BMC: deduplicate property encoding

This removes the duplicated code for encoding temporal operators for
word-level BMC from wl_instantiatet.

Author: kroening

src/temporal-logic/normalize_property.cpp

@@ -9,6 +9,7 @@ Author: Daniel Kroening, dkr@amazon.com
 #include "normalize_property.h"
 
 #include <util/arith_tools.h>
+#include <util/mathematical_types.h>
 #include <util/std_expr.h>
 
 #include <verilog/sva_expr.h>
@@ -75,9 +76,8 @@ exprt normalize_pre_implies(implies_exprt expr)
 exprt normalize_pre_sva_overlapped_implication(
   sva_overlapped_implication_exprt expr)
 {
-  // Same as regular implication if lhs and rhs are not
-  // sequences.
-  if(!is_SVA_sequence(expr.lhs()) && !is_SVA_sequence(expr.rhs()))
+  // Same as regular implication if lhs is not a sequence.
+  if(!is_SVA_sequence(expr.lhs()))
     return or_exprt{not_exprt{expr.lhs()}, expr.rhs()};
   else
     return std::move(expr);
@@ -86,9 +86,9 @@ exprt normalize_pre_sva_overlapped_implication(
 exprt normalize_pre_sva_non_overlapped_implication(
   sva_non_overlapped_implication_exprt expr)
 {
-  // Same as a->Xb if lhs and rhs are not sequences.
-  if(!is_SVA_sequence(expr.lhs()) && !is_SVA_sequence(expr.rhs()))
-    return or_exprt{not_exprt{expr.lhs()}, X_exprt{expr.rhs()}};
+  // Same as a->nexttime b if lhs is not a sequence.
+  if(!is_SVA_sequence(expr.lhs()))
+    return or_exprt{not_exprt{expr.lhs()}, sva_nexttime_exprt{expr.rhs()}};
   else
     return std::move(expr);
 }
@@ -125,13 +125,14 @@ exprt normalize_pre_sva_cycle_delay(sva_cycle_delay_exprt expr)
       expr.from().is_constant() &&
       numeric_cast_v<mp_integer>(to_constant_expr(expr.from())) == 0)
     {
-      // ##[0:$] φ --> F φ
-      return F_exprt{expr.op()};
+      // ##[0:$] φ --> s_eventually φ
+      return sva_s_eventually_exprt{expr.op()};
     }
     else
     {
-      // ##[i:$] φ --> ##i F φ
-      return sva_cycle_delay_exprt{expr.from(), F_exprt{expr.op()}};
+      // ##[i:$] φ --> always[i:i] s_eventually φ
+      return sva_ranged_always_exprt{
+        expr.from(), expr.from(), sva_s_eventually_exprt{expr.op()}};
     }
   }
   else
@@ -171,11 +172,13 @@ exprt normalize_property(exprt expr)
     expr = normalize_pre_sva_or(to_sva_or_expr(expr));
   else if(expr.id() == ID_sva_nexttime)
   {
-    expr = X_exprt{to_sva_nexttime_expr(expr).op()};
+    auto one = natural_typet{}.one_expr();
+    expr = sva_ranged_always_exprt{one, one, to_sva_nexttime_expr(expr).op()};
   }
   else if(expr.id() == ID_sva_s_nexttime)
   {
-    expr = X_exprt{to_sva_s_nexttime_expr(expr).op()};
+    auto one = natural_typet{}.one_expr();
+    expr = sva_ranged_always_exprt{one, one, to_sva_s_nexttime_expr(expr).op()};
   }
   else if(expr.id() == ID_sva_indexed_nexttime)
   {
@@ -195,6 +198,16 @@ exprt normalize_property(exprt expr)
     expr = F_exprt{X_exprt{to_sva_cycle_delay_plus_expr(expr).op()}};
   else if(expr.id() == ID_sva_cycle_delay_star)
     expr = F_exprt{to_sva_cycle_delay_star_expr(expr).op()};
+  else if(expr.id() == ID_sva_sequence_concatenation)
+  {
+    auto &sequence_concatenation = to_sva_sequence_concatenation_expr(expr);
+    if(!is_SVA_sequence(sequence_concatenation.lhs()))
+    {
+      // a ##0 b --> a && b if a is not a sequence
+      expr =
+        and_exprt{sequence_concatenation.lhs(), sequence_concatenation.rhs()};
+    }
+  }
   else if(expr.id() == ID_sva_if)
   {
     auto &sva_if_expr = to_sva_if_expr(expr);

src/temporal-logic/normalize_property.h

@@ -12,38 +12,47 @@ Author: Daniel Kroening, dkr@amazon.com
 #include <util/expr.h>
 
 /// This applies the following rewrites:
+///
 /// cover(φ) --> G¬φ
+///
+/// -----Propositional-----
 /// ¬(a ∨ b) --> ¬a ∧ ¬b
 /// ¬(a ∧ b) --> ¬a ∨ ¬b
 /// (a -> b) --> ¬a ∨ b
+///
+/// -----SVA-----
 /// a sva_iff b --> a <-> b
 /// a sva_implies b --> a -> b
 /// sva_not a --> ¬a
-/// a sva_and b --> a ∧ b                       if a and b are not SVA sequences
-/// a sva_or b --> a ∨ b                        if a and b are not SVA sequences
-/// sva_overlapped_implication --> ¬a ∨ b       if a and b are not SVA sequences
-/// sva_non_overlapped_implication --> ¬a ∨ Xb  if a and b are not SVA sequences
+/// a sva_and b --> a ∧ b                                   if a and b are not SVA sequences
+/// a sva_or b --> a ∨ b                                    if a and b are not SVA sequences
+/// sva_overlapped_implication --> ¬a ∨ b                   if a is not an SVA sequence
+/// sva_non_overlapped_implication --> ¬a ∨ sva_nexttime b  if a is not an SVA sequence
 /// sva_nexttime φ --> Xφ
 /// sva_nexttime[i] φ --> sva_always[i:i] φ
 /// sva_s_nexttime φ --> Xφ
 /// sva_s_nexttime[i] φ --> sva_s_always[i:i] φ
 /// sva_if --> ? :
+/// ##[0:$] φ --> s_eventually φ
+/// ##[i:$] φ --> s_nexttime[i] s_eventually φ
+/// ##[*] φ --> F φ
+/// ##[+] φ --> X F φ
+/// strong(φ) --> φ
+/// weak(φ) --> φ
+/// sva_case --> ? :
 /// a sva_disable_iff b --> a ∨ b
 /// a sva_accept_on b --> a ∨ b
 /// a sva_reject_on b --> ¬a ∧ b
 /// a sva_sync_accept_on b --> a ∨ b
 /// a sva_sync_reject_on b --> ¬a ∧ b
 /// ¬ sva_s_eventually φ --> sva_always ¬φ
 /// ¬ sva_always φ --> sva_s_eventually ¬φ
+///
+/// ----LTL-----
 /// ¬Xφ --> X¬φ
 /// ¬¬φ --> φ
 /// ¬Gφ --> F¬φ
 /// ¬Fφ --> G¬φ
-/// ##[*] φ --> F φ
-/// ##[+] φ --> X F φ
-/// strong(φ) --> φ
-/// weak(φ) --> φ
-/// sva_case --> ? :
 exprt normalize_property(exprt);
 
 #endif

src/temporal-logic/temporal_logic.cpp

@@ -85,9 +85,10 @@ bool is_SVA_operator(const exprt &expr)
          id == ID_sva_sync_accept_on || id == ID_sva_sync_reject_on ||
          id == ID_sva_always || id == ID_sva_ranged_always ||
          id == ID_sva_nexttime || id == ID_sva_s_nexttime ||
-         id == ID_sva_until || id == ID_sva_s_until ||
-         id == ID_sva_until_with || id == ID_sva_s_until_with ||
-         id == ID_sva_eventually || id == ID_sva_s_eventually ||
+         id == ID_sva_indexed_nexttime || id == ID_sva_until ||
+         id == ID_sva_s_until || id == ID_sva_until_with ||
+         id == ID_sva_s_until_with || id == ID_sva_eventually ||
+         id == ID_sva_s_eventually || id == ID_sva_ranged_s_eventually ||
          id == ID_sva_cycle_delay || id == ID_sva_overlapped_followed_by ||
          id == ID_sva_nonoverlapped_followed_by;
 }

src/trans-word-level/Makefile

@@ -1,12 +1,13 @@
-SRC = get_trans.cpp \
+SRC = counterexample_word_level.cpp \
+      get_trans.cpp \
+      obligations.cpp \
+      property.cpp \
+      trans_trace_word_level.cpp \
+      instantiate_word_level.cpp \
       show_modules.cpp \
       show_module_hierarchy.cpp \
       unwind.cpp \
-      word_level_trans.cpp \
-      property.cpp \
-      counterexample_word_level.cpp \
-      trans_trace_word_level.cpp \
-      instantiate_word_level.cpp
+      word_level_trans.cpp
 
 include ../config.inc
 include ../common