Implement code generation for === and !==.

frog/leg/ssa/nodes.dart

Index: frog/leg/ssa/nodes.dart
diff --git a/frog/leg/ssa/nodes.dart b/frog/leg/ssa/nodes.dart
index 08e22e326eb5e805735d10079178cfc55153e148..50f9ed676dce04b967a9fe97e6b9bc6d7c6be4dc 100644
--- a/frog/leg/ssa/nodes.dart
+++ b/frog/leg/ssa/nodes.dart
@@ -18,6 +18,7 @@ interface HVisitor<R> {
   R visitGoto(HGoto node);
   R visitGreater(HGreater node);
   R visitGreaterEqual(HGreaterEqual node);
+  R visitIdentity(HIdentity node);
   R visitIf(HIf node);
   R visitIndex(HIndex node);
   R visitIndexAssign(HIndexAssign node);
@@ -207,6 +208,7 @@ class HBaseVisitor extends HGraphVisitor implements HVisitor {
   visitGoto(HGoto node) => visitControlFlow(node);
   visitGreater(HGreater node) => visitRelational(node);
   visitGreaterEqual(HGreaterEqual node) => visitRelational(node);
+  visitIdentity(HIdentity node) => visitRelational(node);
   visitIf(HIf node) => visitConditionalBranch(node);
   visitIndex(HIndex node) => visitInvokeStatic(node);
   visitIndexAssign(HIndexAssign node) => visitInvokeStatic(node);
@@ -1629,7 +1631,7 @@ class HRelational extends HInvokeBinary {
 
   HType computeDesiredInputType(HInstruction input) {
     // TODO(floitsch): we want the target to be a function.
-    if (input == inputs[0]) return HType.UNKNOWN;
+    if (input == target) return HType.UNKNOWN;
     // For all relational operations exept HEquals, we expect to only
     // get numbers.
     return HType.NUMBER;
@@ -1652,12 +1654,30 @@ class HEquals extends HRelational {
 
   HType computeDesiredInputType(HInstruction input) {
     // TODO(floitsch): we want the target to be a function.
-    if (input == inputs[0]) return HType.UNKNOWN;
+    if (input == target) return HType.UNKNOWN;
     if (left.isNumber() || right.isNumber()) return HType.NUMBER;
     return HType.UNKNOWN;
   }
 }
 
+class HIdentity extends HRelational {
+  HIdentity(HStatic target, HInstruction left, HInstruction right)
+      : super(target, left, right);
+  bool evaluate(num a, num b) => a === b;

[ngeoffray, 2012/01/06 08:10:20]

Should that be really 'num' here?

+  accept(HVisitor visitor) => visitor.visitIdentity(this);
+  bool typeEquals(other) => other is HIdentity;
+  bool dataEquals(HInstruction other) => true;
+
+  HType computeType() {
+    builtin = true;
+    return HType.BOOLEAN;
+  }
+
+  bool hasExpectedType() => true;
+
+  HType computeDesiredInputType(HInstruction input) => HType.UNKNOWN;
+}
+
 class HGreater extends HRelational {
   HGreater(HStatic target, HInstruction left, HInstruction right)
       : super(target, left, right);