink raw reply [flat|nested] 8+ messages in thread* [Bug c++/56481] [4.8 Regression] endless loop compiling a C++ file
2013-02-28 10:32 [Bug c++/56481] New: [4.8 Regression] endless loop compiling a C++ file doko at gcc dot gnu.org
` (5 preceding siblings ...)
2013-02-28 20:45 ` jakub at gcc dot gnu.org
@ 2013-03-17 2:38 ` jason at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: jason at gcc dot gnu.org @ 2013-03-17 2:38 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56481
--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> 2013-03-17 02:37:34 UTC ---
Author: jason
Date: Sun Mar 17 02:37:21 2013
New Revision: 196737
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196737
Log:
PR c++/56481
* semantics.c (potential_constant_expression_1): Use of 'this' in
a non-constexpr function makes the expression not potentially
constant.
Modified:
trunk/gcc/cp/ChangeLog
trunk/gcc/cp/semantics.c
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