IV49595: ALLOCATION PROBLEM FOR NEW[] OPERATOR

XL C/C++ for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C/C++ for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 21 (January 2019 Update) for 12.1

APAR status

• Closed as program error.

Error description

• All the following allocations should call Foo::operator new[]
  with a 'size' argument equal to '420' because they all allocate
  10  'Foo<Buffer>' (or 'Foo<Buf>') objects and the size of each
  of these objects should be '42' (i.e. the size of their 'Buffer'
   or 'Buf' attribute).
  
  Unfortunately XLC calls the new[] opertor with the array arity
  (i.e. '10' instead of the array size (i.e.'420')) if the default
   argument of the new[] operator is not explicitely given and the
   type of the attribute 'bar' is not a POD (e.g. if it has a
  constructor like 'Buffer').
  
  ===== COMPILE COMMAND:
  xlc++ arraynew.cpp
  
  ===== TESTCASE:
  $ cat arraynew.cpp
  #include <stdio.h>
  #include <stdlib.h>
  
  struct Buf {
    char buf[42];
  };
  
  struct Buffer {
    char buf[42];
    Buffer() {}
  };
  
  template<class T>
  struct Foo {
    void* operator new [](size_t size, int foo = 0) {
      fprintf(stdout, "Foo::new [](size=%ld, foo=%d)\n", size,
  foo);
      return malloc(size);
    }
    T bar;
  };
  
  int main(int argc, char **argv) {
  
    fprintf(stdout, "sizeof(Foo<Buffer>[10]) = %ld\n",
  sizeof(Foo<Buffer>[10]));
    Foo<Buffer> *buf1 = new       Foo<Buffer>[10];
    Foo<Buffer> *buf2 = new (123) Foo<Buffer>[10];
  
    fprintf(stdout, "sizeof(Foo<Buf>[10]) = %ld\n",
  sizeof(Foo<Buf>[10]));
    Foo<Buf> *buf3 = new       Foo<Buf>[10];
    Foo<Buf> *buf4 = new (123) Foo<Buf>[10];
  }
  $
  
  ===== ACTUAL OUTPUT:
  $ ./a.out
  sizeof(Foo<Buffer>[10]) = 420
  Foo::new [](size=10, foo=0)      <---- The size value is '10'
  instead of '420'
  Foo::new [](size=420, foo=123)
  sizeof(Foo<Buf>[10]) = 420
  Foo::new [](size=420, foo=0)
  Foo::new [](size=420, foo=123)
  $
  
  
  ===== EXPECTED OUTPUT:
  $ ./a.out
  sizeof(Foo<Buffer>[10]) = 420
  Foo::new [](size=420, foo=0)
  Foo::new [](size=420, foo=123)
  sizeof(Foo<Buf>[10]) = 420
  Foo::new [](size=420, foo=0)
  Foo::new [](size=420, foo=123)
  $
  

Local fix

• n/a
  

Problem summary

• USERS AFFECTED:
  Customers using array new operators may be affected by this
  issue.
  
  PROBLEM DESCRIPTION:
  Incorrect memory sizing is allocated when using new[] operator
  causing incorrect values reported by the sizeof() function.
  This was due to new[] operator being assigned as a regular
  member rather than a static member, which passed the wrong
  *this pointer to the parameters of the new[] operator.
  

Problem conclusion

• The compiler has been fixed so that the new[] operator is now a
  static member.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IV44606

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL C/C++ FOR AI

• Fixed component ID

  5725C7200

Applicable component levels

• RC10 PSY UP

     C