Refactor to support multiple outputs in location summary

runtime/vm/locations.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_LOCATIONS_H_
 #define VM_LOCATIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/bitfield.h"
@@ skipping 378 matching lines @@
 class LocationSummary : public ZoneAllocated {
  public:
   enum ContainsCall {
     kNoCall,
     kCall,
     kCallOnSlowPath
   };
 
   LocationSummary(intptr_t input_count,
                   intptr_t temp_count,
-                  LocationSummary::ContainsCall contains_call);
+                  LocationSummary::ContainsCall contains_call,
+                  intptr_t output_count = 1);

[srdjan, 2014/03/20 23:04:23]

The count is kind of our of order. Instead of the optional argument you could
use  AddOutput (similar to AddTemp). Or maybe have a second constructor with 4
arguments, all counts together.

[Cutch, 2014/03/21 14:36:46]

Done.

 
   intptr_t input_count() const {
     return input_locations_.length();
   }
 
   Location in(intptr_t index) const {
     return input_locations_[index];
   }
 
   Location* in_slot(intptr_t index) {
@@ skipping 20 matching lines @@
   void set_temp(intptr_t index, Location loc) {
     ASSERT(!always_calls() || loc.IsMachineRegister());
     temp_locations_[index] = loc;
   }
 
   void AddTemp(Location loc) {
     ASSERT(!always_calls() || loc.IsMachineRegister());
     temp_locations_.Add(loc);
   }
 
-  Location out() const {
-    return output_location_;
+  intptr_t output_count() const {
+    return output_locations_.length();
   }
 
-  Location* out_slot() {
-    return &output_location_;
+  Location out(intptr_t index) const {
+    return output_locations_[index];
   }
 
-  void set_out(Location loc) {
+  Location* out_slot(intptr_t index) {
+    return &output_locations_[index];
+  }
+
+  void set_out(intptr_t index, Location loc) {
     ASSERT(!always_calls() || (loc.IsMachineRegister() || loc.IsInvalid()));
-    output_location_ = loc;
+    output_locations_[index] = loc;
   }
 
   BitmapBuilder* stack_bitmap() const { return stack_bitmap_; }
 
   bool always_calls() const {
     return contains_call_ == kCall;
   }
 
   bool can_call() {
     return contains_call_ != kNoCall;
   }
 
   void PrintTo(BufferFormatter* f) const;
 
   static LocationSummary* Make(intptr_t input_count,
                                Location out,
                                ContainsCall contains_call);
 
   RegisterSet* live_registers() {
     return &live_registers_;
   }
 
  private:
-  // TODO(vegorov): replace with ZoneArray.
-  GrowableArray<Location> input_locations_;
-  GrowableArray<Location> temp_locations_;
-  Location output_location_;
+  ZoneGrowableArray<Location> input_locations_;

[Florian Schneider, 2014/03/21 10:47:07]

I wonder how often we actually want to add/remove operands from the location
summary. With growable arrays, we use at least 3*5 words for a (1, 1, 1)-operand
summary, which really contains 3 words of payload.

Have you considered using EmbeddedArray which is used in
intermediate_language.h?

[Cutch, 2014/03/21 14:36:46]

Good point but I would prefer to do that change in a follow up CL.

+  ZoneGrowableArray<Location> temp_locations_;
+  ZoneGrowableArray<Location> output_locations_;
+
   BitmapBuilder* stack_bitmap_;
 
   const ContainsCall contains_call_;
   RegisterSet live_registers_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_LOCATIONS_H_