4 files changed, 38 insertions, 0 deletions
diff --git a/llvm/include/llvm/Support/Threading.h b/llvm/include/llvm/Support/Threading.h
index 09b96dfb4c1..7e4a2896b71 100644
--- a/llvm/include/llvm/Support/Threading.h
+++ b/llvm/include/llvm/Support/Threading.h
@@ -115,6 +115,10 @@ namespace llvm {
     TsanHappensAfter(&flag);
 #endif
   }
+
+  /// Get the amount of currency based on physical cores, if available for the
+  /// host system, otherwise falls back to thread::hardware_concurrency().
+  unsigned hardware_physical_concurrency();
 }
 
 #endif
diff --git a/llvm/lib/Support/Threading.cpp b/llvm/lib/Support/Threading.cpp
index e8f5622d0e5..415c63f245d 100644
--- a/llvm/lib/Support/Threading.cpp
+++ b/llvm/lib/Support/Threading.cpp
@@ -15,6 +15,7 @@
 #include "llvm/Support/Threading.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Atomic.h"
+#include "llvm/Support/Host.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/thread.h"
 #include <cassert>
@@ -116,3 +117,10 @@ void llvm::llvm_execute_on_thread(void (*Fn)(void*), void *UserData,
 }
 
 #endif
+
+unsigned llvm::hardware_physical_concurrency() {
+  int NumPhysical = sys::getHostNumPhysicalCores();
+  if (NumPhysical == -1)
+    return thread::hardware_concurrency();
+  return NumPhysical;
+}
diff --git a/llvm/unittests/Support/CMakeLists.txt b/llvm/unittests/Support/CMakeLists.txt
index 9aef7210b1f..6ae2aed59b6 100644
--- a/llvm/unittests/Support/CMakeLists.txt
+++ b/llvm/unittests/Support/CMakeLists.txt
@@ -40,6 +40,7 @@ add_llvm_unittest(SupportTests
   StringPool.cpp
   SwapByteOrderTest.cpp
   TargetParserTest.cpp
+  Threading.cpp
   ThreadLocalTest.cpp
   ThreadPool.cpp
   TimerTest.cpp
diff --git a/llvm/unittests/Support/Threading.cpp b/llvm/unittests/Support/Threading.cpp
new file mode 100644
index 00000000000..30a3c741b35
--- /dev/null
+++ b/llvm/unittests/Support/Threading.cpp
@@ -0,0 +1,25 @@
+//===- unittests/Threading.cpp - Thread tests -----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Threading.h"
+#include "llvm/Support/thread.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(Threading, PhysicalConcurrency) {
+  auto Num = hardware_physical_concurrency();
+  // Since Num is unsigned this will also catch us trying to
+  // return -1.
+  ASSERT_LE(Num, thread::hardware_concurrency());
+}
+
+} // end anon namespace