зеркало из https://github.com/mozilla/gecko-dev.git
96 строки
3.7 KiB
C++
96 строки
3.7 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sts=4 et sw=4 tw=99:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef js_ProfilingStack_h
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#define js_ProfilingStack_h
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#include "mozilla/NullPtr.h"
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#include "jsbytecode.h"
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#include "jstypes.h"
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#include "js/Utility.h"
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struct JSRuntime;
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namespace js {
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// A call stack can be specified to the JS engine such that all JS entry/exits
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// to functions push/pop an entry to/from the specified stack.
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//
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// For more detailed information, see vm/SPSProfiler.h.
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//
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class ProfileEntry
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{
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// All fields are marked volatile to prevent the compiler from re-ordering
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// instructions. Namely this sequence:
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//
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// entry[size] = ...;
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// size++;
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//
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// If the size modification were somehow reordered before the stores, then
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// if a sample were taken it would be examining bogus information.
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//
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// A ProfileEntry represents both a C++ profile entry and a JS one. Both use
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// the string as a description, but JS uses the sp as nullptr to indicate
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// that it is a JS entry. The script_ is then only ever examined for a JS
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// entry, and the idx is used by both, but with different meanings.
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//
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const char * volatile string; // Descriptive string of this entry
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void * volatile sp; // Relevant stack pointer for the entry
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JSScript * volatile script_; // if js(), non-null script which is running
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int32_t volatile idx; // if js(), idx of pc, otherwise line number
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public:
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// All of these methods are marked with the 'volatile' keyword because SPS's
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// representation of the stack is stored such that all ProfileEntry
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// instances are volatile. These methods would not be available unless they
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// were marked as volatile as well.
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bool js() volatile {
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JS_ASSERT_IF(sp == nullptr, script_ != nullptr);
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return sp == nullptr;
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}
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uint32_t line() volatile { JS_ASSERT(!js()); return idx; }
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JSScript *script() volatile { JS_ASSERT(js()); return script_; }
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void *stackAddress() volatile { return sp; }
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const char *label() volatile { return string; }
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void setLine(uint32_t aLine) volatile { JS_ASSERT(!js()); idx = aLine; }
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void setLabel(const char *aString) volatile { string = aString; }
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void setStackAddress(void *aSp) volatile { sp = aSp; }
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void setScript(JSScript *aScript) volatile { script_ = aScript; }
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// We can't know the layout of JSScript, so look in vm/SPSProfiler.cpp.
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JS_FRIEND_API(jsbytecode *) pc() volatile;
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JS_FRIEND_API(void) setPC(jsbytecode *pc) volatile;
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static size_t offsetOfString() { return offsetof(ProfileEntry, string); }
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static size_t offsetOfStackAddress() { return offsetof(ProfileEntry, sp); }
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static size_t offsetOfPCIdx() { return offsetof(ProfileEntry, idx); }
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static size_t offsetOfScript() { return offsetof(ProfileEntry, script_); }
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// The index used in the entry can either be a line number or the offset of
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// a pc into a script's code. To signify a nullptr pc, use a -1 index. This
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// is checked against in pc() and setPC() to set/get the right pc.
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static const int32_t NullPCIndex = -1;
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};
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JS_FRIEND_API(void)
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SetRuntimeProfilingStack(JSRuntime *rt, ProfileEntry *stack, uint32_t *size,
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uint32_t max);
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JS_FRIEND_API(void)
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EnableRuntimeProfilingStack(JSRuntime *rt, bool enabled);
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JS_FRIEND_API(jsbytecode*)
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ProfilingGetPC(JSRuntime *rt, JSScript *script, void *ip);
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} // namespace js
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#endif /* js_ProfilingStack_h */
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