Merge pull request diffblue#271 from danpoe/fixes/dependence-graph-call-control-dependencies

Unconditional control dependency fix

Author: chrisr-diffblue

regression/goto-analyzer/dependence-graph15/main.c

@@ -0,0 +1,23 @@
+int f2(int, const int*);
+extern const int g_map[];
+
+int g_out1;
+int g_out2;
+
+extern int g_in;
+
+void main(void)
+{
+  int t1;
+  int t2;
+
+  t1 = g_in;
+  t2 = f2(t1, g_map);
+
+  if (t2 >= 0)
+    g_out1 = t2;
+  else
+    g_out1 = 0;
+
+  g_out2 = t1;
+}

regression/goto-analyzer/dependence-graph15/test.desc

@@ -0,0 +1,11 @@
+CORE
+main.c
+--show --dependence-graph
+activate-multi-line-match
+^EXIT=0$
+^SIGNAL=0$
+Control dependencies: [0-9]+ \[UNCONDITIONAL\]\n(.*\n){2,3}.*g_out2 = t1;
+Control dependencies: [0-9]+ \[TRUE\]\n(.*\n){2,3}.*g_out1 = t2;
+Control dependencies: [0-9]+ \[FALSE\]\n(.*\n){2,3}.*g_out1 = 0;
+--
+^warning: ignoring

src/analyses/dependence_graph.cpp

@@ -45,7 +45,8 @@ bool dep_graph_domaint::merge(
   changed|=merge_control_dependencies(
     src.control_deps,
     src.control_dep_candidates,
-    src.control_dep_calls);
+    src.control_dep_calls,
+    src.control_dep_call_candidates);
 
   has_changed=false;
   has_values=tvt::unknown();
@@ -71,19 +72,19 @@ void dep_graph_domaint::control_dependencies(
 
   // Add new candidates
 
+  PRECONDITION(!control_dep_call_candidates.empty());
+
   if(from->is_goto() || from->is_assume())
     control_dep_candidates.insert(from);
   else if(from->is_end_function())
   {
     control_deps.clear();
     control_dep_candidates.clear();
     control_dep_calls.clear();
+    control_dep_call_candidates.clear();
     return;
   }
 
-  if(control_dep_candidates.empty())
-    return;
-
   // Compute postdominators if needed
 
   const goto_functionst &goto_functions=dep_graph.goto_functions;
@@ -152,10 +153,18 @@ void dep_graph_domaint::control_dependencies(
       }
 
       control_deps.insert(std::make_pair(cd, branch));
-      control_dep_calls.clear();
     }
   }
 
+  if(control_deps.empty())
+  {
+    util_inplace_set_union(control_dep_calls, control_dep_call_candidates);
+  }
+  else
+  {
+    control_dep_calls.clear();
+  }
+
   // add edges to the graph
   for(const auto &c_dep : control_deps)
     dep_graph.add_dep(dep_edget::kindt::CTRL, c_dep.first, to);
@@ -264,7 +273,8 @@ void dep_graph_domaint::control_dependencies(
 bool dep_graph_domaint::merge_control_dependencies(
   const control_depst &other_control_deps,
   const control_dep_candidatest &other_control_dep_candidates,
-  const control_dep_callst &other_control_dep_calls)
+  const control_dep_callst &other_control_dep_calls,
+  const control_dep_callst &other_control_dep_call_candidates)
 {
   bool changed=false;
 
@@ -323,6 +333,16 @@ bool dep_graph_domaint::merge_control_dependencies(
 
   changed|=n!=control_dep_calls.size();
 
+  // Merge call control dependency candidates
+
+  n=control_dep_call_candidates.size();
+
+  control_dep_call_candidates.insert(
+      other_control_dep_call_candidates.begin(),
+      other_control_dep_call_candidates.end());
+
+  changed|=n!=control_dep_call_candidates.size();
+
   return changed;
 }
 
@@ -489,14 +509,18 @@ void dep_graph_domaint::transform(
       if(s->merge_control_dependencies(
            control_deps,
            control_dep_candidates,
-           control_dep_calls))
+           control_dep_calls,
+           control_dep_call_candidates))
         s->has_changed=true;
 
       control_deps.clear();
       control_dep_candidates.clear();
 
       control_dep_calls.clear();
       control_dep_calls.insert(from);
+
+      control_dep_call_candidates.clear();
+      control_dep_call_candidates.insert(from);
     }
   }
   else

src/analyses/dependence_graph.h

@@ -19,6 +19,7 @@ Date: August 2013
 
 #include <util/graph.h>
 #include <util/threeval.h>
+#include <util/container_utils.h>
 
 #include "ai.h"
 #include "cfg_dominators.h"
@@ -122,6 +123,7 @@ class dep_graph_domaint:public ai_domain_baset
     control_deps.clear();
     control_dep_candidates.clear();
     control_dep_calls.clear();
+    control_dep_call_candidates.clear();
     data_deps.clear();
   }
 
@@ -135,6 +137,7 @@ class dep_graph_domaint:public ai_domain_baset
     control_deps.clear();
     control_dep_candidates.clear();
     control_dep_calls.clear();
+    control_dep_call_candidates.clear();
     data_deps.clear();
   }
 
@@ -198,6 +201,7 @@ class dep_graph_domaint:public ai_domain_baset
 
   typedef std::set<goto_programt::const_targett> control_dep_callst;
   control_dep_callst control_dep_calls;
+  control_dep_callst control_dep_call_candidates;
 
   typedef std::map<goto_programt::const_targett, std::set<exprt>> data_depst;
   data_depst data_deps;
@@ -221,7 +225,8 @@ class dep_graph_domaint:public ai_domain_baset
   bool merge_control_dependencies(
     const control_depst &other_control_deps,
     const control_dep_candidatest &other_control_dep_candidates,
-    const control_dep_callst &other_control_dep_calls);
+    const control_dep_callst &other_control_dep_calls,
+    const control_dep_callst &other_control_dep_call_candidates);
 };
 
 class dependence_grapht: