First step toward an optimizing compiler:

runtime/vm/flow_graph_optimizer.cc

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/flow_graph_optimizer.h"
+
+#include "vm/flow_graph_builder.h"
+#include "vm/il_printer.h"
+#include "vm/object_store.h"
+
+namespace dart {
+
+DECLARE_FLAG(bool, print_flow_graph);
+DECLARE_FLAG(bool, trace_optimization);
+
+void FlowGraphOptimizer::ApplyICData() {
+  VisitBlocks();
+  if (FLAG_print_flow_graph) {
+    OS::Print("After Optimizations:\n");
+    intptr_t length = block_order_.length();
+    GrowableArray<BlockEntryInstr*> reverse_postorder(length);
+    for (intptr_t i = length - 1; i >= 0; --i) {
+      reverse_postorder.Add(block_order_[i]);
+    }
+    FlowGraphPrinter printer(Function::Handle(), reverse_postorder);
+    printer.PrintBlocks();
+  }
+}
+
+
+void FlowGraphOptimizer::VisitBlocks() {
+  for (intptr_t i = 0; i < block_order_.length(); ++i) {
+    Instruction* instr = block_order_[i]->Accept(this);
+    // Compile all successors until an exit, branch, or a block entry.
+    while ((instr != NULL) && !instr->IsBlockEntry()) {
+      instr = instr->Accept(this);
+    }
+  }
+}
+
+
+static Token::Kind GetBinaryOp(const String& name) {
+  if (name.Length() == 1) {
+    switch (name.CharAt(0)) {
+      case '+' : return Token::kADD;
+      default: return Token::kILLEGAL;
+    }
+  }
+  return Token::kILLEGAL;
+}
+
+
+static bool ICDataHasTwoReceiverClasses(const ICData& ic_data,
+                                        const Class& cls1,
+                                        const Class& cls2) {
+  ASSERT(!cls1.IsNull() && !cls2.IsNull());
+  if (ic_data.num_args_tested() != 2) {
+    return false;
+  }
+  for (intptr_t i = 0; i < ic_data.NumberOfChecks(); i++) {
+    GrowableArray<const Class*> classes;
+    Function& target = Function::Handle();
+    ic_data.GetCheckAt(i, &classes, &target);
+    if (!classes.is_empty()) {
+      if (classes[0]->raw() == cls1.raw()) {
+        if (classes[0]->raw() == cls2.raw()) {

[Florian Schneider, 2012/05/24 00:20:39]

I think this should be classes[1] here:

if (classes[0]->raw() == cls1.raw() &&
    classes[1]->raw() == cls2.raw()) {
  return true;
}

[srdjan, 2012/05/24 01:36:26]

Aargh, thanks.

+          return true;
+        }
+      }
+    }
+  }
+  return false;
+}
+
+
+static bool HasTwoSmi(const ICData& ic_data) {
+  const Class& smi_class =
+      Class::Handle(Isolate::Current()->object_store()->smi_class());
+  return ICDataHasTwoReceiverClasses(ic_data, smi_class, smi_class);
+}
+
+
+void FlowGraphOptimizer::VisitInstanceCall(InstanceCallComp* comp) {
+  if ((comp->ic_data() != NULL) && (!comp->ic_data()->IsNull())) {
+    Token::Kind op_kind = GetBinaryOp(comp->function_name());
+    if (op_kind == Token::kILLEGAL) {
+      // Not a recognized binary operation.
+      return;
+    }
+    if (comp->ic_data()->NumberOfChecks() != 1) {
+      // TODO(srdjan): Not yet supported.
+      return;
+    }
+    if (!HasTwoSmi(*comp->ic_data())) {
+      // TODO(srdjan): Not yet supported.
+      return;
+    }
+    if (comp->use() == NULL) {
+      // TODO(srdjan): Cannot handle yet.
+      return;
+    }
+    ASSERT(comp->InputCount() == 2);
+    BinaryOpComp* bin_op =
+        new BinaryOpComp(op_kind, comp, comp->InputAt(0), comp->InputAt(1));
+    ASSERT(bin_op->ic_data() == NULL);
+    bin_op->set_ic_data(comp->ic_data());
+    bin_op->set_use(comp->use());
+    comp->use()->definition()->replace_computation(bin_op);

[Florian Schneider, 2012/05/24 00:20:39]

As discussed offline, with a pointer to the Bind/DoInstr this would simply
become:

comp->instr()->replace_computation(bin_op);

[srdjan, 2012/05/24 01:36:26]

Yes. This was originally done as a step toward eliminating BindInstr/DoInstr.
However, after some discussion, this may not be the right path.

+  }
+}
+
+
+void FlowGraphOptimizer::VisitDo(DoInstr* instr) {
+  instr->computation()->Accept(this);
+}
+
+
+void FlowGraphOptimizer::VisitBind(BindInstr* instr) {
+  instr->computation()->Accept(this);
+}
+
+
+}  // namespace dart