Less aggressive polling when concurrently compiling for OSR.

src/full-codegen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 894 matching lines @@
   uint32_t pc_offset(uint32_t index) {
     return Memory::uint32_at(entry_at(index) + kPcOffsetOffset);
   }
 
   Address pc(uint32_t index) {
     return instruction_start_ + pc_offset(index);
   }
 
   enum BackEdgeState {
     INTERRUPT,
-    ON_STACK_REPLACEMENT
+    ON_STACK_REPLACEMENT,
+    OSR_AFTER_STACK_CHECK
   };
 
   // Patch all interrupts with allowed loop depth in the unoptimized code to
   // unconditionally call replacement_code.
   static void Patch(Isolate* isolate,
                     Code* unoptimized_code);
 
-  // Patch the interrupt at the instruction before pc_after in
-  // the unoptimized code to unconditionally call replacement_code.
+  // Patch the back edge to the target state, provided the correct callee.
   static void PatchAt(Code* unoptimized_code,
-                      Address pc_after,
+                      Address pc,
+                      BackEdgeState target_state,
                       Code* replacement_code);
 
-  // Change all patched interrupts patched in the unoptimized code
-  // back to normal interrupts.
+  // Change all patched back edges back to normal interrupts.
   static void Revert(Isolate* isolate,
                      Code* unoptimized_code);
 
-  // Change patched interrupt in the unoptimized code
-  // back to a normal interrupt.
-  static void RevertAt(Code* unoptimized_code,
-                       Address pc_after,
-                       Code* interrupt_code);
+  // Change a back edge patched for on-stack replacement to perform a
+  // stack check first.
+  static void AddStackCheck(CompilationInfo* info);
 
-#ifdef DEBUG
+  // Remove the stack check, if available, and replace by on-stack replacement.
+  static void RemoveStackCheck(CompilationInfo* info);
+
+  // Return the current patch state of the back edge.
   static BackEdgeState GetBackEdgeState(Isolate* isolate,
                                         Code* unoptimized_code,
                                         Address pc_after);
 
+#ifdef DEBUG
   // Verify that all back edges of a certain loop depth are patched.
   static bool Verify(Isolate* isolate,
                      Code* unoptimized_code,
                      int loop_nesting_level);
 #endif  // DEBUG
 
  private:
   Address entry_at(uint32_t index) {
     ASSERT(index < length_);
     return start_ + index * kEntrySize;
   }
 
   static const int kTableLengthSize = kIntSize;
   static const int kAstIdOffset = 0 * kIntSize;
   static const int kPcOffsetOffset = 1 * kIntSize;
   static const int kLoopDepthOffset = 2 * kIntSize;
   static const int kEntrySize = 3 * kIntSize;
 
   Address start_;
   Address instruction_start_;
   uint32_t length_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FULL_CODEGEN_H_