[VM runtime] Introduce a DeoptIdScope class to safely save/restore deoptid.

Change-Id: I5debdd2accd9735ddabd3862165f3d04824b8247
Reviewed-on: https://dart-review.googlesource.com/71740
Commit-Queue: Régis Crelier <regis@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>

runtime/vm/compiler/aot/precompiler.cc

@@ -2832,8 +2832,7 @@ bool PrecompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
       true, FLAG_max_speculative_inlining_attempts);
 
   while (!done) {
-    const intptr_t prev_deopt_id = thread()->deopt_id();
-    thread()->set_deopt_id(0);
+    DeoptIdScope deopt_id_scope(thread(), 0);
     LongJumpScope jump;
     const intptr_t val = setjmp(*jump.Set());
     if (val == 0) {
@@ -2979,8 +2978,6 @@ bool PrecompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
       }
       is_compiled = false;
     }
-    // Reset global isolate state.
-    thread()->set_deopt_id(prev_deopt_id);
   }
   return is_compiled;
 }

runtime/vm/compiler/backend/il.h

@@ -755,6 +755,21 @@ class CallTargets : public Cids {
   void MergeIntoRanges();
 };
 
+class DeoptIdScope : public StackResource {
+ public:
+  DeoptIdScope(Thread* thread, intptr_t deopt_id)
+      : StackResource(thread), prev_deopt_id_(thread->deopt_id()) {
+    thread->set_deopt_id(deopt_id);
+  }
+
+  ~DeoptIdScope() { thread()->set_deopt_id(prev_deopt_id_); }
+
+ private:
+  const intptr_t prev_deopt_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeoptIdScope);
+};
+
 class Instruction : public ZoneAllocated {
  public:
 #define DECLARE_TAG(type, attrs) k##type,

runtime/vm/compiler/backend/inliner.cc

@@ -908,11 +908,11 @@ class CallSiteInliner : public ValueObject {
       return false;
     }
 
-    // Save and clear deopt id.
-    const intptr_t prev_deopt_id = thread()->deopt_id();
-    thread()->set_deopt_id(0);
     Error& error = Error::Handle();
     {
+      // Save and clear deopt id.
+      DeoptIdScope deopt_id_scope(thread(), 0);
+
       // Install bailout jump.
       LongJumpScope jump;
       if (setjmp(*jump.Set()) == 0) {
@@ -1162,7 +1162,6 @@ class CallSiteInliner : public ValueObject {
               (size > FLAG_inlining_constant_arguments_max_size_threshold)) {
             function.set_is_inlinable(false);
           }
-          thread()->set_deopt_id(prev_deopt_id);
           TRACE_INLINING(
               THR_Print("     Bailout: heuristics (%s) with "
                         "code size:  %" Pd ", "
@@ -1193,7 +1192,6 @@ class CallSiteInliner : public ValueObject {
         if (is_recursive_call) {
           inlined_recursive_call_ = true;
         }
-        thread()->set_deopt_id(prev_deopt_id);
 
         call_data->callee_graph = callee_graph;
         call_data->parameter_stubs = param_stubs;
@@ -1233,7 +1231,6 @@ class CallSiteInliner : public ValueObject {
           if (error.raw() == Object::background_compilation_error().raw()) {
             // Fall through to exit the compilation, and retry it later.
           } else {
-            thread()->set_deopt_id(prev_deopt_id);
             TRACE_INLINING(
                 THR_Print("     Bailout: %s\n", error.ToErrorCString()));
             PRINT_INLINING_TREE("Bailout", &call_data->caller, &function, call);

runtime/vm/compiler/jit/compiler.cc

@@ -788,8 +788,7 @@ RawCode* CompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
   Code* volatile result = &Code::ZoneHandle(zone);
   while (!done) {
     *result = Code::null();
-    const intptr_t prev_deopt_id = thread()->deopt_id();
-    thread()->set_deopt_id(0);
+    DeoptIdScope deopt_id_scope(thread(), 0);
     LongJumpScope jump;
     if (setjmp(*jump.Set()) == 0) {
       FlowGraph* flow_graph = nullptr;
@@ -847,9 +846,6 @@ RawCode* CompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
 #if defined(DART_USE_INTERPRETER)
       // TODO(regis): Revisit.
       if (flow_graph == NULL && function.HasBytecode()) {
-        // Reset global isolate state.
-        thread()->set_deopt_id(prev_deopt_id);
-
         return Code::null();
       }
 #endif
@@ -971,8 +967,6 @@ RawCode* CompileParsedFunctionHelper::Compile(CompilationPipeline* pipeline) {
         thread()->clear_sticky_error();
       }
     }
-    // Reset global isolate state.
-    thread()->set_deopt_id(prev_deopt_id);
   }
   return result->raw();
 }
@@ -1369,8 +1363,7 @@ void Compiler::ComputeLocalVarDescriptors(const Code& code) {
   ASSERT(!function.IsIrregexpFunction());
   // In background compilation, parser can produce 'errors": bailouts
   // if state changed while compiling in background.
-  const intptr_t prev_deopt_id = Thread::Current()->deopt_id();
-  Thread::Current()->set_deopt_id(0);
+  DeoptIdScope deopt_id_scope(Thread::Current(), 0);
   LongJumpScope jump;
   if (setjmp(*jump.Set()) == 0) {
     ZoneGrowableArray<const ICData*>* ic_data_array =
@@ -1402,7 +1395,6 @@ void Compiler::ComputeLocalVarDescriptors(const Code& code) {
     // Only possible with background compilation.
     ASSERT(Compiler::IsBackgroundCompilation());
   }
-  Thread::Current()->set_deopt_id(prev_deopt_id);
 }
 
 RawError* Compiler::CompileAllFunctions(const Class& cls) {