Compressed native PC for stack maps

Compress native PC based on instruction alignment. This reduces the
size of stack maps, boot.oat is 0.4% smaller for arm64.

Test: test-art-host, test-art-target, N6P booting

Change-Id: I2b70eecabda88b06fa80a85688fd992070d54278
diff --git a/oatdump/oatdump.cc b/oatdump/oatdump.cc
index 148ee88..3cf900e 100644
--- a/oatdump/oatdump.cc
+++ b/oatdump/oatdump.cc
@@ -1223,7 +1223,8 @@
     code_info.Dump(vios,
                    oat_method.GetCodeOffset(),
                    code_item.registers_size_,
-                   options_.dump_code_info_stack_maps_);
+                   options_.dump_code_info_stack_maps_,
+                   instruction_set_);
   }
 
   void DumpVregLocations(std::ostream& os, const OatFile::OatMethod& oat_method,
@@ -1329,21 +1330,22 @@
   // For identical native PCs, the order from the CodeInfo is preserved.
   class StackMapsHelper {
    public:
-    explicit StackMapsHelper(const uint8_t* raw_code_info)
+    explicit StackMapsHelper(const uint8_t* raw_code_info, InstructionSet instruction_set)
         : code_info_(raw_code_info),
           encoding_(code_info_.ExtractEncoding()),
           number_of_stack_maps_(code_info_.GetNumberOfStackMaps(encoding_)),
           indexes_(),
-          offset_(static_cast<size_t>(-1)),
-          stack_map_index_(0u) {
+          offset_(static_cast<uint32_t>(-1)),
+          stack_map_index_(0u),
+          instruction_set_(instruction_set) {
       if (number_of_stack_maps_ != 0u) {
         // Check if native PCs are ordered.
         bool ordered = true;
         StackMap last = code_info_.GetStackMapAt(0u, encoding_);
         for (size_t i = 1; i != number_of_stack_maps_; ++i) {
           StackMap current = code_info_.GetStackMapAt(i, encoding_);
-          if (last.GetNativePcOffset(encoding_.stack_map_encoding) >
-              current.GetNativePcOffset(encoding_.stack_map_encoding)) {
+          if (last.GetNativePcOffset(encoding_.stack_map_encoding, instruction_set) >
+              current.GetNativePcOffset(encoding_.stack_map_encoding, instruction_set)) {
             ordered = false;
             break;
           }
@@ -1359,14 +1361,17 @@
                     indexes_.end(),
                     [this](size_t lhs, size_t rhs) {
                       StackMap left = code_info_.GetStackMapAt(lhs, encoding_);
-                      uint32_t left_pc = left.GetNativePcOffset(encoding_.stack_map_encoding);
+                      uint32_t left_pc = left.GetNativePcOffset(encoding_.stack_map_encoding,
+                                                                instruction_set_);
                       StackMap right = code_info_.GetStackMapAt(rhs, encoding_);
-                      uint32_t right_pc = right.GetNativePcOffset(encoding_.stack_map_encoding);
+                      uint32_t right_pc = right.GetNativePcOffset(encoding_.stack_map_encoding,
+                                                                  instruction_set_);
                       // If the PCs are the same, compare indexes to preserve the original order.
                       return (left_pc < right_pc) || (left_pc == right_pc && lhs < rhs);
                     });
         }
-        offset_ = GetStackMapAt(0).GetNativePcOffset(encoding_.stack_map_encoding);
+        offset_ = GetStackMapAt(0).GetNativePcOffset(encoding_.stack_map_encoding,
+                                                     instruction_set_);
       }
     }
 
@@ -1378,7 +1383,7 @@
       return encoding_;
     }
 
-    size_t GetOffset() const {
+    uint32_t GetOffset() const {
       return offset_;
     }
 
@@ -1389,8 +1394,9 @@
     void Next() {
       ++stack_map_index_;
       offset_ = (stack_map_index_ == number_of_stack_maps_)
-          ? static_cast<size_t>(-1)
-          : GetStackMapAt(stack_map_index_).GetNativePcOffset(encoding_.stack_map_encoding);
+          ? static_cast<uint32_t>(-1)
+          : GetStackMapAt(stack_map_index_).GetNativePcOffset(encoding_.stack_map_encoding,
+                                                              instruction_set_);
     }
 
    private:
@@ -1406,8 +1412,9 @@
     const CodeInfoEncoding encoding_;
     const size_t number_of_stack_maps_;
     dchecked_vector<size_t> indexes_;  // Used if stack map native PCs are not ordered.
-    size_t offset_;
+    uint32_t offset_;
     size_t stack_map_index_;
+    const InstructionSet instruction_set_;
   };
 
   void DumpCode(VariableIndentationOutputStream* vios,
@@ -1423,7 +1430,7 @@
       return;
     } else if (!bad_input && IsMethodGeneratedByOptimizingCompiler(oat_method, code_item)) {
       // The optimizing compiler outputs its CodeInfo data in the vmap table.
-      StackMapsHelper helper(oat_method.GetVmapTable());
+      StackMapsHelper helper(oat_method.GetVmapTable(), instruction_set_);
       const uint8_t* quick_native_pc = reinterpret_cast<const uint8_t*>(quick_code);
       size_t offset = 0;
       while (offset < code_size) {
@@ -1436,7 +1443,8 @@
                          helper.GetCodeInfo(),
                          helper.GetEncoding(),
                          oat_method.GetCodeOffset(),
-                         code_item->registers_size_);
+                         code_item->registers_size_,
+                         instruction_set_);
           do {
             helper.Next();
             // There may be multiple stack maps at a given PC. We display only the first one.