- Annotate instructions that load objects from the ObjectPool or Thread.

runtime/vm/instructions_arm64.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/constants_arm64.h"
 #include "vm/cpu.h"
@@ skipping 241 matching lines @@
       offset |= instr->Imm16Field();
     }
   }
   // PP is untagged on ARM64.
   ASSERT(Utils::IsAligned(offset, 8));
   *index = ObjectPool::IndexFromOffset(offset - kHeapObjectTag);
   return start;
 }
 
 
+bool DecodeLoadObjectFromPoolOrThread(uword pc,
+                                      const Code& code,
+                                      Object* obj) {
+  ASSERT(code.ContainsInstructionAt(pc));
+
+  Instr* instr = Instr::At(pc);
+  if (instr->IsLoadStoreRegOp() && (instr->Bit(22) == 1) &&
+      (instr->Bits(30, 2) == 3) && instr->Bit(24) == 1) {
+    intptr_t offset = (instr->Imm12Field() << 3);
+    if (instr->RnField() == PP) {
+      // PP is untagged on ARM64.
+      ASSERT(Utils::IsAligned(offset, 8));
+      intptr_t index = ObjectPool::IndexFromOffset(offset - kHeapObjectTag);
+      const ObjectPool& pool = ObjectPool::Handle(code.object_pool());
+      if (pool.InfoAt(index) == ObjectPool::kTaggedObject) {
+        *obj = pool.ObjectAt(index);
+        return true;
+      }
+    } else if (instr->RnField() == THR) {
+      return Thread::ObjectAtOffset(offset, obj);
+    }
+  }
+  // TODO(rmacnak): Loads with offsets beyond 12 bits.
+
+  return false;
+}
+
+
 // Encodes a load sequence ending at 'end'. Encodes a fixed length two
 // instruction load from the pool pointer in PP using the destination
 // register reg as a temporary for the base address.
 // Assumes that the location has already been validated for patching.
 void InstructionPattern::EncodeLoadWordFromPoolFixed(uword end,
                                                      int32_t offset) {
   uword start = end - Instr::kInstrSize;
   Instr* instr = Instr::At(start);
   const int32_t upper12 = offset & 0x00fff000;
   const int32_t lower12 = offset & 0x00000fff;
@@ skipping 104 matching lines @@
 bool ReturnPattern::IsValid() const {
   Instr* bx_lr = Instr::At(pc_);
   const Register crn = ConcreteRegister(LR);
   const int32_t instruction = RET | (static_cast<int32_t>(crn) << kRnShift);
   return bx_lr->InstructionBits() == instruction;
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64