Reland "Check for semaphore alignment on posix platforms. (patchset #1 id:1 of...

Reland "Check for semaphore alignment on posix platforms. (patchset #1 id:1 of https://codereview.chromium.org/1912923003/ )"

This patch also fixed three misaligned semaphores.

This reverts commit 80c73e2c.

BUG=chromium:605349
LOG=NO

Review URL: https://codereview.chromium.org/1917923002

Cr-Commit-Position: refs/heads/master@{#35773}

src/base/platform/semaphore.cc

@@ -74,6 +74,13 @@ bool Semaphore::WaitFor(const TimeDelta& rel_time) {
 #elif V8_OS_POSIX
 
 Semaphore::Semaphore(int count) {
+  // The sem_init() does not check for alignment of the native handle.
+  // Unaligned native handle can later cause a failure in semaphore signal.
+  // Check the alignment here to catch the failure earlier.
+  // Context: crbug.com/605349.
+  const uintptr_t kPointerAlignmentMask = sizeof(void*) - 1;
+  CHECK_EQ(
+      0, reinterpret_cast<uintptr_t>(&native_handle_) & kPointerAlignmentMask);
   DCHECK(count >= 0);
 #if V8_LIBC_GLIBC
   // sem_init in glibc prior to 2.1 does not zero out semaphores.

src/heap/mark-compact.cc

@@ -62,7 +62,6 @@ MarkCompactCollector::MarkCompactCollector(Heap* heap)
       embedder_heap_tracer_(nullptr),
       have_code_to_deoptimize_(false),
       compacting_(false),
-      pending_compaction_tasks_semaphore_(0),
       sweeper_(heap) {
 }
 

src/heap/mark-compact.h

@@ -461,8 +461,8 @@ class MarkCompactCollector {
     void PrepareToBeSweptPage(AllocationSpace space, Page* page);
 
     Heap* heap_;
-    base::Mutex mutex_;
     base::Semaphore pending_sweeper_tasks_semaphore_;
+    base::Mutex mutex_;
     SweptList swept_list_[kAllocationSpaces];
     SweepingList sweeping_list_[kAllocationSpaces];
     bool sweeping_in_progress_;
@@ -868,9 +868,6 @@ class MarkCompactCollector {
   // candidates.
   bool compacting_;
 
-  // Semaphore used to synchronize compaction tasks.
-  base::Semaphore pending_compaction_tasks_semaphore_;
-
   bool black_allocation_;
 
   Sweeper sweeper_;

src/libplatform/task-queue.h

@@ -33,8 +33,8 @@ class TaskQueue {
   void Terminate();
 
  private:
-  base::Mutex lock_;
   base::Semaphore process_queue_semaphore_;
+  base::Mutex lock_;
   std::queue<Task*> task_queue_;
   bool terminated_;