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/v8.h"
6
7#include "src/runtime-profiler.h"
8
9#include "src/assembler.h"
10#include "src/base/platform/platform.h"
11#include "src/bootstrapper.h"
12#include "src/code-stubs.h"
13#include "src/compilation-cache.h"
14#include "src/execution.h"
15#include "src/full-codegen.h"
16#include "src/global-handles.h"
17#include "src/heap/mark-compact.h"
18#include "src/isolate-inl.h"
19#include "src/scopeinfo.h"
20
21namespace v8 {
22namespace internal {
23
24
25// Number of times a function has to be seen on the stack before it is
26// optimized.
27static const int kProfilerTicksBeforeOptimization = 2;
28// If the function optimization was disabled due to high deoptimization count,
29// but the function is hot and has been seen on the stack this number of times,
30// then we try to reenable optimization for this function.
31static const int kProfilerTicksBeforeReenablingOptimization = 250;
32// If a function does not have enough type info (according to
33// FLAG_type_info_threshold), but has seen a huge number of ticks,
34// optimize it as it is.
35static const int kTicksWhenNotEnoughTypeInfo = 100;
36// We only have one byte to store the number of ticks.
37STATIC_ASSERT(kProfilerTicksBeforeOptimization < 256);
38STATIC_ASSERT(kProfilerTicksBeforeReenablingOptimization < 256);
39STATIC_ASSERT(kTicksWhenNotEnoughTypeInfo < 256);
40
41// Maximum size in bytes of generate code for a function to allow OSR.
42static const int kOSRCodeSizeAllowanceBase =
43    100 * FullCodeGenerator::kCodeSizeMultiplier;
44
45static const int kOSRCodeSizeAllowancePerTick =
46    4 * FullCodeGenerator::kCodeSizeMultiplier;
47
48// Maximum size in bytes of generated code for a function to be optimized
49// the very first time it is seen on the stack.
50static const int kMaxSizeEarlyOpt =
51    5 * FullCodeGenerator::kCodeSizeMultiplier;
52
53
54RuntimeProfiler::RuntimeProfiler(Isolate* isolate)
55    : isolate_(isolate),
56      any_ic_changed_(false) {
57}
58
59
60static void GetICCounts(Code* shared_code, int* ic_with_type_info_count,
61                        int* ic_generic_count, int* ic_total_count,
62                        int* type_info_percentage, int* generic_percentage) {
63  *ic_total_count = 0;
64  *ic_generic_count = 0;
65  *ic_with_type_info_count = 0;
66  Object* raw_info = shared_code->type_feedback_info();
67  if (raw_info->IsTypeFeedbackInfo()) {
68    TypeFeedbackInfo* info = TypeFeedbackInfo::cast(raw_info);
69    *ic_with_type_info_count = info->ic_with_type_info_count();
70    *ic_generic_count = info->ic_generic_count();
71    *ic_total_count = info->ic_total_count();
72  }
73  if (*ic_total_count > 0) {
74    *type_info_percentage = 100 * *ic_with_type_info_count / *ic_total_count;
75    *generic_percentage = 100 * *ic_generic_count / *ic_total_count;
76  } else {
77    *type_info_percentage = 100;  // Compared against lower bound.
78    *generic_percentage = 0;      // Compared against upper bound.
79  }
80}
81
82
83void RuntimeProfiler::Optimize(JSFunction* function, const char* reason) {
84  DCHECK(function->IsOptimizable());
85
86  if (FLAG_trace_opt && function->PassesFilter(FLAG_hydrogen_filter)) {
87    PrintF("[marking ");
88    function->ShortPrint();
89    PrintF(" for recompilation, reason: %s", reason);
90    if (FLAG_type_info_threshold > 0) {
91      int typeinfo, generic, total, type_percentage, generic_percentage;
92      GetICCounts(function->shared()->code(), &typeinfo, &generic, &total,
93                  &type_percentage, &generic_percentage);
94      PrintF(", ICs with typeinfo: %d/%d (%d%%)", typeinfo, total,
95             type_percentage);
96      PrintF(", generic ICs: %d/%d (%d%%)", generic, total, generic_percentage);
97    }
98    PrintF("]\n");
99  }
100
101
102  if (isolate_->concurrent_recompilation_enabled() &&
103      !isolate_->bootstrapper()->IsActive()) {
104    if (isolate_->concurrent_osr_enabled() &&
105        isolate_->optimizing_compiler_thread()->IsQueuedForOSR(function)) {
106      // Do not attempt regular recompilation if we already queued this for OSR.
107      // TODO(yangguo): This is necessary so that we don't install optimized
108      // code on a function that is already optimized, since OSR and regular
109      // recompilation race.  This goes away as soon as OSR becomes one-shot.
110      return;
111    }
112    DCHECK(!function->IsInOptimizationQueue());
113    function->MarkForConcurrentOptimization();
114  } else {
115    // The next call to the function will trigger optimization.
116    function->MarkForOptimization();
117  }
118}
119
120
121void RuntimeProfiler::AttemptOnStackReplacement(JSFunction* function,
122                                                int loop_nesting_levels) {
123  SharedFunctionInfo* shared = function->shared();
124  // See AlwaysFullCompiler (in compiler.cc) comment on why we need
125  // Debug::has_break_points().
126  if (!FLAG_use_osr ||
127      isolate_->DebuggerHasBreakPoints() ||
128      function->IsBuiltin()) {
129    return;
130  }
131
132  // If the code is not optimizable, don't try OSR.
133  if (!shared->code()->optimizable()) return;
134
135  // We are not prepared to do OSR for a function that already has an
136  // allocated arguments object.  The optimized code would bypass it for
137  // arguments accesses, which is unsound.  Don't try OSR.
138  if (shared->uses_arguments()) return;
139
140  // We're using on-stack replacement: patch the unoptimized code so that
141  // any back edge in any unoptimized frame will trigger on-stack
142  // replacement for that frame.
143  if (FLAG_trace_osr) {
144    PrintF("[OSR - patching back edges in ");
145    function->PrintName();
146    PrintF("]\n");
147  }
148
149  for (int i = 0; i < loop_nesting_levels; i++) {
150    BackEdgeTable::Patch(isolate_, shared->code());
151  }
152}
153
154
155void RuntimeProfiler::OptimizeNow() {
156  HandleScope scope(isolate_);
157
158  if (isolate_->DebuggerHasBreakPoints()) return;
159
160  DisallowHeapAllocation no_gc;
161
162  // Run through the JavaScript frames and collect them. If we already
163  // have a sample of the function, we mark it for optimizations
164  // (eagerly or lazily).
165  int frame_count = 0;
166  int frame_count_limit = FLAG_frame_count;
167  for (JavaScriptFrameIterator it(isolate_);
168       frame_count++ < frame_count_limit && !it.done();
169       it.Advance()) {
170    JavaScriptFrame* frame = it.frame();
171    JSFunction* function = frame->function();
172
173    SharedFunctionInfo* shared = function->shared();
174    Code* shared_code = shared->code();
175
176    List<JSFunction*> functions(4);
177    frame->GetFunctions(&functions);
178    for (int i = functions.length(); --i >= 0; ) {
179      SharedFunctionInfo* shared_function_info = functions[i]->shared();
180      int ticks = shared_function_info->profiler_ticks();
181      if (ticks < Smi::kMaxValue) {
182        shared_function_info->set_profiler_ticks(ticks + 1);
183      }
184    }
185
186    if (shared_code->kind() != Code::FUNCTION) continue;
187    if (function->IsInOptimizationQueue()) continue;
188
189    if (FLAG_always_osr) {
190      AttemptOnStackReplacement(function, Code::kMaxLoopNestingMarker);
191      // Fall through and do a normal optimized compile as well.
192    } else if (!frame->is_optimized() &&
193        (function->IsMarkedForOptimization() ||
194         function->IsMarkedForConcurrentOptimization() ||
195         function->IsOptimized())) {
196      // Attempt OSR if we are still running unoptimized code even though the
197      // the function has long been marked or even already been optimized.
198      int ticks = shared_code->profiler_ticks();
199      int allowance = kOSRCodeSizeAllowanceBase +
200                      ticks * kOSRCodeSizeAllowancePerTick;
201      if (shared_code->CodeSize() > allowance) {
202        if (ticks < 255) shared_code->set_profiler_ticks(ticks + 1);
203      } else {
204        AttemptOnStackReplacement(function);
205      }
206      continue;
207    }
208
209    // Only record top-level code on top of the execution stack and
210    // avoid optimizing excessively large scripts since top-level code
211    // will be executed only once.
212    const int kMaxToplevelSourceSize = 10 * 1024;
213    if (shared->is_toplevel() &&
214        (frame_count > 1 || shared->SourceSize() > kMaxToplevelSourceSize)) {
215      continue;
216    }
217
218    // Do not record non-optimizable functions.
219    if (shared->optimization_disabled()) {
220      if (shared->deopt_count() >= FLAG_max_opt_count) {
221        // If optimization was disabled due to many deoptimizations,
222        // then check if the function is hot and try to reenable optimization.
223        int ticks = shared_code->profiler_ticks();
224        if (ticks >= kProfilerTicksBeforeReenablingOptimization) {
225          shared_code->set_profiler_ticks(0);
226          shared->TryReenableOptimization();
227        } else {
228          shared_code->set_profiler_ticks(ticks + 1);
229        }
230      }
231      continue;
232    }
233    if (!function->IsOptimizable()) continue;
234
235    int ticks = shared_code->profiler_ticks();
236
237    if (ticks >= kProfilerTicksBeforeOptimization) {
238      int typeinfo, generic, total, type_percentage, generic_percentage;
239      GetICCounts(shared_code, &typeinfo, &generic, &total, &type_percentage,
240                  &generic_percentage);
241      if (type_percentage >= FLAG_type_info_threshold &&
242          generic_percentage <= FLAG_generic_ic_threshold) {
243        // If this particular function hasn't had any ICs patched for enough
244        // ticks, optimize it now.
245        Optimize(function, "hot and stable");
246      } else if (ticks >= kTicksWhenNotEnoughTypeInfo) {
247        Optimize(function, "not much type info but very hot");
248      } else {
249        shared_code->set_profiler_ticks(ticks + 1);
250        if (FLAG_trace_opt_verbose) {
251          PrintF("[not yet optimizing ");
252          function->PrintName();
253          PrintF(", not enough type info: %d/%d (%d%%)]\n", typeinfo, total,
254                 type_percentage);
255        }
256      }
257    } else if (!any_ic_changed_ &&
258               shared_code->instruction_size() < kMaxSizeEarlyOpt) {
259      // If no IC was patched since the last tick and this function is very
260      // small, optimistically optimize it now.
261      int typeinfo, generic, total, type_percentage, generic_percentage;
262      GetICCounts(shared_code, &typeinfo, &generic, &total, &type_percentage,
263                  &generic_percentage);
264      if (type_percentage >= FLAG_type_info_threshold &&
265          generic_percentage <= FLAG_generic_ic_threshold) {
266        Optimize(function, "small function");
267      } else {
268        shared_code->set_profiler_ticks(ticks + 1);
269      }
270    } else {
271      shared_code->set_profiler_ticks(ticks + 1);
272    }
273  }
274  any_ic_changed_ = false;
275}
276
277
278} }  // namespace v8::internal
279