Remove unused actions whose external name starts with '__'

Signed-off-by: Kyle Cripps <kyle@pensando.io>

frontends/p4/unusedDeclarations.cpp

@@ -112,7 +112,7 @@ const IR::Node *RemoveUnusedDeclarations::process(const IR::IDeclaration *decl)
     LOG3("Visiting " << decl);
     if (decl->getName().name == IR::ParserState::verify && getParent<IR::P4Program>())
         return decl->getNode();
-    if (decl->getName().name.startsWith("__"))
+    if (decl->externalName(decl->getName().name).startsWith("__"))
         // Internal identifiers, e.g., __v1model_version
         return decl->getNode();
     if (refMap->isUsed(getOriginal<IR::IDeclaration>())) return decl->getNode();

testdata/p4_16_errors_outputs/structure-valued-expr-errs-1.p4-stderr

@@ -1,4 +1,4 @@
-structure-valued-expr-errs-1.p4(100): [--Werror=type-error] error: 'hdr.h1 = { }'
+structure-valued-expr-errs-1.p4(100): [--Werror=type-error] error: 'hdr.h1 = {}'
             hdr.h1 = {};
                    ^
   ---- Actual error:
@@ -9,7 +9,7 @@ structure-valued-expr-errs-1.p4(31)
   header h1_t {
          ^^^^
   ---- Originating from:
-structure-valued-expr-errs-1.p4(100): Source expression '{ }' produces a result of type 'tuple<>' which cannot be assigned to a left-value with type 'header h1_t'
+structure-valued-expr-errs-1.p4(100): Source expression '{}' produces a result of type 'tuple<>' which cannot be assigned to a left-value with type 'header h1_t'
               hdr.h1 = {};
                        ^^
 structure-valued-expr-errs-1.p4(100)
@@ -18,7 +18,7 @@ structure-valued-expr-errs-1.p4(100)
 structure-valued-expr-errs-1.p4(31)
   header h1_t {
          ^^^^
-structure-valued-expr-errs-1.p4(101): [--Werror=type-error] error: 'hdr.h2 = { }'
+structure-valued-expr-errs-1.p4(101): [--Werror=type-error] error: 'hdr.h2 = {}'
             hdr.h2 = {};
                    ^
   ---- Actual error:
@@ -29,7 +29,7 @@ structure-valued-expr-errs-1.p4(35)
   header h2_t {
          ^^^^
   ---- Originating from:
-structure-valued-expr-errs-1.p4(101): Source expression '{ }' produces a result of type 'tuple<>' which cannot be assigned to a left-value with type 'header h2_t'
+structure-valued-expr-errs-1.p4(101): Source expression '{}' produces a result of type 'tuple<>' which cannot be assigned to a left-value with type 'header h2_t'
               hdr.h2 = {};
                        ^^
 structure-valued-expr-errs-1.p4(100)

testdata/p4_16_samples/issue4883_dup_has_returned_decl.p4

@@ -0,0 +1,41 @@
+#include <core.p4>
+
+struct S {
+    bit<16> f;
+}
+
+extern bool foo(in bool x, in bool y);
+
+control C(inout S s) {
+    action a1() {
+        if (foo(s.f == 0, false)) {
+            return;
+        }
+    }
+
+    @name("._xyz")
+    action a2() {
+        a1();
+        a1();
+    }
+
+    table t {
+        actions = { a2; }
+    }
+
+    apply {
+        t.apply();
+    }
+}
+
+control C2() {
+    apply {
+        S s;
+        C.apply(s);
+    }
+}
+
+control proto();
+package top(proto p);
+
+top(C2()) main;

testdata/p4_16_samples_outputs/issue4883_dup_has_returned_decl-first.p4

@@ -0,0 +1,40 @@
+#include <core.p4>
+
+struct S {
+    bit<16> f;
+}
+
+extern bool foo(in bool x, in bool y);
+control C(inout S s) {
+    action a1() {
+        if (foo(s.f == 16w0, false)) {
+            return;
+        }
+    }
+    @name("._xyz") action a2() {
+        a1();
+        a1();
+    }
+    table t {
+        actions = {
+            a2();
+            @defaultonly NoAction();
+        }
+        default_action = NoAction();
+    }
+    apply {
+        t.apply();
+    }
+}
+
+control C2() {
+    @name("C") C() C_inst;
+    apply {
+        S s;
+        C_inst.apply(s);
+    }
+}
+
+control proto();
+package top(proto p);
+top(C2()) main;

testdata/p4_16_samples_outputs/issue4883_dup_has_returned_decl-frontend.p4

@@ -0,0 +1,31 @@
+#include <core.p4>
+
+struct S {
+    bit<16> f;
+}
+
+extern bool foo(in bool x, in bool y);
+control C2() {
+    @name("C2.s") S s_0;
+    @name("C2.C.tmp") bool C_tmp;
+    @noWarn("unused") @name(".NoAction") action NoAction_1() {
+    }
+    @name("._xyz") action __xyz_0() {
+        C_tmp = foo(s_0.f == 16w0, false);
+        C_tmp = foo(s_0.f == 16w0, false);
+    }
+    @name("C2.C.t") table C_t {
+        actions = {
+            __xyz_0();
+            @defaultonly NoAction_1();
+        }
+        default_action = NoAction_1();
+    }
+    apply {
+        C_t.apply();
+    }
+}
+
+control proto();
+package top(proto p);
+top(C2()) main;

testdata/p4_16_samples_outputs/issue4883_dup_has_returned_decl-midend.p4

@@ -0,0 +1,30 @@
+#include <core.p4>
+
+struct S {
+    bit<16> f;
+}
+
+extern bool foo(in bool x, in bool y);
+control C2() {
+    @name("C2.s") S s_0;
+    @noWarn("unused") @name(".NoAction") action NoAction_1() {
+    }
+    @name("._xyz") action __xyz_0() {
+        foo(s_0.f == 16w0, false);
+        foo(s_0.f == 16w0, false);
+    }
+    @name("C2.C.t") table C_t {
+        actions = {
+            __xyz_0();
+            @defaultonly NoAction_1();
+        }
+        default_action = NoAction_1();
+    }
+    apply {
+        C_t.apply();
+    }
+}
+
+control proto();
+package top(proto p);
+top(C2()) main;

testdata/p4_16_samples_outputs/issue4883_dup_has_returned_decl.p4

@@ -0,0 +1,37 @@
+#include <core.p4>
+
+struct S {
+    bit<16> f;
+}
+
+extern bool foo(in bool x, in bool y);
+control C(inout S s) {
+    action a1() {
+        if (foo(s.f == 0, false)) {
+            return;
+        }
+    }
+    @name("._xyz") action a2() {
+        a1();
+        a1();
+    }
+    table t {
+        actions = {
+            a2;
+        }
+    }
+    apply {
+        t.apply();
+    }
+}
+
+control C2() {
+    apply {
+        S s;
+        C.apply(s);
+    }
+}
+
+control proto();
+package top(proto p);
+top(C2()) main;

testdata/p4_16_samples_outputs/issue4883_dup_has_returned_decl.p4-stderr

@@ -0,0 +1,6 @@
+issue4883_dup_has_returned_decl.p4(34): [--Wwarn=uninitialized_use] warning: s.f may be uninitialized
+        C.apply(s);
+                ^
+issue4883_dup_has_returned_decl.p4(11): [--Wwarn=uninitialized_use] warning: s.f may be uninitialized
+        if (foo(s.f == 0, false)) {
+                ^^^