Overhaul tree IR visitor and rename IR classes.

pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
index f15418f2188f2903ea1b6b692149abfaff6cc589..db5c00d77ebdffe18d36785daf38aa3880c2d71c 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
@@ -21,9 +21,10 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
 
   visit(cps_ir.Node node) => node.accept(this);
 
-  void traceGraph(String name, cps_ir.ExecutableDefinition graph) {
+  void traceGraph(String name, cps_ir.RootNode graph) {
     tag("cfg", () {
       printProperty("name", name);
+      if (graph.isEmpty) return;
       visit(graph);

[Kevin Millikin (Google), 2015/04/08 15:10:15]

Maybe this can be disentangled a bit after this change.  Right now:

IRTracer.traceGraph(name, graph) calls
IRTracer.visit(graph) when graph.body is non-null, which just calls
IRTracer.printDefinition(graph), which calls
BlockCollector.visit(graph), which just calls
BlockCollector.visit(graph.body)

meanwhile IRTracer.visitBody is unexpected.

It seems simpler to switch so:

IRTracer.traceGraph(name, graph) calls IRTracer.visit(graph.body) when
graph.body is non-null and just move the definition of printDefinition into
IRTracer.visitBody.

[asgerf, 2015/04/09 09:58:23]

I agree, this code has stagnated quite a bit.

I updated both IR tracers to properly handle the multiple bodies of constructors
and print an explicit 'Entry' statement in front of blocks that are entry
points. They also print the parameter list now, which is nice.

The many bodies of a constructor should be passed to the same block collector so
traversing the top-level nodes in the IRTracer did not work. So they are just
unexpected nodes.

     });
   }
@@ -31,7 +32,7 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
   // Temporary field used during tree walk
   Names names;
 
-  printDefinition(cps_ir.ExecutableDefinition node) {
+  printDefinition(cps_ir.RootNode node) {
     names = new Names();
     BlockCollector builder = new BlockCollector(names);
     builder.visit(node);
@@ -46,18 +47,14 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
   }
 
   visitFieldDefinition(cps_ir.FieldDefinition node) {
-    if (node.hasInitializer) {
-      printDefinition(node);
-    }
+    printDefinition(node);
   }
 
   visitFunctionDefinition(cps_ir.FunctionDefinition node) {
-    if (node.isAbstract) return;
     printDefinition(node);
   }
 
   visitConstructorDefinition(cps_ir.ConstructorDefinition node) {
-    if (node.isAbstract) return;
     printDefinition(node);
   }
 
@@ -68,7 +65,7 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
     throw 'The IR tracer reached an unexpected IR instruction: $node';
   }
 
-  visitRunnableBody(cps_ir.RunnableBody node) {
+  visitBody(cps_ir.Body node) {
     unexpectedNode(node);
   }
   visitFieldInitializer(cps_ir.FieldInitializer node) {
@@ -429,9 +426,7 @@ class BlockCollector implements cps_ir.Visitor {
   visit(cps_ir.Node node) => node.accept(this);
 
   visitFieldDefinition(cps_ir.FieldDefinition node) {
-    if (node.hasInitializer) {
-      visit(node.body);
-    }
+    visit(node.body);
   }
 
   visitFunctionDefinition(cps_ir.FunctionDefinition node) {
@@ -442,7 +437,7 @@ class BlockCollector implements cps_ir.Visitor {
     visit(node.body);
   }
 
-  visitRunnableBody(cps_ir.RunnableBody node) {
+  visitBody(cps_ir.Body node) {
     current_block = new Block(names.name(node), [], node.body);
     entries.add(current_block);
     visit(node.body);