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
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_generic_count,int * ic_total_count,int * type_info_percentage,int * generic_percentage)60 static 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
Optimize(JSFunction * function,const char * reason)83 void 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
AttemptOnStackReplacement(JSFunction * function,int loop_nesting_levels)121 void 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
OptimizeNow()155 void 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