vendor/compiler-rt/compiler-rt-trunk-r321017

1 files changed, 56 insertions, 23 deletions

diff --git a/lib/xray/xray_buffer_queue.cc b/lib/xray/xray_buffer_queue.cc
index 7ba755ac30692..a0018f6b0cba4 100644
--- a/lib/xray/xray_buffer_queue.cc
+++ b/lib/xray/xray_buffer_queue.cc
@@ -13,28 +13,34 @@
 //
 //===----------------------------------------------------------------------===//
 #include "xray_buffer_queue.h"
+#include "sanitizer_common/sanitizer_allocator_internal.h"
 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_libc.h"
 
-#include <cstdlib>
-#include <tuple>
-
 using namespace __xray;
 using namespace __sanitizer;
 
-BufferQueue::BufferQueue(std::size_t B, std::size_t N, bool &Success)
-    : BufferSize(B), Buffers(N), Mutex(), OwnedBuffers(), Finalizing{0} {
-  for (auto &T : Buffers) {
-    void *Tmp = malloc(BufferSize);
+BufferQueue::BufferQueue(size_t B, size_t N, bool &Success)
+    : BufferSize(B), Buffers(new BufferRep[N]()), BufferCount(N), Finalizing{0},
+      OwnedBuffers(new void *[N]()), Next(Buffers), First(Buffers),
+      LiveBuffers(0) {
+  for (size_t i = 0; i < N; ++i) {
+    auto &T = Buffers[i];
+    void *Tmp = InternalAlloc(BufferSize, nullptr, 64);
     if (Tmp == nullptr) {
       Success = false;
       return;
     }
-
-    auto &Buf = std::get<0>(T);
+    void *Extents = InternalAlloc(sizeof(BufferExtents), nullptr, 64);
+    if (Extents == nullptr) {
+      Success = false;
+      return;
+    }
+    auto &Buf = T.Buff;
     Buf.Buffer = Tmp;
     Buf.Size = B;
-    OwnedBuffers.emplace(Tmp);
+    Buf.Extents = reinterpret_cast<BufferExtents *>(Extents);
+    OwnedBuffers[i] = Tmp;
   }
   Success = true;
 }
@@ -42,27 +48,50 @@ BufferQueue::BufferQueue(std::size_t B, std::size_t N, bool &Success)
 BufferQueue::ErrorCode BufferQueue::getBuffer(Buffer &Buf) {
   if (__sanitizer::atomic_load(&Finalizing, __sanitizer::memory_order_acquire))
     return ErrorCode::QueueFinalizing;
-  __sanitizer::BlockingMutexLock Guard(&Mutex);
-  if (Buffers.empty())
+  __sanitizer::SpinMutexLock Guard(&Mutex);
+  if (LiveBuffers == BufferCount)
     return ErrorCode::NotEnoughMemory;
-  auto &T = Buffers.front();
-  auto &B = std::get<0>(T);
+
+  auto &T = *Next;
+  auto &B = T.Buff;
   Buf = B;
-  B.Buffer = nullptr;
-  B.Size = 0;
-  Buffers.pop_front();
+  T.Used = true;
+  ++LiveBuffers;
+
+  if (++Next == (Buffers + BufferCount))
+    Next = Buffers;
+
   return ErrorCode::Ok;
 }
 
 BufferQueue::ErrorCode BufferQueue::releaseBuffer(Buffer &Buf) {
-  if (OwnedBuffers.count(Buf.Buffer) == 0)
+  // Blitz through the buffers array to find the buffer.
+  bool Found = false;
+  for (auto I = OwnedBuffers, E = OwnedBuffers + BufferCount; I != E; ++I) {
+    if (*I == Buf.Buffer) {
+      Found = true;
+      break;
+    }
+  }
+  if (!Found)
     return ErrorCode::UnrecognizedBuffer;
-  __sanitizer::BlockingMutexLock Guard(&Mutex);
+
+  __sanitizer::SpinMutexLock Guard(&Mutex);
+
+  // This points to a semantic bug, we really ought to not be releasing more
+  // buffers than we actually get.
+  if (LiveBuffers == 0)
+    return ErrorCode::NotEnoughMemory;
 
   // Now that the buffer has been released, we mark it as "used".
-  Buffers.emplace(Buffers.end(), Buf, true /* used */);
+  First->Buff = Buf;
+  First->Used = true;
   Buf.Buffer = nullptr;
   Buf.Size = 0;
+  --LiveBuffers;
+  if (++First == (Buffers + BufferCount))
+    First = Buffers;
+
   return ErrorCode::Ok;
 }
 
@@ -74,8 +103,12 @@ BufferQueue::ErrorCode BufferQueue::finalize() {
 }
 
 BufferQueue::~BufferQueue() {
-  for (auto &T : Buffers) {
-    auto &Buf = std::get<0>(T);
-    free(Buf.Buffer);
+  for (auto I = Buffers, E = Buffers + BufferCount; I != E; ++I) {
+    auto &T = *I;
+    auto &Buf = T.Buff;
+    InternalFree(Buf.Buffer);
+    InternalFree(Buf.Extents);
   }
+  delete[] Buffers;
+  delete[] OwnedBuffers;
 }