Initial support for count-based profiling

(behind FLAG_count_based_interrupts; only on ia32)

Review URL: https://chromiumcodereview.appspot.com/9373028

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10699 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/code-stubs-arm.cc

@@ -3439,6 +3439,11 @@ void StackCheckStub::Generate(MacroAssembler* masm) {
 }
 
 
+void InterruptStub::Generate(MacroAssembler* masm) {
+  __ TailCallRuntime(Runtime::kInterrupt, 0, 1);
+}
+
+
 void MathPowStub::Generate(MacroAssembler* masm) {
   CpuFeatures::Scope vfp3_scope(VFP3);
   const Register base = r1;

src/arm/full-codegen-arm.cc

@@ -331,7 +331,8 @@ void FullCodeGenerator::ClearAccumulator() {
 }
 
 
-void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt) {
+void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt,
+                                       Label* back_edge_target) {
   Comment cmnt(masm_, "[ Stack check");
   Label ok;
   __ LoadRoot(ip, Heap::kStackLimitRootIndex);
@@ -1106,7 +1107,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ add(r0, r0, Operand(Smi::FromInt(1)));
   __ push(r0);
 
-  EmitStackCheck(stmt);
+  EmitStackCheck(stmt, &loop);
   __ b(&loop);
 
   // Remove the pointers stored on the stack.

src/code-stubs.h

@@ -55,6 +55,7 @@ namespace internal {
   V(ConvertToDouble)                     \
   V(WriteInt32ToHeapNumber)              \
   V(StackCheck)                          \
+  V(Interrupt)                           \
   V(FastNewClosure)                      \
   V(FastNewContext)                      \
   V(FastNewBlockContext)                 \
@@ -297,6 +298,18 @@ class StackCheckStub : public CodeStub {
 };
 
 
+class InterruptStub : public CodeStub {
+ public:
+  InterruptStub() { }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Major MajorKey() { return Interrupt; }
+  int MinorKey() { return 0; }
+};
+
+
 class ToNumberStub: public CodeStub {
  public:
   ToNumberStub() { }

src/execution.cc

@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:
@@ -882,7 +882,9 @@ MaybeObject* Execution::HandleStackGuardInterrupt() {
   }
 
   isolate->counters()->stack_interrupts()->Increment();
-  if (stack_guard->IsRuntimeProfilerTick()) {
+  // If FLAG_count_based_interrupts, every interrupt is a profiler interrupt.
+  if (FLAG_count_based_interrupts ||
+      stack_guard->IsRuntimeProfilerTick()) {
     isolate->counters()->runtime_profiler_ticks()->Increment();
     stack_guard->Continue(RUNTIME_PROFILER_TICK);
     isolate->runtime_profiler()->OptimizeNow();
@@ -904,4 +906,5 @@ MaybeObject* Execution::HandleStackGuardInterrupt() {
   return isolate->heap()->undefined_value();
 }
 
+
 } }  // namespace v8::internal

src/flag-definitions.h

@@ -170,9 +170,16 @@ DEFINE_bool(experimental_profiler, false, "enable all profiler experiments")
 DEFINE_bool(watch_ic_patching, false, "profiler considers IC stability")
 DEFINE_bool(self_optimization, false,
             "primitive functions trigger their own optimization")
+DEFINE_bool(count_based_interrupts, false,
+            "trigger profiler ticks based on counting instead of timing")
+DEFINE_bool(weighted_back_edges, false,
+            "weight back edges by jump distance for interrupt triggering")
+DEFINE_int(interrupt_budget, 100,
+           "execution budget before interrupt is triggered")
 
 DEFINE_implication(experimental_profiler, watch_ic_patching)
 DEFINE_implication(experimental_profiler, self_optimization)
+DEFINE_implication(experimental_profiler, count_based_interrupts)
 
 // assembler-ia32.cc / assembler-arm.cc / assembler-x64.cc
 DEFINE_bool(debug_code, false,

src/full-codegen.cc

@@ -1073,7 +1073,7 @@ void FullCodeGenerator::VisitDoWhileStatement(DoWhileStatement* stmt) {
   // Check stack before looping.
   PrepareForBailoutForId(stmt->BackEdgeId(), NO_REGISTERS);
   __ bind(&stack_check);
-  EmitStackCheck(stmt);
+  EmitStackCheck(stmt, &body);
   __ jmp(&body);
 
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
@@ -1102,7 +1102,7 @@ void FullCodeGenerator::VisitWhileStatement(WhileStatement* stmt) {
   SetStatementPosition(stmt);
 
   // Check stack before looping.
-  EmitStackCheck(stmt);
+  EmitStackCheck(stmt, &body);
 
   __ bind(&test);
   VisitForControl(stmt->cond(),
@@ -1145,7 +1145,7 @@ void FullCodeGenerator::VisitForStatement(ForStatement* stmt) {
   SetStatementPosition(stmt);
 
   // Check stack before looping.
-  EmitStackCheck(stmt);
+  EmitStackCheck(stmt, &body);
 
   __ bind(&test);
   if (stmt->cond() != NULL) {

src/full-codegen.h

@@ -424,7 +424,10 @@ class FullCodeGenerator: public AstVisitor {
 
   // Platform-specific code for checking the stack limit at the back edge of
   // a loop.
-  void EmitStackCheck(IterationStatement* stmt);
+  // This is meant to be called at loop back edges, |back_edge_target| is
+  // the jump target of the back edge and is used to approximate the amount
+  // of code inside the loop.
+  void EmitStackCheck(IterationStatement* stmt, Label* back_edge_target);
   // Record the OSR AST id corresponding to a stack check in the code.
   void RecordStackCheck(unsigned osr_ast_id);
   // Emit a table of stack check ids and pcs into the code stream.  Return
@@ -774,6 +777,7 @@ class FullCodeGenerator: public AstVisitor {
   ZoneList<BailoutEntry> stack_checks_;
   ZoneList<TypeFeedbackCellEntry> type_feedback_cells_;
   Handle<FixedArray> handler_table_;
+  Handle<JSGlobalPropertyCell> profiling_counter_;
 
   friend class NestedStatement;
 

src/ia32/builtins-ia32.cc

@@ -1694,8 +1694,9 @@ void Builtins::Generate_OnStackReplacement(MacroAssembler* masm) {
   __ j(not_equal, &skip, Label::kNear);
   __ ret(0);
 
-  // If we decide not to perform on-stack replacement we perform a
-  // stack guard check to enable interrupts.
+  // Insert a stack guard check so that if we decide not to perform
+  // on-stack replacement right away, the function calling this stub can
+  // still be interrupted.
   __ bind(&stack_check);
   Label ok;
   ExternalReference stack_limit =

src/ia32/code-stubs-ia32.cc

@@ -4573,6 +4573,11 @@ void StackCheckStub::Generate(MacroAssembler* masm) {
 }
 
 
+void InterruptStub::Generate(MacroAssembler* masm) {
+  __ TailCallRuntime(Runtime::kInterrupt, 0, 1);
+}
+
+
 static void GenerateRecordCallTarget(MacroAssembler* masm) {
   // Cache the called function in a global property cell.  Cache states
   // are uninitialized, monomorphic (indicated by a JSFunction), and

src/ia32/deoptimizer-ia32.cc

@@ -205,6 +205,15 @@ void Deoptimizer::DeoptimizeFunction(JSFunction* function) {
 }
 
 
+static const byte kJnsInstruction = 0x79;
+static const byte kJnsOffset = 0x11;
+static const byte kJaeInstruction = 0x73;
+static const byte kJaeOffset = 0x07;
+static const byte kCallInstruction = 0xe8;
+static const byte kNopByteOne = 0x66;
+static const byte kNopByteTwo = 0x90;
+
+
 void Deoptimizer::PatchStackCheckCodeAt(Code* unoptimized_code,
                                         Address pc_after,
                                         Code* check_code,
@@ -228,11 +237,17 @@ void Deoptimizer::PatchStackCheckCodeAt(Code* unoptimized_code,
   //     call <on-stack replacment>
   //     test eax, <loop nesting depth>
   // ok:
-  ASSERT(*(call_target_address - 3) == 0x73 &&  // jae
-         *(call_target_address - 2) == 0x07 &&  // offset
-         *(call_target_address - 1) == 0xe8);   // call
-  *(call_target_address - 3) = 0x66;  // 2 byte nop part 1
-  *(call_target_address - 2) = 0x90;  // 2 byte nop part 2
+
+  if (FLAG_count_based_interrupts) {
+    ASSERT(*(call_target_address - 3) == kJnsInstruction);
+    ASSERT(*(call_target_address - 2) == kJnsOffset);
+  } else {
+    ASSERT(*(call_target_address - 3) == kJaeInstruction);
+    ASSERT(*(call_target_address - 2) == kJaeOffset);
+  }
+  ASSERT(*(call_target_address - 1) == kCallInstruction);
+  *(call_target_address - 3) = kNopByteOne;
+  *(call_target_address - 2) = kNopByteTwo;
   Assembler::set_target_address_at(call_target_address,
                                    replacement_code->entry());
 
@@ -248,13 +263,19 @@ void Deoptimizer::RevertStackCheckCodeAt(Code* unoptimized_code,
   Address call_target_address = pc_after - kIntSize;
   ASSERT(replacement_code->entry() ==
          Assembler::target_address_at(call_target_address));
+
   // Replace the nops from patching (Deoptimizer::PatchStackCheckCode) to
   // restore the conditional branch.
-  ASSERT(*(call_target_address - 3) == 0x66 &&  // 2 byte nop part 1
-         *(call_target_address - 2) == 0x90 &&  // 2 byte nop part 2
-         *(call_target_address - 1) == 0xe8);   // call
-  *(call_target_address - 3) = 0x73;  // jae
-  *(call_target_address - 2) = 0x07;  // offset
+  ASSERT(*(call_target_address - 3) == kNopByteOne &&
+         *(call_target_address - 2) == kNopByteTwo &&
+         *(call_target_address - 1) == kCallInstruction);
+  if (FLAG_count_based_interrupts) {
+    *(call_target_address - 3) = kJnsInstruction;
+    *(call_target_address - 2) = kJnsOffset;
+  } else {
+    *(call_target_address - 3) = kJaeInstruction;
+    *(call_target_address - 2) = kJaeOffset;
+  }
   Assembler::set_target_address_at(call_target_address,
                                    check_code->entry());
 

src/ia32/full-codegen-ia32.cc

@@ -119,6 +119,8 @@ void FullCodeGenerator::Generate(CompilationInfo* info) {
   scope_ = info->scope();
   handler_table_ =
       isolate()->factory()->NewFixedArray(function()->handler_count(), TENURED);
+  profiling_counter_ = isolate()->factory()->NewJSGlobalPropertyCell(
+      Handle<Smi>(Smi::FromInt(FLAG_interrupt_budget)));
   SetFunctionPosition(function());
   Comment cmnt(masm_, "[ function compiled by full code generator");
 
@@ -323,15 +325,34 @@ void FullCodeGenerator::ClearAccumulator() {
 }
 
 
-void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt) {
+void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt,
+                                       Label* back_edge_target) {
   Comment cmnt(masm_, "[ Stack check");
   Label ok;
-  ExternalReference stack_limit =
-      ExternalReference::address_of_stack_limit(isolate());
-  __ cmp(esp, Operand::StaticVariable(stack_limit));
-  __ j(above_equal, &ok, Label::kNear);
-  StackCheckStub stub;
-  __ CallStub(&stub);
+
+  if (FLAG_count_based_interrupts) {
+    int weight = 1;
+    if (FLAG_weighted_back_edges) {
+      ASSERT(back_edge_target->is_bound());
+      int distance = masm_->pc_offset() - back_edge_target->pos();
+      weight = Min(127, Max(1, distance / 100));
+    }
+    __ sub(Operand::Cell(profiling_counter_), Immediate(Smi::FromInt(weight)));
+    __ j(positive, &ok, Label::kNear);
+    InterruptStub stub;
+    __ CallStub(&stub);
+  } else {
+    // Count based interrupts happen often enough when they are enabled
+    // that the additional stack checks are not necessary (they would
+    // only check for interrupts).
+    ExternalReference stack_limit =
+        ExternalReference::address_of_stack_limit(isolate());
+    __ cmp(esp, Operand::StaticVariable(stack_limit));
+    __ j(above_equal, &ok, Label::kNear);
+    StackCheckStub stub;
+    __ CallStub(&stub);
+  }
+
   // Record a mapping of this PC offset to the OSR id.  This is used to find
   // the AST id from the unoptimized code in order to use it as a key into
   // the deoptimization input data found in the optimized code.
@@ -344,6 +365,12 @@ void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt) {
   ASSERT(loop_depth() > 0);
   __ test(eax, Immediate(Min(loop_depth(), Code::kMaxLoopNestingMarker)));
 
+  if (FLAG_count_based_interrupts) {
+    // Reset the countdown.
+    __ mov(Operand::Cell(profiling_counter_),
+           Immediate(Smi::FromInt(FLAG_interrupt_budget)));
+  }
+
   __ bind(&ok);
   PrepareForBailoutForId(stmt->EntryId(), NO_REGISTERS);
   // Record a mapping of the OSR id to this PC.  This is used if the OSR
@@ -1061,7 +1088,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ bind(loop_statement.continue_label());
   __ add(Operand(esp, 0 * kPointerSize), Immediate(Smi::FromInt(1)));
 
-  EmitStackCheck(stmt);
+  EmitStackCheck(stmt, &loop);
   __ jmp(&loop);
 
   // Remove the pointers stored on the stack.

src/mips/full-codegen-mips.cc

@@ -336,7 +336,8 @@ void FullCodeGenerator::ClearAccumulator() {
 }
 
 
-void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt) {
+void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt,
+                                       Label* back_edge_target) {
   // The generated code is used in Deoptimizer::PatchStackCheckCodeAt so we need
   // to make sure it is constant. Branch may emit a skip-or-jump sequence
   // instead of the normal Branch. It seems that the "skip" part of that
@@ -1119,7 +1120,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ Addu(a0, a0, Operand(Smi::FromInt(1)));
   __ push(a0);
 
-  EmitStackCheck(stmt);
+  EmitStackCheck(stmt, &loop);
   __ Branch(&loop);
 
   // Remove the pointers stored on the stack.

src/runtime-profiler.cc

@@ -147,9 +147,16 @@ void RuntimeProfiler::AttemptOnStackReplacement(JSFunction* function) {
 
   // Get the stack check stub code object to match against.  We aren't
   // prepared to generate it, but we don't expect to have to.
-  StackCheckStub check_stub;
+  bool found_code = false;
   Code* stack_check_code = NULL;
-  if (check_stub.FindCodeInCache(&stack_check_code)) {
+  if (FLAG_count_based_interrupts) {
+    InterruptStub interrupt_stub;
+    found_code = interrupt_stub.FindCodeInCache(&stack_check_code);
+  } else {
+    StackCheckStub check_stub;
+    found_code = check_stub.FindCodeInCache(&stack_check_code);
+  }
+  if (found_code) {
     Code* replacement_code =
         isolate_->builtins()->builtin(Builtins::kOnStackReplacement);
     Code* unoptimized_code = shared->code();
@@ -255,7 +262,7 @@ void RuntimeProfiler::OptimizeNow() {
       } else {
         function->shared()->set_profiler_ticks(ticks + 1);
       }
-    } else {  // !FLAG_counting_profiler
+    } else {  // !FLAG_watch_ic_patching
       samples[sample_count++] = function;
 
       int function_size = function->shared()->SourceSize();
@@ -273,7 +280,7 @@ void RuntimeProfiler::OptimizeNow() {
   if (FLAG_watch_ic_patching) {
     any_ic_changed_ = false;
     code_generated_ = false;
-  } else {  // !FLAG_counting_profiler
+  } else {  // !FLAG_watch_ic_patching
     // Add the collected functions as samples. It's important not to do
     // this as part of collecting them because this will interfere with
     // the sample lookup in case of recursive functions.
@@ -285,6 +292,7 @@ void RuntimeProfiler::OptimizeNow() {
 
 
 void RuntimeProfiler::NotifyTick() {
+  if (FLAG_count_based_interrupts) return;
   isolate_->stack_guard()->RequestRuntimeProfilerTick();
 }
 
@@ -303,7 +311,7 @@ void RuntimeProfiler::SetUp() {
 void RuntimeProfiler::Reset() {
   if (FLAG_watch_ic_patching) {
     total_code_generated_ = 0;
-  } else {  // !FLAG_counting_profiler
+  } else {  // !FLAG_watch_ic_patching
     sampler_threshold_ = kSamplerThresholdInit;
     sampler_threshold_size_factor_ = kSamplerThresholdSizeFactorInit;
     sampler_ticks_until_threshold_adjustment_ =

src/runtime.cc

@@ -8711,8 +8711,14 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CompileForOnStackReplacement) {
     function->PrintName();
     PrintF("]\n");
   }
-  StackCheckStub check_stub;
-  Handle<Code> check_code = check_stub.GetCode();
+  Handle<Code> check_code;
+  if (FLAG_count_based_interrupts) {
+    InterruptStub interrupt_stub;
+    check_code = interrupt_stub.GetCode();
+  } else {
+    StackCheckStub check_stub;
+    check_code = check_stub.GetCode();
+  }
   Handle<Code> replacement_code = isolate->builtins()->OnStackReplacement();
   Deoptimizer::RevertStackCheckCode(*unoptimized,
                                     *check_code,
@@ -9266,6 +9272,12 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_StackGuard) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_Interrupt) {
+  ASSERT(args.length() == 0);
+  return Execution::HandleStackGuardInterrupt();
+}
+
+
 static int StackSize() {
   int n = 0;
   for (JavaScriptFrameIterator it; !it.done(); it.Advance()) n++;

src/runtime.h

@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:
@@ -319,6 +319,7 @@ namespace internal {
   F(ReThrow, 1, 1) \
   F(ThrowReferenceError, 1, 1) \
   F(StackGuard, 0, 1) \
+  F(Interrupt, 0, 1) \
   F(PromoteScheduledException, 0, 1) \
   \
   /* Contexts */ \

src/x64/code-stubs-x64.cc

@@ -3579,6 +3579,11 @@ void StackCheckStub::Generate(MacroAssembler* masm) {
 }
 
 
+void InterruptStub::Generate(MacroAssembler* masm) {
+  __ TailCallRuntime(Runtime::kInterrupt, 0, 1);
+}
+
+
 static void GenerateRecordCallTarget(MacroAssembler* masm) {
   // Cache the called function in a global property cell.  Cache states
   // are uninitialized, monomorphic (indicated by a JSFunction), and

src/x64/full-codegen-x64.cc

@@ -317,7 +317,8 @@ void FullCodeGenerator::ClearAccumulator() {
 }
 
 
-void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt) {
+void FullCodeGenerator::EmitStackCheck(IterationStatement* stmt,
+                                       Label* back_edge_target) {
   Comment cmnt(masm_, "[ Stack check");
   Label ok;
   __ CompareRoot(rsp, Heap::kStackLimitRootIndex);
@@ -1071,7 +1072,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ bind(loop_statement.continue_label());
   __ SmiAddConstant(Operand(rsp, 0 * kPointerSize), Smi::FromInt(1));
 
-  EmitStackCheck(stmt);
+  EmitStackCheck(stmt, &loop);
   __ jmp(&loop);
 
   // Remove the pointers stored on the stack.

test/mjsunit/count-based-osr.js

@@ -0,0 +1,38 @@
+// 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --count-based-interrupts --interrupt-budget=10 --weighted-back-edges --allow-natives-syntax
+
+// Test that OSR works properly when using count-based interrupting/profiling.
+
+function osr_this() {
+  var a = 1;
+  // Trigger OSR.
+  while (%GetOptimizationStatus(osr_this) == 2) {}
+  return a;
+}
+assertEquals(1, osr_this());