Build and use stack maps in the SSA compiler.

runtime/vm/flow_graph_allocator.h

 // 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_FLOW_GRAPH_ALLOCATOR_H_
 #define VM_FLOW_GRAPH_ALLOCATOR_H_
 
 #include "vm/growable_array.h"
 #include "vm/intermediate_language.h"
 
@@ skipping 202 matching lines @@
   // Per register lists of allocated live ranges.  Contain only those
   // ranges that can be affected by future allocation decisions.
   // Those live ranges that end before the start of the current live range are
   // removed from the list and will not be affected.
   GrowableArray<LiveRange*> cpu_regs_[kNumberOfCpuRegisters];
 
   // List of used spill slots. Contains positions after which spill slots
   // become free and can be reused for allocation.
   GrowableArray<intptr_t> spill_slots_;
 
+  // List of safepoints.
+  struct Safepoint {

[Vyacheslav Egorov (Google), 2012/08/13 12:54:46]

: public ValueObject ?

[Kevin Millikin (Google), 2012/08/13 15:10:37]

Nah.  The comment in that class indicates that ValueObject is not intended to be
passed by value.  :)

A minor issue is that it would no longer be POD (ValueObject has a user-defined
constructor) so I'd have to write a silly constructor here.

I think I'll probably introduce a SafepointInfo class that wraps this and hides
the bitmap builder as part of a future cleanup, anyway.

+    intptr_t position;
+    BitmapBuilder* stack_bitmap;
+  };
+  GrowableArray<Safepoint> safepoints_;
+
   bool blocked_cpu_regs_[kNumberOfCpuRegisters];
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphAllocator);
 };
 
 
 // Additional information about a block that is not contained in a
 // block entry.
 class BlockInfo : public ZoneAllocated {
  public:
@@ skipping 188 matching lines @@
   void Print();
 
   void AssignLocation(UseInterval* use, Location loc);
 
   LiveRange* SplitAt(intptr_t pos);
 
   bool CanCover(intptr_t pos) const {
     return (Start() <= pos) && (pos < End());
   }
 
+  bool Covers(intptr_t pos) const;

[srdjan, 2012/08/10 23:11:05]

Could you add a brief comment differentiating between 'CanCover' and 'Covers'?

[Vyacheslav Egorov (Google), 2012/08/13 12:54:46]

I suggest renaming Covers to Contains to match naming of Contains in UseInterval
or maybe even AnySiblingContains()

Also please add comment as Srdjan suggested.

[Kevin Millikin (Google), 2012/08/13 15:10:37]

Done.

+
   Location spill_slot() const {
     return spill_slot_;
   }
 
  private:
   LiveRange(intptr_t vreg,
             UsePosition* uses,
             UseInterval* first_use_interval,
             UseInterval* last_use_interval,
             LiveRange* next_sibling)
@@ skipping 18 matching lines @@
 
   AllocationFinger finger_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRange);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_ALLOCATOR_H_