From ac3ebc3150760425ed00abd56da48f9a6e0666bc Mon Sep 17 00:00:00 2001
From: Nicolas Geoffray <ngeoffray@google.com>
Date: Wed, 5 Oct 2016 13:13:50 +0100
Subject: JIT root tables.

Implement root tables for the JIT. Each JIT compiled method
gets a table allocated before the stack maps.

The table gets visited through Runtime::SweepSystemWeaks.

Implement String roots for x86_64 as an example.

Test: test-art-host test-art-target

Change-Id: Id3d5bc67479e08b52dd4b253e970201203a0f0d2
---
 compiler/optimizing/optimizing_compiler.cc | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

(limited to 'compiler/optimizing/optimizing_compiler.cc')

diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index a4847601f5..85f6871795 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -117,6 +117,7 @@ class CodeVectorAllocator FINAL : public CodeAllocator {
 
   size_t GetSize() const { return size_; }
   const ArenaVector<uint8_t>& GetMemory() const { return memory_; }
+  uint8_t* GetData() { return memory_.data(); }
 
  private:
   ArenaVector<uint8_t> memory_;
@@ -1126,7 +1127,7 @@ bool OptimizingCompiler::JitCompile(Thread* self,
                                     jit::JitCodeCache* code_cache,
                                     ArtMethod* method,
                                     bool osr) {
-  StackHandleScope<2> hs(self);
+  StackHandleScope<3> hs(self);
   Handle<mirror::ClassLoader> class_loader(hs.NewHandle(
       method->GetDeclaringClass()->GetClassLoader()));
   Handle<mirror::DexCache> dex_cache(hs.NewHandle(method->GetDexCache()));
@@ -1172,22 +1173,43 @@ bool OptimizingCompiler::JitCompile(Thread* self,
   }
 
   size_t stack_map_size = codegen->ComputeStackMapsSize();
-  uint8_t* stack_map_data = code_cache->ReserveData(self, stack_map_size, method);
-  if (stack_map_data == nullptr) {
+  size_t number_of_roots = codegen->GetNumberOfJitRoots();
+  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+  // We allocate an object array to ensure the JIT roots that we will collect in EmitJitRoots
+  // will be visible by the GC between EmitLiterals and CommitCode. Once CommitCode is
+  // executed, this array is not needed.
+  Handle<mirror::ObjectArray<mirror::Object>> roots(
+      hs.NewHandle(mirror::ObjectArray<mirror::Object>::Alloc(
+          self, class_linker->GetClassRoot(ClassLinker::kObjectArrayClass), number_of_roots)));
+  if (roots.Get() == nullptr) {
+    // Out of memory, just clear the exception to avoid any Java exception uncaught problems.
+    DCHECK(self->IsExceptionPending());
+    self->ClearException();
+    return false;
+  }
+  uint8_t* stack_map_data = nullptr;
+  uint8_t* roots_data = nullptr;
+  code_cache->ReserveData(
+      self, stack_map_size, number_of_roots, method, &stack_map_data, &roots_data);
+  if (stack_map_data == nullptr || roots_data == nullptr) {
     return false;
   }
   MaybeRecordStat(MethodCompilationStat::kCompiled);
   codegen->BuildStackMaps(MemoryRegion(stack_map_data, stack_map_size), *code_item);
+  codegen->EmitJitRoots(code_allocator.GetData(), roots, roots_data, dex_cache);
+
   const void* code = code_cache->CommitCode(
       self,
       method,
       stack_map_data,
+      roots_data,
       codegen->HasEmptyFrame() ? 0 : codegen->GetFrameSize(),
       codegen->GetCoreSpillMask(),
       codegen->GetFpuSpillMask(),
       code_allocator.GetMemory().data(),
       code_allocator.GetSize(),
-      osr);
+      osr,
+      roots);
 
   if (code == nullptr) {
     code_cache->ClearData(self, stack_map_data);
-- 
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