[Bug middle-end/35545] New: virtual call specialization not happening with FDO

[xinliangli at gmail dot com]

In the following example, virtual calls via ap should be speciallized -- there
is one dominatating call target, but compiling the program at -O3 with
-fprofile-use, it does not happen.

g++ -O1 -fprofile-generate devirt.cc
./a.out
g++ -fprofile-use -O3 -fdump-tree-optimized devirt.cc


// devirt.cc

class A {
public:
  virtual int foo() {
     return 1;
  }

int i;
};

class B : public A
{
public:
  virtual int foo() {
     return 2;
  }

 int b;
} ;


int main()
{
 int i;

  A* ap = 0;

  for (i = 0; i < 10000; i++)
  {

     if (i%7==0)
     {
        ap = new A();
     }
     else
        ap = new B();

    ap->foo();

    delete ap;

  }

  return 0;

}


-- 
           Summary: virtual call specialization not happening with FDO
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: xinliangli at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35545