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

runtime/vm/instructions_arm.cc

Index: runtime/vm/instructions_arm.cc
diff --git a/runtime/vm/instructions_arm.cc b/runtime/vm/instructions_arm.cc
index de74bd5ed29840218bf220b2d6751deb595eff54..3222aa676afb12389de26cb4dc459954f4e1a663 100644
--- a/runtime/vm/instructions_arm.cc
+++ b/runtime/vm/instructions_arm.cc
@@ -180,7 +180,7 @@ uword InstructionPattern::DecodeLoadWordFromPool(uword end,
   uword start = end - Instr::kInstrSize;
   int32_t instr = Instr::At(start)->InstructionBits();
   intptr_t offset = 0;
-  if ((instr & 0xffff0000) == (0xe5950000 | (PP << 16))) {
+  if ((instr & 0xffff0000) == (0xe5900000 | (PP << 16))) {

[Cutch, 2015/11/12 17:33:52]

How about a kConst for these patterns?

[rmacnak, 2015/11/12 21:50:46]

Extracted as IsLoadWithOffset

     // ldr reg, [pp, #+offset]
     offset = instr & 0xfff;
     *reg = static_cast<Register>((instr & 0xf000) >> 12);
@@ -206,6 +206,32 @@ uword InstructionPattern::DecodeLoadWordFromPool(uword end,
 }
 
 
+bool DecodeLoadObjectFromPoolOrThread(uword pc,
+                                      const Code& code,
+                                      Object* obj) {
+  ASSERT(code.ContainsInstructionAt(pc));
+
+  int32_t instr = Instr::At(pc)->InstructionBits();
+  if ((instr & 0xffff0000) == (0xe5900000 | (PP << 16))) {
+    // ldr reg, [pp, #+offset]
+    intptr_t offset = instr & 0xfff;
+    intptr_t index = ObjectPool::IndexFromOffset(offset);
+    const ObjectPool& pool = ObjectPool::Handle(code.object_pool());
+    if (pool.InfoAt(index) == ObjectPool::kTaggedObject) {
+      *obj = pool.ObjectAt(index);
+      return true;
+    }
+  } else if ((instr & 0xffff0000) == (0xe5900000 | (THR << 16))) {
+    // ldr reg, [thr, #+offset]
+    intptr_t offset = instr & 0xfff;
+    return Thread::ObjectAtOffset(offset, obj);
+  }
+  // TODO(rmacnak): Sequence for loads beyond 12 bits.
+
+  return false;
+}
+
+
 RawICData* CallPattern::IcData() {
   if (ic_data_.IsNull()) {
     Register reg;