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      1 // Copyright 2012 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "src/runtime-profiler.h"
      6 
      7 #include "src/assembler.h"
      8 #include "src/base/platform/platform.h"
      9 #include "src/bootstrapper.h"
     10 #include "src/code-stubs.h"
     11 #include "src/compilation-cache.h"
     12 #include "src/compiler.h"
     13 #include "src/execution.h"
     14 #include "src/frames-inl.h"
     15 #include "src/full-codegen/full-codegen.h"
     16 #include "src/global-handles.h"
     17 #include "src/interpreter/interpreter.h"
     18 
     19 namespace v8 {
     20 namespace internal {
     21 
     22 
     23 // Number of times a function has to be seen on the stack before it is
     24 // compiled for baseline.
     25 static const int kProfilerTicksBeforeBaseline = 0;
     26 // Number of times a function has to be seen on the stack before it is
     27 // optimized.
     28 static const int kProfilerTicksBeforeOptimization = 2;
     29 // If the function optimization was disabled due to high deoptimization count,
     30 // but the function is hot and has been seen on the stack this number of times,
     31 // then we try to reenable optimization for this function.
     32 static const int kProfilerTicksBeforeReenablingOptimization = 250;
     33 // If a function does not have enough type info (according to
     34 // FLAG_type_info_threshold), but has seen a huge number of ticks,
     35 // optimize it as it is.
     36 static const int kTicksWhenNotEnoughTypeInfo = 100;
     37 // We only have one byte to store the number of ticks.
     38 STATIC_ASSERT(kProfilerTicksBeforeOptimization < 256);
     39 STATIC_ASSERT(kProfilerTicksBeforeReenablingOptimization < 256);
     40 STATIC_ASSERT(kTicksWhenNotEnoughTypeInfo < 256);
     41 
     42 // Maximum size in bytes of generate code for a function to allow OSR.
     43 static const int kOSRCodeSizeAllowanceBase =
     44     100 * FullCodeGenerator::kCodeSizeMultiplier;
     45 static const int kOSRCodeSizeAllowanceBaseIgnition =
     46     10 * interpreter::Interpreter::kCodeSizeMultiplier;
     47 
     48 static const int kOSRCodeSizeAllowancePerTick =
     49     4 * FullCodeGenerator::kCodeSizeMultiplier;
     50 static const int kOSRCodeSizeAllowancePerTickIgnition =
     51     2 * interpreter::Interpreter::kCodeSizeMultiplier;
     52 
     53 // Maximum size in bytes of generated code for a function to be optimized
     54 // the very first time it is seen on the stack.
     55 static const int kMaxSizeEarlyOpt =
     56     5 * FullCodeGenerator::kCodeSizeMultiplier;
     57 static const int kMaxSizeEarlyOptIgnition =
     58     5 * interpreter::Interpreter::kCodeSizeMultiplier;
     59 
     60 // Certain functions are simply too big to be worth optimizing.
     61 // We aren't using the code size multiplier here because there is no
     62 // "kMaxSizeOpt" with which we would need to normalize. This constant is
     63 // only for optimization decisions coming into TurboFan from Ignition.
     64 static const int kMaxSizeOptIgnition = 250 * 1024;
     65 
     66 #define OPTIMIZATION_REASON_LIST(V)                            \
     67   V(DoNotOptimize, "do not optimize")                          \
     68   V(HotAndStable, "hot and stable")                            \
     69   V(HotEnoughForBaseline, "hot enough for baseline")           \
     70   V(HotWithoutMuchTypeInfo, "not much type info but very hot") \
     71   V(SmallFunction, "small function")
     72 
     73 enum class OptimizationReason : uint8_t {
     74 #define OPTIMIZATION_REASON_CONSTANTS(Constant, message) k##Constant,
     75   OPTIMIZATION_REASON_LIST(OPTIMIZATION_REASON_CONSTANTS)
     76 #undef OPTIMIZATION_REASON_CONSTANTS
     77 };
     78 
     79 char const* OptimizationReasonToString(OptimizationReason reason) {
     80   static char const* reasons[] = {
     81 #define OPTIMIZATION_REASON_TEXTS(Constant, message) message,
     82       OPTIMIZATION_REASON_LIST(OPTIMIZATION_REASON_TEXTS)
     83 #undef OPTIMIZATION_REASON_TEXTS
     84   };
     85   size_t const index = static_cast<size_t>(reason);
     86   DCHECK_LT(index, arraysize(reasons));
     87   return reasons[index];
     88 }
     89 
     90 std::ostream& operator<<(std::ostream& os, OptimizationReason reason) {
     91   return os << OptimizationReasonToString(reason);
     92 }
     93 
     94 RuntimeProfiler::RuntimeProfiler(Isolate* isolate)
     95     : isolate_(isolate),
     96       any_ic_changed_(false) {
     97 }
     98 
     99 static void GetICCounts(JSFunction* function, int* ic_with_type_info_count,
    100                         int* ic_generic_count, int* ic_total_count,
    101                         int* type_info_percentage, int* generic_percentage) {
    102   *ic_total_count = 0;
    103   *ic_generic_count = 0;
    104   *ic_with_type_info_count = 0;
    105   if (function->code()->kind() == Code::FUNCTION) {
    106     Code* shared_code = function->shared()->code();
    107     Object* raw_info = shared_code->type_feedback_info();
    108     if (raw_info->IsTypeFeedbackInfo()) {
    109       TypeFeedbackInfo* info = TypeFeedbackInfo::cast(raw_info);
    110       *ic_with_type_info_count = info->ic_with_type_info_count();
    111       *ic_generic_count = info->ic_generic_count();
    112       *ic_total_count = info->ic_total_count();
    113     }
    114   }
    115 
    116   // Harvest vector-ics as well
    117   FeedbackVector* vector = function->feedback_vector();
    118   int with = 0, gen = 0, type_vector_ic_count = 0;
    119   const bool is_interpreted = function->shared()->IsInterpreted();
    120 
    121   vector->ComputeCounts(&with, &gen, &type_vector_ic_count, is_interpreted);
    122   *ic_total_count += type_vector_ic_count;
    123   *ic_with_type_info_count += with;
    124   *ic_generic_count += gen;
    125 
    126   if (*ic_total_count > 0) {
    127     *type_info_percentage = 100 * *ic_with_type_info_count / *ic_total_count;
    128     *generic_percentage = 100 * *ic_generic_count / *ic_total_count;
    129   } else {
    130     *type_info_percentage = 100;  // Compared against lower bound.
    131     *generic_percentage = 0;      // Compared against upper bound.
    132   }
    133 }
    134 
    135 static void TraceRecompile(JSFunction* function, const char* reason,
    136                            const char* type) {
    137   if (FLAG_trace_opt &&
    138       function->shared()->PassesFilter(FLAG_hydrogen_filter)) {
    139     PrintF("[marking ");
    140     function->ShortPrint();
    141     PrintF(" for %s recompilation, reason: %s", type, reason);
    142     if (FLAG_type_info_threshold > 0) {
    143       int typeinfo, generic, total, type_percentage, generic_percentage;
    144       GetICCounts(function, &typeinfo, &generic, &total, &type_percentage,
    145                   &generic_percentage);
    146       PrintF(", ICs with typeinfo: %d/%d (%d%%)", typeinfo, total,
    147              type_percentage);
    148       PrintF(", generic ICs: %d/%d (%d%%)", generic, total, generic_percentage);
    149     }
    150     PrintF("]\n");
    151   }
    152 }
    153 
    154 void RuntimeProfiler::Optimize(JSFunction* function,
    155                                OptimizationReason reason) {
    156   DCHECK_NE(reason, OptimizationReason::kDoNotOptimize);
    157   TraceRecompile(function, OptimizationReasonToString(reason), "optimized");
    158   function->AttemptConcurrentOptimization();
    159 }
    160 
    161 void RuntimeProfiler::Baseline(JSFunction* function,
    162                                OptimizationReason reason) {
    163   DCHECK_NE(reason, OptimizationReason::kDoNotOptimize);
    164   TraceRecompile(function, OptimizationReasonToString(reason), "baseline");
    165   DCHECK(function->shared()->IsInterpreted());
    166   function->MarkForBaseline();
    167 }
    168 
    169 void RuntimeProfiler::AttemptOnStackReplacement(JavaScriptFrame* frame,
    170                                                 int loop_nesting_levels) {
    171   JSFunction* function = frame->function();
    172   SharedFunctionInfo* shared = function->shared();
    173   if (!FLAG_use_osr || !function->shared()->IsUserJavaScript()) {
    174     return;
    175   }
    176 
    177   // If the code is not optimizable, don't try OSR.
    178   if (shared->optimization_disabled()) return;
    179 
    180   // We are not prepared to do OSR for a function that already has an
    181   // allocated arguments object.  The optimized code would bypass it for
    182   // arguments accesses, which is unsound.  Don't try OSR.
    183   if (shared->uses_arguments()) return;
    184 
    185   // We're using on-stack replacement: modify unoptimized code so that
    186   // certain back edges in any unoptimized frame will trigger on-stack
    187   // replacement for that frame.
    188   //  - Ignition: Store new loop nesting level in BytecodeArray header.
    189   //  - FullCodegen: Patch back edges up to new level using BackEdgeTable.
    190   if (FLAG_trace_osr) {
    191     PrintF("[OSR - arming back edges in ");
    192     function->PrintName();
    193     PrintF("]\n");
    194   }
    195 
    196   if (frame->type() == StackFrame::JAVA_SCRIPT) {
    197     DCHECK(shared->HasBaselineCode());
    198     DCHECK(BackEdgeTable::Verify(shared->GetIsolate(), shared->code()));
    199     for (int i = 0; i < loop_nesting_levels; i++) {
    200       BackEdgeTable::Patch(isolate_, shared->code());
    201     }
    202   } else if (frame->type() == StackFrame::INTERPRETED) {
    203     DCHECK(shared->HasBytecodeArray());
    204     if (!FLAG_ignition_osr) return;  // Only use this when enabled.
    205     int level = shared->bytecode_array()->osr_loop_nesting_level();
    206     shared->bytecode_array()->set_osr_loop_nesting_level(
    207         Min(level + loop_nesting_levels, AbstractCode::kMaxLoopNestingMarker));
    208   } else {
    209     UNREACHABLE();
    210   }
    211 }
    212 
    213 void RuntimeProfiler::MaybeOptimizeFullCodegen(JSFunction* function,
    214                                                JavaScriptFrame* frame,
    215                                                int frame_count) {
    216   SharedFunctionInfo* shared = function->shared();
    217   Code* shared_code = shared->code();
    218   if (shared_code->kind() != Code::FUNCTION) return;
    219   if (function->IsInOptimizationQueue()) return;
    220 
    221   if (FLAG_always_osr) {
    222     AttemptOnStackReplacement(frame, AbstractCode::kMaxLoopNestingMarker);
    223     // Fall through and do a normal optimized compile as well.
    224   } else if (!frame->is_optimized() &&
    225              (function->IsMarkedForOptimization() ||
    226               function->IsMarkedForConcurrentOptimization() ||
    227               function->IsOptimized())) {
    228     // Attempt OSR if we are still running unoptimized code even though the
    229     // the function has long been marked or even already been optimized.
    230     int ticks = shared_code->profiler_ticks();
    231     int64_t allowance =
    232         kOSRCodeSizeAllowanceBase +
    233         static_cast<int64_t>(ticks) * kOSRCodeSizeAllowancePerTick;
    234     if (shared_code->CodeSize() > allowance &&
    235         ticks < Code::ProfilerTicksField::kMax) {
    236       shared_code->set_profiler_ticks(ticks + 1);
    237     } else {
    238       AttemptOnStackReplacement(frame);
    239     }
    240     return;
    241   }
    242 
    243   // Only record top-level code on top of the execution stack and
    244   // avoid optimizing excessively large scripts since top-level code
    245   // will be executed only once.
    246   const int kMaxToplevelSourceSize = 10 * 1024;
    247   if (shared->is_toplevel() &&
    248       (frame_count > 1 || shared->SourceSize() > kMaxToplevelSourceSize)) {
    249     return;
    250   }
    251 
    252   // Do not record non-optimizable functions.
    253   if (shared->optimization_disabled()) {
    254     if (shared->deopt_count() >= FLAG_max_opt_count) {
    255       // If optimization was disabled due to many deoptimizations,
    256       // then check if the function is hot and try to reenable optimization.
    257       int ticks = shared_code->profiler_ticks();
    258       if (ticks >= kProfilerTicksBeforeReenablingOptimization) {
    259         shared_code->set_profiler_ticks(0);
    260         shared->TryReenableOptimization();
    261       } else {
    262         shared_code->set_profiler_ticks(ticks + 1);
    263       }
    264     }
    265     return;
    266   }
    267   if (frame->is_optimized()) return;
    268 
    269   int ticks = shared_code->profiler_ticks();
    270 
    271   if (ticks >= kProfilerTicksBeforeOptimization) {
    272     int typeinfo, generic, total, type_percentage, generic_percentage;
    273     GetICCounts(function, &typeinfo, &generic, &total, &type_percentage,
    274                 &generic_percentage);
    275     if (type_percentage >= FLAG_type_info_threshold &&
    276         generic_percentage <= FLAG_generic_ic_threshold) {
    277       // If this particular function hasn't had any ICs patched for enough
    278       // ticks, optimize it now.
    279       Optimize(function, OptimizationReason::kHotAndStable);
    280     } else if (ticks >= kTicksWhenNotEnoughTypeInfo) {
    281       Optimize(function, OptimizationReason::kHotWithoutMuchTypeInfo);
    282     } else {
    283       shared_code->set_profiler_ticks(ticks + 1);
    284       if (FLAG_trace_opt_verbose) {
    285         PrintF("[not yet optimizing ");
    286         function->PrintName();
    287         PrintF(", not enough type info: %d/%d (%d%%)]\n", typeinfo, total,
    288                type_percentage);
    289       }
    290     }
    291   } else if (!any_ic_changed_ &&
    292              shared_code->instruction_size() < kMaxSizeEarlyOpt) {
    293     // If no IC was patched since the last tick and this function is very
    294     // small, optimistically optimize it now.
    295     int typeinfo, generic, total, type_percentage, generic_percentage;
    296     GetICCounts(function, &typeinfo, &generic, &total, &type_percentage,
    297                 &generic_percentage);
    298     if (type_percentage >= FLAG_type_info_threshold &&
    299         generic_percentage <= FLAG_generic_ic_threshold) {
    300       Optimize(function, OptimizationReason::kSmallFunction);
    301     } else {
    302       shared_code->set_profiler_ticks(ticks + 1);
    303     }
    304   } else {
    305     shared_code->set_profiler_ticks(ticks + 1);
    306   }
    307 }
    308 
    309 void RuntimeProfiler::MaybeBaselineIgnition(JSFunction* function,
    310                                             JavaScriptFrame* frame) {
    311   if (function->IsInOptimizationQueue()) return;
    312 
    313   if (FLAG_always_osr) {
    314     AttemptOnStackReplacement(frame, AbstractCode::kMaxLoopNestingMarker);
    315     // Fall through and do a normal baseline compile as well.
    316   } else if (MaybeOSRIgnition(function, frame)) {
    317     return;
    318   }
    319 
    320   SharedFunctionInfo* shared = function->shared();
    321   int ticks = shared->profiler_ticks();
    322 
    323   if (shared->optimization_disabled() &&
    324       shared->disable_optimization_reason() == kOptimizationDisabledForTest) {
    325     // Don't baseline functions which have been marked by NeverOptimizeFunction
    326     // in a test.
    327     return;
    328   }
    329 
    330   if (ticks >= kProfilerTicksBeforeBaseline) {
    331     Baseline(function, OptimizationReason::kHotEnoughForBaseline);
    332   }
    333 }
    334 
    335 void RuntimeProfiler::MaybeOptimizeIgnition(JSFunction* function,
    336                                             JavaScriptFrame* frame) {
    337   if (function->IsInOptimizationQueue()) return;
    338 
    339   if (FLAG_always_osr) {
    340     AttemptOnStackReplacement(frame, AbstractCode::kMaxLoopNestingMarker);
    341     // Fall through and do a normal optimized compile as well.
    342   } else if (MaybeOSRIgnition(function, frame)) {
    343     return;
    344   }
    345 
    346   SharedFunctionInfo* shared = function->shared();
    347   int ticks = shared->profiler_ticks();
    348 
    349   if (shared->optimization_disabled()) {
    350     if (shared->deopt_count() >= FLAG_max_opt_count) {
    351       // If optimization was disabled due to many deoptimizations,
    352       // then check if the function is hot and try to reenable optimization.
    353       if (ticks >= kProfilerTicksBeforeReenablingOptimization) {
    354         shared->set_profiler_ticks(0);
    355         shared->TryReenableOptimization();
    356       }
    357     }
    358     return;
    359   }
    360 
    361   if (frame->is_optimized()) return;
    362 
    363   OptimizationReason reason = ShouldOptimizeIgnition(function, frame);
    364 
    365   if (reason != OptimizationReason::kDoNotOptimize) {
    366     Optimize(function, reason);
    367   }
    368 }
    369 
    370 bool RuntimeProfiler::MaybeOSRIgnition(JSFunction* function,
    371                                        JavaScriptFrame* frame) {
    372   SharedFunctionInfo* shared = function->shared();
    373   int ticks = shared->profiler_ticks();
    374 
    375   // TODO(rmcilroy): Also ensure we only OSR top-level code if it is smaller
    376   // than kMaxToplevelSourceSize.
    377 
    378   bool osr_before_baselined = function->IsMarkedForBaseline() &&
    379                               ShouldOptimizeIgnition(function, frame) !=
    380                                   OptimizationReason::kDoNotOptimize;
    381   if (!frame->is_optimized() &&
    382       (osr_before_baselined || function->IsMarkedForOptimization() ||
    383        function->IsMarkedForConcurrentOptimization() ||
    384        function->IsOptimized())) {
    385     // Attempt OSR if we are still running interpreted code even though the
    386     // the function has long been marked or even already been optimized.
    387     int64_t allowance =
    388         kOSRCodeSizeAllowanceBaseIgnition +
    389         static_cast<int64_t>(ticks) * kOSRCodeSizeAllowancePerTickIgnition;
    390     if (shared->bytecode_array()->Size() <= allowance) {
    391       AttemptOnStackReplacement(frame);
    392     }
    393     return true;
    394   }
    395   return false;
    396 }
    397 
    398 OptimizationReason RuntimeProfiler::ShouldOptimizeIgnition(
    399     JSFunction* function, JavaScriptFrame* frame) {
    400   SharedFunctionInfo* shared = function->shared();
    401   int ticks = shared->profiler_ticks();
    402 
    403   if (shared->bytecode_array()->Size() > kMaxSizeOptIgnition) {
    404     return OptimizationReason::kDoNotOptimize;
    405   }
    406 
    407   if (ticks >= kProfilerTicksBeforeOptimization) {
    408     int typeinfo, generic, total, type_percentage, generic_percentage;
    409     GetICCounts(function, &typeinfo, &generic, &total, &type_percentage,
    410                 &generic_percentage);
    411     if (type_percentage >= FLAG_type_info_threshold) {
    412       // If this particular function hasn't had any ICs patched for enough
    413       // ticks, optimize it now.
    414       return OptimizationReason::kHotAndStable;
    415     } else if (ticks >= kTicksWhenNotEnoughTypeInfo) {
    416       return OptimizationReason::kHotWithoutMuchTypeInfo;
    417     } else {
    418       if (FLAG_trace_opt_verbose) {
    419         PrintF("[not yet optimizing ");
    420         function->PrintName();
    421         PrintF(", not enough type info: %d/%d (%d%%)]\n", typeinfo, total,
    422                type_percentage);
    423       }
    424       return OptimizationReason::kDoNotOptimize;
    425     }
    426   } else if (!any_ic_changed_ &&
    427              shared->bytecode_array()->Size() < kMaxSizeEarlyOptIgnition) {
    428     // If no IC was patched since the last tick and this function is very
    429     // small, optimistically optimize it now.
    430     int typeinfo, generic, total, type_percentage, generic_percentage;
    431     GetICCounts(function, &typeinfo, &generic, &total, &type_percentage,
    432                 &generic_percentage);
    433     if (type_percentage >= FLAG_type_info_threshold) {
    434       return OptimizationReason::kSmallFunction;
    435     }
    436   }
    437   return OptimizationReason::kDoNotOptimize;
    438 }
    439 
    440 void RuntimeProfiler::MarkCandidatesForOptimization() {
    441   HandleScope scope(isolate_);
    442 
    443   if (!isolate_->use_crankshaft()) return;
    444 
    445   DisallowHeapAllocation no_gc;
    446 
    447   // Run through the JavaScript frames and collect them. If we already
    448   // have a sample of the function, we mark it for optimizations
    449   // (eagerly or lazily).
    450   int frame_count = 0;
    451   int frame_count_limit = FLAG_frame_count;
    452   for (JavaScriptFrameIterator it(isolate_);
    453        frame_count++ < frame_count_limit && !it.done();
    454        it.Advance()) {
    455     JavaScriptFrame* frame = it.frame();
    456     JSFunction* function = frame->function();
    457 
    458     Compiler::CompilationTier next_tier =
    459         Compiler::NextCompilationTier(function);
    460     if (function->shared()->IsInterpreted()) {
    461       if (next_tier == Compiler::BASELINE) {
    462         MaybeBaselineIgnition(function, frame);
    463       } else {
    464         DCHECK_EQ(next_tier, Compiler::OPTIMIZED);
    465         MaybeOptimizeIgnition(function, frame);
    466       }
    467     } else {
    468       DCHECK_EQ(next_tier, Compiler::OPTIMIZED);
    469       MaybeOptimizeFullCodegen(function, frame, frame_count);
    470     }
    471 
    472     // Update shared function info ticks after checking for whether functions
    473     // should be optimized to keep FCG (which updates ticks on code) and
    474     // Ignition (which updates ticks on shared function info) in sync.
    475     List<SharedFunctionInfo*> functions(4);
    476     frame->GetFunctions(&functions);
    477     for (int i = functions.length(); --i >= 0;) {
    478       SharedFunctionInfo* shared_function_info = functions[i];
    479       int ticks = shared_function_info->profiler_ticks();
    480       if (ticks < Smi::kMaxValue) {
    481         shared_function_info->set_profiler_ticks(ticks + 1);
    482       }
    483     }
    484   }
    485   any_ic_changed_ = false;
    486 }
    487 
    488 }  // namespace internal
    489 }  // namespace v8
    490