[Bug rtl-optimization/52888] New: Unable to inline function pointer call with inexact signature match

[Bug rtl-optimization/52888] New: Unable to inline function pointer call with inexact signature match

[msharov at users dot sourceforge.net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888

             Bug #: 52888
           Summary: Unable to inline function pointer call with inexact
                    signature match
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: msharov@users.sourceforge.net


#include <stdio.h>

struct A {
    template <typename T>
    static inline __attribute__((always_inline))
    void Caller (T* pn, void (T::*pm)(void))
        { (pn->*pm)(); }

    void Call (int i) {
        if (i == 1) Caller(this, &A::Func1);
        else if (i == 2) Caller(this, &A::Func2);
    }
    inline void Func1 (void)            { puts ("Func1"); }
    inline void Func2 (void) noexcept   { puts ("Func2"); }
};

int main (void) { A a; a.Call(1); a.Call(2); return (0); }
-------------------------------------------------------------
Compiling with: g++ (GCC) 4.7.0 20120324 (prerelease), x86_64
> g++ -O -std=c++11 a.cc
a.cc: In function 'int main()':
a.cc:5:55: error: inlining failed in call to always_inline 'static void
A::Caller(T*, void (T::*)()) [with T = A]': mismatched arguments
a.cc:10:42: error: called from here
a.cc:5:55: error: inlining failed in call to always_inline 'static void
A::Caller(T*, void (T::*)()) [with T = A]': mismatched arguments
a.cc:10:42: error: called from here
-------------------------------------------------------------
I'm using always_inline to force the error; without it Caller is not inlined
errorlessly.

The problem occurs when the function pointer has an inexact signature match to
the pointed function. In the above example, Func2 has a noexcept tacked on to
it. In more complex examples involving pointer to function with arguments,
using a typedef of an object in argument list results in this error, while
using the actual object works (typedef A a_t; void good(A&); void bad(a_t&)).
So the compiler is able to explicitly convert an inexact match like &A::Func2
to void(A::*)(void) when instantiating the template, but the inliner is not
able to make the same match even though it should have the same information.

[Bug rtl-optimization/52888] Unable to inline function pointer call with inexact signature match

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-04-10
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-04-10 11:49:14 UTC ---
It's the pointer-to-member function descriptor that is rejected.  The
compatibility check is too constrained, I have a fix (for this particular case
at least).

[Bug middle-end/52888] Unable to inline function pointer call with inexact signature match

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
          Component|rtl-optimization            |middle-end
         Resolution|                            |FIXED
   Target Milestone|---                         |4.8.0

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-04-10 13:21:11 UTC ---
Fixed for trunk.

[Bug rtl-optimization/52888] Unable to inline function pointer call with inexact signature match

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-04-10 13:20:55 UTC ---
Author: rguenth
Date: Tue Apr 10 13:20:50 2012
New Revision: 186276

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186276
Log:
2012-04-10  Richard Guenther  <rguenther@suse.de>

    PR middle-end/52888
    * gimple-low.c (gimple_check_call_args): Properly account for
    compatible aggregate types.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/gimple-low.c

[Bug middle-end/52888] Unable to inline function pointer call with inexact signature match

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |geza at bitquad dot com

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-01 11:08:02 UTC ---
*** Bug 55788 has been marked as a duplicate of this bug. ***

[Bug middle-end/52888] Unable to inline function pointer call with inexact signature match

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-01 12:46:17 UTC ---
Author: rguenth
Date: Fri Mar  1 12:46:12 2013
New Revision: 196378

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196378
Log:
2013-03-01  Richard Biener  <rguenther@suse.de>

    Backport from mainline
    2012-04-10  Richard Guenther  <rguenther@suse.de>

    PR middle-end/52888
    * gimple-low.c (gimple_check_call_args): Properly account for
    compatible aggregate types.

Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/gimple-low.c

[Bug middle-end/52888] Unable to inline function pointer call with inexact signature match

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |4.7.3, 4.8.0
   Target Milestone|4.8.0                       |4.7.3
      Known to fail|                            |4.7.2

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-01 13:09:58 UTC ---
Fixed for 4.7.3, too.