[P4_Symbolic] Create symbolic variables and add constraints for symbolic table entries.

p4_symbolic/ir/ir.proto

@@ -512,6 +512,9 @@ message SymbolicTableEntry {
   //     https://p4.org/p4-spec/p4runtime/v1.3.0/P4Runtime-Spec.html#sec-match-format
   //   - To specify a symbolic match, provide a concrete match name without any
   //     values.
+  //   - For the prefix lengths in symbolic LPM matches, any negative value
+  //     denotes a symbolic prefix length and a non-negative value represents a
+  //     concrete prefix length value.
   //   - The `priority` must be concrete. It must be strictly positive if there
   //     are range, ternary, or optional matches, and must be zero if there are
   //     only LPM or exact matches.

p4_symbolic/symbolic/symbolic.cc

@@ -23,13 +23,16 @@
 #include <vector>
 
 #include "absl/cleanup/cleanup.h"
+#include "absl/container/btree_map.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
 #include "glog/logging.h"
 #include "gutil/status.h"
 #include "p4/v1/p4runtime.pb.h"
 #include "p4_pdpi/internal/ordered_map.h"
+#include "p4_pdpi/ir.pb.h"
 #include "p4_symbolic/ir/ir.h"
 #include "p4_symbolic/ir/ir.pb.h"
 #include "p4_symbolic/ir/parser.h"
@@ -46,6 +49,19 @@ namespace symbolic {
 
 namespace {
 
+// Returns a pointer to the P4-Symbolic IR table with the given `table_name`
+// from the `program` IR. The returned pointer would not be null when the status
+// is ok.
+absl::StatusOr<const ir::Table *> GetIrTable(const ir::P4Program &program,
+                                             absl::string_view table_name) {
+  auto it = program.tables().find(table_name);
+  if (it == program.tables().end()) {
+    return gutil::NotFoundErrorBuilder()
+           << "Table '" << table_name << "' not found";
+  }
+  return &it->second;
+}
+
 // Initializes the table entry objects in the symbolic context based on the
 // given `ir_entries`. For symbolic table entries, symbolic variables and their
 // corresponding constraints will be created within the given solver context.
@@ -69,6 +85,35 @@ absl::Status InitializeTableEntries(SolverState &state,
     }
   }
 
+  // For each symbolic table entry object in each table, create respective
+  // symbolic variables and add corresponding constraints as Z3 assertions.
+  for (auto &[table_name, table_entries] : state.context.table_entries) {
+    ASSIGN_OR_RETURN(const ir::Table *table,
+                     GetIrTable(state.program, table_name));
+
+    for (TableEntry &entry : table_entries) {
+      // Skip concrete table entries.
+      if (entry.IsConcrete()) continue;
+
+      // Initialize the symbolic match fields of the current entry.
+      RETURN_IF_ERROR(InitializeSymbolicMatches(
+          entry, *table, state.program, *state.context.z3_context,
+          *state.solver, state.translator));
+
+      // Entries with symbolic action sets are not supported for now.
+      if (table->table_definition().has_action_profile_id()) {
+        return gutil::UnimplementedErrorBuilder()
+               << "Table entries with symbolic action sets are not supported "
+                  "at the moment.";
+      }
+
+      // Initialize the symbolic actions of the current entry.
+      RETURN_IF_ERROR(InitializeSymbolicActions(
+          entry, *table, state.program, *state.context.z3_context,
+          *state.solver, state.translator));
+    }
+  }
+
   return absl::OkStatus();
 }