Use implicit null checks inside try blocks.
Make implicit null check entrypoint save all registers, use
platform-specific approach to still pass the fault address.
Allow implicit null checks in try blocks.
On Nexus 9, AOSP ToT, the boot.oat size reduction is
prebuilt multi-part boot image:
- 32-bit boot.oat: -452KiB (-0.7%)
- 64-bit boot.oat: -482KiB (-0.7%)
on-device built single boot image:
- 32-bit boot.oat: -444KiB (-0.7%)
- 64-bit boot.oat: -488KiB (-0.7%)
Test: Run ART test suite on host and Nexus 9.
Test: Build aosp_mips64-eng.
Change-Id: I279f3ab57e2e2f338131c5cac45c51b673bdca19
diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index 2087888..ac7d5fe 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -1081,13 +1081,6 @@
}
}
-bool CodeGenerator::IsImplicitNullCheckAllowed(HNullCheck* null_check) const {
- return compiler_options_.GetImplicitNullChecks() &&
- // Null checks which might throw into a catch block need to save live
- // registers and therefore cannot be done implicitly.
- !null_check->CanThrowIntoCatchBlock();
-}
-
bool CodeGenerator::CanMoveNullCheckToUser(HNullCheck* null_check) {
HInstruction* first_next_not_move = null_check->GetNextDisregardingMoves();
@@ -1096,6 +1089,10 @@
}
void CodeGenerator::MaybeRecordImplicitNullCheck(HInstruction* instr) {
+ if (!compiler_options_.GetImplicitNullChecks()) {
+ return;
+ }
+
// If we are from a static path don't record the pc as we can't throw NPE.
// NB: having the checks here makes the code much less verbose in the arch
// specific code generators.
@@ -1114,16 +1111,31 @@
// and needs to record the pc.
if (first_prev_not_move != nullptr && first_prev_not_move->IsNullCheck()) {
HNullCheck* null_check = first_prev_not_move->AsNullCheck();
- if (IsImplicitNullCheckAllowed(null_check)) {
- // TODO: The parallel moves modify the environment. Their changes need to be
- // reverted otherwise the stack maps at the throw point will not be correct.
- RecordPcInfo(null_check, null_check->GetDexPc());
- }
+ // TODO: The parallel moves modify the environment. Their changes need to be
+ // reverted otherwise the stack maps at the throw point will not be correct.
+ RecordPcInfo(null_check, null_check->GetDexPc());
}
}
+LocationSummary* CodeGenerator::CreateNullCheckLocations(HNullCheck* null_check) {
+ // Note: Using kNoCall allows the method to be treated as leaf (and eliminate the
+ // HSuspendCheck from entry block). However, it will still get a valid stack frame
+ // because the HNullCheck needs an environment.
+ LocationSummary::CallKind call_kind = LocationSummary::kNoCall;
+ // When throwing from a try block, we may need to retrieve dalvik registers from
+ // physical registers. For implicit null checks, this is done by using kSaveEverything
+ // runtime method but for explicit null checks we need to save live registers.
+ if (!compiler_options_.GetImplicitNullChecks() && null_check->CanThrowIntoCatchBlock()) {
+ call_kind = LocationSummary::kCallOnSlowPath;
+ }
+ LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(null_check, call_kind);
+ locations->SetInAt(0, Location::RequiresRegister());
+ DCHECK(!null_check->HasUses());
+ return locations;
+}
+
void CodeGenerator::GenerateNullCheck(HNullCheck* instruction) {
- if (IsImplicitNullCheckAllowed(instruction)) {
+ if (compiler_options_.GetImplicitNullChecks()) {
MaybeRecordStat(kImplicitNullCheckGenerated);
GenerateImplicitNullCheck(instruction);
} else {
diff --git a/compiler/optimizing/code_generator.h b/compiler/optimizing/code_generator.h
index 0c60a98..b4d4b9b 100644
--- a/compiler/optimizing/code_generator.h
+++ b/compiler/optimizing/code_generator.h
@@ -313,6 +313,7 @@
bool CanMoveNullCheckToUser(HNullCheck* null_check);
void MaybeRecordImplicitNullCheck(HInstruction* instruction);
+ LocationSummary* CreateNullCheckLocations(HNullCheck* null_check);
void GenerateNullCheck(HNullCheck* null_check);
virtual void GenerateImplicitNullCheck(HNullCheck* null_check) = 0;
virtual void GenerateExplicitNullCheck(HNullCheck* null_check) = 0;
@@ -322,12 +323,6 @@
// TODO: Replace with a catch-entering instruction that records the environment.
void RecordCatchBlockInfo();
- // Returns true if implicit null checks are allowed in the compiler options
- // and if the null check is not inside a try block. We currently cannot do
- // implicit null checks in that case because we need the NullCheckSlowPath to
- // save live registers, which may be needed by the runtime to set catch phis.
- bool IsImplicitNullCheckAllowed(HNullCheck* null_check) const;
-
// TODO: Avoid creating the `std::unique_ptr` here.
void AddSlowPath(SlowPathCode* slow_path) {
slow_paths_.push_back(std::unique_ptr<SlowPathCode>(slow_path));
@@ -713,6 +708,8 @@
bool is_leaf_;
// Whether an instruction in the graph accesses the current method.
+ // TODO: Rename: this actually indicates that some instruction in the method
+ // needs the environment including a valid stack frame.
bool requires_current_method_;
friend class OptimizingCFITest;
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 5301a6b..4f80931 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -4251,14 +4251,7 @@
}
void LocationsBuilderARM::VisitNullCheck(HNullCheck* instruction) {
- LocationSummary::CallKind call_kind = instruction->CanThrowIntoCatchBlock()
- ? LocationSummary::kCallOnSlowPath
- : LocationSummary::kNoCall;
- LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
- locations->SetInAt(0, Location::RequiresRegister());
- if (instruction->HasUses()) {
- locations->SetOut(Location::SameAsFirstInput());
- }
+ codegen_->CreateNullCheckLocations(instruction);
}
void CodeGeneratorARM::GenerateImplicitNullCheck(HNullCheck* instruction) {
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 36f7b4d..09808bb 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -4539,14 +4539,7 @@
}
void LocationsBuilderARM64::VisitNullCheck(HNullCheck* instruction) {
- LocationSummary::CallKind call_kind = instruction->CanThrowIntoCatchBlock()
- ? LocationSummary::kCallOnSlowPath
- : LocationSummary::kNoCall;
- LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
- locations->SetInAt(0, Location::RequiresRegister());
- if (instruction->HasUses()) {
- locations->SetOut(Location::SameAsFirstInput());
- }
+ codegen_->CreateNullCheckLocations(instruction);
}
void CodeGeneratorARM64::GenerateImplicitNullCheck(HNullCheck* instruction) {
diff --git a/compiler/optimizing/code_generator_mips.cc b/compiler/optimizing/code_generator_mips.cc
index 92e9cd9..9abe485 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -4856,14 +4856,7 @@
}
void LocationsBuilderMIPS::VisitNullCheck(HNullCheck* instruction) {
- LocationSummary::CallKind call_kind = instruction->CanThrowIntoCatchBlock()
- ? LocationSummary::kCallOnSlowPath
- : LocationSummary::kNoCall;
- LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
- locations->SetInAt(0, Location::RequiresRegister());
- if (instruction->HasUses()) {
- locations->SetOut(Location::SameAsFirstInput());
- }
+ codegen_->CreateNullCheckLocations(instruction);
}
void CodeGeneratorMIPS::GenerateImplicitNullCheck(HNullCheck* instruction) {
diff --git a/compiler/optimizing/code_generator_mips64.cc b/compiler/optimizing/code_generator_mips64.cc
index 664d498..4d87523 100644
--- a/compiler/optimizing/code_generator_mips64.cc
+++ b/compiler/optimizing/code_generator_mips64.cc
@@ -3461,14 +3461,7 @@
}
void LocationsBuilderMIPS64::VisitNullCheck(HNullCheck* instruction) {
- LocationSummary::CallKind call_kind = instruction->CanThrowIntoCatchBlock()
- ? LocationSummary::kCallOnSlowPath
- : LocationSummary::kNoCall;
- LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
- locations->SetInAt(0, Location::RequiresRegister());
- if (instruction->HasUses()) {
- locations->SetOut(Location::SameAsFirstInput());
- }
+ codegen_->CreateNullCheckLocations(instruction);
}
void CodeGeneratorMIPS64::GenerateImplicitNullCheck(HNullCheck* instruction) {
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 4689ccb..bf96be2 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -4979,16 +4979,10 @@
}
void LocationsBuilderX86::VisitNullCheck(HNullCheck* instruction) {
- LocationSummary::CallKind call_kind = instruction->CanThrowIntoCatchBlock()
- ? LocationSummary::kCallOnSlowPath
- : LocationSummary::kNoCall;
- LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
- Location loc = codegen_->IsImplicitNullCheckAllowed(instruction)
- ? Location::RequiresRegister()
- : Location::Any();
- locations->SetInAt(0, loc);
- if (instruction->HasUses()) {
- locations->SetOut(Location::SameAsFirstInput());
+ LocationSummary* locations = codegen_->CreateNullCheckLocations(instruction);
+ if (!codegen_->GetCompilerOptions().GetImplicitNullChecks()) {
+ // Explicit null checks can use any location.
+ locations->SetInAt(0, Location::Any());
}
}
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index a21a09e..d569f1f 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -4490,16 +4490,10 @@
}
void LocationsBuilderX86_64::VisitNullCheck(HNullCheck* instruction) {
- LocationSummary::CallKind call_kind = instruction->CanThrowIntoCatchBlock()
- ? LocationSummary::kCallOnSlowPath
- : LocationSummary::kNoCall;
- LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
- Location loc = codegen_->IsImplicitNullCheckAllowed(instruction)
- ? Location::RequiresRegister()
- : Location::Any();
- locations->SetInAt(0, loc);
- if (instruction->HasUses()) {
- locations->SetOut(Location::SameAsFirstInput());
+ LocationSummary* locations = codegen_->CreateNullCheckLocations(instruction);
+ if (!codegen_->GetCompilerOptions().GetImplicitNullChecks()) {
+ // Explicit null checks can use any location.
+ locations->SetInAt(0, Location::Any());
}
}