if (VM.VerifyAssertions) VM.assert (aBlock == bBlock);
if (VM.VerifyAssertions) VM._assert (aBlock == bBlock);
  private OPT_Instruction maxDominatorDepth (OPT_Instruction a,					     OPT_Instruction b)  {    OPT_BasicBlock aBlock = getBlock(a);    OPT_BasicBlock bBlock = getBlock(b);    int aDomDepth = dominator.depth(aBlock);    int bDomDepth = dominator.depth(bBlock);    if (aDomDepth > bDomDepth) return a;    if (aDomDepth < bDomDepth) return b;    if (VM.VerifyAssertions) VM.assert (aBlock == bBlock);        // if an instruction depends on a branch, it can not be placed in    // this block. Make sure we record this fact. We use this    // information in upto()    return a.isBranch() ? a : b;  }