[sanitizer] Reverting D34152

Summary:
This broke thread_local_quarantine_pthread_join.cc on some architectures, due
to the overhead of the stashed regions. Reverting while figuring out the best
way to deal with it.

Reviewers: alekseyshl

Reviewed By: alekseyshl

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D34213

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@305404 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 50 deletions

diff --git a/lib/sanitizer_common/sanitizer_allocator_primary32.h b/lib/sanitizer_common/sanitizer_allocator_primary32.h
index bfedbc0a7..e13510ba3 100644
--- a/lib/sanitizer_common/sanitizer_allocator_primary32.h
+++ b/lib/sanitizer_common/sanitizer_allocator_primary32.h
@@ -24,7 +24,7 @@ template<class SizeClassAllocator> struct SizeClassAllocator32LocalCache;
 // be returned by MmapOrDie().
 //
 // Region:
-//   a result of an allocation of kRegionSize bytes aligned on kRegionSize.
+//   a result of a single call to MmapAlignedOrDie(kRegionSize, kRegionSize).
 // Since the regions are aligned by kRegionSize, there are exactly
 // kNumPossibleRegions possible regions in the address space and so we keep
 // a ByteMap possible_regions to store the size classes of each Region.
@@ -106,7 +106,6 @@ class SizeClassAllocator32 {
   void Init(s32 release_to_os_interval_ms) {
     possible_regions.TestOnlyInit();
     internal_memset(size_class_info_array, 0, sizeof(size_class_info_array));
-    num_stashed_regions = 0;
   }
 
   s32 ReleaseToOSIntervalMs() const {
@@ -276,49 +275,15 @@ class SizeClassAllocator32 {
     return mem & ~(kRegionSize - 1);
   }
 
-  // Allocates a region of kRegionSize bytes, aligned on kRegionSize. If we get
-  // more than one region back (in the event the allocation is aligned on the
-  // first try), attempt to store the second region into a stash. If the stash
-  // is full, just unmap the superfluous memory.
-  uptr AllocateRegionSlow(AllocatorStats *stat) {
-    uptr map_size = kRegionSize;
-    uptr padding_chunk;
-    uptr region = reinterpret_cast<uptr>(
-        MmapAlignedOrDie(kRegionSize, kRegionSize, "SizeClassAllocator32",
-                         &padding_chunk));
-    if (padding_chunk) {
-      // We have an extra region, attempt to stash it.
-      CHECK_EQ(padding_chunk, region + kRegionSize);
-      bool trim_extra = true;
-      {
-        SpinMutexLock l(&regions_stash_mutex);
-        if (num_stashed_regions < kMaxStashedRegions) {
-          regions_stash[num_stashed_regions++] = padding_chunk;
-          map_size = 2 * kRegionSize;
-          trim_extra = false;
-        }
-      }
-      if (trim_extra)
-        UnmapOrDie((void*)padding_chunk, kRegionSize);
-    }
-    MapUnmapCallback().OnMap(region, map_size);
-    stat->Add(AllocatorStatMapped, map_size);
-    return region;
-  }
-
   uptr AllocateRegion(AllocatorStats *stat, uptr class_id) {
     CHECK_LT(class_id, kNumClasses);
-    uptr region = 0;
-    {
-      SpinMutexLock l(&regions_stash_mutex);
-      if (num_stashed_regions > 0)
-        region = regions_stash[--num_stashed_regions];
-    }
-    if (!region)
-      region = AllocateRegionSlow(stat);
-    CHECK(IsAligned(region, kRegionSize));
-    possible_regions.set(ComputeRegionId(region), static_cast<u8>(class_id));
-    return region;
+    uptr res = reinterpret_cast<uptr>(MmapAlignedOrDie(kRegionSize, kRegionSize,
+                                      "SizeClassAllocator32"));
+    MapUnmapCallback().OnMap(res, kRegionSize);
+    stat->Add(AllocatorStatMapped, kRegionSize);
+    CHECK_EQ(0U, (res & (kRegionSize - 1)));
+    possible_regions.set(ComputeRegionId(res), static_cast<u8>(class_id));
+    return res;
   }
 
   SizeClassInfo *GetSizeClassInfo(uptr class_id) {
@@ -351,13 +316,6 @@ class SizeClassAllocator32 {
     }
   }
 
-  // Unless several threads request regions simultaneously from different size
-  // classes, the stash rarely contains more than 1 entry.
-  static const uptr kMaxStashedRegions = 8;
-  SpinMutex regions_stash_mutex;
-  uptr num_stashed_regions;
-  uptr regions_stash[kMaxStashedRegions];
-
   ByteMap possible_regions;
   SizeClassInfo size_class_info_array[kNumClasses];
 };