Improved check of entries in key-less tables (#5310)

Signed-off-by: Denis Matousek <[email protected]>

Author: dmatousek

frontends/p4/entryPriorities.cpp

@@ -70,6 +70,9 @@ const IR::Node *EntryPriorities::preorder(IR::EntriesList *entries) {
     // check to see if priorities are required or allowed
     bool requiresPriorities = false;
     auto key = table->getKey();
+    if (!key || key->keyElements.empty()) {
+        return entries;
+    }
     for (auto element : key->keyElements) {
         if (requiresPriority(element)) {
             requiresPriorities = true;

midend/checkTableEntries.cpp

@@ -59,7 +59,7 @@ bool P4::CheckTableEntries::ternary_covers(const IR::Expression *k1, const IR::E
 
 bool P4::CheckTableEntries::preorder(const IR::P4Table *tbl) {
     auto *entries = tbl->getEntries();
-    if (!entries) return false;
+    if (!entries || entries->entries.empty()) return false;
     auto *key = tbl->getKey();
     BUG_CHECK(key, "%1% table has entries and no key", tbl);
     std::vector<bool> ternary_keys;

testdata/p4_16_errors/entries-keyless.p4

@@ -0,0 +1,31 @@
+/*
+Copyright 2025 Altera Corporation
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+control c() {
+    action a() {}
+    table t {
+        actions = { a; }
+        default_action = a;
+        entries = { _ : a; }
+    }
+    apply {
+        t.apply();
+    }
+}
+
+control cc();
+package top(cc p);
+
+top(c()) main;

testdata/p4_16_errors_outputs/entries-keyless.p4

@@ -0,0 +1,20 @@
+control c() {
+    action a() {
+    }
+    table t {
+        actions = {
+            a;
+        }
+        default_action = a;
+        entries = {
+                        default : a;
+        }
+    }
+    apply {
+        t.apply();
+    }
+}
+
+control cc();
+package top(cc p);
+top(c()) main;

testdata/p4_16_errors_outputs/entries-keyless.p4-stderr

@@ -0,0 +1,3 @@
+entries-keyless.p4(18): [--Werror=type-error] error: Entries cannot be specified for a table with no key t
+    table t {
+          ^

testdata/p4_16_samples/entries-empty-keyless.p4

@@ -0,0 +1,31 @@
+/*
+Copyright 2025 Altera Corporation
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+control c() {
+    action a() {}
+    table t {
+        actions = { a; }
+        default_action = a;
+        entries = {}
+    }
+    apply {
+        t.apply();
+    }
+}
+
+control cc();
+package top(cc p);
+
+top(c()) main;

testdata/p4_16_samples_outputs/entries-empty-keyless-first.p4

@@ -0,0 +1,19 @@
+control c() {
+    action a() {
+    }
+    table t {
+        actions = {
+            a();
+        }
+        default_action = a();
+        entries = {
+        }
+    }
+    apply {
+        t.apply();
+    }
+}
+
+control cc();
+package top(cc p);
+top(c()) main;

testdata/p4_16_samples_outputs/entries-empty-keyless-frontend.p4

@@ -0,0 +1,19 @@
+control c() {
+    @name("c.a") action a() {
+    }
+    @name("c.t") table t_0 {
+        actions = {
+            a();
+        }
+        default_action = a();
+        entries = {
+        }
+    }
+    apply {
+        t_0.apply();
+    }
+}
+
+control cc();
+package top(cc p);
+top(c()) main;

testdata/p4_16_samples_outputs/entries-empty-keyless-midend.p4

@@ -0,0 +1,19 @@
+control c() {
+    @name("c.a") action a() {
+    }
+    @name("c.t") table t_0 {
+        actions = {
+            a();
+        }
+        default_action = a();
+        entries = {
+        }
+    }
+    apply {
+        t_0.apply();
+    }
+}
+
+control cc();
+package top(cc p);
+top(c()) main;

testdata/p4_16_samples_outputs/entries-empty-keyless.p4

@@ -0,0 +1,19 @@
+control c() {
+    action a() {
+    }
+    table t {
+        actions = {
+            a;
+        }
+        default_action = a;
+        entries = {
+        }
+    }
+    apply {
+        t.apply();
+    }
+}
+
+control cc();
+package top(cc p);
+top(c()) main;