Compress the Dex register maps built by the optimizing compiler.

- Replace the current list-based (fixed-size) Dex register
  encoding in stack maps emitted by the optimizing compiler
  with another list-based variable-size Dex register
  encoding compressing short locations on 1 byte (3 bits for
  the location kind, 5 bits for the value); other (large)
  values remain encoded on 5 bytes.
- In addition, use slot offsets instead of byte offsets to
  encode the location of Dex registers placed in stack
  slots at small offsets, as it enables more values to use
  the short (1-byte wide) encoding instead of the large
  (5-byte wide) one.
- Rename art::DexRegisterMap::LocationKind as
  art::DexRegisterLocation::Kind, turn it into a
  strongly-typed enum based on a uint8_t, and extend it to
  support new kinds (kInStackLargeOffset and
  kConstantLargeValue).
- Move art::DexRegisterEntry from
  compiler/optimizing/stack_map_stream.h to
  runtime/stack_map.h and rename it as
  art::DexRegisterLocation.
- Adjust art::StackMapStream,
  art::CodeGenerator::RecordPcInfo,
  art::CheckReferenceMapVisitor::CheckOptimizedMethod,
  art::StackVisitor::GetVRegFromOptimizedCode, and
  art::StackVisitor::SetVRegFromOptimizedCode.
- Implement unaligned memory accesses in art::MemoryRegion.
- Use them to manipulate data in Dex register maps.
- Adjust oatdump to support the new Dex register encoding.
- Update compiler/optimizing/stack_map_test.cc.

Change-Id: Icefaa2e2b36b3c80bb1b882fe7ea2f77ba85c505

1 files changed, 33 insertions, 12 deletions

diff --git a/oatdump/oatdump.cc b/oatdump/oatdump.cc
index aab4f8b..9ae3b79 100644
--- a/oatdump/oatdump.cc
+++ b/oatdump/oatdump.cc
@@ -1039,6 +1039,33 @@ class OatDumper {
     }
   }
 
+  void DumpRegisterMapping(std::ostream& os,
+                           size_t dex_register_num,
+                           DexRegisterLocation::Kind kind,
+                           int32_t value,
+                           const std::string& prefix = "v",
+                           const std::string& suffix = "") {
+    os << "      " << prefix << dex_register_num << ": "
+       << DexRegisterLocation::PrettyDescriptor(kind)
+       << " (" << value << ")" << suffix << '\n';
+  }
+
+  void DumpStackMapHeader(std::ostream& os, const CodeInfo& code_info, size_t stack_map_num) {
+    StackMap stack_map = code_info.GetStackMapAt(stack_map_num);
+    os << "    StackMap " << stack_map_num
+       << std::hex
+       << " (dex_pc=0x" << stack_map.GetDexPc()
+       << ", native_pc_offset=0x" << stack_map.GetNativePcOffset()
+       << ", register_mask=0x" << stack_map.GetRegisterMask()
+       << std::dec
+       << ", stack_mask=0b";
+    MemoryRegion stack_mask = stack_map.GetStackMask();
+    for (size_t i = 0, e = stack_mask.size_in_bits(); i < e; ++i) {
+      os << stack_mask.LoadBit(e - i - 1);
+    }
+    os << ")\n";
+  };
+
   // Display a CodeInfo object emitted by the optimizing compiler.
   void DumpCodeInfo(std::ostream& os,
                     const CodeInfo& code_info,
@@ -1049,27 +1076,21 @@ class OatDumper {
     os << "  Optimized CodeInfo (size=" << code_info_size
        << ", number_of_dex_registers=" << number_of_dex_registers
        << ", number_of_stack_maps=" << number_of_stack_maps << ")\n";
+
+    // Display stack maps along with Dex register maps.
     for (size_t i = 0; i < number_of_stack_maps; ++i) {
       StackMap stack_map = code_info.GetStackMapAt(i);
-      // TODO: Display stack_mask value.
-      os << "    StackMap " << i
-         << std::hex
-         << " (dex_pc=0x" << stack_map.GetDexPc()
-         << ", native_pc_offset=0x" << stack_map.GetNativePcOffset()
-         << ", register_mask=0x" << stack_map.GetRegisterMask()
-         << std::dec
-         << ")\n";
+      DumpStackMapHeader(os, code_info, i);
       if (stack_map.HasDexRegisterMap()) {
         DexRegisterMap dex_register_map =
             code_info.GetDexRegisterMapOf(stack_map, number_of_dex_registers);
         for (size_t j = 0; j < number_of_dex_registers; ++j) {
-          os << "      v" << j << ": "
-             << DexRegisterMap::PrettyDescriptor(dex_register_map.GetLocationKind(j))
-             << " (" << dex_register_map.GetValue(j) << ")\n";
+          DexRegisterLocation location = dex_register_map.GetLocationKindAndValue(j);
+          DumpRegisterMapping(os, j, location.GetInternalKind(), location.GetValue());
         }
       }
-      // TODO: Display more information from code_info.
     }
+    // TODO: Dump the stack map's inline information.
   }
 
   // Display a vmap table.