3 files changed, 31 insertions, 11 deletions

diff --git a/gcc/gimple-range-path.cc b/gcc/gimple-range-path.cc
index db15eb3..f4509b5 100644
--- a/gcc/gimple-range-path.cc
+++ b/gcc/gimple-range-path.cc
@@ -115,7 +115,7 @@ path_range_query::debug ()
 // Return the range of NAME at the end of the path being analyzed.
 
 bool
-path_range_query::range_of_expr (irange &r, tree name, gimple *stmt)
+path_range_query::internal_range_of_expr (irange &r, tree name, gimple *stmt)
 {
   if (!irange::supports_type_p (TREE_TYPE (name)))
     return false;
@@ -135,6 +135,25 @@ path_range_query::range_of_expr (irange &r, tree name, gimple *stmt)
   return true;
 }
 
+bool
+path_range_query::range_of_expr (irange &r, tree name, gimple *stmt)
+{
+  if (internal_range_of_expr (r, name, stmt))
+    {
+      if (r.undefined_p ())
+	m_undefined_path = true;
+
+      return true;
+    }
+  return false;
+}
+
+bool
+path_range_query::unreachable_path_p ()
+{
+  return m_undefined_path;
+}
+
 // Return the range of STMT at the end of the path being analyzed.
 // Anything but the final conditional in a BB will return VARYING.
 
@@ -345,6 +364,7 @@ path_range_query::precompute_ranges (const vec<basic_block> &path,
 {
   set_path (path);
   m_imports = imports;
+  m_undefined_path = false;
 
   if (DEBUG_SOLVER)
     {
diff --git a/gcc/gimple-range-path.h b/gcc/gimple-range-path.h
index 5177313..c75721f 100644
--- a/gcc/gimple-range-path.h
+++ b/gcc/gimple-range-path.h
@@ -41,10 +41,13 @@ public:
 			  const bitmap_head *imports);
   bool range_of_expr (irange &r, tree name, gimple * = NULL) override;
   bool range_of_stmt (irange &r, gimple *, tree name = NULL) override;
+  bool unreachable_path_p ();
   void dump (FILE *) override;
   void debug ();
 
 private:
+  bool internal_range_of_expr (irange &r, tree name, gimple *);
+
   // Cache manipulation.
   void set_cache (const irange &r, tree name);
   bool get_cache (irange &r, tree name);
@@ -82,6 +85,9 @@ private:
   const bitmap_head *m_imports;
   gimple_ranger &m_ranger;
   non_null_ref m_non_null;
+
+  // Set if there were any undefined expressions while pre-calculating path.
+  bool m_undefined_path;
 };
 
 #endif // GCC_TREE_SSA_THREADSOLVER_H
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c
index 6827d00..449232c 100644
--- a/gcc/tree-ssa-threadbackward.c
+++ b/gcc/tree-ssa-threadbackward.c
@@ -213,20 +213,14 @@ edge
 back_threader::find_taken_edge_cond (const vec<basic_block> &path,
 				     gcond *cond)
 {
-  m_solver.precompute_ranges (path, m_imports);
-
-  // Check if either operand is unreachable since this knowledge could
-  // help the caller cut down the search space.
   int_range_max r;
-  m_solver.range_of_expr (r, gimple_cond_lhs (cond));
-  if (r.undefined_p ())
-    return UNREACHABLE_EDGE;
-  m_solver.range_of_expr (r, gimple_cond_rhs (cond));
-  if (r.undefined_p ())
-    return UNREACHABLE_EDGE;
 
+  m_solver.precompute_ranges (path, m_imports);
   m_solver.range_of_stmt (r, cond);
 
+  if (m_solver.unreachable_path_p ())
+    return UNREACHABLE_EDGE;
+
   int_range<2> true_range (boolean_true_node, boolean_true_node);
   int_range<2> false_range (boolean_false_node, boolean_false_node);