[vm/bytecode] Optimize comparisons with null

alexmarkov · commit-bot@chromium.org · commit 4fbd758f9e75 · 2019-09-05T17:52:41.000Z
BinaryTrees(RunTime): 72191.33325 us. -> 68058.06103333333 us. (linux/x64, bytecode compiler enabled) Issue: #36429 Change-Id: Ie5344d874f6b4afc5e8b6516fc6283d83963f17f Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/115601 Commit-Queue: Alexander Markov <alexmarkov@google.com> Reviewed-by: Régis Crelier <regis@google.com>
diff --git a/pkg/vm/lib/bytecode/gen_bytecode.dart b/pkg/vm/lib/bytecode/gen_bytecode.dart
@@ -1366,6 +1366,29 @@ class BytecodeGenerator extends RecursiveVisitor<Null> {
       }
       return;
     }
+    if (condition is MethodInvocation &&
+        condition.name.name == '==' &&
+        (condition.receiver is NullLiteral ||
+            condition.arguments.positional.single is NullLiteral)) {
+      if (condition.receiver is NullLiteral) {
+        _generateNode(condition.arguments.positional.single);
+      } else {
+        _generateNode(condition.receiver);
+      }
+      if (options.emitDebuggerStops &&
+          condition.fileOffset != TreeNode.noOffset) {
+        final savedSourcePosition = asm.currentSourcePosition;
+        _recordSourcePosition(condition.fileOffset);
+        asm.emitDebugCheck();
+        asm.currentSourcePosition = savedSourcePosition;
+      }
+      if (value) {
+        asm.emitJumpIfNull(dest);
+      } else {
+        asm.emitJumpIfNotNull(dest);
+      }
+      return;
+    }
     bool negated = _genCondition(condition);
     if (value) {
       _genJumpIfTrue(negated, dest);
diff --git a/pkg/vm/testcases/bytecode/bootstrapping.dart.expect b/pkg/vm/testcases/bytecode/bootstrapping.dart.expect
@@ -210,8 +210,7 @@ Bytecode {
   Entry                2
   CheckStack           0
   LoadStatic           CP#0
-  EqualsNull
-  JumpIfFalse          L1
+  JumpIfNotNull        L1
   LoadStatic           CP#1
   DirectCall           CP#2, 1
   StoreLocal           r1
@@ -383,8 +382,7 @@ Bytecode {
   Entry                2
   CheckStack           0
   LoadStatic           CP#0
-  EqualsNull
-  JumpIfFalse          L1
+  JumpIfNotNull        L1
   Allocate             CP#1
   StoreLocal           r1
   Push                 r1
@@ -583,8 +581,7 @@ Bytecode {
   Entry                1
   CheckStack           0
   LoadStatic           CP#0
-  EqualsNull
-  JumpIfFalse          L1
+  JumpIfNotNull        L1
   LoadStatic           CP#1
   EqualsNull
   BooleanNegateTOS
