Supporting de-virtualization for precise types.
Sharpening invoke-virtual and invoke-interface calls to invoke-direct for cases
where the type of "this" pointer in the invoke- params is precisely known.
Instructions that have an invoke opcode are marked as interesting, for each invoke-virtual/interface
we come across with a precise type for "this" we mark the location as a candidate for sharpening,
resolve the concrete method and save its method reference <DexFile, DexMethodIndex> to be sharpened
in CompilerDriver::ComputeInvokeInfo().
Added a new entry to AOT statistics showing the percentage of sharpened calls that were based on
type analysis.
Fix a minor bug in type creation for GetSuperClass(). Previously super class of a precise reference
had precise types created which is not necessarily the case.
Change-Id: Iee61858e84242dfc82be363ee221d2747a1ac86a
diff --git a/src/compiler/driver/compiler_driver.cc b/src/compiler/driver/compiler_driver.cc
index e6f4b67..d53d60c 100644
--- a/src/compiler/driver/compiler_driver.cc
+++ b/src/compiler/driver/compiler_driver.cc
@@ -72,7 +72,8 @@
strings_in_dex_cache_(0), strings_not_in_dex_cache_(0),
resolved_types_(0), unresolved_types_(0),
resolved_instance_fields_(0), unresolved_instance_fields_(0),
- resolved_local_static_fields_(0), resolved_static_fields_(0), unresolved_static_fields_(0) {
+ resolved_local_static_fields_(0), resolved_static_fields_(0), unresolved_static_fields_(0),
+ type_based_devirtualization_(0) {
for (size_t i = 0; i <= kMaxInvokeType; i++) {
resolved_methods_[i] = 0;
unresolved_methods_[i] = 0;
@@ -91,6 +92,8 @@
"static fields resolved");
DumpStat(resolved_local_static_fields_, resolved_static_fields_ + unresolved_static_fields_,
"static fields local to a class");
+ DumpStat(type_based_devirtualization_,virtual_made_direct_[kInterface] + virtual_made_direct_[kVirtual]
+ - type_based_devirtualization_, "sharpened calls based on type information");
for (size_t i = 0; i <= kMaxInvokeType; i++) {
std::ostringstream oss;
@@ -182,6 +185,11 @@
unresolved_static_fields_++;
}
+ void PreciseTypeDevirtualization() {
+ STATS_LOCK();
+ type_based_devirtualization_++;
+ }
+
void ResolvedMethod(InvokeType type) {
DCHECK_LE(type, kMaxInvokeType);
STATS_LOCK();
@@ -230,6 +238,8 @@
size_t resolved_local_static_fields_;
size_t resolved_static_fields_;
size_t unresolved_static_fields_;
+ // Type based devirtualization for invoke interface and virtual.
+ size_t type_based_devirtualization_;
size_t resolved_methods_[kMaxInvokeType + 1];
size_t unresolved_methods_[kMaxInvokeType + 1];
@@ -836,15 +846,24 @@
}
}
-bool CompilerDriver::ComputeInvokeInfo(uint32_t method_idx, const DexCompilationUnit* mUnit,
- InvokeType& type, int& vtable_idx, uintptr_t& direct_code,
+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) {
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);
+
+
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.
@@ -867,8 +886,10 @@
}
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());
@@ -877,6 +898,7 @@
referrer_class->IsSubClass(methods_class) &&
vtable_idx < methods_class->GetVTable()->GetLength() &&
methods_class->GetVTable()->Get(vtable_idx) == resolved_method);
+
if (kEnableSharpening && can_sharpen) {
stats_->ResolvedMethod(type);
// Sharpen a virtual call into a direct call. The method_idx is into referrer's
@@ -888,7 +910,28 @@
direct_code, direct_method);
type = kDirect;
return true;
- } else if (type == kSuper) {
+
+ } 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);
+ type = kDirect;
+ stats_->VirtualMadeDirect(type);
+ stats_->PreciseTypeDevirtualization();
+ }
+ stats_->ResolvedMethod(type);
+
+ return true;
+ }
+ else if (type == kSuper) {
// Unsharpened super calls are suspicious so go slow-path.
} else {
stats_->ResolvedMethod(type);