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, 21 insertions, 18 deletions

diff --git a/runtime/stack.cc b/runtime/stack.cc
index 48becf6..e420c57 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -204,29 +204,32 @@ bool StackVisitor::GetVRegFromOptimizedCode(mirror::ArtMethod* m, uint16_t vreg,
   DCHECK(code_item != nullptr) << PrettyMethod(m);  // Can't be NULL or how would we compile
                                                     // its instructions?
   DCHECK_LT(vreg, code_item->registers_size_);
-  DexRegisterMap dex_register_map = code_info.GetDexRegisterMapOf(stack_map,
-                                                                  code_item->registers_size_);
-  DexRegisterMap::LocationKind location_kind = dex_register_map.GetLocationKind(vreg);
+  DexRegisterMap dex_register_map =
+      code_info.GetDexRegisterMapOf(stack_map, code_item->registers_size_);
+  DexRegisterLocation::Kind location_kind = dex_register_map.GetLocationKind(vreg);
   switch (location_kind) {
-    case DexRegisterMap::kInStack: {
+    case DexRegisterLocation::Kind::kInStack: {
       const int32_t offset = dex_register_map.GetStackOffsetInBytes(vreg);
       const uint8_t* addr = reinterpret_cast<const uint8_t*>(cur_quick_frame_) + offset;
       *val = *reinterpret_cast<const uint32_t*>(addr);
       return true;
     }
-    case DexRegisterMap::kInRegister:
-    case DexRegisterMap::kInFpuRegister: {
+    case DexRegisterLocation::Kind::kInRegister:
+    case DexRegisterLocation::Kind::kInFpuRegister: {
       uint32_t reg = dex_register_map.GetMachineRegister(vreg);
       return GetRegisterIfAccessible(reg, kind, val);
     }
-    case DexRegisterMap::kConstant:
+    case DexRegisterLocation::Kind::kConstant:
       *val = dex_register_map.GetConstant(vreg);
       return true;
-    case DexRegisterMap::kNone:
+    case DexRegisterLocation::Kind::kNone:
       return false;
+    default:
+      LOG(FATAL)
+          << "Unexpected location kind"
+          << DexRegisterLocation::PrettyDescriptor(dex_register_map.GetLocationInternalKind(vreg));
+      UNREACHABLE();
   }
-  UNREACHABLE();
-  return false;
 }
 
 bool StackVisitor::GetRegisterIfAccessible(uint32_t reg, VRegKind kind, uint32_t* val) const {
@@ -386,29 +389,29 @@ bool StackVisitor::SetVRegFromOptimizedCode(mirror::ArtMethod* m, uint16_t vreg,
   DCHECK(code_item != nullptr) << PrettyMethod(m);  // Can't be NULL or how would we compile
                                                     // its instructions?
   DCHECK_LT(vreg, code_item->registers_size_);
-  DexRegisterMap dex_register_map = code_info.GetDexRegisterMapOf(stack_map,
-                                                                  code_item->registers_size_);
-  DexRegisterMap::LocationKind location_kind = dex_register_map.GetLocationKind(vreg);
+  DexRegisterMap dex_register_map =
+      code_info.GetDexRegisterMapOf(stack_map, code_item->registers_size_);
+  DexRegisterLocation::Kind location_kind = dex_register_map.GetLocationKind(vreg);
   uint32_t dex_pc = m->ToDexPc(cur_quick_frame_pc_, false);
   switch (location_kind) {
-    case DexRegisterMap::kInStack: {
+    case DexRegisterLocation::Kind::kInStack: {
       const int32_t offset = dex_register_map.GetStackOffsetInBytes(vreg);
       uint8_t* addr = reinterpret_cast<uint8_t*>(cur_quick_frame_) + offset;
       *reinterpret_cast<uint32_t*>(addr) = new_value;
       return true;
     }
-    case DexRegisterMap::kInRegister:
-    case DexRegisterMap::kInFpuRegister: {
+    case DexRegisterLocation::Kind::kInRegister:
+    case DexRegisterLocation::Kind::kInFpuRegister: {
       uint32_t reg = dex_register_map.GetMachineRegister(vreg);
       return SetRegisterIfAccessible(reg, new_value, kind);
     }
-    case DexRegisterMap::kConstant:
+    case DexRegisterLocation::Kind::kConstant:
       LOG(ERROR) << StringPrintf("Cannot change value of DEX register v%u used as a constant at "
                                  "DEX pc 0x%x (native pc 0x%x) of method %s",
                                  vreg, dex_pc, native_pc_offset,
                                  PrettyMethod(cur_quick_frame_->AsMirrorPtr()).c_str());
       return false;
-    case DexRegisterMap::kNone:
+    case DexRegisterLocation::Kind::kNone:
       LOG(ERROR) << StringPrintf("No location for DEX register v%u at DEX pc 0x%x "
                                  "(native pc 0x%x) of method %s",
                                  vreg, dex_pc, native_pc_offset,