[P4_Symbolic] Adding p4_symbolic/testdata/parser/fall_through_transit…

…ion.p4 [Evaluate parsers symbolically.] (#822)



Co-authored-by: kishanps <[email protected]>

p4_symbolic/ir/BUILD.bazel

@@ -243,3 +243,10 @@ ir_parsing_test(
     p4_deps = ["//p4_symbolic/testdata:common/headers.p4"],
     p4_program = "//p4_symbolic/testdata:parser/hex_string_transition.p4",
 )
+
+ir_parsing_test(
+    name = "fall_through_transition_test",
+    golden_file = "expected/fall_through_transition.txt",
+    p4_deps = ["//p4_symbolic/testdata:common/headers.p4"],
+    p4_program = "//p4_symbolic/testdata:parser/fall_through_transition.p4",
+)

p4_symbolic/ir/expected/fall_through_transition.txt

@@ -394,11 +394,4 @@ errors {
     value: 3
   }
 }
-deparsers {
-  key: "deparser"
-  value {
-    name: "deparser"
-    header_order: "ethernet"
-  }
-}
 

p4_symbolic/testdata/parser/fall_through_transition.p4

@@ -0,0 +1,68 @@
+#include <v1model.p4>
+#include "../common/headers.p4"
+
+struct local_metadata_t {
+  /* empty */
+}
+
+struct headers_t {
+  ethernet_t ethernet;
+  ipv4_t     ipv4;
+}
+
+parser packet_parser(packet_in packet, out headers_t headers,
+                     inout local_metadata_t local_metadata,
+                     inout standard_metadata_t standard_metadata) {
+  state start {
+    transition parse_ethernet;
+  }
+
+  state parse_ethernet {
+    packet.extract(headers.ethernet);
+    transition select(headers.ethernet.ether_type) {
+      ETHERTYPE_IPV4:    parse_ipv4;
+    }
+  }
+
+  state parse_ipv4 {
+    packet.extract(headers.ipv4);
+    transition accept;
+  }
+}
+
+control empty_verify_checksum(inout headers_t headers,
+                        inout local_metadata_t local_metadata) {
+  apply {}
+}  // control empty_verify_checksum
+
+control ingress(inout headers_t headers,
+                inout local_metadata_t local_metadata,
+                inout standard_metadata_t standard_metadata) {
+  apply {}
+}  // control ingress
+
+control egress(inout headers_t headers,
+               inout local_metadata_t local_metadata,
+               inout standard_metadata_t standard_metadata) {
+  apply {}
+}  // control egress
+
+control empty_compute_checksum(inout headers_t headers,
+                         inout local_metadata_t local_metadata) {
+  apply {}
+}  // control empty_compute_checksum
+
+control packet_deparser(packet_out packet, in headers_t headers) {
+  apply {
+    packet.emit(headers.ethernet);
+  }
+}  // control packet_deparser
+
+V1Switch(
+  packet_parser(),
+  empty_verify_checksum(),
+  ingress(),
+  egress(),
+  empty_compute_checksum(),
+  packet_deparser()
+) main;