Add command line option to turn off precise access paths

Quick hack to allow turning of precise access paths via a command line
option. If this is still in the code in 2019 then shoot Chris Smowton
and Nathan Phillips for allowing me to do it.

Author: Owen Jones

src/driver/sec_driver_parse_options.cpp

@@ -60,6 +60,7 @@
 #include <taint-analysis/taint_security_scanner.h>
 
 #include <pointer-analysis/evs_pretty_printer.h>
+#include <pointer-analysis/local_value_set.h>
 
 #include "sec_driver_parse_options.h"
 
@@ -170,6 +171,11 @@ int sec_driver_parse_optionst::doit()
     return 6;
   }
 
+  if (cmdline.isset("do-not-use-precise-access-paths"))
+  {
+    local_value_sett::do_not_use_precise_access_paths = true;
+  }
+
   if (cmdline.isset("security-scanner"))
   {
     return taint_do_security_scan(

src/driver/sec_driver_parse_options.h

@@ -40,6 +40,7 @@ class optionst;
   "(lvsa-summary-directory):" \
   "(local-value-set-analysis)(show-value-sets)(lvsa-function):" \
   "(security-scanner):" \
+  "(do-not-use-precise-access-paths)" \
   "(rebuild-taint-cache)" \
   UI_MESSAGE_OPTIONS \
   JAVA_BYTECODE_LANGUAGE_OPTIONS \

src/pointer-analysis/external_value_set_expr.h

@@ -8,6 +8,7 @@
 
 #include <sstream>
 #include <util/std_expr.h>
+#include "local_value_set.h"
 
 // An access path entry, indicating that an external object
 // was accessed using e.g. member-x--of-dereference (written
@@ -167,6 +168,8 @@ class external_value_set_exprt : public exprt
 
   bool can_extend_to_precise() const
   {
+    if(local_value_sett::do_not_use_precise_access_paths)
+      return false;
 #ifdef DO_NOT_USE_PRECISE_EXTERNAL_VALUE_SETS
     return false;
 #else

src/pointer-analysis/local_value_set.cpp

@@ -18,6 +18,8 @@
 // For documentation of members of `local_value_sett`, see the corresponding
 // header file, `local_value_set.h`.
 
+bool local_value_sett::do_not_use_precise_access_paths = false;
+
 void local_value_sett::make_union_adjusting_evs_types(
   object_mapt &dest,
   const object_mapt &src,

src/pointer-analysis/local_value_set.h

@@ -17,13 +17,21 @@ class local_value_sett : public value_sett
 public:
   typedef value_sett baset;
 
+  /// Quick hack to allow turning of precise access paths via a command line
+  /// option. If this is still in the code in 2019 then shoot Chris Smowton
+  /// and Nathan Phillips for allowing me to do it.
+  static bool do_not_use_precise_access_paths;
+
+
   mutable bool precise_evs_curtailed_because_of_loop = false;
 
   /// Determines whether we should export precise or per_field external value
   /// sets in function summaries.
   /// \return
   bool should_export_precise_external_value_sets() const
   {
+    if(do_not_use_precise_access_paths)
+      return false;
 #ifdef DO_NOT_USE_PRECISE_EXTERNAL_VALUE_SETS
     return false;
 #else