[PPL-devel] [GIT] ppl/ppl(master): Exploit new helper function least_significant_one_mask(),

[Enea Zaffanella]

Module: ppl/ppl
Branch: master
Commit: 73aee8ff7b811416d25b4c54344fbaa214ea7804
URL:    http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=73aee8ff7b811416d25b4c54344fbaa214ea7804

Author: Enea Zaffanella <zaffanella at cs.unipr.it>
Date:   Sat Feb 25 16:11:07 2012 +0100

Exploit new helper function least_significant_one_mask(),
thereby avoiding unary minus on unsigned integer values.
Detected by ECLAIR service utypflag.

---

 src/CO_Tree.inlines.hh |   19 ++++++++++---------
 1 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/CO_Tree.inlines.hh b/src/CO_Tree.inlines.hh
index ece7ab0..0032029 100644
--- a/src/CO_Tree.inlines.hh
+++ b/src/CO_Tree.inlines.hh
@@ -679,7 +679,7 @@ CO_Tree::tree_iterator::tree_iterator(CO_Tree& tree1, dimension_type i1)
   PPL_ASSERT(tree.reserved_size != 0);
   PPL_ASSERT(i1 <= tree.reserved_size + 1);
   i = i1;
-  offset = i & -i;
+  offset = least_significant_one_mask(i);
   PPL_ASSERT(OK());
 }
 
@@ -703,9 +703,7 @@ inline CO_Tree::tree_iterator&
 CO_Tree::tree_iterator::operator=(const iterator& itr) {
   PPL_ASSERT(itr != tree.end());
   i = tree.dfs_index(itr);
-  offset = i;
-  // This assumes two's complement encoding.
-  offset &= -i;
+  offset = least_significant_one_mask(i);
   return *this;
 }
 
@@ -762,9 +760,10 @@ CO_Tree::tree_iterator::follow_left_children_with_value() {
   p -= (offset - 1);
   while (*p == unused_index)
     ++p;
-  PPL_ASSERT(p >= tree.indexes);
-  i = static_cast<dimension_type>(p - tree.indexes);
-  offset = i & -i;
+  ptrdiff_t distance = p - tree.indexes;
+  PPL_ASSERT(distance >= 0);
+  i = static_cast<dimension_type>(distance);
+  offset = least_significant_one_mask(i);
   PPL_ASSERT(OK());
 }
 
@@ -776,8 +775,10 @@ CO_Tree::tree_iterator::follow_right_children_with_value() {
   p += (offset - 1);
   while (*p == unused_index)
     --p;
-  i = static_cast<dimension_type>(p - tree.indexes);
-  offset = i & -i;
+  ptrdiff_t distance = p - tree.indexes;
+  PPL_ASSERT(distance >= 0);
+  i = static_cast<dimension_type>(distance);
+  offset = least_significant_one_mask(i);
   PPL_ASSERT(OK());
 }