AOT: Enable branch merging for checked smi comparisons

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index db190ac6b704eb8c6fcd343bc0af6e16e417591e..6cdb0542bb492d5870fb4b9e286e4bc770a35f7c 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -1757,14 +1757,30 @@ Definition* CheckedSmiOpInstr::Canonicalize(FlowGraph* flow_graph) {
       default:
         break;
     }
-    if (Token::IsRelationalOperator(op_kind())) {
-      replacement = new RelationalOpInstr(token_pos(), op_kind(),
+  }
+  return this;
+}
+
+
+ComparisonInstr* CheckedSmiComparisonInstr::CopyWithNewOperands(
+    Value* left, Value* right) {
+  UNREACHABLE();
+  return NULL;
+}
+
+
+Definition* CheckedSmiComparisonInstr::Canonicalize(FlowGraph* flow_graph) {
+  if ((left()->Type()->ToCid() == kSmiCid) &&
+      (right()->Type()->ToCid() == kSmiCid)) {
+    Definition* replacement = NULL;
+    if (Token::IsRelationalOperator(kind())) {
+      replacement = new RelationalOpInstr(token_pos(), kind(),
                                           new Value(left()->definition()),
                                           new Value(right()->definition()),
                                           kSmiCid,
                                           Thread::kNoDeoptId);
-    } else if (Token::IsEqualityOperator(op_kind())) {
-      replacement = new EqualityCompareInstr(token_pos(), op_kind(),
+    } else if (Token::IsEqualityOperator(kind())) {
+      replacement = new EqualityCompareInstr(token_pos(), kind(),
                                              new Value(left()->definition()),
                                              new Value(right()->definition()),
                                              kSmiCid,
@@ -2356,9 +2372,9 @@ Definition* UnboxedIntConverterInstr::Canonicalize(FlowGraph* flow_graph) {
 
 Definition* BooleanNegateInstr::Canonicalize(FlowGraph* flow_graph) {
   Definition* defn = value()->definition();
-  if (defn->IsComparison() && defn->HasOnlyUse(value())) {
-    // Comparisons always have a bool result.
-    ASSERT(value()->definition()->Type()->ToCid() == kBoolCid);
+  if (defn->IsComparison() &&
+      defn->HasOnlyUse(value()) &&
+      defn->Type()->ToCid() == kBoolCid) {
     defn->AsComparison()->NegateComparison();
     return defn;
   }
@@ -2387,7 +2403,8 @@ static bool MaybeNumber(CompileType* type) {
 // Returns a replacement for a strict comparison and signals if the result has
 // to be negated.
 static Definition* CanonicalizeStrictCompare(StrictCompareInstr* compare,
-                                             bool* negated) {
+                                             bool* negated,
+                                             bool is_branch) {
   // Use propagated cid and type information to eliminate number checks.
   // If one of the inputs is not a boxable number (Mint, Double, Bigint), or
   // is not a subtype of num, no need for number checks.
@@ -2400,7 +2417,6 @@ static Definition* CanonicalizeStrictCompare(StrictCompareInstr* compare,
       compare->set_needs_number_check(false);
     }
   }
-
   *negated = false;
   PassiveObject& constant = PassiveObject::Handle();
   Value* other = NULL;
@@ -2414,25 +2430,26 @@ static Definition* CanonicalizeStrictCompare(StrictCompareInstr* compare,
     return compare;
   }
 
+  const bool can_merge = is_branch || (other->Type()->ToCid() == kBoolCid);
   Definition* other_defn = other->definition();
   Token::Kind kind = compare->kind();
   // Handle e === true.
   if ((kind == Token::kEQ_STRICT) &&
       (constant.raw() == Bool::True().raw()) &&
-      (other->Type()->ToCid() == kBoolCid)) {
+      can_merge) {
     return other_defn;
   }
   // Handle e !== false.
   if ((kind == Token::kNE_STRICT) &&
       (constant.raw() == Bool::False().raw()) &&
-      (other->Type()->ToCid() == kBoolCid)) {
+      can_merge) {
     return other_defn;
   }
   // Handle e !== true.
   if ((kind == Token::kNE_STRICT) &&
       (constant.raw() == Bool::True().raw()) &&
       other_defn->IsComparison() &&
-      (other->Type()->ToCid() == kBoolCid) &&
+      can_merge &&
       other_defn->HasOnlyUse(other)) {
     *negated = true;
     return other_defn;
@@ -2441,7 +2458,7 @@ static Definition* CanonicalizeStrictCompare(StrictCompareInstr* compare,
   if ((kind == Token::kEQ_STRICT) &&
       (constant.raw() == Bool::False().raw()) &&
       other_defn->IsComparison() &&
-      (other->Type()->ToCid() == kBoolCid) &&
+      can_merge &&
       other_defn->HasOnlyUse(other)) {
     *negated = true;
     return other_defn;
@@ -2501,7 +2518,8 @@ Instruction* BranchInstr::Canonicalize(FlowGraph* flow_graph) {
   if (comparison()->IsStrictCompare()) {
     bool negated = false;
     Definition* replacement =
-        CanonicalizeStrictCompare(comparison()->AsStrictCompare(), &negated);
+        CanonicalizeStrictCompare(comparison()->AsStrictCompare(),
+                                  &negated, /* is_branch = */ true);
     if (replacement == comparison()) {
       return this;
     }
@@ -2573,7 +2591,8 @@ Instruction* BranchInstr::Canonicalize(FlowGraph* flow_graph) {
 Definition* StrictCompareInstr::Canonicalize(FlowGraph* flow_graph) {
   if (!HasUses()) return NULL;
   bool negated = false;
-  Definition* replacement = CanonicalizeStrictCompare(this, &negated);
+  Definition* replacement = CanonicalizeStrictCompare(this, &negated,
+                                                      /* is_branch = */ false);
   if (negated && replacement->IsComparison()) {
     ASSERT(replacement != this);
     replacement->AsComparison()->NegateComparison();