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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <sys/mman.h>
     18 #include <errno.h>
     19 #include <cutils/ashmem.h>
     20 
     21 #include "Dalvik.h"
     22 #include "interp/Jit.h"
     23 #include "CompilerInternals.h"
     24 #ifdef ARCH_IA32
     25 #include "codegen/x86/Translator.h"
     26 #include "codegen/x86/Lower.h"
     27 #endif
     28 
     29 extern "C" void dvmCompilerTemplateStart(void);
     30 extern "C" void dvmCompilerTemplateEnd(void);
     31 
     32 static inline bool workQueueLength(void)
     33 {
     34     return gDvmJit.compilerQueueLength;
     35 }
     36 
     37 static CompilerWorkOrder workDequeue(void)
     38 {
     39     assert(gDvmJit.compilerWorkQueue[gDvmJit.compilerWorkDequeueIndex].kind
     40            != kWorkOrderInvalid);
     41     CompilerWorkOrder work =
     42         gDvmJit.compilerWorkQueue[gDvmJit.compilerWorkDequeueIndex];
     43     gDvmJit.compilerWorkQueue[gDvmJit.compilerWorkDequeueIndex++].kind =
     44         kWorkOrderInvalid;
     45     if (gDvmJit.compilerWorkDequeueIndex == COMPILER_WORK_QUEUE_SIZE) {
     46         gDvmJit.compilerWorkDequeueIndex = 0;
     47     }
     48     gDvmJit.compilerQueueLength--;
     49     if (gDvmJit.compilerQueueLength == 0) {
     50         dvmSignalCond(&gDvmJit.compilerQueueEmpty);
     51     }
     52 
     53     /* Remember the high water mark of the queue length */
     54     if (gDvmJit.compilerQueueLength > gDvmJit.compilerMaxQueued)
     55         gDvmJit.compilerMaxQueued = gDvmJit.compilerQueueLength;
     56 
     57     return work;
     58 }
     59 
     60 /*
     61  * Enqueue a work order - retrying until successful.  If attempt to enqueue
     62  * is repeatedly unsuccessful, assume the JIT is in a bad state and force a
     63  * code cache reset.
     64  */
     65 #define ENQUEUE_MAX_RETRIES 20
     66 void dvmCompilerForceWorkEnqueue(const u2 *pc, WorkOrderKind kind, void* info)
     67 {
     68     bool success;
     69     int retries = 0;
     70     do {
     71         success = dvmCompilerWorkEnqueue(pc, kind, info);
     72         if (!success) {
     73             retries++;
     74             if (retries > ENQUEUE_MAX_RETRIES) {
     75                 ALOGE("JIT: compiler queue wedged - forcing reset");
     76                 gDvmJit.codeCacheFull = true;  // Force reset
     77                 success = true;  // Because we'll drop the order now anyway
     78             } else {
     79                 dvmLockMutex(&gDvmJit.compilerLock);
     80                 pthread_cond_wait(&gDvmJit.compilerQueueActivity,
     81                                   &gDvmJit.compilerLock);
     82                 dvmUnlockMutex(&gDvmJit.compilerLock);
     83 
     84             }
     85         }
     86     } while (!success);
     87 }
     88 
     89 /*
     90  * Attempt to enqueue a work order, returning true if successful.
     91  *
     92  * NOTE: Make sure that the caller frees the info pointer if the return value
     93  * is false.
     94  */
     95 bool dvmCompilerWorkEnqueue(const u2 *pc, WorkOrderKind kind, void* info)
     96 {
     97     int cc;
     98     int i;
     99     int numWork;
    100     bool result = true;
    101 
    102     dvmLockMutex(&gDvmJit.compilerLock);
    103 
    104     /*
    105      * Return if queue or code cache is full.
    106      */
    107     if (gDvmJit.compilerQueueLength == COMPILER_WORK_QUEUE_SIZE ||
    108         gDvmJit.codeCacheFull == true) {
    109         dvmUnlockMutex(&gDvmJit.compilerLock);
    110         return false;
    111     }
    112 
    113     for (numWork = gDvmJit.compilerQueueLength,
    114            i = gDvmJit.compilerWorkDequeueIndex;
    115          numWork > 0;
    116          numWork--) {
    117         /* Already enqueued */
    118         if (gDvmJit.compilerWorkQueue[i++].pc == pc) {
    119             dvmUnlockMutex(&gDvmJit.compilerLock);
    120             return true;
    121         }
    122         /* Wrap around */
    123         if (i == COMPILER_WORK_QUEUE_SIZE)
    124             i = 0;
    125     }
    126 
    127     CompilerWorkOrder *newOrder =
    128         &gDvmJit.compilerWorkQueue[gDvmJit.compilerWorkEnqueueIndex];
    129     newOrder->pc = pc;
    130     newOrder->kind = kind;
    131     newOrder->info = info;
    132     newOrder->result.methodCompilationAborted = NULL;
    133     newOrder->result.codeAddress = NULL;
    134     newOrder->result.discardResult =
    135         (kind == kWorkOrderTraceDebug) ? true : false;
    136     newOrder->result.cacheVersion = gDvmJit.cacheVersion;
    137     newOrder->result.requestingThread = dvmThreadSelf();
    138 
    139     gDvmJit.compilerWorkEnqueueIndex++;
    140     if (gDvmJit.compilerWorkEnqueueIndex == COMPILER_WORK_QUEUE_SIZE)
    141         gDvmJit.compilerWorkEnqueueIndex = 0;
    142     gDvmJit.compilerQueueLength++;
    143     cc = pthread_cond_signal(&gDvmJit.compilerQueueActivity);
    144     assert(cc == 0);
    145 
    146     dvmUnlockMutex(&gDvmJit.compilerLock);
    147     return result;
    148 }
    149 
    150 /* Block until the queue length is 0, or there is a pending suspend request */
    151 void dvmCompilerDrainQueue(void)
    152 {
    153     Thread *self = dvmThreadSelf();
    154 
    155     dvmLockMutex(&gDvmJit.compilerLock);
    156     while (workQueueLength() != 0 && !gDvmJit.haltCompilerThread &&
    157            self->suspendCount == 0) {
    158         /*
    159          * Use timed wait here - more than one mutator threads may be blocked
    160          * but the compiler thread will only signal once when the queue is
    161          * emptied. Furthermore, the compiler thread may have been shutdown
    162          * so the blocked thread may never get the wakeup signal.
    163          */
    164         dvmRelativeCondWait(&gDvmJit.compilerQueueEmpty, &gDvmJit.compilerLock,                             1000, 0);
    165     }
    166     dvmUnlockMutex(&gDvmJit.compilerLock);
    167 }
    168 
    169 bool dvmCompilerSetupCodeCache(void)
    170 {
    171     int fd;
    172 
    173     /* Allocate the code cache */
    174     fd = ashmem_create_region("dalvik-jit-code-cache", gDvmJit.codeCacheSize);
    175     if (fd < 0) {
    176         ALOGE("Could not create %u-byte ashmem region for the JIT code cache",
    177              gDvmJit.codeCacheSize);
    178         return false;
    179     }
    180     gDvmJit.codeCache = mmap(NULL, gDvmJit.codeCacheSize,
    181                              PROT_READ | PROT_WRITE | PROT_EXEC,
    182                              MAP_PRIVATE , fd, 0);
    183     close(fd);
    184     if (gDvmJit.codeCache == MAP_FAILED) {
    185         ALOGE("Failed to mmap the JIT code cache of size %d: %s", gDvmJit.codeCacheSize, strerror(errno));
    186         return false;
    187     }
    188 
    189     gDvmJit.pageSizeMask = getpagesize() - 1;
    190 
    191     /* This can be found through "dalvik-jit-code-cache" in /proc/<pid>/maps */
    192     // ALOGD("Code cache starts at %p", gDvmJit.codeCache);
    193 
    194 #ifndef ARCH_IA32
    195     /* Copy the template code into the beginning of the code cache */
    196     int templateSize = (intptr_t) dvmCompilerTemplateEnd -
    197                        (intptr_t) dvmCompilerTemplateStart;
    198     memcpy((void *) gDvmJit.codeCache,
    199            (void *) dvmCompilerTemplateStart,
    200            templateSize);
    201 
    202     /*
    203      * Work around a CPU bug by keeping the 32-bit ARM handler code in its own
    204      * page.
    205      */
    206     if (dvmCompilerInstructionSet() == DALVIK_JIT_THUMB2) {
    207         templateSize = (templateSize + 4095) & ~4095;
    208     }
    209 
    210     gDvmJit.templateSize = templateSize;
    211     gDvmJit.codeCacheByteUsed = templateSize;
    212 
    213     /* Only flush the part in the code cache that is being used now */
    214     dvmCompilerCacheFlush((intptr_t) gDvmJit.codeCache,
    215                           (intptr_t) gDvmJit.codeCache + templateSize, 0);
    216 #else
    217     gDvmJit.codeCacheByteUsed = 0;
    218     stream = (char*)gDvmJit.codeCache + gDvmJit.codeCacheByteUsed;
    219     ALOGV("codeCache = %p stream = %p before initJIT", gDvmJit.codeCache, stream);
    220     streamStart = stream;
    221     initJIT(NULL, NULL);
    222     gDvmJit.templateSize = (stream - streamStart);
    223     gDvmJit.codeCacheByteUsed = (stream - streamStart);
    224     ALOGV("stream = %p after initJIT", stream);
    225 #endif
    226 
    227     int result = mprotect(gDvmJit.codeCache, gDvmJit.codeCacheSize,
    228                           PROTECT_CODE_CACHE_ATTRS);
    229 
    230     if (result == -1) {
    231         ALOGE("Failed to remove the write permission for the code cache");
    232         dvmAbort();
    233     }
    234 
    235     return true;
    236 }
    237 
    238 static void crawlDalvikStack(Thread *thread, bool print)
    239 {
    240     void *fp = thread->interpSave.curFrame;
    241     StackSaveArea* saveArea = NULL;
    242     int stackLevel = 0;
    243 
    244     if (print) {
    245         ALOGD("Crawling tid %d (%s / %p %s)", thread->systemTid,
    246              dvmGetThreadStatusStr(thread->status),
    247              thread->inJitCodeCache,
    248              thread->inJitCodeCache ? "jit" : "interp");
    249     }
    250     /* Crawl the Dalvik stack frames to clear the returnAddr field */
    251     while (fp != NULL) {
    252         saveArea = SAVEAREA_FROM_FP(fp);
    253 
    254         if (print) {
    255             if (dvmIsBreakFrame((u4*)fp)) {
    256                 ALOGD("  #%d: break frame (%p)",
    257                      stackLevel, saveArea->returnAddr);
    258             }
    259             else {
    260                 ALOGD("  #%d: %s.%s%s (%p)",
    261                      stackLevel,
    262                      saveArea->method->clazz->descriptor,
    263                      saveArea->method->name,
    264                      dvmIsNativeMethod(saveArea->method) ?
    265                          " (native)" : "",
    266                      saveArea->returnAddr);
    267             }
    268         }
    269         stackLevel++;
    270         saveArea->returnAddr = NULL;
    271         assert(fp != saveArea->prevFrame);
    272         fp = saveArea->prevFrame;
    273     }
    274     /* Make sure the stack is fully unwound to the bottom */
    275     assert(saveArea == NULL ||
    276            (u1 *) (saveArea+1) == thread->interpStackStart);
    277 }
    278 
    279 static void resetCodeCache(void)
    280 {
    281     Thread* thread;
    282     u8 startTime = dvmGetRelativeTimeUsec();
    283     int inJit = 0;
    284     int byteUsed = gDvmJit.codeCacheByteUsed;
    285 
    286     /* If any thread is found stuck in the JIT state, don't reset the cache  */
    287     dvmLockThreadList(NULL);
    288     for (thread = gDvm.threadList; thread != NULL; thread = thread->next) {
    289         /*
    290          * Crawl the stack to wipe out the returnAddr field so that
    291          * 1) the soon-to-be-deleted code in the JIT cache won't be used
    292          * 2) or the thread stuck in the JIT land will soon return
    293          *    to the interpreter land
    294          */
    295         crawlDalvikStack(thread, false);
    296         if (thread->inJitCodeCache) {
    297             inJit++;
    298         }
    299         /* Cancel any ongoing trace selection */
    300         dvmDisableSubMode(thread, kSubModeJitTraceBuild);
    301     }
    302     dvmUnlockThreadList();
    303 
    304     if (inJit) {
    305         ALOGD("JIT code cache reset delayed (%d bytes %d/%d)",
    306              gDvmJit.codeCacheByteUsed, gDvmJit.numCodeCacheReset,
    307              ++gDvmJit.numCodeCacheResetDelayed);
    308         return;
    309     }
    310 
    311     /* Lock the mutex to clean up the work queue */
    312     dvmLockMutex(&gDvmJit.compilerLock);
    313 
    314     /* Update the translation cache version */
    315     gDvmJit.cacheVersion++;
    316 
    317     /* Drain the work queue to free the work orders */
    318     while (workQueueLength()) {
    319         CompilerWorkOrder work = workDequeue();
    320         free(work.info);
    321     }
    322 
    323     /* Reset the JitEntry table contents to the initial unpopulated state */
    324     dvmJitResetTable();
    325 
    326     UNPROTECT_CODE_CACHE(gDvmJit.codeCache, gDvmJit.codeCacheByteUsed);
    327     /*
    328      * Wipe out the code cache content to force immediate crashes if
    329      * stale JIT'ed code is invoked.
    330      */
    331     dvmCompilerCacheClear((char *) gDvmJit.codeCache + gDvmJit.templateSize,
    332                           gDvmJit.codeCacheByteUsed - gDvmJit.templateSize);
    333 
    334     dvmCompilerCacheFlush((intptr_t) gDvmJit.codeCache,
    335                           (intptr_t) gDvmJit.codeCache +
    336                           gDvmJit.codeCacheByteUsed, 0);
    337 
    338     PROTECT_CODE_CACHE(gDvmJit.codeCache, gDvmJit.codeCacheByteUsed);
    339 
    340     /* Reset the current mark of used bytes to the end of template code */
    341     gDvmJit.codeCacheByteUsed = gDvmJit.templateSize;
    342     gDvmJit.numCompilations = 0;
    343 
    344     /* Reset the work queue */
    345     memset(gDvmJit.compilerWorkQueue, 0,
    346            sizeof(CompilerWorkOrder) * COMPILER_WORK_QUEUE_SIZE);
    347     gDvmJit.compilerWorkEnqueueIndex = gDvmJit.compilerWorkDequeueIndex = 0;
    348     gDvmJit.compilerQueueLength = 0;
    349 
    350     /* Reset the IC patch work queue */
    351     dvmLockMutex(&gDvmJit.compilerICPatchLock);
    352     gDvmJit.compilerICPatchIndex = 0;
    353     dvmUnlockMutex(&gDvmJit.compilerICPatchLock);
    354 
    355     /*
    356      * Reset the inflight compilation address (can only be done in safe points
    357      * or by the compiler thread when its thread state is RUNNING).
    358      */
    359     gDvmJit.inflightBaseAddr = NULL;
    360 
    361     /* All clear now */
    362     gDvmJit.codeCacheFull = false;
    363 
    364     dvmUnlockMutex(&gDvmJit.compilerLock);
    365 
    366     ALOGD("JIT code cache reset in %lld ms (%d bytes %d/%d)",
    367          (dvmGetRelativeTimeUsec() - startTime) / 1000,
    368          byteUsed, ++gDvmJit.numCodeCacheReset,
    369          gDvmJit.numCodeCacheResetDelayed);
    370 }
    371 
    372 /*
    373  * Perform actions that are only safe when all threads are suspended. Currently
    374  * we do:
    375  * 1) Check if the code cache is full. If so reset it and restart populating it
    376  *    from scratch.
    377  * 2) Patch predicted chaining cells by consuming recorded work orders.
    378  */
    379 void dvmCompilerPerformSafePointChecks(void)
    380 {
    381     if (gDvmJit.codeCacheFull) {
    382         resetCodeCache();
    383     }
    384     dvmCompilerPatchInlineCache();
    385 }
    386 
    387 static bool compilerThreadStartup(void)
    388 {
    389     JitEntry *pJitTable = NULL;
    390     unsigned char *pJitProfTable = NULL;
    391     JitTraceProfCounters *pJitTraceProfCounters = NULL;
    392     unsigned int i;
    393 
    394     if (!dvmCompilerArchInit())
    395         goto fail;
    396 
    397     /*
    398      * Setup the code cache if we have not inherited a valid code cache
    399      * from the zygote.
    400      */
    401     if (gDvmJit.codeCache == NULL) {
    402         if (!dvmCompilerSetupCodeCache())
    403             goto fail;
    404     }
    405 
    406     /* Allocate the initial arena block */
    407     if (dvmCompilerHeapInit() == false) {
    408         goto fail;
    409     }
    410 
    411     /* Cache the thread pointer */
    412     gDvmJit.compilerThread = dvmThreadSelf();
    413 
    414     dvmLockMutex(&gDvmJit.compilerLock);
    415 
    416     /* Track method-level compilation statistics */
    417     gDvmJit.methodStatsTable =  dvmHashTableCreate(32, NULL);
    418 
    419 #if defined(WITH_JIT_TUNING)
    420     gDvm.verboseShutdown = true;
    421 #endif
    422 
    423     dvmUnlockMutex(&gDvmJit.compilerLock);
    424 
    425     /* Set up the JitTable */
    426 
    427     /* Power of 2? */
    428     assert(gDvmJit.jitTableSize &&
    429            !(gDvmJit.jitTableSize & (gDvmJit.jitTableSize - 1)));
    430 
    431     dvmInitMutex(&gDvmJit.tableLock);
    432     dvmLockMutex(&gDvmJit.tableLock);
    433     pJitTable = (JitEntry*)
    434                 calloc(gDvmJit.jitTableSize, sizeof(*pJitTable));
    435     if (!pJitTable) {
    436         ALOGE("jit table allocation failed");
    437         dvmUnlockMutex(&gDvmJit.tableLock);
    438         goto fail;
    439     }
    440     /*
    441      * NOTE: the profile table must only be allocated once, globally.
    442      * Profiling is turned on and off by nulling out gDvm.pJitProfTable
    443      * and then restoring its original value.  However, this action
    444      * is not synchronized for speed so threads may continue to hold
    445      * and update the profile table after profiling has been turned
    446      * off by null'ng the global pointer.  Be aware.
    447      */
    448     pJitProfTable = (unsigned char *)malloc(JIT_PROF_SIZE);
    449     if (!pJitProfTable) {
    450         ALOGE("jit prof table allocation failed");
    451         free(pJitTable);
    452         dvmUnlockMutex(&gDvmJit.tableLock);
    453         goto fail;
    454     }
    455     memset(pJitProfTable, gDvmJit.threshold, JIT_PROF_SIZE);
    456     for (i=0; i < gDvmJit.jitTableSize; i++) {
    457        pJitTable[i].u.info.chain = gDvmJit.jitTableSize;
    458     }
    459     /* Is chain field wide enough for termination pattern? */
    460     assert(pJitTable[0].u.info.chain == gDvmJit.jitTableSize);
    461 
    462     /* Allocate the trace profiling structure */
    463     pJitTraceProfCounters = (JitTraceProfCounters*)
    464                              calloc(1, sizeof(*pJitTraceProfCounters));
    465     if (!pJitTraceProfCounters) {
    466         ALOGE("jit trace prof counters allocation failed");
    467         free(pJitTable);
    468         free(pJitProfTable);
    469         dvmUnlockMutex(&gDvmJit.tableLock);
    470         goto fail;
    471     }
    472 
    473     gDvmJit.pJitEntryTable = pJitTable;
    474     gDvmJit.jitTableMask = gDvmJit.jitTableSize - 1;
    475     gDvmJit.jitTableEntriesUsed = 0;
    476     gDvmJit.compilerHighWater =
    477         COMPILER_WORK_QUEUE_SIZE - (COMPILER_WORK_QUEUE_SIZE/4);
    478     /*
    479      * If the VM is launched with wait-on-the-debugger, we will need to hide
    480      * the profile table here
    481      */
    482     gDvmJit.pProfTable = dvmDebuggerOrProfilerActive() ? NULL : pJitProfTable;
    483     gDvmJit.pProfTableCopy = pJitProfTable;
    484     gDvmJit.pJitTraceProfCounters = pJitTraceProfCounters;
    485     dvmJitUpdateThreadStateAll();
    486     dvmUnlockMutex(&gDvmJit.tableLock);
    487 
    488     /* Signal running threads to refresh their cached pJitTable pointers */
    489     dvmSuspendAllThreads(SUSPEND_FOR_REFRESH);
    490     dvmResumeAllThreads(SUSPEND_FOR_REFRESH);
    491 
    492     /* Enable signature breakpoints by customizing the following code */
    493 #if defined(SIGNATURE_BREAKPOINT)
    494     /*
    495      * Suppose one sees the following native crash in the bugreport:
    496      * I/DEBUG   ( 1638): Build fingerprint: 'unknown'
    497      * I/DEBUG   ( 1638): pid: 2468, tid: 2507  >>> com.google.android.gallery3d
    498      * I/DEBUG   ( 1638): signal 11 (SIGSEGV), fault addr 00001400
    499      * I/DEBUG   ( 1638):  r0 44ea7190  r1 44e4f7b8  r2 44ebc710  r3 00000000
    500      * I/DEBUG   ( 1638):  r4 00000a00  r5 41862dec  r6 4710dc10  r7 00000280
    501      * I/DEBUG   ( 1638):  r8 ad010f40  r9 46a37a12  10 001116b0  fp 42a78208
    502      * I/DEBUG   ( 1638):  ip 00000090  sp 4710dbc8  lr ad060e67  pc 46b90682
    503      * cpsr 00000030
    504      * I/DEBUG   ( 1638):  #00  pc 46b90682 /dev/ashmem/dalvik-jit-code-cache
    505      * I/DEBUG   ( 1638):  #01  pc 00060e62  /system/lib/libdvm.so
    506      *
    507      * I/DEBUG   ( 1638): code around pc:
    508      * I/DEBUG   ( 1638): 46b90660 6888d01c 34091dcc d2174287 4a186b68
    509      * I/DEBUG   ( 1638): 46b90670 d0052800 68006809 28004790 6b68d00e
    510      * I/DEBUG   ( 1638): 46b90680 512000bc 37016eaf 6ea866af 6f696028
    511      * I/DEBUG   ( 1638): 46b90690 682a6069 429a686b e003da08 6df1480b
    512      * I/DEBUG   ( 1638): 46b906a0 1c2d4788 47806d70 46a378fa 47806d70
    513      *
    514      * Clearly it is a JIT bug. To find out which translation contains the
    515      * offending code, the content of the memory dump around the faulting PC
    516      * can be pasted into the gDvmJit.signatureBreakpoint[] array and next time
    517      * when a similar compilation is being created, the JIT compiler replay the
    518      * trace in the verbose mode and one can investigate the instruction
    519      * sequence in details.
    520      *
    521      * The length of the signature may need additional experiments to determine.
    522      * The rule of thumb is don't include PC-relative instructions in the
    523      * signature since it may be affected by the alignment of the compiled code.
    524      * However, a signature that's too short might increase the chance of false
    525      * positive matches. Using gdbjithelper to disassembly the memory content
    526      * first might be a good companion approach.
    527      *
    528      * For example, if the next 4 words starting from 46b90680 is pasted into
    529      * the data structure:
    530      */
    531 
    532     gDvmJit.signatureBreakpointSize = 4;
    533     gDvmJit.signatureBreakpoint =
    534         malloc(sizeof(u4) * gDvmJit.signatureBreakpointSize);
    535     gDvmJit.signatureBreakpoint[0] = 0x512000bc;
    536     gDvmJit.signatureBreakpoint[1] = 0x37016eaf;
    537     gDvmJit.signatureBreakpoint[2] = 0x6ea866af;
    538     gDvmJit.signatureBreakpoint[3] = 0x6f696028;
    539 
    540     /*
    541      * The following log will be printed when a match is found in subsequent
    542      * testings:
    543      *
    544      * D/dalvikvm( 2468): Signature match starting from offset 0x34 (4 words)
    545      * D/dalvikvm( 2468): --------
    546      * D/dalvikvm( 2468): Compiler: Building trace for computeVisibleItems,
    547      * offset 0x1f7
    548      * D/dalvikvm( 2468): 0x46a37a12: 0x0090 add-int v42, v5, v26
    549      * D/dalvikvm( 2468): 0x46a37a16: 0x004d aput-object v13, v14, v42
    550      * D/dalvikvm( 2468): 0x46a37a1a: 0x0028 goto, (#0), (#0)
    551      * D/dalvikvm( 2468): 0x46a3794e: 0x00d8 add-int/lit8 v26, v26, (#1)
    552      * D/dalvikvm( 2468): 0x46a37952: 0x0028 goto, (#0), (#0)
    553      * D/dalvikvm( 2468): 0x46a378ee: 0x0002 move/from16 v0, v26, (#0)
    554      * D/dalvikvm( 2468): 0x46a378f2: 0x0002 move/from16 v1, v29, (#0)
    555      * D/dalvikvm( 2468): 0x46a378f6: 0x0035 if-ge v0, v1, (#10)
    556      * D/dalvikvm( 2468): TRACEINFO (554): 0x46a37624
    557      * Lcom/cooliris/media/GridLayer;computeVisibleItems 0x1f7 14 of 934, 8
    558      * blocks
    559      *     :
    560      *     :
    561      * D/dalvikvm( 2468): 0x20 (0020): ldr     r0, [r5, #52]
    562      * D/dalvikvm( 2468): 0x22 (0022): ldr     r2, [pc, #96]
    563      * D/dalvikvm( 2468): 0x24 (0024): cmp     r0, #0
    564      * D/dalvikvm( 2468): 0x26 (0026): beq     0x00000034
    565      * D/dalvikvm( 2468): 0x28 (0028): ldr     r1, [r1, #0]
    566      * D/dalvikvm( 2468): 0x2a (002a): ldr     r0, [r0, #0]
    567      * D/dalvikvm( 2468): 0x2c (002c): blx     r2
    568      * D/dalvikvm( 2468): 0x2e (002e): cmp     r0, #0
    569      * D/dalvikvm( 2468): 0x30 (0030): beq     0x00000050
    570      * D/dalvikvm( 2468): 0x32 (0032): ldr     r0, [r5, #52]
    571      * D/dalvikvm( 2468): 0x34 (0034): lsls    r4, r7, #2
    572      * D/dalvikvm( 2468): 0x36 (0036): str     r0, [r4, r4]
    573      * D/dalvikvm( 2468): -------- dalvik offset: 0x01fb @ goto, (#0), (#0)
    574      * D/dalvikvm( 2468): L0x0195:
    575      * D/dalvikvm( 2468): -------- dalvik offset: 0x0195 @ add-int/lit8 v26,
    576      * v26, (#1)
    577      * D/dalvikvm( 2468): 0x38 (0038): ldr     r7, [r5, #104]
    578      * D/dalvikvm( 2468): 0x3a (003a): adds    r7, r7, #1
    579      * D/dalvikvm( 2468): 0x3c (003c): str     r7, [r5, #104]
    580      * D/dalvikvm( 2468): -------- dalvik offset: 0x0197 @ goto, (#0), (#0)
    581      * D/dalvikvm( 2468): L0x0165:
    582      * D/dalvikvm( 2468): -------- dalvik offset: 0x0165 @ move/from16 v0, v26,
    583      * (#0)
    584      * D/dalvikvm( 2468): 0x3e (003e): ldr     r0, [r5, #104]
    585      * D/dalvikvm( 2468): 0x40 (0040): str     r0, [r5, #0]
    586      *
    587      * The "str r0, [r4, r4]" is indeed the culprit of the native crash.
    588      */
    589 #endif
    590 
    591     return true;
    592 
    593 fail:
    594     return false;
    595 
    596 }
    597 
    598 static void *compilerThreadStart(void *arg)
    599 {
    600     dvmChangeStatus(NULL, THREAD_VMWAIT);
    601 
    602     /*
    603      * If we're not running stand-alone, wait a little before
    604      * recieving translation requests on the assumption that process start
    605      * up code isn't worth compiling.  We'll resume when the framework
    606      * signals us that the first screen draw has happened, or the timer
    607      * below expires (to catch daemons).
    608      *
    609      * There is a theoretical race between the callback to
    610      * VMRuntime.startJitCompiation and when the compiler thread reaches this
    611      * point. In case the callback happens earlier, in order not to permanently
    612      * hold the system_server (which is not using the timed wait) in
    613      * interpreter-only mode we bypass the delay here.
    614      */
    615     if (gDvmJit.runningInAndroidFramework &&
    616         !gDvmJit.alreadyEnabledViaFramework) {
    617         /*
    618          * If the current VM instance is the system server (detected by having
    619          * 0 in gDvm.systemServerPid), we will use the indefinite wait on the
    620          * conditional variable to determine whether to start the JIT or not.
    621          * If the system server detects that the whole system is booted in
    622          * safe mode, the conditional variable will never be signaled and the
    623          * system server will remain in the interpreter-only mode. All
    624          * subsequent apps will be started with the --enable-safemode flag
    625          * explicitly appended.
    626          */
    627         if (gDvm.systemServerPid == 0) {
    628             dvmLockMutex(&gDvmJit.compilerLock);
    629             pthread_cond_wait(&gDvmJit.compilerQueueActivity,
    630                               &gDvmJit.compilerLock);
    631             dvmUnlockMutex(&gDvmJit.compilerLock);
    632             ALOGD("JIT started for system_server");
    633         } else {
    634             dvmLockMutex(&gDvmJit.compilerLock);
    635             /*
    636              * TUNING: experiment with the delay & perhaps make it
    637              * target-specific
    638              */
    639             dvmRelativeCondWait(&gDvmJit.compilerQueueActivity,
    640                                  &gDvmJit.compilerLock, 3000, 0);
    641             dvmUnlockMutex(&gDvmJit.compilerLock);
    642         }
    643         if (gDvmJit.haltCompilerThread) {
    644              return NULL;
    645         }
    646     }
    647 
    648     compilerThreadStartup();
    649 
    650     dvmLockMutex(&gDvmJit.compilerLock);
    651     /*
    652      * Since the compiler thread will not touch any objects on the heap once
    653      * being created, we just fake its state as VMWAIT so that it can be a
    654      * bit late when there is suspend request pending.
    655      */
    656     while (!gDvmJit.haltCompilerThread) {
    657         if (workQueueLength() == 0) {
    658             int cc;
    659             cc = pthread_cond_signal(&gDvmJit.compilerQueueEmpty);
    660             assert(cc == 0);
    661             pthread_cond_wait(&gDvmJit.compilerQueueActivity,
    662                               &gDvmJit.compilerLock);
    663             continue;
    664         } else {
    665             do {
    666                 CompilerWorkOrder work = workDequeue();
    667                 dvmUnlockMutex(&gDvmJit.compilerLock);
    668 #if defined(WITH_JIT_TUNING)
    669                 /*
    670                  * This is live across setjmp().  Mark it volatile to suppress
    671                  * a gcc warning.  We should not need this since it is assigned
    672                  * only once but gcc is not smart enough.
    673                  */
    674                 volatile u8 startTime = dvmGetRelativeTimeUsec();
    675 #endif
    676                 /*
    677                  * Check whether there is a suspend request on me.  This
    678                  * is necessary to allow a clean shutdown.
    679                  *
    680                  * However, in the blocking stress testing mode, let the
    681                  * compiler thread continue doing compilations to unblock
    682                  * other requesting threads. This may occasionally cause
    683                  * shutdown from proceeding cleanly in the standalone invocation
    684                  * of the vm but this should be acceptable.
    685                  */
    686                 if (!gDvmJit.blockingMode)
    687                     dvmCheckSuspendPending(dvmThreadSelf());
    688                 /* Is JitTable filling up? */
    689                 if (gDvmJit.jitTableEntriesUsed >
    690                     (gDvmJit.jitTableSize - gDvmJit.jitTableSize/4)) {
    691                     bool resizeFail =
    692                         dvmJitResizeJitTable(gDvmJit.jitTableSize * 2);
    693                     /*
    694                      * If the jit table is full, consider it's time to reset
    695                      * the code cache too.
    696                      */
    697                     gDvmJit.codeCacheFull |= resizeFail;
    698                 }
    699                 if (gDvmJit.haltCompilerThread) {
    700                     ALOGD("Compiler shutdown in progress - discarding request");
    701                 } else if (!gDvmJit.codeCacheFull) {
    702                     jmp_buf jmpBuf;
    703                     work.bailPtr = &jmpBuf;
    704                     bool aborted = setjmp(jmpBuf);
    705                     if (!aborted) {
    706                         bool codeCompiled = dvmCompilerDoWork(&work);
    707                         /*
    708                          * Make sure we are still operating with the
    709                          * same translation cache version.  See
    710                          * Issue 4271784 for details.
    711                          */
    712                         dvmLockMutex(&gDvmJit.compilerLock);
    713                         if ((work.result.cacheVersion ==
    714                              gDvmJit.cacheVersion) &&
    715                              codeCompiled &&
    716                              !work.result.discardResult &&
    717                              work.result.codeAddress) {
    718                             dvmJitSetCodeAddr(work.pc, work.result.codeAddress,
    719                                               work.result.instructionSet,
    720                                               false, /* not method entry */
    721                                               work.result.profileCodeSize);
    722                         }
    723                         dvmUnlockMutex(&gDvmJit.compilerLock);
    724                     }
    725                     dvmCompilerArenaReset();
    726                 }
    727                 free(work.info);
    728 #if defined(WITH_JIT_TUNING)
    729                 gDvmJit.jitTime += dvmGetRelativeTimeUsec() - startTime;
    730 #endif
    731                 dvmLockMutex(&gDvmJit.compilerLock);
    732             } while (workQueueLength() != 0);
    733         }
    734     }
    735     pthread_cond_signal(&gDvmJit.compilerQueueEmpty);
    736     dvmUnlockMutex(&gDvmJit.compilerLock);
    737 
    738     /*
    739      * As part of detaching the thread we need to call into Java code to update
    740      * the ThreadGroup, and we should not be in VMWAIT state while executing
    741      * interpreted code.
    742      */
    743     dvmChangeStatus(NULL, THREAD_RUNNING);
    744 
    745     if (gDvm.verboseShutdown)
    746         ALOGD("Compiler thread shutting down");
    747     return NULL;
    748 }
    749 
    750 bool dvmCompilerStartup(void)
    751 {
    752 
    753     dvmInitMutex(&gDvmJit.compilerLock);
    754     dvmInitMutex(&gDvmJit.compilerICPatchLock);
    755     dvmInitMutex(&gDvmJit.codeCacheProtectionLock);
    756     dvmLockMutex(&gDvmJit.compilerLock);
    757     pthread_cond_init(&gDvmJit.compilerQueueActivity, NULL);
    758     pthread_cond_init(&gDvmJit.compilerQueueEmpty, NULL);
    759 
    760     /* Reset the work queue */
    761     gDvmJit.compilerWorkEnqueueIndex = gDvmJit.compilerWorkDequeueIndex = 0;
    762     gDvmJit.compilerQueueLength = 0;
    763     dvmUnlockMutex(&gDvmJit.compilerLock);
    764 
    765     /*
    766      * Defer rest of initialization until we're sure JIT'ng makes sense. Launch
    767      * the compiler thread, which will do the real initialization if and
    768      * when it is signalled to do so.
    769      */
    770     return dvmCreateInternalThread(&gDvmJit.compilerHandle, "Compiler",
    771                                    compilerThreadStart, NULL);
    772 }
    773 
    774 void dvmCompilerShutdown(void)
    775 {
    776     void *threadReturn;
    777 
    778     /* Disable new translation requests */
    779     gDvmJit.pProfTable = NULL;
    780     gDvmJit.pProfTableCopy = NULL;
    781     dvmJitUpdateThreadStateAll();
    782 
    783     if (gDvm.verboseShutdown ||
    784             gDvmJit.profileMode == kTraceProfilingContinuous) {
    785         dvmCompilerDumpStats();
    786         while (gDvmJit.compilerQueueLength)
    787           sleep(5);
    788     }
    789 
    790     if (gDvmJit.compilerHandle) {
    791 
    792         gDvmJit.haltCompilerThread = true;
    793 
    794         dvmLockMutex(&gDvmJit.compilerLock);
    795         pthread_cond_signal(&gDvmJit.compilerQueueActivity);
    796         dvmUnlockMutex(&gDvmJit.compilerLock);
    797 
    798         if (pthread_join(gDvmJit.compilerHandle, &threadReturn) != 0)
    799             ALOGW("Compiler thread join failed");
    800         else if (gDvm.verboseShutdown)
    801             ALOGD("Compiler thread has shut down");
    802     }
    803 
    804     /* Break loops within the translation cache */
    805     dvmJitUnchainAll();
    806 
    807     /*
    808      * NOTE: our current implementatation doesn't allow for the compiler
    809      * thread to be restarted after it exits here.  We aren't freeing
    810      * the JitTable or the ProfTable because threads which still may be
    811      * running or in the process of shutting down may hold references to
    812      * them.
    813      */
    814 }
    815 
    816 void dvmCompilerUpdateGlobalState()
    817 {
    818     bool jitActive;
    819     bool jitActivate;
    820     bool needUnchain = false;
    821 
    822     /*
    823      * The tableLock might not be initialized yet by the compiler thread if
    824      * debugger is attached from the very beginning of the VM launch. If
    825      * pProfTableCopy is NULL, the lock is not initialized yet and we don't
    826      * need to refresh anything either.
    827      */
    828     if (gDvmJit.pProfTableCopy == NULL) {
    829         return;
    830     }
    831 
    832     /*
    833      * On the first enabling of method tracing, switch the compiler
    834      * into a mode that includes trace support for invokes and returns.
    835      * If there are any existing translations, flush them.  NOTE:  we
    836      * can't blindly flush the translation cache because this code
    837      * may be executed before the compiler thread has finished
    838      * initialization.
    839      */
    840     if ((gDvm.activeProfilers != 0) &&
    841         !gDvmJit.methodTraceSupport) {
    842         bool resetRequired;
    843         /*
    844          * compilerLock will prevent new compilations from being
    845          * installed while we are working.
    846          */
    847         dvmLockMutex(&gDvmJit.compilerLock);
    848         gDvmJit.cacheVersion++; // invalidate compilations in flight
    849         gDvmJit.methodTraceSupport = true;
    850         resetRequired = (gDvmJit.numCompilations != 0);
    851         dvmUnlockMutex(&gDvmJit.compilerLock);
    852         if (resetRequired) {
    853             dvmSuspendAllThreads(SUSPEND_FOR_CC_RESET);
    854             resetCodeCache();
    855             dvmResumeAllThreads(SUSPEND_FOR_CC_RESET);
    856         }
    857     }
    858 
    859     dvmLockMutex(&gDvmJit.tableLock);
    860     jitActive = gDvmJit.pProfTable != NULL;
    861     jitActivate = !dvmDebuggerOrProfilerActive();
    862 
    863     if (jitActivate && !jitActive) {
    864         gDvmJit.pProfTable = gDvmJit.pProfTableCopy;
    865     } else if (!jitActivate && jitActive) {
    866         gDvmJit.pProfTable = NULL;
    867         needUnchain = true;
    868     }
    869     dvmUnlockMutex(&gDvmJit.tableLock);
    870     if (needUnchain)
    871         dvmJitUnchainAll();
    872     // Make sure all threads have current values
    873     dvmJitUpdateThreadStateAll();
    874 }
    875