/*
* Perform actions that are only safe when all threads are suspended. Currently
* we do:
* 1) Check if the code cache is full. If so reset it and restart populating it
* from scratch.
* 2) Patch predicted chaining cells by consuming recorded work orders.
*/
void dvmCompilerPerformSafePointChecks(void)
{
if (gDvmJit.codeCacheFull) {
resetCodeCache();
}
dvmCompilerPatchInlineCache();
}
void dvmCompilerUpdateGlobalState()
{
bool jitActive;
bool jitActivate;
bool needUnchain = false;
/*
* The tableLock might not be initialized yet by the compiler thread if
* debugger is attached from the very beginning of the VM launch. If
* pProfTableCopy is NULL, the lock is not initialized yet and we don't
* need to refresh anything either.
*/
if (gDvmJit.pProfTableCopy == NULL) {
return;
}
/*
* On the first enabling of method tracing, switch the compiler
* into a mode that includes trace support for invokes and returns.
* If there are any existing translations, flush them. NOTE: we
* can't blindly flush the translation cache because this code
* may be executed before the compiler thread has finished
* initialization.
*/
if ((gDvm.activeProfilers != 0) &&
!gDvmJit.methodTraceSupport) {
bool resetRequired;
/*
* compilerLock will prevent new compilations from being
* installed while we are working.
*/
dvmLockMutex(&gDvmJit.compilerLock);
gDvmJit.cacheVersion++; // invalidate compilations in flight
gDvmJit.methodTraceSupport = true;
resetRequired = (gDvmJit.numCompilations != 0);
dvmUnlockMutex(&gDvmJit.compilerLock);
if (resetRequired) {
dvmSuspendAllThreads(SUSPEND_FOR_CC_RESET);
resetCodeCache();
dvmResumeAllThreads(SUSPEND_FOR_CC_RESET);
}
}
dvmLockMutex(&gDvmJit.tableLock);
jitActive = gDvmJit.pProfTable != NULL;
jitActivate = !dvmDebuggerOrProfilerActive();
if (jitActivate && !jitActive) {
gDvmJit.pProfTable = gDvmJit.pProfTableCopy;
} else if (!jitActivate && jitActive) {
gDvmJit.pProfTable = NULL;
needUnchain = true;
}
dvmUnlockMutex(&gDvmJit.tableLock);
if (needUnchain)
dvmJitUnchainAll();
// Make sure all threads have current values
dvmJitUpdateThreadStateAll();
}
/**
* @brief 更新编译器全局状态
* @note 在"vm/Profile.cpp"中的updateActiveProfilers中被调用
*/
void dvmCompilerUpdateGlobalState()
{
bool jitActive;
bool jitActivate;
bool needUnchain = false;
/*
* The tableLock might not be initialized yet by the compiler thread if
* debugger is attached from the very beginning of the VM launch. If
* pProfTableCopy is NULL, the lock is not initialized yet and we don't
* need to refresh anything either.
*/
/*
* 如果在调试器附加到虚拟机启动器的非常早之前，编译器线程对tableLock
* 并没有初始化完成。这是我们不能更新任何状态。
*/
if (gDvmJit.pProfTableCopy == NULL) {
return;
}
/*
* On the first enabling of method tracing, switch the compiler
* into a mode that includes trace support for invokes and returns.
* If there are any existing translations, flush them. NOTE: we
* can't blindly flush the translation cache because this code
* may be executed before the compiler thread has finished
* initialization.
*/
/*
* 第一次启用函数tracing，转化编译器到保护支持invokes与returns
* 指令的trace格式。如果已经存在了一些编译代码则直接刷入他们到缓存中。
* NOTE：我们不能在编译器线程未初始化完成之前刷入代码
*/
/* activeProfilers 表明 开启profiler */
if ((gDvm.activeProfilers != 0) &&
!gDvmJit.methodTraceSupport) { /* 这里表明第一次启动tracing */
bool resetRequired;
/*
* compilerLock will prevent new compilations from being
* installed while we are working.
*/
dvmLockMutex(&gDvmJit.compilerLock);
/* 增加缓冲版本，无效编译 */
gDvmJit.cacheVersion++; // invalidate compilations in flight
gDvmJit.methodTraceSupport = true; /* 开启 */
resetRequired = (gDvmJit.numCompilations != 0); /* 检测是否重设代码缓冲区*/
dvmUnlockMutex(&gDvmJit.compilerLock);
if (resetRequired) {
dvmSuspendAllThreads(SUSPEND_FOR_CC_RESET);
resetCodeCache(); /* 重新更新代码缓冲区 */
dvmResumeAllThreads(SUSPEND_FOR_CC_RESET);
}
}
dvmLockMutex(&gDvmJit.tableLock);
/* 通过判断pProfTable表判断JIT是否被激活 */
jitActive = gDvmJit.pProfTable != NULL;
jitActivate = !dvmDebuggerOrProfilerActive(); /* 处于调试阶段或者profile开启 */
/* jitActivate为TRUE表明处于调试阶段 */
if (jitActivate && !jitActive) {
gDvmJit.pProfTable = gDvmJit.pProfTableCopy; /* 处于调试获取副本 */
} else if (!jitActivate && jitActive) { /* 处于正常运行 */
gDvmJit.pProfTable = NULL;
needUnchain = true;/* 需要解链操作 */
}
dvmUnlockMutex(&gDvmJit.tableLock);
if (needUnchain) /* 不再调试模式下为TRUE */
dvmJitUnchainAll();
// Make sure all threads have current values
/* 对所有线程设置JitTable表 */
dvmJitUpdateThreadStateAll();
}
