Move ConstantPropagator from flow_graph_optimizer.cc/.h into separate files.

flow_graph_optimizer.cc is becoming unnecessarily large, so
I'm  moving self-contained optimization passes into
separate files.

In a separate CL I'll also move load/store optimization into
separate files.

R=srdjan@google.com

Review URL: https://codereview.chromium.org//820883004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@42567 260f80e4-7a28-3924-810f-c04153c831b5

runtime/vm/compiler.cc

@@ -11,6 +11,7 @@
 #include "vm/cha.h"
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
+#include "vm/constant_propagator.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/deopt_instructions.h"

runtime/vm/constant_propagator.h

@@ -0,0 +1,92 @@
+// 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.
+
+#ifndef VM_CONSTANT_PROPAGATOR_H_
+#define VM_CONSTANT_PROPAGATOR_H_
+
+#include "vm/intermediate_language.h"
+#include "vm/flow_graph.h"
+
+namespace dart {
+
+// Sparse conditional constant propagation and unreachable code elimination.
+// Assumes that use lists are computed and preserves them.
+class ConstantPropagator : public FlowGraphVisitor {
+ public:
+  ConstantPropagator(FlowGraph* graph,
+                     const GrowableArray<BlockEntryInstr*>& ignored);
+
+  static void Optimize(FlowGraph* graph);
+
+  // (1) Visit branches to optimize away unreachable blocks discovered  by range
+  // analysis.
+  // (2) Eliminate branches that have the same true- and false-target: For
+  // example, this occurs after expressions like
+  //
+  // if (a == null || b == null) {
+  //   ...
+  // }
+  //
+  // where b is known to be null.
+  static void OptimizeBranches(FlowGraph* graph);
+
+  // Used to initialize the abstract value of definitions.
+  static RawObject* Unknown() { return Object::unknown_constant().raw(); }
+
+ private:
+  void Analyze();
+  void Transform();
+  void EliminateRedundantBranches();
+
+  void SetReachable(BlockEntryInstr* block);
+  bool SetValue(Definition* definition, const Object& value);
+
+  Definition* UnwrapPhi(Definition* defn);
+  void MarkPhi(Definition* defn);
+
+  // Assign the join (least upper bound) of a pair of abstract values to the
+  // first one.
+  void Join(Object* left, const Object& right);
+
+  bool IsUnknown(const Object& value) {
+    return value.raw() == unknown_.raw();
+  }
+  bool IsNonConstant(const Object& value) {
+    return value.raw() == non_constant_.raw();
+  }
+  bool IsConstant(const Object& value) {
+    return !IsNonConstant(value) && !IsUnknown(value);
+  }
+
+  void VisitBinaryIntegerOp(BinaryIntegerOpInstr* binary_op);
+
+  virtual void VisitBlocks() { UNREACHABLE(); }
+
+#define DECLARE_VISIT(type) virtual void Visit##type(type##Instr* instr);
+  FOR_EACH_INSTRUCTION(DECLARE_VISIT)
+#undef DECLARE_VISIT
+
+  Isolate* isolate() const { return graph_->isolate(); }
+
+  FlowGraph* graph_;
+
+  // Sentinels for unknown constant and non-constant values.
+  const Object& unknown_;
+  const Object& non_constant_;
+
+  // Analysis results. For each block, a reachability bit.  Indexed by
+  // preorder number.
+  BitVector* reachable_;
+
+  BitVector* marked_phis_;
+
+  // Worklists of blocks and definitions.
+  GrowableArray<BlockEntryInstr*> block_worklist_;
+  DefinitionWorklist definition_worklist_;
+};
+
+
+}  // namespace dart
+
+#endif  // VM_CONSTANT_PROPAGATOR_H_

runtime/vm/flow_graph_optimizer.h

@@ -316,83 +316,6 @@ class DeadCodeElimination : public AllStatic {
 };
 
 
-// Sparse conditional constant propagation and unreachable code elimination.
-// Assumes that use lists are computed and preserves them.
-class ConstantPropagator : public FlowGraphVisitor {
- public:
-  ConstantPropagator(FlowGraph* graph,
-                     const GrowableArray<BlockEntryInstr*>& ignored);
-
-  static void Optimize(FlowGraph* graph);
-
-  // (1) Visit branches to optimize away unreachable blocks discovered  by range
-  // analysis.
-  // (2) Eliminate branches that have the same true- and false-target: For
-  // example, this occurs after expressions like
-  //
-  // if (a == null || b == null) {
-  //   ...
-  // }
-  //
-  // where b is known to be null.
-  static void OptimizeBranches(FlowGraph* graph);
-
-  // Used to initialize the abstract value of definitions.
-  static RawObject* Unknown() { return Object::unknown_constant().raw(); }
-
- private:
-  void Analyze();
-  void Transform();
-  void EliminateRedundantBranches();
-
-  void SetReachable(BlockEntryInstr* block);
-  bool SetValue(Definition* definition, const Object& value);
-
-  Definition* UnwrapPhi(Definition* defn);
-  void MarkPhi(Definition* defn);
-
-  // Assign the join (least upper bound) of a pair of abstract values to the
-  // first one.
-  void Join(Object* left, const Object& right);
-
-  bool IsUnknown(const Object& value) {
-    return value.raw() == unknown_.raw();
-  }
-  bool IsNonConstant(const Object& value) {
-    return value.raw() == non_constant_.raw();
-  }
-  bool IsConstant(const Object& value) {
-    return !IsNonConstant(value) && !IsUnknown(value);
-  }
-
-  void VisitBinaryIntegerOp(BinaryIntegerOpInstr* binary_op);
-
-  virtual void VisitBlocks() { UNREACHABLE(); }
-
-#define DECLARE_VISIT(type) virtual void Visit##type(type##Instr* instr);
-  FOR_EACH_INSTRUCTION(DECLARE_VISIT)
-#undef DECLARE_VISIT
-
-  Isolate* isolate() const { return graph_->isolate(); }
-
-  FlowGraph* graph_;
-
-  // Sentinels for unknown constant and non-constant values.
-  const Object& unknown_;
-  const Object& non_constant_;
-
-  // Analysis results. For each block, a reachability bit.  Indexed by
-  // preorder number.
-  BitVector* reachable_;
-
-  BitVector* marked_phis_;
-
-  // Worklists of blocks and definitions.
-  GrowableArray<BlockEntryInstr*> block_worklist_;
-  DefinitionWorklist definition_worklist_;
-};
-
-
 // Rewrite branches to eliminate materialization of boolean values after
 // inlining, and to expose other optimizations (e.g., constant folding of
 // branches, unreachable code elimination).

runtime/vm/intermediate_language.cc

@@ -5,6 +5,7 @@
 #include "vm/intermediate_language.h"
 
 #include "vm/bit_vector.h"
+#include "vm/constant_propagator.h"
 #include "vm/cpu.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
@@ -39,7 +40,6 @@ DEFINE_FLAG(bool, unbox_numeric_fields, true,
 DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(bool, eliminate_type_checks);
 DECLARE_FLAG(bool, trace_optimization);
-DECLARE_FLAG(bool, trace_constant_propagation);
 DECLARE_FLAG(bool, throw_on_javascript_int_overflow);
 
 Definition::Definition(intptr_t deopt_id)

runtime/vm/vm_sources.gypi

@@ -95,6 +95,8 @@
     'compiler_stats.cc',
     'compiler_stats.h',
     'compiler_test.cc',
+    'constant_propagator.h',
+    'constant_propagator.cc',
     'constants_arm.h',
     'constants_arm64.h',
     'constants_ia32.h',