Handle table.apply().hit correctly in ubpf backend (#3498)

Signed-off-by: Mihai Budiu <[email protected]>

backends/ubpf/ubpfControl.cpp

@@ -429,8 +429,21 @@ namespace UBPF {
     }
 
     bool UBPFControlBodyTranslator::preorder(const IR::IfStatement *statement) {
+        bool isHit = P4::TableApplySolver::isHit(statement->condition, control->program->refMap,
+                                                 control->program->typeMap);
+        if (isHit) {
+            // visit first the table, and then the conditional
+            auto member = statement->condition->to<IR::Member>();
+            CHECK_NULL(member);
+            visit(member->expr);  // table application.  Sets 'hitVariable'
+            builder->emitIndent();
+        }
+
         builder->append("if (");
-        visit(statement->condition);
+        if (isHit)
+            builder->append(control->hitVariable);
+        else
+            visit(statement->condition);
         builder->append(") ");
         if (!statement->ifTrue->is<IR::BlockStatement>()) {
             builder->blockStart();

testdata/p4_16_samples/issue3483_ubpf.p4

@@ -0,0 +1,74 @@
+#include <ubpf_model.p4>
+
+#include "ebpf_headers.p4"
+
+struct Headers_t
+{
+    Ethernet_h ethernet;
+    IPv4_h     ipv4;
+}
+
+struct Meta {
+    bit b;
+}
+
+parser prs(packet_in p, out Headers_t headers, inout Meta meta, inout standard_metadata std_meta)
+{
+    state start
+    {
+        p.extract(headers.ethernet);
+        transition select(headers.ethernet.etherType)
+        {
+            16w0x800 : ip;
+            default : reject;
+        }
+    }
+
+    state ip
+    {
+        p.extract(headers.ipv4);
+        transition accept;
+    }
+}
+
+control pipe(inout Headers_t headers, inout Meta meta, inout standard_metadata unused)
+{
+    action Reject(IPv4Address add)
+    {
+        headers.ipv4.srcAddr = add;
+    }
+
+    table Check_src_ip {
+        key = { headers.ipv4.srcAddr : exact; }
+        actions =
+        {
+            Reject;
+            NoAction;
+        }
+
+        default_action = NoAction;
+    }
+
+    apply {
+        if (!Check_src_ip.apply().hit) {
+            meta.b = 1;
+        }
+
+        switch (Check_src_ip.apply().action_run) {
+        Reject: {
+            meta.b = 0;
+        }
+        NoAction: {}
+        }
+    }
+}
+
+control dprs(packet_out packet, in Headers_t headers) {
+    apply {
+        packet.emit(headers.ethernet);
+        packet.emit(headers.ipv4);
+    }
+}
+
+
+ubpf(prs(), pipe(), dprs()) main;

testdata/p4_16_samples_outputs/issue3483_ubpf-first.p4

@@ -0,0 +1,88 @@
+#include <core.p4>
+#include <ubpf_model.p4>
+
+@ethernetaddress typedef bit<48> EthernetAddress;
+@ipv4address typedef bit<32> IPv4Address;
+header Ethernet_h {
+    EthernetAddress dstAddr;
+    EthernetAddress srcAddr;
+    bit<16>         etherType;
+}
+
+header IPv4_h {
+    bit<4>      version;
+    bit<4>      ihl;
+    bit<8>      diffserv;
+    bit<16>     totalLen;
+    bit<16>     identification;
+    bit<3>      flags;
+    bit<13>     fragOffset;
+    bit<8>      ttl;
+    bit<8>      protocol;
+    bit<16>     hdrChecksum;
+    IPv4Address srcAddr;
+    IPv4Address dstAddr;
+}
+
+struct Headers_t {
+    Ethernet_h ethernet;
+    IPv4_h     ipv4;
+}
+
+struct Meta {
+    bit<1> b;
+}
+
+parser prs(packet_in p, out Headers_t headers, inout Meta meta, inout standard_metadata std_meta) {
+    state start {
+        p.extract<Ethernet_h>(headers.ethernet);
+        transition select(headers.ethernet.etherType) {
+            16w0x800: ip;
+            default: reject;
+        }
+    }
+    state ip {
+        p.extract<IPv4_h>(headers.ipv4);
+        transition accept;
+    }
+}
+
+control pipe(inout Headers_t headers, inout Meta meta, inout standard_metadata unused) {
+    action Reject(IPv4Address add) {
+        headers.ipv4.srcAddr = add;
+    }
+    table Check_src_ip {
+        key = {
+            headers.ipv4.srcAddr: exact @name("headers.ipv4.srcAddr") ;
+        }
+        actions = {
+            Reject();
+            NoAction();
+        }
+        default_action = NoAction();
+    }
+    apply {
+        if (Check_src_ip.apply().hit) {
+            ;
+        } else {
+            meta.b = 1w1;
+        }
+        switch (Check_src_ip.apply().action_run) {
+            Reject: {
+                meta.b = 1w0;
+            }
+            NoAction: {
+            }
+        }
+    }
+}
+
+control dprs(packet_out packet, in Headers_t headers) {
+    apply {
+        packet.emit<Ethernet_h>(headers.ethernet);
+        packet.emit<IPv4_h>(headers.ipv4);
+    }
+}
+
+ubpf<Headers_t, Meta>(prs(), pipe(), dprs()) main;
+

testdata/p4_16_samples_outputs/issue3483_ubpf-frontend.p4

@@ -0,0 +1,90 @@
+#include <core.p4>
+#include <ubpf_model.p4>
+
+@ethernetaddress typedef bit<48> EthernetAddress;
+@ipv4address typedef bit<32> IPv4Address;
+header Ethernet_h {
+    EthernetAddress dstAddr;
+    EthernetAddress srcAddr;
+    bit<16>         etherType;
+}
+
+header IPv4_h {
+    bit<4>      version;
+    bit<4>      ihl;
+    bit<8>      diffserv;
+    bit<16>     totalLen;
+    bit<16>     identification;
+    bit<3>      flags;
+    bit<13>     fragOffset;
+    bit<8>      ttl;
+    bit<8>      protocol;
+    bit<16>     hdrChecksum;
+    IPv4Address srcAddr;
+    IPv4Address dstAddr;
+}
+
+struct Headers_t {
+    Ethernet_h ethernet;
+    IPv4_h     ipv4;
+}
+
+struct Meta {
+    bit<1> b;
+}
+
+parser prs(packet_in p, out Headers_t headers, inout Meta meta, inout standard_metadata std_meta) {
+    state start {
+        p.extract<Ethernet_h>(headers.ethernet);
+        transition select(headers.ethernet.etherType) {
+            16w0x800: ip;
+            default: reject;
+        }
+    }
+    state ip {
+        p.extract<IPv4_h>(headers.ipv4);
+        transition accept;
+    }
+}
+
+control pipe(inout Headers_t headers, inout Meta meta, inout standard_metadata unused) {
+    @noWarn("unused") @name(".NoAction") action NoAction_1() {
+    }
+    @name("pipe.Reject") action Reject(@name("add") IPv4Address add) {
+        headers.ipv4.srcAddr = add;
+    }
+    @name("pipe.Check_src_ip") table Check_src_ip_0 {
+        key = {
+            headers.ipv4.srcAddr: exact @name("headers.ipv4.srcAddr") ;
+        }
+        actions = {
+            Reject();
+            NoAction_1();
+        }
+        default_action = NoAction_1();
+    }
+    apply {
+        if (Check_src_ip_0.apply().hit) {
+            ;
+        } else {
+            meta.b = 1w1;
+        }
+        switch (Check_src_ip_0.apply().action_run) {
+            Reject: {
+                meta.b = 1w0;
+            }
+            NoAction_1: {
+            }
+        }
+    }
+}
+
+control dprs(packet_out packet, in Headers_t headers) {
+    apply {
+        packet.emit<Ethernet_h>(headers.ethernet);
+        packet.emit<IPv4_h>(headers.ipv4);
+    }
+}
+
+ubpf<Headers_t, Meta>(prs(), pipe(), dprs()) main;
+

testdata/p4_16_samples_outputs/issue3483_ubpf-midend.p4

@@ -0,0 +1,117 @@
+#include <core.p4>
+#include <ubpf_model.p4>
+
+@ethernetaddress typedef bit<48> EthernetAddress;
+@ipv4address typedef bit<32> IPv4Address;
+header Ethernet_h {
+    EthernetAddress dstAddr;
+    EthernetAddress srcAddr;
+    bit<16>         etherType;
+}
+
+header IPv4_h {
+    bit<4>      version;
+    bit<4>      ihl;
+    bit<8>      diffserv;
+    bit<16>     totalLen;
+    bit<16>     identification;
+    bit<3>      flags;
+    bit<13>     fragOffset;
+    bit<8>      ttl;
+    bit<8>      protocol;
+    bit<16>     hdrChecksum;
+    IPv4Address srcAddr;
+    IPv4Address dstAddr;
+}
+
+struct Headers_t {
+    Ethernet_h ethernet;
+    IPv4_h     ipv4;
+}
+
+struct Meta {
+    bit<1> b;
+}
+
+parser prs(packet_in p, out Headers_t headers, inout Meta meta, inout standard_metadata std_meta) {
+    state start {
+        p.extract<Ethernet_h>(headers.ethernet);
+        transition select(headers.ethernet.etherType) {
+            16w0x800: ip;
+            default: reject;
+        }
+    }
+    state ip {
+        p.extract<IPv4_h>(headers.ipv4);
+        transition accept;
+    }
+}
+
+control pipe(inout Headers_t headers, inout Meta meta, inout standard_metadata unused) {
+    @noWarn("unused") @name(".NoAction") action NoAction_1() {
+    }
+    @name("pipe.Reject") action Reject(@name("add") IPv4Address add) {
+        headers.ipv4.srcAddr = add;
+    }
+    @name("pipe.Check_src_ip") table Check_src_ip_0 {
+        key = {
+            headers.ipv4.srcAddr: exact @name("headers.ipv4.srcAddr") ;
+        }
+        actions = {
+            Reject();
+            NoAction_1();
+        }
+        default_action = NoAction_1();
+    }
+    @hidden action issue3483_ubpf54() {
+        meta.b = 1w1;
+    }
+    @hidden action issue3483_ubpf59() {
+        meta.b = 1w0;
+    }
+    @hidden table tbl_issue3483_ubpf54 {
+        actions = {
+            issue3483_ubpf54();
+        }
+        const default_action = issue3483_ubpf54();
+    }
+    @hidden table tbl_issue3483_ubpf59 {
+        actions = {
+            issue3483_ubpf59();
+        }
+        const default_action = issue3483_ubpf59();
+    }
+    apply {
+        if (Check_src_ip_0.apply().hit) {
+            ;
+        } else {
+            tbl_issue3483_ubpf54.apply();
+        }
+        switch (Check_src_ip_0.apply().action_run) {
+            Reject: {
+                tbl_issue3483_ubpf59.apply();
+            }
+            NoAction_1: {
+            }
+        }
+    }
+}
+
+control dprs(packet_out packet, in Headers_t headers) {
+    @hidden action issue3483_ubpf68() {
+        packet.emit<Ethernet_h>(headers.ethernet);
+        packet.emit<IPv4_h>(headers.ipv4);
+    }
+    @hidden table tbl_issue3483_ubpf68 {
+        actions = {
+            issue3483_ubpf68();
+        }
+        const default_action = issue3483_ubpf68();
+    }
+    apply {
+        tbl_issue3483_ubpf68.apply();
+    }
+}
+
+ubpf<Headers_t, Meta>(prs(), pipe(), dprs()) main;
+