commit fb8464ae5f5194dc16278e528cfcbff71498c767
author Mingyao Yang <mingyao@google.com> Mon Nov 02 10:56:59 2015 -0800
committer Mingyao Yang <mingyao@google.com> Wed Nov 18 13:27:16 2015 -0800
tree 9361521497f31fd024f36980464d17bee7c83d52
parent 9231730cd0e285373afd73331168b289309ebee4

Revert "Revert "Enable store elimination for singleton objects.""

This reverts commit 55d02cf056f993aeafebd54e7b7c68c7a48507c9, and
makes the following change:
Currently we leverage loop side effects to decide whether heap values are
killed by the loop. Stores need to be kept if heap values may be killed
by loops and the corresponding loads cannot be eliminated. Similar thing
need to be done for each predecessor when we merge predecessor heap values.
To do that, the HInstanceFieldSet instruction itself is put in the heap
value array instead of the value of the store instruction. The store
instruction may be added to possibly_removed_stores_ first, but can later
be removed from possibly_removed_stores_ when it's found out that the store
needs to be kept due to merging/loop side effects.

Change-Id: I4f7bb1960f7b47240873e00ff1adac46fc102a02

compiler/optimizing/nodes.h

diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 1da2a1d..e3c810e 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -3643,10 +3643,14 @@
                uint32_t dex_pc,
                uint16_t type_index,
                const DexFile& dex_file,
+               bool can_throw,
+               bool finalizable,
                QuickEntrypointEnum entrypoint)
       : HExpression(Primitive::kPrimNot, SideEffects::CanTriggerGC(), dex_pc),
         type_index_(type_index),
         dex_file_(dex_file),
+        can_throw_(can_throw),
+        finalizable_(finalizable),
         entrypoint_(entrypoint) {
     SetRawInputAt(0, current_method);
   }
@@ -3656,11 +3660,13 @@
 
   // Calls runtime so needs an environment.
   bool NeedsEnvironment() const OVERRIDE { return true; }
-  // It may throw when called on:
-  //   - interfaces
-  //   - abstract/innaccessible/unknown classes
-  // TODO: optimize when possible.
-  bool CanThrow() const OVERRIDE { return true; }
+
+  // It may throw when called on type that's not instantiable/accessible.
+  // It can throw OOME.
+  // TODO: distinguish between the two cases so we can for example allow allocation elimination.
+  bool CanThrow() const OVERRIDE { return can_throw_ || true; }
+
+  bool IsFinalizable() const { return finalizable_; }
 
   bool CanBeNull() const OVERRIDE { return false; }
 
@@ -3671,6 +3677,8 @@
  private:
   const uint16_t type_index_;
   const DexFile& dex_file_;
+  const bool can_throw_;
+  const bool finalizable_;
   const QuickEntrypointEnum entrypoint_;
 
   DISALLOW_COPY_AND_ASSIGN(HNewInstance);