x86/x86-64 read barrier support for concurrent GC in Optimizing.
This first implementation uses slow paths to instrument heap
reference loads and GC root loads for the concurrent copying
collector, respectively calling the artReadBarrierSlow and
artReadBarrierForRootSlow (new) runtime entry points.
Notes:
- This implementation does not instrument HInvokeVirtual
nor HInvokeInterface instructions (for class reference
loads), as the corresponding read barriers are not stricly
required with the current concurrent copying collector.
- Intrinsics which may eventually call (on slow path) are
disabled when read barriers are enabled, as the current
slow path infrastructure does not support this case.
- When read barriers are enabled, the code generated for a
HArraySet instruction always go into the array set slow
path for object arrays (delegating the operation to the
runtime), as we are lacking a mechanism to keep a
temporary register live accross a runtime call (needed for
the instrumentation of type checking code, which requires
two successive read barriers).
Bug: 12687968
Change-Id: I14cd6107233c326389120336f93955b28ffbb329
diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index 2be0680..27ee472 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -383,6 +383,13 @@
|| instruction_set == kX86_64;
}
+// Read barrier are supported only on x86 and x86-64 at the moment.
+// TODO: Add support for other architectures and remove this function
+static bool InstructionSetSupportsReadBarrier(InstructionSet instruction_set) {
+ return instruction_set == kX86
+ || instruction_set == kX86_64;
+}
+
static void RunOptimizations(HOptimization* optimizations[],
size_t length,
PassObserver* pass_observer) {
@@ -673,6 +680,12 @@
return nullptr;
}
+ // When read barriers are enabled, do not attempt to compile for
+ // instruction sets that have no read barrier support.
+ if (kEmitCompilerReadBarrier && !InstructionSetSupportsReadBarrier(instruction_set)) {
+ return nullptr;
+ }
+
if (Compiler::IsPathologicalCase(*code_item, method_idx, dex_file)) {
MaybeRecordStat(MethodCompilationStat::kNotCompiledPathological);
return nullptr;
@@ -841,9 +854,14 @@
if (kIsDebugBuild &&
IsCompilingWithCoreImage() &&
- IsInstructionSetSupported(compiler_driver->GetInstructionSet())) {
- // For testing purposes, we put a special marker on method names that should be compiled
- // with this compiler. This makes sure we're not regressing.
+ IsInstructionSetSupported(compiler_driver->GetInstructionSet()) &&
+ (!kEmitCompilerReadBarrier ||
+ InstructionSetSupportsReadBarrier(compiler_driver->GetInstructionSet()))) {
+ // For testing purposes, we put a special marker on method names
+ // that should be compiled with this compiler (when the the
+ // instruction set is supported -- and has support for read
+ // barriers, if they are enabled). This makes sure we're not
+ // regressing.
std::string method_name = PrettyMethod(method_idx, dex_file);
bool shouldCompile = method_name.find("$opt$") != std::string::npos;
DCHECK((method != nullptr) || !shouldCompile) << "Didn't compile " << method_name;