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/bootstrapper.h"
11 #include "src/code-stubs.h"
12 #include "src/compilation-cache.h"
13 #include "src/execution.h"
14 #include "src/full-codegen.h"
15 #include "src/global-handles.h"
16 #include "src/isolate-inl.h"
17 #include "src/mark-compact.h"
18 #include "src/platform.h"
19 #include "src/scopeinfo.h"
20
21 namespace v8 {
22 namespace internal {
23
24
25 // Number of times a function has to be seen on the stack before it is
26 // optimized.
27 static 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.
31 static 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.
35 static const int kTicksWhenNotEnoughTypeInfo = 100;
36 // We only have one byte to store the number of ticks.
37 STATIC_ASSERT(kProfilerTicksBeforeOptimization < 256);
38 STATIC_ASSERT(kProfilerTicksBeforeReenablingOptimization < 256);
39 STATIC_ASSERT(kTicksWhenNotEnoughTypeInfo < 256);
40
41 // Maximum size in bytes of generate code for a function to allow OSR.
42 static const int kOSRCodeSizeAllowanceBase =
43 100 * FullCodeGenerator::kCodeSizeMultiplier;
44
45 static 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.
50 static const int kMaxSizeEarlyOpt =
51 5 * FullCodeGenerator::kCodeSizeMultiplier;
52
53
RuntimeProfiler(Isolate * isolate)54 RuntimeProfiler::RuntimeProfiler(Isolate* isolate)
55 : isolate_(isolate),
56 any_ic_changed_(false) {
57 }
58
59
GetICCounts(Code * shared_code,int * ic_with_type_info_count,int * ic_total_count,int * percentage)60 static void GetICCounts(Code* shared_code,
61 int* ic_with_type_info_count,
62 int* ic_total_count,
63 int* percentage) {
64 *ic_total_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_total_count = info->ic_total_count();
71 }
72 *percentage = *ic_total_count > 0
73 ? 100 * *ic_with_type_info_count / *ic_total_count
74 : 100;
75 }
76
77
Optimize(JSFunction * function,const char * reason)78 void RuntimeProfiler::Optimize(JSFunction* function, const char* reason) {
79 ASSERT(function->IsOptimizable());
80
81 if (FLAG_trace_opt && function->PassesFilter(FLAG_hydrogen_filter)) {
82 PrintF("[marking ");
83 function->ShortPrint();
84 PrintF(" for recompilation, reason: %s", reason);
85 if (FLAG_type_info_threshold > 0) {
86 int typeinfo, total, percentage;
87 GetICCounts(function->shared()->code(), &typeinfo, &total, &percentage);
88 PrintF(", ICs with typeinfo: %d/%d (%d%%)", typeinfo, total, percentage);
89 }
90 PrintF("]\n");
91 }
92
93
94 if (isolate_->concurrent_recompilation_enabled() &&
95 !isolate_->bootstrapper()->IsActive()) {
96 if (isolate_->concurrent_osr_enabled() &&
97 isolate_->optimizing_compiler_thread()->IsQueuedForOSR(function)) {
98 // Do not attempt regular recompilation if we already queued this for OSR.
99 // TODO(yangguo): This is necessary so that we don't install optimized
100 // code on a function that is already optimized, since OSR and regular
101 // recompilation race. This goes away as soon as OSR becomes one-shot.
102 return;
103 }
104 ASSERT(!function->IsInOptimizationQueue());
105 function->MarkForConcurrentOptimization();
106 } else {
107 // The next call to the function will trigger optimization.
108 function->MarkForOptimization();
109 }
110 }
111
112
AttemptOnStackReplacement(JSFunction * function)113 void RuntimeProfiler::AttemptOnStackReplacement(JSFunction* function) {
114 // See AlwaysFullCompiler (in compiler.cc) comment on why we need
115 // Debug::has_break_points().
116 if (!FLAG_use_osr ||
117 isolate_->DebuggerHasBreakPoints() ||
118 function->IsBuiltin()) {
119 return;
120 }
121
122 SharedFunctionInfo* shared = function->shared();
123 // If the code is not optimizable, don't try OSR.
124 if (!shared->code()->optimizable()) return;
125
126 // We are not prepared to do OSR for a function that already has an
127 // allocated arguments object. The optimized code would bypass it for
128 // arguments accesses, which is unsound. Don't try OSR.
129 if (shared->uses_arguments()) return;
130
131 // We're using on-stack replacement: patch the unoptimized code so that
132 // any back edge in any unoptimized frame will trigger on-stack
133 // replacement for that frame.
134 if (FLAG_trace_osr) {
135 PrintF("[OSR - patching back edges in ");
136 function->PrintName();
137 PrintF("]\n");
138 }
139
140 BackEdgeTable::Patch(isolate_, shared->code());
141 }
142
143
OptimizeNow()144 void RuntimeProfiler::OptimizeNow() {
145 HandleScope scope(isolate_);
146
147 if (isolate_->DebuggerHasBreakPoints()) return;
148
149 DisallowHeapAllocation no_gc;
150
151 // Run through the JavaScript frames and collect them. If we already
152 // have a sample of the function, we mark it for optimizations
153 // (eagerly or lazily).
154 int frame_count = 0;
155 int frame_count_limit = FLAG_frame_count;
156 for (JavaScriptFrameIterator it(isolate_);
157 frame_count++ < frame_count_limit && !it.done();
158 it.Advance()) {
159 JavaScriptFrame* frame = it.frame();
160 JSFunction* function = frame->function();
161
162 SharedFunctionInfo* shared = function->shared();
163 Code* shared_code = shared->code();
164
165 List<JSFunction*> functions(4);
166 frame->GetFunctions(&functions);
167 for (int i = functions.length(); --i >= 0; ) {
168 SharedFunctionInfo* shared_function_info = functions[i]->shared();
169 int ticks = shared_function_info->profiler_ticks();
170 if (ticks < Smi::kMaxValue) {
171 shared_function_info->set_profiler_ticks(ticks + 1);
172 }
173 }
174
175 if (shared_code->kind() != Code::FUNCTION) continue;
176 if (function->IsInOptimizationQueue()) continue;
177
178 if (FLAG_always_osr &&
179 shared_code->allow_osr_at_loop_nesting_level() == 0) {
180 // Testing mode: always try an OSR compile for every function.
181 for (int i = 0; i < Code::kMaxLoopNestingMarker; i++) {
182 // TODO(titzer): fix AttemptOnStackReplacement to avoid this dumb loop.
183 shared_code->set_allow_osr_at_loop_nesting_level(i);
184 AttemptOnStackReplacement(function);
185 }
186 // Fall through and do a normal optimized compile as well.
187 } else if (!frame->is_optimized() &&
188 (function->IsMarkedForOptimization() ||
189 function->IsMarkedForConcurrentOptimization() ||
190 function->IsOptimized())) {
191 // Attempt OSR if we are still running unoptimized code even though the
192 // the function has long been marked or even already been optimized.
193 int ticks = shared_code->profiler_ticks();
194 int allowance = kOSRCodeSizeAllowanceBase +
195 ticks * kOSRCodeSizeAllowancePerTick;
196 if (shared_code->CodeSize() > allowance) {
197 if (ticks < 255) shared_code->set_profiler_ticks(ticks + 1);
198 } else {
199 int nesting = shared_code->allow_osr_at_loop_nesting_level();
200 if (nesting < Code::kMaxLoopNestingMarker) {
201 int new_nesting = nesting + 1;
202 shared_code->set_allow_osr_at_loop_nesting_level(new_nesting);
203 AttemptOnStackReplacement(function);
204 }
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, total, percentage;
239 GetICCounts(shared_code, &typeinfo, &total, &percentage);
240 if (percentage >= FLAG_type_info_threshold) {
241 // If this particular function hasn't had any ICs patched for enough
242 // ticks, optimize it now.
243 Optimize(function, "hot and stable");
244 } else if (ticks >= kTicksWhenNotEnoughTypeInfo) {
245 Optimize(function, "not much type info but very hot");
246 } else {
247 shared_code->set_profiler_ticks(ticks + 1);
248 if (FLAG_trace_opt_verbose) {
249 PrintF("[not yet optimizing ");
250 function->PrintName();
251 PrintF(", not enough type info: %d/%d (%d%%)]\n",
252 typeinfo, total, percentage);
253 }
254 }
255 } else if (!any_ic_changed_ &&
256 shared_code->instruction_size() < kMaxSizeEarlyOpt) {
257 // If no IC was patched since the last tick and this function is very
258 // small, optimistically optimize it now.
259 Optimize(function, "small function");
260 } else {
261 shared_code->set_profiler_ticks(ticks + 1);
262 }
263 }
264 any_ic_changed_ = false;
265 }
266
267
268 } } // namespace v8::internal
269