Error handling cleanup in solvers/flattening

Author: danpoe

src/solvers/flattening/boolbv.cpp

@@ -113,7 +113,9 @@ bool boolbvt::literal(
   throw "found no literal for expression";
 }
 
-const bvt &boolbvt::convert_bv(const exprt &expr)
+const bvt &boolbvt::convert_bv(
+  const exprt &expr,
+  optionalt<std::size_t> expected_width)
 {
   // check cache first
   std::pair<bv_cachet::iterator, bool> cache_result=
@@ -126,18 +128,21 @@ const bvt &boolbvt::convert_bv(const exprt &expr)
   // Iterators into hash_maps supposedly stay stable
   // even though we are inserting more elements recursively.
 
-  cache_result.first->second=convert_bitvector(expr);
+  const bvt &bv = convert_bitvector(expr);
+  CHECK_RETURN(!expected_width || bv.size() == *expected_width);
+
+  cache_result.first->second = bv;
 
   // check
   forall_literals(it, cache_result.first->second)
   {
     if(freeze_all && !it->is_constant())
       prop.set_frozen(*it);
-    if(it->var_no()==literalt::unused_var_no())
-    {
-      error() << "unused_var_no: " << expr.pretty() << eom;
-      assert(false);
-    }
+
+    INVARIANT(
+      it->var_no() != literalt::unused_var_no(),
+      "variable number must be different from the unused variable number",
+      expr.pretty());
   }
 
   return cache_result.first->second;

src/solvers/flattening/boolbv.h

@@ -17,6 +17,7 @@ Author: Daniel Kroening, [email protected]
 #include <util/mp_arith.h>
 #include <util/expr.h>
 #include <util/byte_operators.h>
+#include <util/optional.h>
 
 #include "bv_utils.h"
 #include "boolbv_width.h"
@@ -43,7 +44,10 @@ class boolbvt:public arrayst
   {
   }
 
-  virtual const bvt &convert_bv(const exprt &expr); // check cache
+  virtual const bvt &convert_bv( // check cache
+    const exprt &expr,
+    const optionalt<std::size_t> expected_width = nullopt);
+
   virtual bvt convert_bitvector(const exprt &expr); // no cache
 
   // overloading

src/solvers/flattening/boolbv_add_sub.cpp

@@ -15,6 +15,10 @@ Author: Daniel Kroening, [email protected]
 
 bvt boolbvt::convert_add_sub(const exprt &expr)
 {
+  PRECONDITION(
+    expr.id() == ID_plus || expr.id() == ID_minus ||
+    expr.id() == "no-overflow-plus" || expr.id() == "no-overflow-minus");
+
   const typet &type=ns.follow(expr.type());
 
   if(type.id()!=ID_unsignedbv &&
@@ -33,17 +37,15 @@ bvt boolbvt::convert_add_sub(const exprt &expr)
 
   const exprt::operandst &operands=expr.operands();
 
-  if(operands.empty())
-    throw "operator "+expr.id_string()+" takes at least one operand";
+  DATA_INVARIANT(
+    !operands.empty(),
+    "operator " + expr.id_string() + " takes at least one operand");
 
   const exprt &op0=expr.op0();
   DATA_INVARIANT(
     op0.type() == type, "add/sub with mixed types:\n" + expr.pretty());
 
-  bvt bv=convert_bv(op0);
-
-  if(bv.size()!=width)
-    throw "convert_add_sub: unexpected operand 0 width";
+  bvt bv=convert_bv(op0, width);
 
   bool subtract=(expr.id()==ID_minus ||
                  expr.id()=="no-overflow-minus");
@@ -67,19 +69,18 @@ bvt boolbvt::convert_add_sub(const exprt &expr)
     DATA_INVARIANT(
       it->type() == type, "add/sub with mixed types:\n" + expr.pretty());
 
-    const bvt &op=convert_bv(*it);
-
-    if(op.size()!=width)
-      throw "convert_add_sub: unexpected operand width";
+    const bvt &op=convert_bv(*it, width);
 
     if(type.id()==ID_vector || type.id()==ID_complex)
     {
-      const typet &subtype=ns.follow(type.subtype());
+      //const typet &subtype=ns.follow(type.subtype());
 
-      std::size_t sub_width=boolbv_width(subtype);
+      std::size_t sub_width=boolbv_width(type.subtype());
 
-      if(sub_width==0 || width%sub_width!=0)
-        throw "convert_add_sub: unexpected vector operand width";
+      INVARIANT(sub_width != 0, "vector elements shall have nonzero bit width");
+      INVARIANT(
+        width % sub_width == 0,
+        "total vector bit width shall be a multiple of the element bit width");
 
       std::size_t size=width/sub_width;
       bv.resize(width);
@@ -91,34 +92,39 @@ bvt boolbvt::convert_add_sub(const exprt &expr)
 
         for(std::size_t j=0; j<tmp_op.size(); j++)
         {
-          assert(i*sub_width+j<op.size());
-          tmp_op[j]=op[i*sub_width+j];
+          const std::size_t index = i * sub_width + j;
+          INVARIANT(index < op.size(), "bit index shall be within bounds");
+          tmp_op[j] = op[index];
         }
 
         bvt tmp_result;
         tmp_result.resize(sub_width);
 
         for(std::size_t j=0; j<tmp_result.size(); j++)
         {
-          assert(i*sub_width+j<bv.size());
-          tmp_result[j]=bv[i*sub_width+j];
+          const std::size_t index = i * sub_width + j;
+          INVARIANT(index < bv.size(), "bit index shall be within bounds");
+          tmp_result[j] = bv[index];
         }
 
         if(type.subtype().id()==ID_floatbv)
         {
           // needs to change due to rounding mode
-          float_utilst float_utils(prop, to_floatbv_type(subtype));
+          float_utilst float_utils(prop, to_floatbv_type(type.subtype()));
           tmp_result=float_utils.add_sub(tmp_result, tmp_op, subtract);
         }
         else
           tmp_result=bv_utils.add_sub(tmp_result, tmp_op, subtract);
 
-        assert(tmp_result.size()==sub_width);
+        INVARIANT(
+          tmp_result.size() == sub_width,
+          "applying the add/sub operation shall not change the bitwidth");
 
         for(std::size_t j=0; j<tmp_result.size(); j++)
         {
-          assert(i*sub_width+j<bv.size());
-          bv[i*sub_width+j]=tmp_result[j];
+          const std::size_t index = i * sub_width + j;
+          INVARIANT(index < bv.size(), "bit index shall be within bounds");
+          bv[index] = tmp_result[j];
         }
       }
     }

src/solvers/flattening/boolbv_array.cpp

@@ -6,9 +6,10 @@ Author: Daniel Kroening, [email protected]
 
 \*******************************************************************/
 
-
 #include "boolbv.h"
 
+#include <util/invariant.h>
+
 bvt boolbvt::convert_array(const exprt &expr)
 {
   std::size_t width=boolbv_width(expr.type());
@@ -18,20 +19,19 @@ bvt boolbvt::convert_array(const exprt &expr)
 
   if(expr.type().id()==ID_array)
   {
-    assert(expr.has_operands());
+    DATA_INVARIANT(
+      expr.has_operands(),
+      "the bit width being nonzero implies that the array has a nonzero size "
+      "in which case the array shall have operands");
     const exprt::operandst &operands=expr.operands();
-    assert(!operands.empty());
     std::size_t op_width=width/operands.size();
 
     bvt bv;
     bv.reserve(width);
 
     forall_expr(it, operands)
     {
-      const bvt &tmp=convert_bv(*it);
-
-      if(tmp.size()!=op_width)
-        throw "convert_array: unexpected operand width";
+      const bvt &tmp=convert_bv(*it, op_width);
 
       forall_literals(it2, tmp)
         bv.push_back(*it2);

src/solvers/flattening/boolbv_array_of.cpp

@@ -9,12 +9,13 @@ Author: Daniel Kroening, [email protected]
 #include "boolbv.h"
 
 #include <util/arith_tools.h>
+#include <util/invariant.h>
 #include <util/std_types.h>
 
 bvt boolbvt::convert_array_of(const array_of_exprt &expr)
 {
-  if(expr.type().id()!=ID_array)
-    throw "array_of must be array-typed";
+  DATA_INVARIANT(
+    expr.type().id() == ID_array, "array_of expression shall have array type");
 
   const array_typet &array_type=to_array_type(expr.type());
 
@@ -42,21 +43,25 @@ bvt boolbvt::convert_array_of(const array_of_exprt &expr)
 
   const bvt &tmp=convert_bv(expr.op0());
 
+  INVARIANT(
+    size * tmp.size() == width,
+    "total array bit width shall equal the number of elements times the "
+    "element bit with");
+
   bvt bv;
   bv.resize(width);
 
-  if(size*tmp.size()!=width)
-    throw "convert_array_of: unexpected operand width";
-
-  std::size_t offset=0;
+  auto b_it = tmp.begin();
 
-  for(mp_integer i=0; i<size; i=i+1)
+  for(auto &b : bv)
   {
-    for(std::size_t j=0; j<tmp.size(); j++, offset++)
-      bv[offset]=tmp[j];
-  }
+    b = *b_it;
 
-  assert(offset==bv.size());
+    b_it++;
+
+    if(b_it == tmp.end())
+      b_it = tmp.begin();
+  }
 
   return bv;
 }

src/solvers/flattening/boolbv_byte_update.cpp

@@ -9,19 +9,16 @@ Author: Daniel Kroening, [email protected]
 #include "boolbv.h"
 
 #include <iostream>
-#include <cassert>
 
 #include <util/arith_tools.h>
 #include <util/byte_operators.h>
+#include <util/invariant.h>
 
 #include "bv_endianness_map.h"
 
 bvt boolbvt::convert_byte_update(const byte_update_exprt &expr)
 {
-  if(expr.operands().size()!=3)
-    throw "byte_update takes three operands";
-
-  const exprt &op=expr.op0();
+  const exprt &op=expr.op();
   const exprt &offset_expr=expr.offset();
   const exprt &value=expr.value();
 
@@ -70,8 +67,11 @@ bvt boolbvt::convert_byte_update(const byte_update_exprt &expr)
           size_t index_op=map_op.map_bit(offset_i+i);
           size_t index_value=map_value.map_bit(i);
 
-          assert(index_op<bv.size());
-          assert(index_value<value_bv.size());
+          INVARIANT(
+            index_op < bv.size(), "bit vector index shall be within bounds");
+          INVARIANT(
+            index_value < value_bv.size(),
+            "bit vector index shall be within bounds");
 
           bv[index_op]=value_bv[index_value];
         }

src/solvers/flattening/boolbv_case.cpp

@@ -12,6 +12,8 @@ Author: Daniel Kroening, [email protected]
 
 bvt boolbvt::convert_case(const exprt &expr)
 {
+  PRECONDITION(expr.id() == ID_case);
+
   const std::vector<exprt> &operands=expr.operands();
 
   std::size_t width=boolbv_width(expr.type());
@@ -26,11 +28,11 @@ bvt boolbvt::convert_case(const exprt &expr)
   Forall_literals(it, bv)
     *it=prop.new_variable();
 
-  if(operands.size()<3)
-    throw "case takes at least three operands";
+  DATA_INVARIANT(
+    operands.size() >= 3, "case should have at least three operands");
 
-  if((operands.size()%2)!=1)
-    throw "number of case operands must be odd";
+  DATA_INVARIANT(
+    operands.size() % 2 == 1, "number of case operands should be odd");
 
   enum { FIRST, COMPARE, VALUE } what=FIRST;
   bvt compare_bv;
@@ -81,7 +83,7 @@ bvt boolbvt::convert_case(const exprt &expr)
       break;
 
     default:
-      assert(false);
+      UNREACHABLE;
     }
   }
 

src/solvers/flattening/boolbv_complex.cpp

@@ -6,11 +6,14 @@ Author: Daniel Kroening, [email protected]
 
 \*******************************************************************/
 
-
 #include "boolbv.h"
 
+#include <util/invariant.h>
+
 bvt boolbvt::convert_complex(const exprt &expr)
 {
+  PRECONDITION(expr.id() == ID_complex);
+
   std::size_t width=boolbv_width(expr.type());
 
   if(width==0)
@@ -29,10 +32,7 @@ bvt boolbvt::convert_complex(const exprt &expr)
 
       forall_expr(it, operands)
       {
-        const bvt &tmp=convert_bv(*it);
-
-        if(tmp.size()!=op_width)
-          throw "convert_complex: unexpected operand width";
+        const bvt &tmp=convert_bv(*it, op_width);
 
         forall_literals(it2, tmp)
           bv.push_back(*it2);
@@ -47,6 +47,8 @@ bvt boolbvt::convert_complex(const exprt &expr)
 
 bvt boolbvt::convert_complex_real(const exprt &expr)
 {
+  PRECONDITION(expr.id() == ID_complex_real);
+
   std::size_t width=boolbv_width(expr.type());
 
   if(width==0)
@@ -57,14 +59,16 @@ bvt boolbvt::convert_complex_real(const exprt &expr)
 
   bvt bv=convert_bv(expr.op0());
 
-  assert(bv.size()==width*2);
+  INVARIANT(bv.size() == width * 2, "");
   bv.resize(width); // chop
 
   return bv;
 }
 
 bvt boolbvt::convert_complex_imag(const exprt &expr)
 {
+  PRECONDITION(expr.id() == ID_complex_imag);
+
   std::size_t width=boolbv_width(expr.type());
 
   if(width==0)
@@ -75,7 +79,7 @@ bvt boolbvt::convert_complex_imag(const exprt &expr)
 
   bvt bv=convert_bv(expr.op0());
 
-  assert(bv.size()==width*2);
+  INVARIANT(bv.size() == width * 2, "");
   bv.erase(bv.begin(), bv.begin()+width);
 
   return bv;