Revert "Revert "ART: Register allocation and runtime support for try/catch""

The original CL triggered b/24084144 which has been fixed
by Ib72e12a018437c404e82f7ad414554c66a4c6f8c.

This reverts commit 659562aaf133c41b8d90ec9216c07646f0f14362.

Change-Id: Id8980436172457d0fcb276349c4405f7c4110a55
diff --git a/compiler/optimizing/register_allocator.h b/compiler/optimizing/register_allocator.h
index c29fe75..e030464 100644
--- a/compiler/optimizing/register_allocator.h
+++ b/compiler/optimizing/register_allocator.h
@@ -29,6 +29,7 @@
 class HGraph;
 class HInstruction;
 class HParallelMove;
+class HPhi;
 class LiveInterval;
 class Location;
 class SsaLivenessAnalysis;
@@ -72,7 +73,8 @@
     return int_spill_slots_.Size()
         + long_spill_slots_.Size()
         + float_spill_slots_.Size()
-        + double_spill_slots_.Size();
+        + double_spill_slots_.Size()
+        + catch_phi_spill_slots_;
   }
 
   static constexpr const char* kRegisterAllocatorPassName = "register";
@@ -99,10 +101,17 @@
 
   // Update the interval for the register in `location` to cover [start, end).
   void BlockRegister(Location location, size_t start, size_t end);
+  void BlockRegisters(size_t start, size_t end, bool caller_save_only = false);
 
-  // Allocate a spill slot for the given interval.
+  // Allocate a spill slot for the given interval. Should be called in linear
+  // order of interval starting positions.
   void AllocateSpillSlotFor(LiveInterval* interval);
 
+  // Allocate a spill slot for the given catch phi. Will allocate the same slot
+  // for phis which share the same vreg. Must be called in reverse linear order
+  // of lifetime positions and ascending vreg numbers for correctness.
+  void AllocateSpillSlotForCatchPhi(HPhi* phi);
+
   // Connect adjacent siblings within blocks.
   void ConnectSiblings(LiveInterval* interval);
 
@@ -202,6 +211,11 @@
   GrowableArray<size_t> float_spill_slots_;
   GrowableArray<size_t> double_spill_slots_;
 
+  // Spill slots allocated to catch phis. This category is special-cased because
+  // (1) slots are allocated prior to linear scan and in reverse linear order,
+  // (2) equivalent phis need to share slots despite having different types.
+  size_t catch_phi_spill_slots_;
+
   // Instructions that need a safepoint.
   GrowableArray<HInstruction*> safepoints_;