Add support for inputs dying at entry of instructions.

- Start using it in places where it makes sense.
- Also improve suspend check on arm to use subs directly.

Change-Id: I09ac0589f5ccb9b850ee757c76dcbcf35ee8cd01

6 files changed, 87 insertions, 59 deletions

diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 1876cb9..2aa04d4 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -611,7 +611,7 @@ void LocationsBuilderARM::VisitIf(HIf* if_instr) {
   DCHECK(cond->IsCondition());
   HCondition* condition = cond->AsCondition();
   if (condition->NeedsMaterialization()) {
-    locations->SetInAt(0, Location::RequiresRegister());
+    locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   }
 }
 
@@ -657,8 +657,8 @@ void InstructionCodeGeneratorARM::VisitIf(HIf* if_instr) {
 void LocationsBuilderARM::VisitCondition(HCondition* comp) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(comp, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RegisterOrConstant(comp->InputAt(1)));
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(1, Location::RegisterOrConstant(comp->InputAt(1)), Location::kDiesAtEntry);
   if (comp->NeedsMaterialization()) {
     locations->SetOut(Location::RequiresRegister());
   }
@@ -960,8 +960,9 @@ void LocationsBuilderARM::VisitAdd(HAdd* add) {
   switch (add->GetResultType()) {
     case Primitive::kPrimInt:
     case Primitive::kPrimLong: {
-      locations->SetInAt(0, Location::RequiresRegister());
-      locations->SetInAt(1, Location::RegisterOrConstant(add->InputAt(1)));
+      bool dies_at_entry = add->GetResultType() != Primitive::kPrimLong;
+      locations->SetInAt(0, Location::RequiresRegister(), dies_at_entry);
+      locations->SetInAt(1, Location::RegisterOrConstant(add->InputAt(1)), dies_at_entry);
       locations->SetOut(Location::RequiresRegister());
       break;
     }
@@ -1020,8 +1021,9 @@ void LocationsBuilderARM::VisitSub(HSub* sub) {
   switch (sub->GetResultType()) {
     case Primitive::kPrimInt:
     case Primitive::kPrimLong: {
-      locations->SetInAt(0, Location::RequiresRegister());
-      locations->SetInAt(1, Location::RegisterOrConstant(sub->InputAt(1)));
+      bool dies_at_entry = sub->GetResultType() != Primitive::kPrimLong;
+      locations->SetInAt(0, Location::RequiresRegister(), dies_at_entry);
+      locations->SetInAt(1, Location::RegisterOrConstant(sub->InputAt(1)), dies_at_entry);
       locations->SetOut(Location::RequiresRegister());
       break;
     }
@@ -1116,7 +1118,7 @@ void InstructionCodeGeneratorARM::VisitParameterValue(HParameterValue* instructi
 void LocationsBuilderARM::VisitNot(HNot* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1129,8 +1131,8 @@ void InstructionCodeGeneratorARM::VisitNot(HNot* instruction) {
 void LocationsBuilderARM::VisitCompare(HCompare* compare) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(compare, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(1, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1186,10 +1188,12 @@ void InstructionCodeGeneratorARM::VisitPhi(HPhi* instruction) {
 void LocationsBuilderARM::VisitInstanceFieldSet(HInstanceFieldSet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  bool is_object_type = instruction->GetFieldType() == Primitive::kPrimNot;
+  bool dies_at_entry = !is_object_type;
+  locations->SetInAt(0, Location::RequiresRegister(), dies_at_entry);
+  locations->SetInAt(1, Location::RequiresRegister(), dies_at_entry);
   // Temporary registers for the write barrier.
-  if (instruction->GetFieldType() == Primitive::kPrimNot) {
+  if (is_object_type) {
     locations->AddTemp(Location::RequiresRegister());
     locations->AddTemp(Location::RequiresRegister());
   }
@@ -1246,7 +1250,7 @@ void InstructionCodeGeneratorARM::VisitInstanceFieldSet(HInstanceFieldSet* instr
 void LocationsBuilderARM::VisitInstanceFieldGet(HInstanceFieldGet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1328,8 +1332,9 @@ void InstructionCodeGeneratorARM::VisitNullCheck(HNullCheck* instruction) {
 void LocationsBuilderARM::VisitArrayGet(HArrayGet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(
+      1, Location::RegisterOrConstant(instruction->InputAt(1)), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1439,9 +1444,10 @@ void LocationsBuilderARM::VisitArraySet(HArraySet* instruction) {
     locations->SetInAt(1, ArmCoreLocation(calling_convention.GetRegisterAt(1)));
     locations->SetInAt(2, ArmCoreLocation(calling_convention.GetRegisterAt(2)));
   } else {
-    locations->SetInAt(0, Location::RequiresRegister());
-    locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
-    locations->SetInAt(2, Location::RequiresRegister());
+    locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+    locations->SetInAt(
+        1, Location::RegisterOrConstant(instruction->InputAt(1)), Location::kDiesAtEntry);
+    locations->SetInAt(2, Location::RequiresRegister(), Location::kDiesAtEntry);
   }
 }
 
@@ -1527,7 +1533,7 @@ void InstructionCodeGeneratorARM::VisitArraySet(HArraySet* instruction) {
 void LocationsBuilderARM::VisitArrayLength(HArrayLength* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1610,13 +1616,12 @@ void InstructionCodeGeneratorARM::GenerateSuspendCheck(HSuspendCheck* instructio
       new (GetGraph()->GetArena()) SuspendCheckSlowPathARM(instruction, successor);
   codegen_->AddSlowPath(slow_path);
 
-  __ AddConstant(R4, R4, -1);
-  __ cmp(R4, ShifterOperand(0));
+  __ subs(R4, R4, ShifterOperand(1));
   if (successor == nullptr) {
-    __ b(slow_path->GetEntryLabel(), LE);
+    __ b(slow_path->GetEntryLabel(), EQ);
     __ Bind(slow_path->GetReturnLabel());
   } else {
-    __ b(codegen_->GetLabelOf(successor), GT);
+    __ b(codegen_->GetLabelOf(successor), NE);
     __ b(slow_path->GetEntryLabel());
   }
 }
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index ea67dfd..6791003 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -563,7 +563,7 @@ void LocationsBuilderX86::VisitIf(HIf* if_instr) {
   DCHECK(cond->IsCondition());
   HCondition* condition = cond->AsCondition();
   if (condition->NeedsMaterialization()) {
-    locations->SetInAt(0, Location::Any());
+    locations->SetInAt(0, Location::Any(), Location::kDiesAtEntry);
   }
 }
 
@@ -650,8 +650,8 @@ void InstructionCodeGeneratorX86::VisitStoreLocal(HStoreLocal* store) {
 void LocationsBuilderX86::VisitCondition(HCondition* comp) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(comp, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::Any());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(1, Location::Any(), Location::kDiesAtEntry);
   if (comp->NeedsMaterialization()) {
     locations->SetOut(Location::RequiresRegister());
   }
@@ -1094,8 +1094,8 @@ void InstructionCodeGeneratorX86::VisitNot(HNot* instruction) {
 void LocationsBuilderX86::VisitCompare(HCompare* compare) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(compare, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::Any());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(1, Location::Any(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1159,14 +1159,16 @@ void LocationsBuilderX86::VisitInstanceFieldSet(HInstanceFieldSet* instruction)
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
   locations->SetInAt(0, Location::RequiresRegister());
   Primitive::Type field_type = instruction->GetFieldType();
+  bool is_object_type = field_type == Primitive::kPrimNot;
+  bool dies_at_entry = !is_object_type;
   if (field_type == Primitive::kPrimBoolean || field_type == Primitive::kPrimByte) {
     // Ensure the value is in a byte register.
-    locations->SetInAt(1, X86CpuLocation(EAX));
+    locations->SetInAt(1, X86CpuLocation(EAX), dies_at_entry);
   } else {
-    locations->SetInAt(1, Location::RequiresRegister());
+    locations->SetInAt(1, Location::RequiresRegister(), dies_at_entry);
   }
   // Temporary registers for the write barrier.
-  if (field_type == Primitive::kPrimNot) {
+  if (is_object_type) {
     locations->AddTemp(Location::RequiresRegister());
     // Ensure the card is in a byte register.
     locations->AddTemp(X86CpuLocation(ECX));
@@ -1238,7 +1240,7 @@ void CodeGeneratorX86::MarkGCCard(Register temp, Register card, Register object,
 void LocationsBuilderX86::VisitInstanceFieldGet(HInstanceFieldGet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1324,8 +1326,9 @@ void InstructionCodeGeneratorX86::VisitNullCheck(HNullCheck* instruction) {
 void LocationsBuilderX86::VisitArrayGet(HArrayGet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(
+      1, Location::RegisterOrConstant(instruction->InputAt(1)), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1433,13 +1436,16 @@ void LocationsBuilderX86::VisitArraySet(HArraySet* instruction) {
     locations->SetInAt(1, X86CpuLocation(calling_convention.GetRegisterAt(1)));
     locations->SetInAt(2, X86CpuLocation(calling_convention.GetRegisterAt(2)));
   } else {
-    locations->SetInAt(0, Location::RequiresRegister());
-    locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
+    // We need the inputs to be different than the output in case of long operation.
+    bool dies_at_entry = value_type != Primitive::kPrimLong;
+    locations->SetInAt(0, Location::RequiresRegister(), dies_at_entry);
+    locations->SetInAt(
+        1, Location::RegisterOrConstant(instruction->InputAt(1)), dies_at_entry);
     if (value_type == Primitive::kPrimBoolean || value_type == Primitive::kPrimByte) {
       // Ensure the value is in a byte register.
-      locations->SetInAt(2, X86CpuLocation(EAX));
+      locations->SetInAt(2, X86CpuLocation(EAX), dies_at_entry);
     } else {
-      locations->SetInAt(2, Location::RequiresRegister());
+      locations->SetInAt(2, Location::RequiresRegister(), dies_at_entry);
     }
   }
 }
@@ -1523,7 +1529,7 @@ void InstructionCodeGeneratorX86::VisitArraySet(HArraySet* instruction) {
 
 void LocationsBuilderX86::VisitArrayLength(HArrayLength* instruction) {
   LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction);
-  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
   instruction->SetLocations(locations);
 }
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 78c7d9d..e0e0c79 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -446,7 +446,7 @@ void LocationsBuilderX86_64::VisitIf(HIf* if_instr) {
   DCHECK(cond->IsCondition());
   HCondition* condition = cond->AsCondition();
   if (condition->NeedsMaterialization()) {
-    locations->SetInAt(0, Location::Any());
+    locations->SetInAt(0, Location::Any(), Location::kDiesAtEntry);
   }
 }
 
@@ -530,8 +530,8 @@ void InstructionCodeGeneratorX86_64::VisitStoreLocal(HStoreLocal* store) {
 void LocationsBuilderX86_64::VisitCondition(HCondition* comp) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(comp, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::Any());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(1, Location::Any(), Location::kDiesAtEntry);
   if (comp->NeedsMaterialization()) {
     locations->SetOut(Location::RequiresRegister());
   }
@@ -608,8 +608,8 @@ void InstructionCodeGeneratorX86_64::VisitGreaterThanOrEqual(HGreaterThanOrEqual
 void LocationsBuilderX86_64::VisitCompare(HCompare* compare) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(compare, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(1, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -970,6 +970,9 @@ void InstructionCodeGeneratorX86_64::VisitSub(HSub* sub) {
 void LocationsBuilderX86_64::VisitNewInstance(HNewInstance* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kCall);
+  InvokeRuntimeCallingConvention calling_convention;
+  locations->AddTemp(X86_64CpuLocation(calling_convention.GetRegisterAt(0)));
+  locations->AddTemp(X86_64CpuLocation(calling_convention.GetRegisterAt(1)));
   locations->SetOut(X86_64CpuLocation(RAX));
 }
 
@@ -1031,10 +1034,13 @@ void InstructionCodeGeneratorX86_64::VisitPhi(HPhi* instruction) {
 void LocationsBuilderX86_64::VisitInstanceFieldSet(HInstanceFieldSet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
-  // Temporary registers for the write barrier.
-  if (instruction->GetFieldType() == Primitive::kPrimNot) {
+  Primitive::Type field_type = instruction->GetFieldType();
+  bool is_object_type = field_type == Primitive::kPrimNot;
+  bool dies_at_entry = !is_object_type;
+  locations->SetInAt(0, Location::RequiresRegister(), dies_at_entry);
+  locations->SetInAt(1, Location::RequiresRegister(), dies_at_entry);
+  if (is_object_type) {
+    // Temporary registers for the write barrier.
     locations->AddTemp(Location::RequiresRegister());
     locations->AddTemp(Location::RequiresRegister());
   }
@@ -1088,7 +1094,7 @@ void InstructionCodeGeneratorX86_64::VisitInstanceFieldSet(HInstanceFieldSet* in
 void LocationsBuilderX86_64::VisitInstanceFieldGet(HInstanceFieldGet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1167,8 +1173,9 @@ void InstructionCodeGeneratorX86_64::VisitNullCheck(HNullCheck* instruction) {
 void LocationsBuilderX86_64::VisitArrayGet(HArrayGet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+  locations->SetInAt(
+      1, Location::RegisterOrConstant(instruction->InputAt(1)), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
@@ -1272,9 +1279,10 @@ void LocationsBuilderX86_64::VisitArraySet(HArraySet* instruction) {
     locations->SetInAt(1, X86_64CpuLocation(calling_convention.GetRegisterAt(1)));
     locations->SetInAt(2, X86_64CpuLocation(calling_convention.GetRegisterAt(2)));
   } else {
-    locations->SetInAt(0, Location::RequiresRegister());
-    locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
-    locations->SetInAt(2, Location::RequiresRegister());
+    locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
+    locations->SetInAt(
+        1, Location::RegisterOrConstant(instruction->InputAt(1)), Location::kDiesAtEntry);
+    locations->SetInAt(2, Location::RequiresRegister(), Location::kDiesAtEntry);
   }
 }
 
@@ -1354,7 +1362,7 @@ void InstructionCodeGeneratorX86_64::VisitArraySet(HArraySet* instruction) {
 void LocationsBuilderX86_64::VisitArrayLength(HArrayLength* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
-  locations->SetInAt(0, Location::RequiresRegister());
+  locations->SetInAt(0, Location::RequiresRegister(), Location::kDiesAtEntry);
   locations->SetOut(Location::RequiresRegister());
 }
 
diff --git a/compiler/optimizing/live_ranges_test.cc b/compiler/optimizing/live_ranges_test.cc
index 03f8625..8be4746 100644
--- a/compiler/optimizing/live_ranges_test.cc
+++ b/compiler/optimizing/live_ranges_test.cc
@@ -268,7 +268,7 @@ TEST(LiveRangesTest, Loop1) {
   range = interval->GetFirstRange();
   // Instruction is consumed by the if.
   ASSERT_EQ(14u, range->GetStart());
-  ASSERT_EQ(17u, range->GetEnd());
+  ASSERT_EQ(16u, range->GetEnd());
   ASSERT_TRUE(range->GetNext() == nullptr);
 }
 
diff --git a/compiler/optimizing/locations.cc b/compiler/optimizing/locations.cc
index 1c36cdf..114d69c 100644
--- a/compiler/optimizing/locations.cc
+++ b/compiler/optimizing/locations.cc
@@ -25,13 +25,16 @@ LocationSummary::LocationSummary(HInstruction* instruction, CallKind call_kind)
       temps_(instruction->GetBlock()->GetGraph()->GetArena(), 0),
       environment_(instruction->GetBlock()->GetGraph()->GetArena(),
                    instruction->EnvironmentSize()),
+      dies_at_entry_(instruction->GetBlock()->GetGraph()->GetArena(), instruction->InputCount()),
       call_kind_(call_kind),
       stack_mask_(nullptr),
       register_mask_(0),
       live_registers_() {
   inputs_.SetSize(instruction->InputCount());
+  dies_at_entry_.SetSize(instruction->InputCount());
   for (size_t i = 0; i < instruction->InputCount(); ++i) {
     inputs_.Put(i, Location());
+    dies_at_entry_.Put(i, false);
   }
   environment_.SetSize(instruction->EnvironmentSize());
   for (size_t i = 0; i < instruction->EnvironmentSize(); ++i) {
diff --git a/compiler/optimizing/locations.h b/compiler/optimizing/locations.h
index f358e05..8d0715a 100644
--- a/compiler/optimizing/locations.h
+++ b/compiler/optimizing/locations.h
@@ -34,6 +34,8 @@ class HInstruction;
  */
 class Location : public ValueObject {
  public:
+  static constexpr bool kDiesAtEntry = true;
+
   enum Kind {
     kInvalid = 0,
     kConstant = 1,
@@ -312,7 +314,8 @@ class LocationSummary : public ArenaObject {
 
   LocationSummary(HInstruction* instruction, CallKind call_kind = kNoCall);
 
-  void SetInAt(uint32_t at, Location location) {
+  void SetInAt(uint32_t at, Location location, bool dies_at_entry = false) {
+    dies_at_entry_.Put(at, dies_at_entry);
     inputs_.Put(at, location);
   }
 
@@ -390,10 +393,12 @@ class LocationSummary : public ArenaObject {
   bool InputOverlapsWithOutputOrTemp(uint32_t input, bool is_environment) const {
     if (is_environment) return true;
     Location location = Out();
-    // TODO: Add more policies.
     if (input == 0 && location.IsUnallocated() && location.GetPolicy() == Location::kSameAsFirstInput) {
       return false;
     }
+    if (dies_at_entry_.Get(input)) {
+      return false;
+    }
     return true;
   }
 
@@ -401,6 +406,7 @@ class LocationSummary : public ArenaObject {
   GrowableArray<Location> inputs_;
   GrowableArray<Location> temps_;
   GrowableArray<Location> environment_;
+  GrowableArray<bool> dies_at_entry_;
   Location output_;
   const CallKind call_kind_;