Fix incorrect copy propagation into table match keys

midend/local_copyprop.cpp

@@ -585,8 +585,10 @@ void DoLocalCopyPropagation::apply_function(DoLocalCopyPropagation::FuncInfo *ac
 
 void DoLocalCopyPropagation::apply_table(DoLocalCopyPropagation::TableInfo *tbl) {
     ++tbl->apply_count;
+    std::unordered_set<cstring> remaps_seen;
     for (auto key : tbl->keyreads) {
-        forOverlapAvail(key, [key, tbl, this](cstring vname, VarInfo *var) {
+        forOverlapAvail(key, [&remaps_seen, key, tbl, this](cstring vname, VarInfo *var) {
+            remaps_seen.insert(vname);
             if (var->val && lvalue_out(var->val)->is<IR::PathExpression>()) {
                 if (tbl->apply_count > 1 &&
                     (!tbl->key_remap.count(vname) || !tbl->key_remap.at(vname)->equiv(*var->val))) {
@@ -606,6 +608,12 @@ void DoLocalCopyPropagation::apply_table(DoLocalCopyPropagation::TableInfo *tbl)
                 LOG4("  table using " << key << " with " <<
                      (var->val ? "value to complex for key" : "no propagated value"));
                 var->live = true; } }); }
+    for (auto it = tbl->key_remap.begin(); it != tbl->key_remap.end(); ) {
+        if (remaps_seen.count(it->first) == 0) {
+            LOG3("  no value used for some applies for key " << it->first);
+            it = tbl->key_remap.erase(it);
+        } else {
+            ++it; } }
     for (auto action : tbl->actions)
         apply_function(&actions[action]);
 }

testdata/p4_16_samples/copyprop1.p4

@@ -0,0 +1,65 @@
+#include <core.p4>
+#include <v1model.p4>
+
+header payload_t {
+    bit<8> x;
+    bit<8> y;
+}
+struct header_t {
+    payload_t payload;
+}
+struct metadata {}
+
+parser MyParser(packet_in packet,
+                out header_t hdr,
+                inout metadata meta,
+                inout standard_metadata_t standard_metadata) {
+    state start {
+        packet.extract(hdr.payload);
+        transition accept;
+    }
+}
+
+control MyIngress(inout header_t hdr,
+                  inout metadata meta,
+                  inout standard_metadata_t standard_metadata) {
+
+    action a1() {
+        hdr.payload.x = 0xaa;
+    }
+
+    table t1 {
+        key = { hdr.payload.x : exact; }
+        actions = { a1; }
+        size = 1024;
+    }
+
+    apply {
+        if (hdr.payload.y == 0) {
+            hdr.payload.x = hdr.payload.y;
+            t1.apply();
+        } else {
+            t1.apply();
+        }
+        standard_metadata.egress_spec = 2;
+    }
+}
+
+control MyVerifyChecksum(inout header_t hdr, inout metadata meta) { apply { } }
+control MyEgress(inout header_t hdr, inout metadata meta,
+                 inout standard_metadata_t standard_metadata) { apply {  } }
+control MyDeparser(packet_out packet, in header_t hdr) {
+    apply {
+        packet.emit(hdr);
+    }
+}
+control MyComputeChecksum(inout header_t hdr, inout metadata meta) { apply { } }
+
+V1Switch(
+MyParser(),
+MyVerifyChecksum(),
+MyIngress(),
+MyEgress(),
+MyComputeChecksum(),
+MyDeparser()
+) main;

testdata/p4_16_samples_outputs/copyprop1-first.p4

@@ -0,0 +1,72 @@
+#include <core.p4>
+#define V1MODEL_VERSION 20180101
+#include <v1model.p4>
+
+header payload_t {
+    bit<8> x;
+    bit<8> y;
+}
+
+struct header_t {
+    payload_t payload;
+}
+
+struct metadata {
+}
+
+parser MyParser(packet_in packet, out header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    state start {
+        packet.extract<payload_t>(hdr.payload);
+        transition accept;
+    }
+}
+
+control MyIngress(inout header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    action a1() {
+        hdr.payload.x = 8w0xaa;
+    }
+    table t1 {
+        key = {
+            hdr.payload.x: exact @name("hdr.payload.x") ;
+        }
+        actions = {
+            a1();
+            @defaultonly NoAction();
+        }
+        size = 1024;
+        default_action = NoAction();
+    }
+    apply {
+        if (hdr.payload.y == 8w0) {
+            hdr.payload.x = hdr.payload.y;
+            t1.apply();
+        } else {
+            t1.apply();
+        }
+        standard_metadata.egress_spec = 9w2;
+    }
+}
+
+control MyVerifyChecksum(inout header_t hdr, inout metadata meta) {
+    apply {
+    }
+}
+
+control MyEgress(inout header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    apply {
+    }
+}
+
+control MyDeparser(packet_out packet, in header_t hdr) {
+    apply {
+        packet.emit<header_t>(hdr);
+    }
+}
+
+control MyComputeChecksum(inout header_t hdr, inout metadata meta) {
+    apply {
+    }
+}
+
+V1Switch<header_t, metadata>(MyParser(), MyVerifyChecksum(), MyIngress(), MyEgress(), MyComputeChecksum(), MyDeparser()) main;
+

testdata/p4_16_samples_outputs/copyprop1-frontend.p4

@@ -0,0 +1,74 @@
+#include <core.p4>
+#define V1MODEL_VERSION 20180101
+#include <v1model.p4>
+
+header payload_t {
+    bit<8> x;
+    bit<8> y;
+}
+
+struct header_t {
+    payload_t payload;
+}
+
+struct metadata {
+}
+
+parser MyParser(packet_in packet, out header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    state start {
+        packet.extract<payload_t>(hdr.payload);
+        transition accept;
+    }
+}
+
+control MyIngress(inout header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    @noWarn("unused") @name(".NoAction") action NoAction_1() {
+    }
+    @name("MyIngress.a1") action a1() {
+        hdr.payload.x = 8w0xaa;
+    }
+    @name("MyIngress.t1") table t1_0 {
+        key = {
+            hdr.payload.x: exact @name("hdr.payload.x") ;
+        }
+        actions = {
+            a1();
+            @defaultonly NoAction_1();
+        }
+        size = 1024;
+        default_action = NoAction_1();
+    }
+    apply {
+        if (hdr.payload.y == 8w0) {
+            hdr.payload.x = hdr.payload.y;
+            t1_0.apply();
+        } else {
+            t1_0.apply();
+        }
+        standard_metadata.egress_spec = 9w2;
+    }
+}
+
+control MyVerifyChecksum(inout header_t hdr, inout metadata meta) {
+    apply {
+    }
+}
+
+control MyEgress(inout header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    apply {
+    }
+}
+
+control MyDeparser(packet_out packet, in header_t hdr) {
+    apply {
+        packet.emit<header_t>(hdr);
+    }
+}
+
+control MyComputeChecksum(inout header_t hdr, inout metadata meta) {
+    apply {
+    }
+}
+
+V1Switch<header_t, metadata>(MyParser(), MyVerifyChecksum(), MyIngress(), MyEgress(), MyComputeChecksum(), MyDeparser()) main;
+

testdata/p4_16_samples_outputs/copyprop1-midend.p4

@@ -0,0 +1,92 @@
+#include <core.p4>
+#define V1MODEL_VERSION 20180101
+#include <v1model.p4>
+
+header payload_t {
+    bit<8> x;
+    bit<8> y;
+}
+
+struct header_t {
+    payload_t payload;
+}
+
+struct metadata {
+}
+
+parser MyParser(packet_in packet, out header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    state start {
+        packet.extract<payload_t>(hdr.payload);
+        transition accept;
+    }
+}
+
+control MyIngress(inout header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    @noWarn("unused") @name(".NoAction") action NoAction_1() {
+    }
+    @name("MyIngress.a1") action a1() {
+        hdr.payload.x = 8w0xaa;
+    }
+    @name("MyIngress.t1") table t1_0 {
+        key = {
+            hdr.payload.x: exact @name("hdr.payload.x") ;
+        }
+        actions = {
+            a1();
+            @defaultonly NoAction_1();
+        }
+        size = 1024;
+        default_action = NoAction_1();
+    }
+    @hidden action copyprop1l39() {
+        hdr.payload.x = hdr.payload.y;
+    }
+    @hidden action copyprop1l44() {
+        standard_metadata.egress_spec = 9w2;
+    }
+    @hidden table tbl_copyprop1l39 {
+        actions = {
+            copyprop1l39();
+        }
+        const default_action = copyprop1l39();
+    }
+    @hidden table tbl_copyprop1l44 {
+        actions = {
+            copyprop1l44();
+        }
+        const default_action = copyprop1l44();
+    }
+    apply {
+        if (hdr.payload.y == 8w0) {
+            tbl_copyprop1l39.apply();
+            t1_0.apply();
+        } else {
+            t1_0.apply();
+        }
+        tbl_copyprop1l44.apply();
+    }
+}
+
+control MyVerifyChecksum(inout header_t hdr, inout metadata meta) {
+    apply {
+    }
+}
+
+control MyEgress(inout header_t hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
+    apply {
+    }
+}
+
+control MyDeparser(packet_out packet, in header_t hdr) {
+    apply {
+        packet.emit<payload_t>(hdr.payload);
+    }
+}
+
+control MyComputeChecksum(inout header_t hdr, inout metadata meta) {
+    apply {
+    }
+}
+
+V1Switch<header_t, metadata>(MyParser(), MyVerifyChecksum(), MyIngress(), MyEgress(), MyComputeChecksum(), MyDeparser()) main;
+