Remove CHECK that GetThis() must always work.

Ensures GetVReg of a reference on compiled code checks that the
value is indeed a reference from the stack maps.

bug: 116683601
bug: 117452149
Test: 686-get-this
Change-Id: I3a370c45786a4892c7888491bec6d5ae64672f6c

1 files changed, 25 insertions, 6 deletions

diff --git a/runtime/stack.cc b/runtime/stack.cc
index eb9c661d18..25939d2f2c 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -139,9 +139,9 @@ mirror::Object* StackVisitor::GetThisObject() const {
     } else {
       uint16_t reg = accessor.RegistersSize() - accessor.InsSize();
       uint32_t value = 0;
-      bool success = GetVReg(m, reg, kReferenceVReg, &value);
-      // We currently always guarantee the `this` object is live throughout the method.
-      CHECK(success) << "Failed to read the this object in " << ArtMethod::PrettyMethod(m);
+      if (!GetVReg(m, reg, kReferenceVReg, &value)) {
+        return nullptr;
+      }
       return reinterpret_cast<mirror::Object*>(value);
     }
   }
@@ -223,20 +223,39 @@ bool StackVisitor::GetVRegFromOptimizedCode(ArtMethod* m, uint16_t vreg, VRegKin
   switch (location_kind) {
     case DexRegisterLocation::Kind::kInStack: {
       const int32_t offset = dex_register_map[vreg].GetStackOffsetInBytes();
+      BitMemoryRegion stack_mask = code_info.GetStackMaskOf(stack_map);
+      if (kind == kReferenceVReg && !stack_mask.LoadBit(offset / kFrameSlotSize)) {
+        return false;
+      }
       const uint8_t* addr = reinterpret_cast<const uint8_t*>(cur_quick_frame_) + offset;
       *val = *reinterpret_cast<const uint32_t*>(addr);
       return true;
     }
-    case DexRegisterLocation::Kind::kInRegister:
+    case DexRegisterLocation::Kind::kInRegister: {
+      uint32_t register_mask = code_info.GetRegisterMaskOf(stack_map);
+      uint32_t reg = dex_register_map[vreg].GetMachineRegister();
+      if (kind == kReferenceVReg && !(register_mask & (1 << reg))) {
+        return false;
+      }
+      return GetRegisterIfAccessible(reg, kind, val);
+    }
     case DexRegisterLocation::Kind::kInRegisterHigh:
     case DexRegisterLocation::Kind::kInFpuRegister:
     case DexRegisterLocation::Kind::kInFpuRegisterHigh: {
+      if (kind == kReferenceVReg) {
+        return false;
+      }
       uint32_t reg = dex_register_map[vreg].GetMachineRegister();
       return GetRegisterIfAccessible(reg, kind, val);
     }
-    case DexRegisterLocation::Kind::kConstant:
-      *val = dex_register_map[vreg].GetConstant();
+    case DexRegisterLocation::Kind::kConstant: {
+      uint32_t result = dex_register_map[vreg].GetConstant();
+      if (kind == kReferenceVReg && result != 0) {
+        return false;
+      }
+      *val = result;
       return true;
+    }
     case DexRegisterLocation::Kind::kNone:
       return false;
     default: