Track fields which are known to be always set to integer constants

lib/compiler/implementation/ssa/optimize.dart

Index: lib/compiler/implementation/ssa/optimize.dart
diff --git a/lib/compiler/implementation/ssa/optimize.dart b/lib/compiler/implementation/ssa/optimize.dart
index ab0b54f1d689146ea7508cf6ebb1c50005375343..4eba79907fee2910147e9a50abf5968963a882b8 100644
--- a/lib/compiler/implementation/ssa/optimize.dart
+++ b/lib/compiler/implementation/ssa/optimize.dart
@@ -36,7 +36,8 @@ class SsaOptimizerTask extends CompilerTask {
           new SsaDeadPhiEliminator(),
           new SsaGlobalValueNumberer(compiler),
           new SsaCodeMotion(),
-          new SsaDeadCodeEliminator()];
+          new SsaDeadCodeEliminator(),
+          new SsaGatherRecompileCandidates(backend, work)];
       runPhases(graph, phases);
     });
   }
@@ -1169,3 +1170,52 @@ class SsaTypeConversionInserter extends HBaseVisitor
     }
   }
 }
+
+class SsaGatherRecompileCandidates
+      extends HBaseVisitor implements OptimizationPhase {
+  final String name = "SsaGatherRecompileCandidates";
+  final JavaScriptBackend backend;
+  final WorkItem work;
+  HGraph graph;
+  Compiler get compiler() => backend.compiler;
+
+  SsaGatherRecompileCandidates(this.backend, this.work);
+
+  void visitGraph(HGraph visitee) {
+    graph = visitee;
+    visitDominatorTree(visitee);
+  }
+
+  HInstruction visitEquals(HEquals node) {
+    // Try to optimize the case where a field which is known to always be an
+    // integer is compared with a constant integer literal.
+    if (node.left is HFieldGet &&
+        node.right is HConstant &&
+        node.right.isInteger()) {
+      HFieldGet left = node.left;
+      HConstant right = node.right;
+      Type type = left.receiver.propagatedType.computeType(compiler);

[floitsch, 2012/06/15 15:00:50]

move type into the 'if'?

[Søren Gjesse, 2012/06/18 11:32:17]

Done.

+      if (left.element != null && right.isInteger()) {

[floitsch, 2012/06/15 15:00:50]

we know already that right is an integer.

[Søren Gjesse, 2012/06/18 11:32:17]

Done.

+        switch (compiler.pass) {
+          case 1:
+            if (compiler.codegenWorld.couldHaveFieldOnlyIntegerSetters(
+                    type, left.element.name) &&
+                compiler.codegenWorld.couldHaveFieldOnlyIntegerInitializer(
+                    type, left.element.name)) {
+              compiler.enqueuer.codegen.registerRecompilationCandidate(
+                  work.element);
+            }
+            break;
+          case 2:
+            if (compiler.codegenWorld.hasFieldOnlyIntegerSetters(
+                    type, left.element.name) &&
+                compiler.codegenWorld.hasFieldOnlyIntegerInitializer(
+                    type, left.element.name)) {
+              left.guaranteedType = HType.INTEGER;
+            }
+            break;
+        }
+      }
+    }
+  }
+}