Enable devirtualization for abstract and sub-class methods.
If we know the type of a receiver in the verifier we record devirtualization
data. Currently we only use this data to avoid virtual method dispatch when
we know the receiver of a method isn't a sub-class. This change allows
devirtualization of virtual and interface methods when we know the receiver's
type and the method the we'd find via dispatch is either known within boot or
has a reference from the current dex file.
Pass the receiver through to the method resolution trampoline as
devirtualization may mean the dex method index needs to be made more accurate
for the receiver.
Tidy up method devirtualization and related statistics.
Push the devirtualization map lookup into a less common case to avoid
taking its lock.
Make MethodReference a struct rather than a typedef of a pair, so the members
can have more meaningful names than first and second.
Rough statistics show that we devirtualize using this change around 2.5% of
the time, whilst some apps like GMS core devirtualize over 3.4% of the time.
Change-Id: Ieed3471dbedfc4cc881d652631b67176bb37d394
diff --git a/src/compiler/driver/compiler_driver.cc b/src/compiler/driver/compiler_driver.cc
index 6985172..bf8bb8a 100644
--- a/src/compiler/driver/compiler_driver.cc
+++ b/src/compiler/driver/compiler_driver.cc
@@ -184,34 +184,43 @@
unresolved_static_fields_++;
}
+ // Indicate that type information from the verifier led to devirtualization.
void PreciseTypeDevirtualization() {
STATS_LOCK();
type_based_devirtualization_++;
}
+
+ // Indicate that a method of the given type was resolved at compile time.
void ResolvedMethod(InvokeType type) {
DCHECK_LE(type, kMaxInvokeType);
STATS_LOCK();
resolved_methods_[type]++;
}
+ // Indicate that a method of the given type was unresolved at compile time as it was in an
+ // unknown dex file.
void UnresolvedMethod(InvokeType type) {
DCHECK_LE(type, kMaxInvokeType);
STATS_LOCK();
unresolved_methods_[type]++;
}
+ // Indicate that a type of virtual method dispatch has been converted into a direct method
+ // dispatch.
void VirtualMadeDirect(InvokeType type) {
- DCHECK_LE(type, kMaxInvokeType);
+ DCHECK(type == kVirtual || type == kInterface || type == kSuper);
STATS_LOCK();
virtual_made_direct_[type]++;
}
+ // Indicate that a method of the given type was able to call directly into boot.
void DirectCallsToBoot(InvokeType type) {
DCHECK_LE(type, kMaxInvokeType);
STATS_LOCK();
direct_calls_to_boot_[type]++;
}
+ // Indicate that a method of the given type was able to be resolved directly from boot.
void DirectMethodsToBoot(InvokeType type) {
DCHECK_LE(type, kMaxInvokeType);
STATS_LOCK();
@@ -312,6 +321,7 @@
compiler_(NULL),
compiler_context_(NULL),
jni_compiler_(NULL),
+ compiler_enable_auto_elf_loading_(NULL),
compiler_get_method_code_addr_(NULL)
{
std::string compiler_so_name(MakeCompilerSoName(compiler_backend_));
@@ -764,7 +774,8 @@
mirror::Class* referrer_class,
mirror::AbstractMethod* method,
uintptr_t& direct_code,
- uintptr_t& direct_method) {
+ uintptr_t& direct_method,
+ bool update_stats) {
// For direct and static methods compute possible direct_code and direct_method values, ie
// an address for the Method* being invoked and an address of the code for that Method*.
// For interface calls compute a value for direct_method that is the interface method being
@@ -789,10 +800,12 @@
// Ensure we run the clinit trampoline unless we are invoking a static method in the same class.
return;
}
- if (sharp_type != kInterface) { // Interfaces always go via a trampoline.
- stats_->DirectCallsToBoot(type);
+ if (update_stats) {
+ if (sharp_type != kInterface) { // Interfaces always go via a trampoline.
+ stats_->DirectCallsToBoot(type);
+ }
+ stats_->DirectMethodsToBoot(type);
}
- stats_->DirectMethodsToBoot(type);
bool compiling_boot = Runtime::Current()->GetHeap()->GetSpaces().size() == 1;
if (compiling_boot) {
const bool kSupportBootImageFixup = true;
@@ -813,26 +826,24 @@
}
}
-bool CompilerDriver::ComputeInvokeInfo(uint32_t method_idx,const uint32_t dex_pc,
- const DexCompilationUnit* mUnit, InvokeType& type,
- int& vtable_idx, uintptr_t& direct_code,
- uintptr_t& direct_method) {
+bool CompilerDriver::ComputeInvokeInfo(const DexCompilationUnit* mUnit, const uint32_t dex_pc,
+ InvokeType& invoke_type,
+ MethodReference& target_method,
+ int& vtable_idx,
+ uintptr_t& direct_code, uintptr_t& direct_method,
+ bool update_stats) {
ScopedObjectAccess soa(Thread::Current());
-
- const bool kEnableVerifierBasedSharpening = true;
- const CompilerDriver::MethodReference ref_caller(mUnit->GetDexFile(), mUnit->GetDexMethodIndex());
- const CompilerDriver::MethodReference* ref_sharpen = verifier::MethodVerifier::GetDevirtMap(ref_caller, dex_pc);
- bool can_devirtualize = (dex_pc != art::kDexPCNotReady) && (ref_sharpen != NULL);
vtable_idx = -1;
direct_code = 0;
direct_method = 0;
mirror::AbstractMethod* resolved_method =
- ComputeMethodReferencedFromCompilingMethod(soa, mUnit, method_idx, type);
+ ComputeMethodReferencedFromCompilingMethod(soa, mUnit, target_method.dex_method_index,
+ invoke_type);
if (resolved_method != NULL) {
// Don't try to fast-path if we don't understand the caller's class or this appears to be an
// Incompatible Class Change Error.
mirror::Class* referrer_class = ComputeCompilingMethodsClass(soa, mUnit);
- bool icce = resolved_method->CheckIncompatibleClassChange(type);
+ bool icce = resolved_method->CheckIncompatibleClassChange(invoke_type);
if (referrer_class != NULL && !icce) {
mirror::Class* methods_class = resolved_method->GetDeclaringClass();
if (!referrer_class->CanAccess(methods_class) ||
@@ -842,71 +853,151 @@
// protected method being made public by implementing an interface that re-declares the
// method public. Resort to the dex file to determine the correct class for the access
// check.
- const DexFile& dex_file = *referrer_class->GetDexCache()->GetDexFile();
- methods_class =
- mUnit->GetClassLinker()->ResolveType(dex_file,
- dex_file.GetMethodId(method_idx).class_idx_,
- referrer_class);
+ uint16_t class_idx =
+ target_method.dex_file->GetMethodId(target_method.dex_method_index).class_idx_;
+ methods_class = mUnit->GetClassLinker()->ResolveType(*target_method.dex_file,
+ class_idx, referrer_class);
}
if (referrer_class->CanAccess(methods_class) &&
referrer_class->CanAccessMember(methods_class, resolved_method->GetAccessFlags())) {
- vtable_idx = resolved_method->GetMethodIndex();
- const bool kEnableSharpening = true;
- // Sharpen a virtual call into a direct call when the target is known.
- bool can_sharpen = type == kVirtual && (resolved_method->IsFinal() ||
- methods_class->IsFinal());
- // Ensure the vtable index will be correct to dispatch in the vtable of the super class.
- can_sharpen = can_sharpen || (type == kSuper && referrer_class != methods_class &&
- referrer_class->IsSubClass(methods_class) &&
- vtable_idx < methods_class->GetVTable()->GetLength() &&
- methods_class->GetVTable()->Get(vtable_idx) == resolved_method);
+ const bool kEnableFinalBasedSharpening = true;
+ // Sharpen a virtual call into a direct call when the target is known not to have been
+ // overridden (ie is final).
+ bool can_sharpen_virtual_based_on_type =
+ (invoke_type == kVirtual) && (resolved_method->IsFinal() || methods_class->IsFinal());
+ // For invoke-super, ensure the vtable index will be correct to dispatch in the vtable of
+ // the super class.
+ bool can_sharpen_super_based_on_type = (invoke_type == kSuper) &&
+ (referrer_class != methods_class) && referrer_class->IsSubClass(methods_class) &&
+ resolved_method->GetMethodIndex() < methods_class->GetVTable()->GetLength() &&
+ (methods_class->GetVTable()->Get(resolved_method->GetMethodIndex()) == resolved_method);
- if (kEnableSharpening && can_sharpen) {
- stats_->ResolvedMethod(type);
+ if (kEnableFinalBasedSharpening && (can_sharpen_virtual_based_on_type ||
+ can_sharpen_super_based_on_type)) {
// Sharpen a virtual call into a direct call. The method_idx is into referrer's
// dex cache, check that this resolved method is where we expect it.
- CHECK(referrer_class->GetDexCache()->GetResolvedMethod(method_idx) == resolved_method)
- << PrettyMethod(resolved_method);
- stats_->VirtualMadeDirect(type);
- GetCodeAndMethodForDirectCall(type, kDirect, referrer_class, resolved_method,
- direct_code, direct_method);
- type = kDirect;
+ CHECK(referrer_class->GetDexCache()->GetResolvedMethod(target_method.dex_method_index) ==
+ resolved_method) << PrettyMethod(resolved_method);
+ if (update_stats) {
+ stats_->ResolvedMethod(invoke_type);
+ stats_->VirtualMadeDirect(invoke_type);
+ }
+ GetCodeAndMethodForDirectCall(invoke_type, kDirect, referrer_class, resolved_method,
+ direct_code, direct_method, update_stats);
+ invoke_type = kDirect;
return true;
- } else if(can_devirtualize && kEnableSharpening && kEnableVerifierBasedSharpening) {
- // If traditional sharpening fails, try the sharpening based on type information (Devirtualization)
- mirror::DexCache* dex_cache = mUnit->GetClassLinker()->FindDexCache(*ref_sharpen->first);
- mirror::ClassLoader* class_loader = soa.Decode<mirror::ClassLoader*>(mUnit->GetClassLoader());
- mirror::AbstractMethod* concrete_method = mUnit->GetClassLinker()->ResolveMethod(
- *ref_sharpen->first, ref_sharpen->second, dex_cache, class_loader, NULL, kVirtual);
- CHECK(concrete_method != NULL);
- CHECK(!concrete_method->IsAbstract());
- // TODO: fix breakage in image patching to be able to devirtualize cases with different
- // resolved and concrete methods.
- if(resolved_method == concrete_method) {
- GetCodeAndMethodForDirectCall(type, kDirect, referrer_class, concrete_method, direct_code, direct_method);
- stats_->VirtualMadeDirect(type);
- type = kDirect;
- stats_->PreciseTypeDevirtualization();
- }
- stats_->ResolvedMethod(type);
- return true;
}
- else if (type == kSuper) {
+ const bool kEnableVerifierBasedSharpening = true;
+ if (kEnableVerifierBasedSharpening && (invoke_type == kVirtual ||
+ invoke_type == kInterface)) {
+ // Did the verifier record a more precise invoke target based on its type information?
+ const CompilerDriver::MethodReference caller_method(mUnit->GetDexFile(),
+ mUnit->GetDexMethodIndex());
+ const CompilerDriver::MethodReference* devirt_map_target =
+ verifier::MethodVerifier::GetDevirtMap(caller_method, dex_pc);
+ if (devirt_map_target != NULL) {
+ mirror::DexCache* target_dex_cache =
+ mUnit->GetClassLinker()->FindDexCache(*devirt_map_target->dex_file);
+ mirror::ClassLoader* class_loader =
+ soa.Decode<mirror::ClassLoader*>(mUnit->GetClassLoader());
+ mirror::AbstractMethod* called_method =
+ mUnit->GetClassLinker()->ResolveMethod(*devirt_map_target->dex_file,
+ devirt_map_target->dex_method_index,
+ target_dex_cache, class_loader, NULL,
+ kVirtual);
+ CHECK(called_method != NULL);
+ CHECK(!called_method->IsAbstract());
+ GetCodeAndMethodForDirectCall(invoke_type, kDirect, referrer_class, called_method,
+ direct_code, direct_method, update_stats);
+ bool compiler_needs_dex_cache =
+ (GetCompilerBackend() == kQuick && instruction_set_ != kThumb2) ||
+ (direct_code == 0) || (direct_code == static_cast<unsigned int>(-1)) ||
+ (direct_method == 0) || (direct_method == static_cast<unsigned int>(-1));
+ if ((devirt_map_target->dex_file != target_method.dex_file) &&
+ compiler_needs_dex_cache) {
+ // We need to use the dex cache to find either the method or code, and the dex file
+ // containing the method isn't the one expected for the target method. Try to find
+ // the method within the expected target dex file.
+ // TODO: the -1 could be handled as direct code if the patching new the target dex
+ // file.
+ // TODO: quick only supports direct pointers with Thumb2.
+ // TODO: the following should be factored into a common helper routine to find
+ // one dex file's method within another.
+ const DexFile* dexfile = target_method.dex_file;
+ const DexFile* cm_dexfile =
+ called_method->GetDeclaringClass()->GetDexCache()->GetDexFile();
+ const DexFile::MethodId& cm_method_id =
+ cm_dexfile->GetMethodId(called_method->GetDexMethodIndex());
+ const char* cm_descriptor = cm_dexfile->StringByTypeIdx(cm_method_id.class_idx_);
+ const DexFile::StringId* descriptor = dexfile->FindStringId(cm_descriptor);
+ if (descriptor != NULL) {
+ const DexFile::TypeId* type_id =
+ dexfile->FindTypeId(dexfile->GetIndexForStringId(*descriptor));
+ if (type_id != NULL) {
+ const char* cm_name = cm_dexfile->GetMethodName(cm_method_id);
+ const DexFile::StringId* name = dexfile->FindStringId(cm_name);
+ if (name != NULL) {
+ uint16_t return_type_idx;
+ std::vector<uint16_t> param_type_idxs;
+ bool success = dexfile->CreateTypeList(&return_type_idx, ¶m_type_idxs,
+ cm_dexfile->GetMethodSignature(cm_method_id));
+ if (success) {
+ const DexFile::ProtoId* sig =
+ dexfile->FindProtoId(return_type_idx, param_type_idxs);
+ if (sig != NULL) {
+ const DexFile::MethodId* method_id = dexfile->FindMethodId(*type_id,
+ *name, *sig);
+ if (method_id != NULL) {
+ if (update_stats) {
+ stats_->ResolvedMethod(invoke_type);
+ stats_->VirtualMadeDirect(invoke_type);
+ stats_->PreciseTypeDevirtualization();
+ }
+ target_method.dex_method_index = dexfile->GetIndexForMethodId(*method_id);
+ invoke_type = kDirect;
+ return true;
+ }
+ }
+ }
+ }
+ }
+ }
+ } else {
+ if (update_stats) {
+ stats_->ResolvedMethod(invoke_type);
+ stats_->VirtualMadeDirect(invoke_type);
+ stats_->PreciseTypeDevirtualization();
+ }
+ target_method = *devirt_map_target;
+ invoke_type = kDirect;
+ return true;
+ }
+ }
+ }
+ if (invoke_type == kSuper) {
// Unsharpened super calls are suspicious so go slow-path.
} else {
- stats_->ResolvedMethod(type);
- GetCodeAndMethodForDirectCall(type, type, referrer_class, resolved_method,
- direct_code, direct_method);
+ // Sharpening failed so generate a regular resolved method dispatch.
+ if (update_stats) {
+ stats_->ResolvedMethod(invoke_type);
+ }
+ if (invoke_type == kVirtual || invoke_type == kSuper) {
+ vtable_idx = resolved_method->GetMethodIndex();
+ }
+ GetCodeAndMethodForDirectCall(invoke_type, invoke_type, referrer_class, resolved_method,
+ direct_code, direct_method, update_stats);
return true;
}
}
}
}
- // Clean up any exception left by method/type resolution
+ // Clean up any exception left by method/invoke_type resolution
if (soa.Self()->IsExceptionPending()) {
soa.Self()->ClearException();
}
- stats_->UnresolvedMethod(type);
+ if (update_stats) {
+ stats_->UnresolvedMethod(invoke_type);
+ }
return false; // Incomplete knowledge needs slow path.
}
diff --git a/src/compiler/driver/compiler_driver.h b/src/compiler/driver/compiler_driver.h
index 75d276d..250532b 100644
--- a/src/compiler/driver/compiler_driver.h
+++ b/src/compiler/driver/compiler_driver.h
@@ -39,7 +39,6 @@
class DexCompilationUnit;
class TimingLogger;
-const uint32_t kDexPCNotReady = 0xFFFFFF;
enum CompilerBackend {
kQuick,
kPortable,
@@ -106,7 +105,22 @@
LOCKS_EXCLUDED(compiled_classes_lock_);
// A method is uniquely located by its DexFile and the method_ids_ table index into that DexFile
- typedef std::pair<const DexFile*, uint32_t> MethodReference;
+ struct MethodReference {
+ MethodReference(const DexFile* file, uint32_t index) : dex_file(file), dex_method_index(index) {
+ }
+ const DexFile* dex_file;
+ uint32_t dex_method_index;
+ };
+
+ struct MethodReferenceComparator {
+ bool operator()(MethodReference mr1, MethodReference mr2) const {
+ if (mr1.dex_file == mr2.dex_file) {
+ return mr1.dex_method_index < mr2.dex_method_index;
+ } else {
+ return mr1.dex_file < mr2.dex_file;
+ }
+ }
+ };
CompiledMethod* GetCompiledMethod(MethodReference ref) const
LOCKS_EXCLUDED(compiled_methods_lock_);
@@ -146,9 +160,9 @@
// Can we fastpath a interface, super class or virtual method call? Computes method's vtable
// index.
- bool ComputeInvokeInfo(uint32_t method_idx, uint32_t dex_pc,
- const DexCompilationUnit* mUnit, InvokeType& type, int& vtable_idx,
- uintptr_t& direct_code, uintptr_t& direct_method)
+ bool ComputeInvokeInfo(const DexCompilationUnit* mUnit, const uint32_t dex_pc,
+ InvokeType& type, MethodReference& target_method, int& vtable_idx,
+ uintptr_t& direct_code, uintptr_t& direct_method, bool update_stats)
LOCKS_EXCLUDED(Locks::mutator_lock_);
// Record patch information for later fix up.
@@ -262,7 +276,8 @@
void GetCodeAndMethodForDirectCall(InvokeType type, InvokeType sharp_type,
mirror::Class* referrer_class,
mirror::AbstractMethod* method,
- uintptr_t& direct_code, uintptr_t& direct_method)
+ uintptr_t& direct_code, uintptr_t& direct_method,
+ bool update_stats)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void PreCompile(jobject class_loader, const std::vector<const DexFile*>& dex_files,
@@ -321,7 +336,7 @@
mutable Mutex compiled_classes_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
ClassTable compiled_classes_ GUARDED_BY(compiled_classes_lock_);
- typedef SafeMap<const MethodReference, CompiledMethod*> MethodTable;
+ typedef SafeMap<const MethodReference, CompiledMethod*, MethodReferenceComparator> MethodTable;
// All method references that this compiler has compiled.
mutable Mutex compiled_methods_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
MethodTable compiled_methods_ GUARDED_BY(compiled_methods_lock_);