initial commit, 4.5 stable

thirdparty/embree/common/sys/barrier.h

@@ -0,0 +1,112 @@
+// Copyright 2009-2021 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include "intrinsics.h"
+#include "sysinfo.h"
+#include "atomic.h"
+
+namespace embree
+{
+  /*! system barrier using operating system */
+  class BarrierSys
+  {
+  public:
+
+    /*! construction / destruction */
+    BarrierSys (size_t N = 0);
+    ~BarrierSys ();
+
+  private:
+    /*! class in non-copyable */
+    BarrierSys (const BarrierSys& other) DELETED; // do not implement
+    BarrierSys& operator= (const BarrierSys& other) DELETED; // do not implement
+
+  public:
+    /*! initializes the barrier with some number of threads */
+    void init(size_t count);
+
+    /*! lets calling thread wait in barrier */
+    void wait();
+
+  private:
+    void* opaque;
+  };
+
+  /*! fast active barrier using atomic counter */
+  struct BarrierActive 
+  {
+  public:
+    BarrierActive () 
+      : cntr(0) {}
+    
+    void reset() {
+      cntr.store(0);
+    }
+
+    void wait (size_t numThreads) 
+    {
+      cntr++;
+      while (cntr.load() != numThreads) 
+        pause_cpu();
+    }
+
+  private:
+    std::atomic<size_t> cntr;
+  };
+
+  /*! fast active barrier that does not require initialization to some number of threads */
+  struct BarrierActiveAutoReset
+  {
+  public:
+    BarrierActiveAutoReset () 
+      : cntr0(0), cntr1(0) {}
+
+    void wait (size_t threadCount) 
+    {
+      cntr0.fetch_add(1);
+      while (cntr0 != threadCount) pause_cpu();
+      cntr1.fetch_add(1);
+      while (cntr1 != threadCount) pause_cpu();
+      cntr0.fetch_add(-1);
+      while (cntr0 != 0) pause_cpu();
+      cntr1.fetch_add(-1);
+      while (cntr1 != 0) pause_cpu();
+    }
+
+  private:
+    std::atomic<size_t> cntr0;
+    std::atomic<size_t> cntr1;
+  };
+
+  class LinearBarrierActive
+  {
+  public:
+
+    /*! construction and destruction */
+    LinearBarrierActive (size_t threadCount = 0);
+    ~LinearBarrierActive();
+    
+  private:
+    /*! class in non-copyable */
+    LinearBarrierActive (const LinearBarrierActive& other) DELETED; // do not implement
+    LinearBarrierActive& operator= (const LinearBarrierActive& other) DELETED; // do not implement
+
+  public:
+    /*! initializes the barrier with some number of threads */
+    void init(size_t threadCount);
+    
+    /*! thread with threadIndex waits in the barrier */
+    void wait (const size_t threadIndex);
+    
+  private:
+    volatile unsigned char* count0;
+    volatile unsigned char* count1; 
+    volatile unsigned int mode;
+    volatile unsigned int flag0;
+    volatile unsigned int flag1;
+    volatile size_t threadCount;
+  };
+}
+