Use implicit null checks inside try blocks.

Make implicit null check entrypoint save all registers, use
platform-specific approach to still pass the fault address.
Allow implicit null checks in try blocks.

On Nexus 9, AOSP ToT, the boot.oat size reduction is
  prebuilt multi-part boot image:
    - 32-bit boot.oat: -452KiB (-0.7%)
    - 64-bit boot.oat: -482KiB (-0.7%)
  on-device built single boot image:
    - 32-bit boot.oat: -444KiB (-0.7%)
    - 64-bit boot.oat: -488KiB (-0.7%)

Test: Run ART test suite on host and Nexus 9.
Test: Build aosp_mips64-eng.
Change-Id: I279f3ab57e2e2f338131c5cac45c51b673bdca19

1 files changed, 3 insertions, 6 deletions

diff --git a/compiler/optimizing/code_generator.h b/compiler/optimizing/code_generator.h
index 0c60a98139..b4d4b9b760 100644
--- a/compiler/optimizing/code_generator.h
+++ b/compiler/optimizing/code_generator.h
@@ -313,6 +313,7 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
 
   bool CanMoveNullCheckToUser(HNullCheck* null_check);
   void MaybeRecordImplicitNullCheck(HInstruction* instruction);
+  LocationSummary* CreateNullCheckLocations(HNullCheck* null_check);
   void GenerateNullCheck(HNullCheck* null_check);
   virtual void GenerateImplicitNullCheck(HNullCheck* null_check) = 0;
   virtual void GenerateExplicitNullCheck(HNullCheck* null_check) = 0;
@@ -322,12 +323,6 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
   // TODO: Replace with a catch-entering instruction that records the environment.
   void RecordCatchBlockInfo();
 
-  // Returns true if implicit null checks are allowed in the compiler options
-  // and if the null check is not inside a try block. We currently cannot do
-  // implicit null checks in that case because we need the NullCheckSlowPath to
-  // save live registers, which may be needed by the runtime to set catch phis.
-  bool IsImplicitNullCheckAllowed(HNullCheck* null_check) const;
-
   // TODO: Avoid creating the `std::unique_ptr` here.
   void AddSlowPath(SlowPathCode* slow_path) {
     slow_paths_.push_back(std::unique_ptr<SlowPathCode>(slow_path));
@@ -713,6 +708,8 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
   bool is_leaf_;
 
   // Whether an instruction in the graph accesses the current method.
+  // TODO: Rename: this actually indicates that some instruction in the method
+  // needs the environment including a valid stack frame.
   bool requires_current_method_;
 
   friend class OptimizingCFITest;