[v8-dev] Support full deoptimization during GC via stack guard. (issue 14173007)

Thu, 11 Apr 2013 10:45:14 -0700 

Reviewers: ulan, Hannes Payer,

Description:
Support full deoptimization during GC via stack guard.

This adds support to the stack guard to trigger a full deoptimization of
all optimized code when the GC kicks into high promotion mode. Global
pretenuring decisions in optimized code can then be based on the high
promotion mode.

R=u...@chromium.org


Please review this at https://codereview.chromium.org/14173007/

SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge

Affected files:
  M src/execution.h
  M src/execution.cc
  M src/heap.h
  M src/heap.cc


Index: src/execution.cc
diff --git a/src/execution.cc b/src/execution.cc
index dee31126829f55095662a3e1e6e9b402ff6b478f..f343868060da516624815c727dbe526ebc116c7a 100644 
--- a/src/execution.cc
+++ b/src/execution.cc
@@ -33,6 +33,7 @@
 #include "bootstrapper.h"
 #include "codegen.h"
 #include "debug.h"
+#include "deoptimizer.h"
 #include "isolate-inl.h"
 #include "runtime-profiler.h"
 #include "simulator.h"
@@ -448,6 +449,19 @@ void StackGuard::RequestGC() {
 }


+bool StackGuard::IsFullDeopt() {
+  ExecutionAccess access(isolate_);
+  return (thread_local_.interrupt_flags_ & FULL_DEOPT) != 0;
+}
+
+
+void StackGuard::FullDeopt() {
+  ExecutionAccess access(isolate_);
+  thread_local_.interrupt_flags_ |= FULL_DEOPT;
+  set_interrupt_limits(access);
+}
+
+
 #ifdef ENABLE_DEBUGGER_SUPPORT
 bool StackGuard::IsDebugBreak() {
   ExecutionAccess access(isolate_);
@@ -880,7 +894,6 @@ MaybeObject* Execution::HandleStackGuardInterrupt(Isolate* isolate) { 
     stack_guard->Continue(GC_REQUEST);
   }

-
   isolate->counters()->stack_interrupts()->Increment();
   isolate->counters()->runtime_profiler_ticks()->Increment();
   isolate->runtime_profiler()->OptimizeNow();
@@ -898,6 +911,10 @@ MaybeObject* Execution::HandleStackGuardInterrupt(Isolate* isolate) { 
     stack_guard->Continue(INTERRUPT);
     return isolate->StackOverflow();
   }
+  if (stack_guard->IsFullDeopt()) {
+    stack_guard->Continue(FULL_DEOPT);
+    Deoptimizer::DeoptimizeAll(isolate);
+  }
   return isolate->heap()->undefined_value();
 }

Index: src/execution.h
diff --git a/src/execution.h b/src/execution.h
index b104180c9e0c1c87c71213c389dc2ec05601303c..9cf8ac649c9e683f6a8254bf3559ceedaf1326cc 100644 
--- a/src/execution.h
+++ b/src/execution.h
@@ -41,7 +41,8 @@ enum InterruptFlag {
   DEBUGCOMMAND = 1 << 2,
   PREEMPT = 1 << 3,
   TERMINATE = 1 << 4,
-  GC_REQUEST = 1 << 5
+  GC_REQUEST = 1 << 5,
+  FULL_DEOPT = 1 << 6
 };


@@ -197,6 +198,8 @@ class StackGuard {
 #endif
   bool IsGCRequest();
   void RequestGC();
+  bool IsFullDeopt();
+  void FullDeopt();
   void Continue(InterruptFlag after_what);

   // This provides an asynchronous read of the stack limits for the current
Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index f71d9cc8f836e2f13f1bcb9fc35df5f1d03a649e..2aa699946e5323be62e086456a68ef643dfb900c 100644 
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -952,6 +952,13 @@ bool Heap::PerformGarbageCollection(GarbageCollector collector, PrintPID("Limited new space size due to high promotion rate: %d MB\n", 
                new_space_.InitialCapacity() / MB);
     }
+    // Support for global pre-tenuring uses the high promotion mode as a
+    // heuristic indicator of whether to pretenure or not, we trigger
+    // deoptimization here to take advantage of pre-tenuring as soon as
+    // possible.
+    if (FLAG_pretenure_literals) {
+      isolate_->stack_guard()->FullDeopt();
+    }
   } else if (new_space_high_promotion_mode_active_ &&
       IsStableOrDecreasingSurvivalTrend() &&
       IsLowSurvivalRate()) {
Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 9e758aaa06441317d2952d32feb9eddb2a34de6f..46c75fe141efb7789d6eebc52508543952c2dd13 100644 
--- a/src/heap.h
+++ b/src/heap.h
@@ -1498,6 +1498,12 @@ class Heap {
   MUST_USE_RESULT MaybeObject* AllocateRawFixedArray(int length,
PretenureFlag pretenure); 

+  // Predicate that governs global pre-tenuring decisions based on observed
+  // promotion rates of previous collections.
+  inline bool ShouldGloballyPretenure() {
+    return new_space_high_promotion_mode_active_;
+  }
+
   inline intptr_t PromotedTotalSize() {
     return PromotedSpaceSizeOfObjects() + PromotedExternalMemorySize();
   }


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