VM: [DBC] Fix lazy deoptimization after calls that return no values.

runtime/vm/flow_graph_compiler.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_FLOW_GRAPH_COMPILER_H_
 #define RUNTIME_VM_FLOW_GRAPH_COMPILER_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/code_descriptors.h"
@@ skipping 104 matching lines @@
 class CompilerDeoptInfo : public ZoneAllocated {
  public:
   CompilerDeoptInfo(intptr_t deopt_id,
                     ICData::DeoptReasonId reason,
                     uint32_t flags,
                     Environment* deopt_env)
       : pc_offset_(-1),
         deopt_id_(deopt_id),
         reason_(reason),
         flags_(flags),
+#if defined(TARGET_ARCH_DBC)
+        lazy_deopt_with_result_(false),
+#endif
         deopt_env_(deopt_env) {
     ASSERT(deopt_env != NULL);
   }
   virtual ~CompilerDeoptInfo() {}
 
   RawTypedData* CreateDeoptInfo(FlowGraphCompiler* compiler,
                                 DeoptInfoBuilder* builder,
                                 const Array& deopt_table);
 
 
   // No code needs to be generated.
   virtual void GenerateCode(FlowGraphCompiler* compiler, intptr_t stub_ix) {}
 
   intptr_t pc_offset() const { return pc_offset_; }
   void set_pc_offset(intptr_t offset) { pc_offset_ = offset; }
 
   intptr_t deopt_id() const { return deopt_id_; }
   ICData::DeoptReasonId reason() const { return reason_; }
   uint32_t flags() const { return flags_; }
   const Environment* deopt_env() const { return deopt_env_; }
 
+#if defined(TARGET_ARCH_DBC)
+  // On DBC calls return results on the stack but not all calls have a result.
+  // This needs to be taken into account when constructing lazy deoptimization
+  // environment.
+  // For calls with results we add a deopt instruction that would copy top
+  // of the stack from optimized frame to unoptimized frame effectively
+  // preserving the result of the call.
+  // For calls with no results we don't emit such instruction - because there
+  // is no result pushed by the return sequence.
+  void mark_lazy_deopt_with_result() { lazy_deopt_with_result_ = true; }
+#endif
+
  private:
   void EmitMaterializations(Environment* env, DeoptInfoBuilder* builder);
 
   void AllocateIncomingParametersRecursive(Environment* env,
                                            intptr_t* stack_height);
 
   intptr_t pc_offset_;
   const intptr_t deopt_id_;
   const ICData::DeoptReasonId reason_;
   const uint32_t flags_;
+#if defined(TARGET_ARCH_DBC)
+  bool lazy_deopt_with_result_;
+#endif
   Environment* deopt_env_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilerDeoptInfo);
 };
 
 
 class CompilerDeoptInfoWithStub : public CompilerDeoptInfo {
  public:
   CompilerDeoptInfoWithStub(intptr_t deopt_id,
                             ICData::DeoptReasonId reason,
@@ skipping 326 matching lines @@
 
 #if defined(TARGET_ARCH_DBC)
   void EmitDeopt(intptr_t deopt_id,
                  ICData::DeoptReasonId reason,
                  uint32_t flags = 0);
 
   // If the cid does not fit in 16 bits, then this will cause a bailout.
   uint16_t ToEmbeddableCid(intptr_t cid, Instruction* instruction);
 #endif  // defined(TARGET_ARCH_DBC)
 
-  void AddDeoptIndexAtCall(intptr_t deopt_id);
+  CompilerDeoptInfo* AddDeoptIndexAtCall(intptr_t deopt_id);
 
   void AddSlowPathCode(SlowPathCode* slow_path);
 
   void FinalizeExceptionHandlers(const Code& code);
   void FinalizePcDescriptors(const Code& code);
   RawArray* CreateDeoptInfo(Assembler* assembler);
   void FinalizeStackMaps(const Code& code);
   void FinalizeVarDescriptors(const Code& code);
   void FinalizeStaticCallTargetsTable(const Code& code);
 
@@ skipping 63 matching lines @@
       code_source_map_builder_ = new CodeSourceMapBuilder();
     }
     ASSERT(code_source_map_builder_ != NULL);
     return code_source_map_builder_;
   }
 
   void BeginCodeSourceRange();
   bool EndCodeSourceRange(TokenPosition token_pos);
 
 #if defined(TARGET_ARCH_DBC)
+  enum CallResult {
+    kHasResult,
+    kNoResult,
+  };
   void RecordAfterCallHelper(TokenPosition token_pos,
                              intptr_t deopt_id,
                              intptr_t argument_count,
+                             CallResult result,
                              LocationSummary* locs);
-  void RecordAfterCall(Instruction* instr);
+  void RecordAfterCall(Instruction* instr, CallResult result);
 #endif
 
  private:
   friend class CheckStackOverflowSlowPath;  // For pending_deoptimization_env_.
 
   static bool ShouldInlineSmiStringHashCode(const ICData& ic_data);
 
   void EmitFrameEntry();
 
   void AddStaticCallTarget(const Function& function);
@@ skipping 191 matching lines @@
   const GrowableArray<const Function*>& inline_id_to_function_;
   const GrowableArray<TokenPosition>& inline_id_to_token_pos_;
   const GrowableArray<intptr_t>& caller_inline_id_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphCompiler);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_FLOW_GRAPH_COMPILER_H_