support key=value annotations (#1300)

* Support for key=value annotations

Author: Mihai Budiu

frontends/p4/toP4/toP4.cpp

@@ -1014,6 +1014,19 @@ bool ToP4::preorder(const IR::Annotation * a) {
         doneVec();
         builder.append(")");
     }
+    if (!a->kv.empty()) {
+        builder.append("(");
+        bool first = true;
+        for (auto kvp : a->kv) {
+            if (!first)
+                builder.append(", ");
+            first = false;
+            builder.append(kvp.first);
+            builder.append("=");
+            visit(kvp.second);
+        }
+        builder.append(")");
+    }
     builder.spc();
     return false;
 }

frontends/parsers/p4/p4parser.ypp

@@ -59,6 +59,11 @@ inline std::ostream& operator<<(std::ostream& out, const P4::OptionalConst& oc)
     return out;
 }
 
+struct KV {
+    cstring name;
+    const IR::Expression* expression;
+};
+
 // Bison uses the types you provide to %type to make constructors for the
 // variant type it uses under the hood, but its code generation is a little
 // naive and it always prepends 'const' to the type. This is problematic when
@@ -220,6 +225,8 @@ typedef const IR::Type ConstType;
 %type<IR::Entry*>           entry
 %type<IR::Vector<IR::Entry>*>  entriesList
 %type<IR::MethodCallExpression*>  actionBinding
+%type<IR::NameMap<IR::Expression>*> kvList
+%type<KV*> kvPair
 
 %left COMMA
 %nonassoc QUESTION
@@ -303,6 +310,17 @@ annotations
 annotation
     : "@" name                        { $$ = new IR::Annotation(@1, *$2, {}); }
     | "@" name "(" expressionList ")" { $$ = new IR::Annotation(@1, *$2, *$4); }
+    | "@" name "(" kvList ")"         { $$ = new IR::Annotation(@1, *$2, *$4); }
+    ;
+
+kvList
+    : kvPair                          { $$ = new IR::NameMap<IR::Expression>;
+                                        $$->add($1->name, $1->expression); }
+    | kvList "," kvPair               { $$ = $1; $$->add($3->name, $3->expression); }
+    ;
+
+kvPair
+    : name "=" expression             { $$ = new KV; $$->name = $1->name; $$->expression = $3; }
     ;
 
 parameterList

ir/base.def

@@ -175,11 +175,20 @@ class Path {
 /// Most P4 entities can be optionally annotated
 class Annotation {
     ID name;
+    /// Annotations that are simple expressions
     inline Vector<Expression> expr;
+    /// Annotations described as key-value pairs
+    // TODO: this should be a map from ID not from cstring
+    inline NameMap<Expression> kv;
     Annotation { if (!srcInfo) srcInfo = name.srcInfo; }
     Annotation(Util::SourceInfo si, ID n, const std::initializer_list<const IR::Expression *> &a)
     : Node(si), name(n), expr(a) {}
+    Annotation(Util::SourceInfo si, ID n, const IR::Vector<IR::Expression> &a)
+    : Node(si), name(n), expr(a) {}
+    Annotation(Util::SourceInfo si, ID n, const NameMap<IR::Expression> &kv)
+    : Node(si), name(n), kv(kv) {}
     Annotation(ID n, const std::initializer_list<const IR::Expression *> &a) : name(n), expr(a) {}
+    Annotation(ID n, const IR::Vector<IR::Expression> &a) : name(n), expr(a) {}
     Annotation(ID n, intmax_t v) : name(n) {
         expr.push_back(new IR::Constant(v)); }
     /// Predefined annotations used by the compiler

midend/actionSynthesis.cpp

@@ -72,8 +72,7 @@ const IR::Node* DoMoveActionsToTables::postorder(IR::MethodCallStatement* statem
     cstring tblName = IR::ID(refMap->newName(cstring("tbl_") + ac->action->name.name), nullptr);
 
     auto annos = new IR::Annotations();
-    annos->add(new IR::Annotation(IR::Annotation::hiddenAnnotation,
-                                  IR::Vector<IR::Expression>()));
+    annos->add(new IR::Annotation(IR::Annotation::hiddenAnnotation, {}));
     auto tbl = new IR::P4Table(tblName, annos, props);
     tables.push_back(tbl);
 
@@ -177,8 +176,7 @@ const IR::Statement* DoSynthesizeActions::createAction(const IR::Statement* toAd
     }
 
     auto annos = new IR::Annotations();
-    annos->add(new IR::Annotation(IR::Annotation::hiddenAnnotation,
-                                  IR::Vector<IR::Expression>()));
+    annos->add(new IR::Annotation(IR::Annotation::hiddenAnnotation, {}));
     auto action = new IR::P4Action(name, annos, new IR::ParameterList(), body);
     actions.push_back(action);
     auto actpath = new IR::PathExpression(name);

testdata/p4_16_samples/kvanno.p4

@@ -0,0 +1,5 @@
+@kvanno(
+name="x",
+value=0
+)
+const bit<32> x = 0;

testdata/p4_16_samples_outputs/kvanno-first.p4

@@ -0,0 +1 @@
+@kvanno(name="x", value=0) const bit<32> x = 32w0;

testdata/p4_16_samples_outputs/kvanno-frontend.p4

@@ -0,0 +1 @@
+@kvanno(name="x", value=0) const bit<32> x = 0;

testdata/p4_16_samples_outputs/kvanno.p4

@@ -0,0 +1 @@
+warning: Program does not contain a `main' module