5255 uts shouldn't open-code ISP2

*** 918,928 ****
  {
          int hb;
          int flist = 0;
          ASSERT(MUTEX_HELD(&vmp->vm_lock));
  
!         if ((size & (size - 1)) == 0)
                  flist = lowbit(P2ALIGN(vmp->vm_freemap, size));
          else if ((hb = highbit(size)) < VMEM_FREELISTS)
                  flist = lowbit(P2ALIGN(vmp->vm_freemap, 1UL << hb));
  
          return (flist);
--- 918,928 ----
  {
          int hb;
          int flist = 0;
          ASSERT(MUTEX_HELD(&vmp->vm_lock));
  
!         if (ISP2(size))
                  flist = lowbit(P2ALIGN(vmp->vm_freemap, size));
          else if ((hb = highbit(size)) < VMEM_FREELISTS)
                  flist = lowbit(P2ALIGN(vmp->vm_freemap, 1UL << hb));
  
          return (flist);
*** 957,968 ****
                  panic("vmem_xalloc(%p, %lu, %lu, %lu, %lu, %p, %p, %x): "
                      "overconstrained allocation",
                      (void *)vmp, size, align_arg, phase, nocross,
                      minaddr, maxaddr, vmflag);
  
!         if (phase >= align || (align & (align - 1)) != 0 ||
!             (nocross & (nocross - 1)) != 0)
                  panic("vmem_xalloc(%p, %lu, %lu, %lu, %lu, %p, %p, %x): "
                      "parameters inconsistent or invalid",
                      (void *)vmp, size, align_arg, phase, nocross,
                      minaddr, maxaddr, vmflag);
  
--- 957,967 ----
                  panic("vmem_xalloc(%p, %lu, %lu, %lu, %lu, %p, %p, %x): "
                      "overconstrained allocation",
                      (void *)vmp, size, align_arg, phase, nocross,
                      minaddr, maxaddr, vmflag);
  
!         if (phase >= align || !ISP2(align) || !ISP2(nocross))
                  panic("vmem_xalloc(%p, %lu, %lu, %lu, %lu, %p, %p, %x): "
                      "parameters inconsistent or invalid",
                      (void *)vmp, size, align_arg, phase, nocross,
                      minaddr, maxaddr, vmflag);
  
*** 992,1002 ****
                   * (3)  We're in the highest possible freelist, which is
                   *      always empty (e.g. the 4GB freelist on 32-bit systems);
                   *
                   * (4)  We're doing a best-fit or first-fit allocation.
                   */
!                 if ((size & (size - 1)) == 0) {
                          flist = lowbit(P2ALIGN(vmp->vm_freemap, size));
                  } else {
                          hb = highbit(size);
                          if ((vmp->vm_freemap >> hb) == 0 ||
                              hb == VMEM_FREELISTS ||
--- 991,1001 ----
                   * (3)  We're in the highest possible freelist, which is
                   *      always empty (e.g. the 4GB freelist on 32-bit systems);
                   *
                   * (4)  We're doing a best-fit or first-fit allocation.
                   */
!                 if (ISP2(size)) {
                          flist = lowbit(P2ALIGN(vmp->vm_freemap, size));
                  } else {
                          hb = highbit(size);
                          if ((vmp->vm_freemap >> hb) == 0 ||
                              hb == VMEM_FREELISTS ||
*** 1288,1298 ****
           * Unconstrained instant-fit allocation from the segment list.
           */
          mutex_enter(&vmp->vm_lock);
  
          if (vmp->vm_nsegfree >= VMEM_MINFREE || vmem_populate(vmp, vmflag)) {
!                 if ((size & (size - 1)) == 0)
                          flist = lowbit(P2ALIGN(vmp->vm_freemap, size));
                  else if ((hb = highbit(size)) < VMEM_FREELISTS)
                          flist = lowbit(P2ALIGN(vmp->vm_freemap, 1UL << hb));
          }
  
--- 1287,1297 ----
           * Unconstrained instant-fit allocation from the segment list.
           */
          mutex_enter(&vmp->vm_lock);
  
          if (vmp->vm_nsegfree >= VMEM_MINFREE || vmem_populate(vmp, vmflag)) {
!                 if (ISP2(size))
                          flist = lowbit(P2ALIGN(vmp->vm_freemap, size));
                  else if ((hb = highbit(size)) < VMEM_FREELISTS)
                          flist = lowbit(P2ALIGN(vmp->vm_freemap, 1UL << hb));
          }