Catch exceptions by const-reference

Exceptions caught by value incur needless cost in C++, most of them can
be caught by const-reference, especially as nearly none are actually
used. This could allow compiler generate a slightly more efficient code.

src/tactic/arith/bv2real_rewriter.cpp

@@ -89,7 +89,7 @@ bool bv2real_util::contains_bv2real(expr* e) const {
     try {
         for_each_expr(p, e);
     }
-    catch (contains_bv2real_proc::found) {
+    catch (const contains_bv2real_proc::found &) {
         return true;
     }
     return false;

src/tactic/arith/fix_dl_var_tactic.cpp

@@ -226,7 +226,7 @@ class fix_dl_var_tactic : public tactic {
                 }
                 return most_occs();
             }
-            catch (failed) {
+            catch (const failed &) {
                 return nullptr;
             }
         }

src/tactic/arith/lia2pb_tactic.cpp

@@ -156,7 +156,7 @@ class lia2pb_tactic : public tactic {
                 }
                 return true;
             }
-            catch (failed) {
+            catch (const failed &) {
                 return false;
             }
         }

src/tactic/arith/pb2bv_tactic.cpp

@@ -1034,7 +1034,7 @@ struct is_pb_probe : public probe {
             
             return true;
         }
-        catch (pb2bv_tactic::non_pb) {
+        catch (const pb2bv_tactic::non_pb &) {
             return false;
         }
     }

src/tactic/bv/bv1_blaster_tactic.cpp

@@ -371,7 +371,7 @@ class bv1_blaster_tactic : public tactic {
                     for_each_expr_core<visitor, expr_fast_mark1, false, true>(proc, visited, f);
                 }
             }
-            catch (not_target) {
+            catch (const not_target &) {
                 return false;
             }
             return true;

src/tactic/goal.h

@@ -195,7 +195,7 @@ bool test(goal const & g, Predicate & proc) {
         for (unsigned i = 0; i < sz; i++)
             quick_for_each_expr(proc, visited, g.form(i));
     }
-    catch (typename Predicate::found) {
+    catch (const typename Predicate::found &) {
         return true;
     }
     return false;

src/tactic/probe.cpp

@@ -524,7 +524,7 @@ public:
             }
             return false;
         }
-        catch (found) {
+        catch (const found &) {
             return true;
         }
     }
@@ -554,7 +554,7 @@ public:
             }
             return false;
         }
-        catch (found) {
+        catch (const found &) {
             return true;
         }
     }

src/tactic/ufbv/ufbv_rewriter.cpp

@@ -870,7 +870,7 @@ bool ufbv_rewriter::match_subst::match_args(app * lhs, expr * const * args) {
                 m_cache.insert(p);
                 continue;
             }
-            catch (match_args_aux_proc::no_match) {
+            catch (const match_args_aux_proc::no_match &) {
                 return false;
             }
         }