[Bug c++/56419] New: [4.8 regression] transactions in for-loops disappear

["torvald at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56419

             Bug #: 56419
           Summary: [4.8 regression] transactions in for-loops disappear
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: torvald@gcc.gnu.org
                CC: aldyh@gcc.gnu.org, spear@cse.lehigh.edu


Transaction statements in for-loops don't show up in Gimple.  For example:

int x = 0;
int inc_func(int i) {
     for (int j = 0; j < i; ++j)
     {
         __transaction_atomic { x+=1; }
     }
     return 0;
}

g++ -v -O0 test.cc -c -fgnu-tm -fdump-tree-all -Wall
leads to the following test.cc.004t.gimple:

int inc_func(int) (int i)
{
  int D.2360;

  {
    int j;

    j = 0;
    goto <D.2358>;
    <D.2357>:
    j = j + 1;
    <D.2358>:
    if (j < i) goto <D.2357>; else goto <D.2355>;
    <D.2355>:
  }
  D.2360 = 0;
  return D.2360;
}

This does work when using the C frontend.  Seems to also work when the
transaction is in while loops or on an if-branch.  Doesn't seem to be sensitive
to which C++ standard is requested.

Originally reported by Mike Spear.  Mike says this works with 4.7.2, but
doesn't with g++ (GCC) 4.8.0 20130221 (experimental) (revision 
196192).  I've confirmed with an early-December build.