if (VM.VerifyAssertions) VM.assert(IfCmp.conforms(cb));
if (VM.VerifyAssertions) VM._assert(IfCmp.conforms(cb));
  private static OPT_Diamond fourElementDiamond(OPT_BasicBlock top,                                                OPT_BasicBlock left,                                                OPT_BasicBlock right,                                                OPT_BasicBlock bottom) {        OPT_Instruction cb = top.firstBranchInstruction();    // for now we only support IfCmp diamonds.    if (VM.VerifyAssertions) VM.assert(IfCmp.conforms(cb));    OPT_BranchOperand takenTarget = IfCmp.getTarget(cb);    if (Label.getBlock(takenTarget.target).block == left) {      return new OPT_Diamond(top,left,right,bottom);    } else {      return new OPT_Diamond(top,right,left,bottom);    }  }