Fix a nullptr access in the DPDK back end.

backends/dpdk/backend.cpp

@@ -32,6 +32,7 @@ limitations under the License.
 #include "midend/eliminateTypedefs.h"
 #include "midend/removeComplexExpressions.h"
 #include "midend/simplifyKey.h"
+
 namespace DPDK {
 
 void DpdkBackend::convert(const IR::ToplevelBlock *tlb) {
@@ -129,29 +130,40 @@ void DpdkBackend::convert(const IR::ToplevelBlock *tlb) {
     };
     simplify.addDebugHook(hook, true);
     program = program->apply(simplify);
-    ordered_set<cstring> used_fields;
+    if (errorCount() > 0) {
+        return;
+    }
+
     dpdk_program = convertToDpdk->getDpdkProgram();
-    if (!dpdk_program) return;
+    if (dpdk_program == nullptr) {
+        return;
+    }
+
+    PassManager postCodeGen;
+    ordered_map<cstring, cstring> newNameMap;
+    ordered_set<cstring> usedFields;
     if (structure.p4arch == "pna") {
-        PassManager post_code_gen = {
+        postCodeGen.addPasses({
             new PrependPassRecircId(),
             new DirectionToRegRead(),
-        };
-        dpdk_program = dpdk_program->apply(post_code_gen)->to<IR::DpdkAsmProgram>();
+        });
     }
-    ordered_map<cstring, cstring> newNameMap;
-    PassManager post_code_gen = {
+    postCodeGen.addPasses({
         new EliminateUnusedAction(),
         new DpdkAsmOptimization,
         new CopyPropagationAndElimination(typeMap),
-        new CollectUsedMetadataField(used_fields),
-        new RemoveUnusedMetadataFields(used_fields),
+        new CollectUsedMetadataField(usedFields),
+        new RemoveUnusedMetadataFields(usedFields),
         new ShortenTokenLength(newNameMap),
         new EmitDpdkTableConfig(refMap, typeMap, newNameMap),
-    };
-
-    dpdk_program = dpdk_program->apply(post_code_gen)->to<IR::DpdkAsmProgram>();
+    });
+    const auto *optimizedProgram = dpdk_program->apply(postCodeGen);
+    if (errorCount() > 0) {
+        return;
+    }
+    dpdk_program = optimizedProgram->to<IR::DpdkAsmProgram>();
 }
 
 void DpdkBackend::codegen(std::ostream &out) const { dpdk_program->toSpec(out) << std::endl; }
+
 }  // namespace DPDK

backends/dpdk/dpdkArch.cpp

@@ -1566,6 +1566,11 @@ cstring CopyMatchKeysToSingleStruct::getTableKeyName(const IR::Expression *e) {
 }
 
 const IR::Node *CopyMatchKeysToSingleStruct::preorder(IR::Key *keys) {
+    // If copyNeeded is false at this point, it means the keys are from same struct.
+    // Check remaining conditions to see if the copy is needed or not
+    // TODO: This indirection should not be needed. Instead of using a visitor for IR::KeyElement
+    // just resolve each key element directly.
+    metaCopyNeeded = false;
     // If any key field is from different structure, put all keys in metadata
     LOG3("Visiting " << keys);
     bool copyNeeded = false;
@@ -1645,10 +1650,6 @@ const IR::Node *CopyMatchKeysToSingleStruct::preorder(IR::Key *keys) {
     } else {
         structure->table_type_map.emplace(table->name.name, InternalTableType::WILDCARD);
     }
-
-    // If copyNeeded is false at this point, it means the keys are from same struct.
-    // Check remaining conditions to see if the copy is needed or not
-    metaCopyNeeded = false;
     if (copyNeeded) contiguous = false;
 
     if (!contiguous &&
@@ -1670,6 +1671,7 @@ const IR::Node *CopyMatchKeysToSingleStruct::preorder(IR::Key *keys) {
     }
     return keys;
 }
+
 const IR::Node *CopyMatchKeysToSingleStruct::postorder(IR::KeyElement *element) {
     // If we got here we need to put the key element in metadata.
     LOG3("Extracting key element " << element);

backends/dpdk/dpdkArch.h

@@ -826,7 +826,7 @@ struct keyInfo {
 class CopyMatchKeysToSingleStruct : public P4::KeySideEffect {
     IR::IndexedVector<IR::Declaration> decls;
     DpdkProgramStructure *structure;
-    bool metaCopyNeeded;
+    bool metaCopyNeeded = false;
 
  public:
     CopyMatchKeysToSingleStruct(P4::ReferenceMap *refMap, P4::TypeMap *typeMap,