Use hash map for the SSA builder constant pool.

runtime/vm/flow_graph.h

 // Copyright (c) 2013, 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_FLOW_GRAPH_H_
 #define VM_FLOW_GRAPH_H_
 
 #include "vm/growable_array.h"
+#include "vm/hash_map.h"
 #include "vm/intermediate_language.h"
 #include "vm/parser.h"
 
 namespace dart {
 
 class BlockEffects;
 class FlowGraphBuilder;
 class ValueInliningContext;
 class VariableLivenessAnalysis;
 
@@ skipping 15 matching lines @@
   bool Done() const { return current_ >= block_order_.length(); }
 
   BlockEntryInstr* Current() const { return block_order_[current_]; }
 
  private:
   const GrowableArray<BlockEntryInstr*>& block_order_;
   intptr_t current_;
 };
 
 
+struct ConstantPoolTrait {
+  typedef ConstantInstr* Value;
+  typedef const Object& Key;
+  typedef ConstantInstr* Pair;
+
+  static Key KeyOf(Pair kv) {
+    return kv->value();
+  }
+
+  static Value ValueOf(Pair kv) {
+    return kv;
+  }
+
+  static inline intptr_t Hashcode(Key key) {
+    if (key.IsSmi()) {
+      return Smi::Cast(key).Value();
+    }
+    if (key.IsDouble()) {

[Vyacheslav Egorov (Google), 2014/06/30 12:13:57]

Add mint to cover all common number types.

[Florian Schneider, 2014/06/30 12:38:10]

Done.

+      return static_cast<intptr_t>(
+          bit_cast<int32_t, float>(
+              static_cast<float>(Double::Cast(key).value())));
+    }
+    if (key.IsString()) {
+      return String::Cast(key).Hash();
+    }
+    return key.GetClassId();

[Vyacheslav Egorov (Google), 2014/06/30 12:13:58]

So we still will degrade to linear search when there are a lot of constants of
the same type that are not numbers or strings :-/

[Vyacheslav Egorov (Google), 2014/06/30 12:13:58]

So we still will degrade to linear search when there are a lot of constants of
the same type that are not numbers or strings :-/

[Florian Schneider, 2014/06/30 12:38:10]

Yep. Currently, there is no fast, generic hash-code function. I covered those
that frequenly occur in code, but we can easily add better handling of
individual types, if necessary.

+  }
+
+  static inline bool IsKeyEqual(Pair kv, Key key) {
+    return kv->value().raw() == key.raw();

[Vyacheslav Egorov (Google), 2014/06/30 12:13:58]

identity is not the best equality for numbers and strings.

[Florian Schneider, 2014/06/30 12:38:10]

Yes, but this is used mostly for canonicalized constants where raw-comparison
works fine. Nothing bad happens if it returns false instead of true in other
cases.

+  }
+};
+
+
 // Class to encapsulate the construction and manipulation of the flow graph.
 class FlowGraph : public ZoneAllocated {
  public:
   FlowGraph(const FlowGraphBuilder& builder,
             GraphEntryInstr* graph_entry,
             intptr_t max_block_id);
 
   const FlowGraphBuilder& builder() const {
     return builder_;
   }
@@ skipping 240 matching lines @@
 
   BlockEffects* block_effects_;
   bool licm_allowed_;
 
   bool use_far_branches_;
 
   ZoneGrowableArray<BlockEntryInstr*>* loop_headers_;
   ZoneGrowableArray<BitVector*>* loop_invariant_loads_;
   ZoneGrowableArray<const Field*>* guarded_fields_;
   ZoneGrowableArray<const LibraryPrefix*>* deferred_prefixes_;
+  DirectChainedHashMap<ConstantPoolTrait> constant_instr_pool_;
 };
 
 
 class LivenessAnalysis : public ValueObject {
  public:
   LivenessAnalysis(intptr_t variable_count,
                    const GrowableArray<BlockEntryInstr*>& postorder);
 
   void Analyze();
 
@@ skipping 89 matching lines @@
   // Per block sets of available blocks. Block A is available at the block B if
   // and only if A dominates B and all paths from A to B are free of side
   // effects.
   GrowableArray<BitVector*> available_at_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_H_