Add @likely/@unlikely annotations for blocks

- fix a few places annotations on blocks are accidentally lost - allow merging blocks with same annotation Signed-off-by: Chris Dodd <[email protected]>
p4lang · Dec 9, 2024 · 001dbd8 · 001dbd8
1 parent 9d97cb5
commit 001dbd8
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Showing 10 changed files with 33 additions and 14 deletions.
diff --git a/frontends/p4/dontcareArgs.h b/frontends/p4/dontcareArgs.h
@@ -40,15 +40,17 @@ class DontcareArgs : public Transform, public ResolutionContext {
         IR::IndexedVector<IR::StatOrDecl> body;
         for (auto d : toAdd) body.push_back(d);
         body.append(function->body->components);
-        function->body = new IR::BlockStatement(function->body->srcInfo, body);
+        function->body =
+            new IR::BlockStatement(function->body->srcInfo, function->body->annotations, body);
         toAdd.clear();
         return function;
     }
     const IR::Node *postorder(IR::P4Action *action) override {
         IR::IndexedVector<IR::StatOrDecl> body;
         for (auto d : toAdd) body.push_back(d);
         body.append(action->body->components);
-        action->body = new IR::BlockStatement(action->body->srcInfo, body);
+        action->body =
+            new IR::BlockStatement(action->body->srcInfo, action->body->annotations, body);
         toAdd.clear();
         return action;
     }

diff --git a/frontends/p4/parseAnnotations.cpp b/frontends/p4/parseAnnotations.cpp
@@ -21,13 +21,15 @@ namespace P4 {
 ParseAnnotations::HandlerMap ParseAnnotations::standardHandlers() {
     return {
         // These annotations have empty bodies.
-        PARSE_EMPTY(IR::Annotation::tableOnlyAnnotation),
+        PARSE_EMPTY(IR::Annotation::atomicAnnotation),
         PARSE_EMPTY(IR::Annotation::defaultOnlyAnnotation),
         PARSE_EMPTY(IR::Annotation::hiddenAnnotation),
-        PARSE_EMPTY(IR::Annotation::atomicAnnotation),
+        PARSE_EMPTY(IR::Annotation::likelyAnnotation),
+        PARSE_EMPTY(IR::Annotation::noSideEffectsAnnotation),
         PARSE_EMPTY(IR::Annotation::optionalAnnotation),
         PARSE_EMPTY(IR::Annotation::pureAnnotation),
-        PARSE_EMPTY(IR::Annotation::noSideEffectsAnnotation),
+        PARSE_EMPTY(IR::Annotation::tableOnlyAnnotation),
+        PARSE_EMPTY(IR::Annotation::unlikelyAnnotation),
         PARSE_EMPTY("disable_optimization"_cs),
         PARSE_EMPTY("unroll"_cs),
         PARSE_EMPTY("nounroll"_cs),

diff --git a/frontends/p4/removeParameters.cpp b/frontends/p4/removeParameters.cpp
@@ -155,7 +155,7 @@ const IR::Node *DoRemoveActionParameters::postorder(IR::P4Action *action) {
     body.append(postamble);
 
     action->parameters = new IR::ParameterList(action->parameters->srcInfo, std::move(leftParams));
-    action->body = new IR::BlockStatement(action->body->srcInfo, std::move(body));
+    action->body = new IR::BlockStatement(action->body->srcInfo, action->body->annotations, std::move(body));
     LOG1("To replace " << dbp(action));
     result->push_back(action);
     return result;

diff --git a/frontends/p4/removeReturns.cpp b/frontends/p4/removeReturns.cpp
@@ -215,7 +215,7 @@ const IR::Node *DoRemoveReturns::preorder(IR::ExitStatement *statement) {
 }
 
 const IR::Node *DoRemoveReturns::preorder(IR::BlockStatement *statement) {
-    auto block = new IR::BlockStatement;
+    auto block = new IR::BlockStatement(statement->srcInfo, statement->annotations);
     auto currentBlock = block;
     TernaryBool ret = TernaryBool::No;
     for (auto s : statement->components) {

diff --git a/frontends/p4/sideEffects.cpp b/frontends/p4/sideEffects.cpp
@@ -580,7 +580,7 @@ const IR::Node *DoSimplifyExpressions::preorder(IR::MethodCallExpression *mce) {
 
 const IR::Node *DoSimplifyExpressions::postorder(IR::Function *function) {
     if (toInsert.empty()) return function;
-    auto body = new IR::BlockStatement(function->body->srcInfo);
+    auto body = new IR::BlockStatement(function->body->srcInfo, function->body->annotations);
     for (auto a : toInsert) body->push_back(a);
     for (auto s : function->body->components) body->push_back(s);
     function->body = body;
@@ -604,7 +604,7 @@ const IR::Node *DoSimplifyExpressions::postorder(IR::P4Control *control) {
 
 const IR::Node *DoSimplifyExpressions::postorder(IR::P4Action *action) {
     if (toInsert.empty()) return action;
-    auto body = new IR::BlockStatement(action->body->srcInfo);
+    auto body = new IR::BlockStatement(action->body->srcInfo, action->body->annotations);
     for (auto a : toInsert) body->push_back(a);
     for (auto s : action->body->components) body->push_back(s);
     action->body = body;

diff --git a/frontends/p4/simplify.cpp b/frontends/p4/simplify.cpp
@@ -23,7 +23,19 @@ namespace P4 {
 
 const IR::Node *DoSimplifyControlFlow::postorder(IR::BlockStatement *statement) {
     LOG3("Visiting " << dbp(getOriginal()));
-    if (statement->hasAnnotations()) return statement;
+    if (statement->hasAnnotations()) {
+        if (auto *pblk = getParent<IR::BlockStatement>()) {
+            for (auto *annot : statement->annotations) {
+                if (auto *p = pblk->getAnnotation(annot->name)) {
+                    if (!p->equiv(*annot)) return statement;
+                } else {
+                    return statement;
+                }
+            }
+        } else {
+            return statement;
+        }
+    }
     auto parent = getContext()->node;
     CHECK_NULL(parent);
     if (parent->is<IR::SwitchCase>() || parent->is<IR::P4Control>() || parent->is<IR::Function>() ||

diff --git a/ir/annotations.cpp b/ir/annotations.cpp
@@ -38,6 +38,8 @@ const cstring IR::Annotation::matchAnnotation = "match"_cs;
 const cstring IR::Annotation::fieldListAnnotation = "field_list"_cs;
 const cstring IR::Annotation::debugLoggingAnnotation = "__debug"_cs;
 const cstring IR::Annotation::disableOptimizationAnnotation = "disable_optimization"_cs;
+const cstring IR::Annotation::likelyAnnotation = "likely"_cs;
+const cstring IR::Annotation::unlikelyAnnotation = "unlikely"_cs;
 
 namespace Annotations {
 void addIfNew(Vector<Annotation> &annotations, cstring name, const Expression *expr,

diff --git a/ir/base.def b/ir/base.def
@@ -290,7 +290,8 @@ class Annotation {
     static const cstring fieldListAnnotation;  /// Used for recirculate, etc.
     static const cstring debugLoggingAnnotation;  /// Used by compiler implementer to limit debug log to the annotated IR context.
     static const cstring disableOptimizationAnnotation; /// annotation to disable certain optimization
-
+    static const cstring likelyAnnotation;  /// annotation for likely taken blocks/branchs
+    static const cstring unlikelyAnnotation;  /// annotation for likely not taken blocks/branchs
     toString{ return absl::StrCat("@", name); }
     validate{
         BUG_CHECK(!name.name.isNullOrEmpty(), "empty annotation name");

diff --git a/midend/flattenUnions.cpp b/midend/flattenUnions.cpp
@@ -169,7 +169,7 @@ const IR::Node *HandleValidityHeaderUnion::postorder(IR::MethodCallStatement *mc
 
 const IR::Node *HandleValidityHeaderUnion::postorder(IR::P4Action *action) {
     if (toInsert.empty()) return action;
-    auto body = new IR::BlockStatement(action->body->srcInfo);
+    auto body = new IR::BlockStatement(action->body->srcInfo, action->body->annotations);
     for (auto a : toInsert) body->push_back(a);
     for (auto s : action->body->components) body->push_back(s);
     action->body = body;
@@ -380,7 +380,7 @@ const IR::Node *DoFlattenHeaderUnion::postorder(IR::P4Action *action) {
             }
         }
     }
-    auto body = new IR::BlockStatement(action->body->srcInfo);
+    auto body = new IR::BlockStatement(action->body->srcInfo, action->body->annotations);
     for (auto a : actiondecls) body->push_back(a);
     action->body = body;
     return action;

diff --git a/midend/removeExits.cpp b/midend/removeExits.cpp
@@ -128,7 +128,7 @@ const IR::Node *DoRemoveExits::preorder(IR::P4Control *control) {
 }
 
 const IR::Node *DoRemoveExits::preorder(IR::BlockStatement *statement) {
-    auto block = new IR::BlockStatement;
+    auto block = new IR::BlockStatement(statement->srcInfo, statement->annotations);
     auto currentBlock = block;
     TernaryBool ret = TernaryBool::No;
     for (auto s : statement->components) {