[Bug bootstrap/38607] AIX error messages about TOC during build

["lukasz.filipkowski at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38607

Lukasz Filipkowski <lukasz.filipkowski at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lukasz.filipkowski at gmail
                   |                            |dot com

--- Comment #15 from Lukasz Filipkowski <lukasz.filipkowski at gmail dot com> 2011-09-23 10:10:58 UTC ---
Hello,

regarding ld: 0711-768 WARNING when compiling:

>   #include <string>
>   #include <map>
>   void foo()
>   {
>     std::map<std::string, std::string> bar;
>   }

into rtl-enabled shared library. Warning is caused by code construction similar
to the one presented in the following example:

   //g++ -save-temps -shared -Wl,-G -o libshare.so share.cc
   #include <iostream>
   #include <string>
   using namespace std;

   template<typename Key> class MyClass
   {
    public:
     typedef Key KeyType;
     MyClass(KeyType aNumber)
     {
         cout << aNumber << "! = " << factorial(aNumber) << endl;
     }
     ~MyClass(){}
    private:
     long factorial(KeyType __x);
     long factorialHelper(KeyType __x);
   };

   template<typename Key> long MyClass<Key>::factorial(KeyType __x)
   {
    if (__x <= 0) return 1;
    else return __x * factorial(__x-1);
    //else return __x * factorialHelper(__x-1);
   }

   template<typename Key> long MyClass<Key>::factorialHelper(KeyType __x)
   {
    return factorial(__x);
   }

   void foo()
   {
    MyClass<int> myClass(5);
   }


$ g++ -save-temps -shared -Wl,-G -o libshare.so share.cc
ld: 0711-768 WARNING: Object share.o, section 1, function
.MyClass<int>::factorial(int):
        The branch at address 0x36c is not followed by a recognized no-op
        or TOC-reload instruction. The unrecognized instruction is 0x7C691B78.


Example code is based on contents of stl_tree.h file in which class _Rb_tree is
defined. 
Warning is generated in case creation of shared libraries using TEMPLATE
CLASSES with RECURSIVE METHODS.
In the presented example "factorial" method is a recursive one.

When modifying:

   template<typename Key> long MyClass<Key>::factorial(KeyType __x)
   {
    if (__x <= 0) return 1;
    else return __x * factorial(__x-1);
    //else return __x * factorialHelper(__x-1);
   }

into:

   template<typename Key> long MyClass<Key>::factorial(KeyType __x)
   {
    if (__x <= 0) return 1;
    //else return __x * factorial(__x-1);
    else return __x * factorialHelper(__x-1);
   }

there is no linker warning.


The _Rb_tree class, defined in stl_tree.h, contains _M_erase and _M_copy
methods, both recursive.

Warning is present when using both GCC4.4.5 and GCC4.6.1 on AIX 5300-11-03-1013
(AIX5.3 TL11 SP03)
When using assembler program (as) from AIX 5300-08-02-0822 (AIX5.3 TL08 SP02)
there is no warning generated.

I'm not sure but problematic warning might be a result of fixes similar to
https://www-304.ibm.com/support/docview.wss?uid=isg1IZ24688