Add DexInstructionIterator and use it a few places

Motivation:
Want to start abstracting away dex specific functionality to enable
CompactDex. Adding an iterator will enable CompactDex iteration to
work differently than normal dex iteration.

Will eventually replace CodeItemIterator.

Bug: 63756964
Test: test-art-host

Change-Id: I90e67c1a994b7698aaac0523a82816b0a003fbdc

1 files changed, 6 insertions, 7 deletions

diff --git a/compiler/optimizing/instruction_builder.cc b/compiler/optimizing/instruction_builder.cc
index e832b10b79..6ad8036870 100644
--- a/compiler/optimizing/instruction_builder.cc
+++ b/compiler/optimizing/instruction_builder.cc
@@ -368,17 +368,16 @@ void HInstructionBuilder::FindNativeDebugInfoLocations(ArenaBitVector* locations
   };
   dex_file_->DecodeDebugPositionInfo(&code_item_, Callback::Position, locations);
   // Instruction-specific tweaks.
-  const Instruction* const begin = Instruction::At(code_item_.insns_);
-  const Instruction* const end = begin->RelativeAt(code_item_.insns_size_in_code_units_);
-  for (const Instruction* inst = begin; inst < end; inst = inst->Next()) {
-    switch (inst->Opcode()) {
+  IterationRange<DexInstructionIterator> instructions = code_item_.Instructions();
+  for (const Instruction& inst : instructions) {
+    switch (inst.Opcode()) {
       case Instruction::MOVE_EXCEPTION: {
         // Stop in native debugger after the exception has been moved.
         // The compiler also expects the move at the start of basic block so
         // we do not want to interfere by inserting native-debug-info before it.
-        locations->ClearBit(inst->GetDexPc(code_item_.insns_));
-        const Instruction* next = inst->Next();
-        if (next < end) {
+        locations->ClearBit(inst.GetDexPc(code_item_.insns_));
+        const Instruction* next = inst.Next();
+        if (DexInstructionIterator(next) != instructions.end()) {
           locations->SetBit(next->GetDexPc(code_item_.insns_));
         }
         break;