Revert "[Support] Move getHostNumPhysicalCores to Threading.h"

This reverts commit 5577207d6d3e0642ea047a8dfbfcf3ad372a7f25.

This breaks building LLVM on recent macOS. Error messages below:

llvm/lib/Support/Threading.cpp:190:3: error: use of undeclared
identifier 'sysctlbyname'
  sysctlbyname("hw.physicalcpu", &count, &len, NULL, 0);
    ^

llvm/lib/Support/Threading.cpp:193:13: error: use of undeclared
identifier 'CTL_HW'
    nm[0] = CTL_HW;
            ^

llvm/lib/Support/Threading.cpp:194:13: error: use of undeclared identifier 'HW_AVAILCPU'
    nm[1] = HW_AVAILCPU;
            ^

llvm/lib/Support/Threading.cpp:195:5: error: use of undeclared identifier 'sysctl'
    sysctl(nm, 2, &count, &len, NULL, 0);
    ^

1 files changed, 3 insertions, 129 deletions

diff --git a/llvm/lib/Support/Threading.cpp b/llvm/lib/Support/Threading.cpp
index 6c2ff11..bd954fd 100644
--- a/llvm/lib/Support/Threading.cpp
+++ b/llvm/lib/Support/Threading.cpp
@@ -13,12 +13,8 @@
 
 #include "llvm/Support/Threading.h"
 #include "llvm/ADT/Optional.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringRef.h"
 #include "llvm/Config/config.h"
-#include "llvm/Config/llvm-config.h"
-#include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Host.h"
 
 #include <cassert>
 #include <errno.h>
@@ -54,8 +50,8 @@ unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
 static int computeHostNumHardwareThreads();
 
 unsigned llvm::ThreadPoolStrategy::compute_thread_count() const {
-  int MaxThreadCount =
-      UseHyperThreads ? computeHostNumHardwareThreads() : get_physical_cores();
+  int MaxThreadCount = UseHyperThreads ? computeHostNumHardwareThreads()
+                                       : sys::getHostNumPhysicalCores();
   if (MaxThreadCount <= 0)
     MaxThreadCount = 1;
   if (ThreadsRequested == 0)
@@ -110,125 +106,3 @@ llvm::get_threadpool_strategy(StringRef Num, ThreadPoolStrategy Default) {
   S.ThreadsRequested = V;
   return S;
 }
-
-#if defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
-// On Linux, the number of physical cores can be computed from /proc/cpuinfo,
-// using the number of unique physical/core id pairs. The following
-// implementation reads the /proc/cpuinfo format on an x86_64 system.
-static int computeHostNumPhysicalCores() {
-  // Enabled represents the number of physical id/core id pairs with at least
-  // one processor id enabled by the CPU affinity mask.
-  cpu_set_t Affinity, Enabled;
-  if (sched_getaffinity(0, sizeof(Affinity), &Affinity) != 0)
-    return -1;
-  CPU_ZERO(&Enabled);
-
-  // Read /proc/cpuinfo as a stream (until EOF reached). It cannot be
-  // mmapped because it appears to have 0 size.
-  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> Text =
-      llvm::MemoryBuffer::getFileAsStream("/proc/cpuinfo");
-  if (std::error_code EC = Text.getError()) {
-    llvm::errs() << "Can't read "
-                 << "/proc/cpuinfo: " << EC.message() << "\n";
-    return -1;
-  }
-  SmallVector<StringRef, 8> strs;
-  (*Text)->getBuffer().split(strs, "\n", /*MaxSplit=*/-1,
-                             /*KeepEmpty=*/false);
-  int CurProcessor = -1;
-  int CurPhysicalId = -1;
-  int CurSiblings = -1;
-  int CurCoreId = -1;
-  for (StringRef Line : strs) {
-    std::pair<StringRef, StringRef> Data = Line.split(':');
-    auto Name = Data.first.trim();
-    auto Val = Data.second.trim();
-    // These fields are available if the kernel is configured with CONFIG_SMP.
-    if (Name == "processor")
-      Val.getAsInteger(10, CurProcessor);
-    else if (Name == "physical id")
-      Val.getAsInteger(10, CurPhysicalId);
-    else if (Name == "siblings")
-      Val.getAsInteger(10, CurSiblings);
-    else if (Name == "core id") {
-      Val.getAsInteger(10, CurCoreId);
-      // The processor id corresponds to an index into cpu_set_t.
-      if (CPU_ISSET(CurProcessor, &Affinity))
-        CPU_SET(CurPhysicalId * CurSiblings + CurCoreId, &Enabled);
-    }
-  }
-  return CPU_COUNT(&Enabled);
-}
-#elif defined(__linux__) && defined(__s390x__)
-static int computeHostNumPhysicalCores() {
-  return sysconf(_SC_NPROCESSORS_ONLN);
-}
-#elif defined(__linux__) && !defined(__ANDROID__)
-static int computeHostNumPhysicalCores() {
-  cpu_set_t Affinity;
-  if (sched_getaffinity(0, sizeof(Affinity), &Affinity) == 0)
-    return CPU_COUNT(&Affinity);
-
-  // The call to sched_getaffinity() may have failed because the Affinity
-  // mask is too small for the number of CPU's on the system (i.e. the
-  // system has more than 1024 CPUs). Allocate a mask large enough for
-  // twice as many CPUs.
-  cpu_set_t *DynAffinity;
-  DynAffinity = CPU_ALLOC(2048);
-  if (sched_getaffinity(0, CPU_ALLOC_SIZE(2048), DynAffinity) == 0) {
-    int NumCPUs = CPU_COUNT(DynAffinity);
-    CPU_FREE(DynAffinity);
-    return NumCPUs;
-  }
-  return -1;
-}
-#elif defined(__APPLE__)
-// Gets the number of *physical cores* on the machine.
-static int computeHostNumPhysicalCores() {
-  uint32_t count;
-  size_t len = sizeof(count);
-  sysctlbyname("hw.physicalcpu", &count, &len, NULL, 0);
-  if (count < 1) {
-    int nm[2];
-    nm[0] = CTL_HW;
-    nm[1] = HW_AVAILCPU;
-    sysctl(nm, 2, &count, &len, NULL, 0);
-    if (count < 1)
-      return -1;
-  }
-  return count;
-}
-#elif defined(__MVS__)
-static int computeHostNumPhysicalCores() {
-  enum {
-    // Byte offset of the pointer to the Communications Vector Table (CVT) in
-    // the Prefixed Save Area (PSA). The table entry is a 31-bit pointer and
-    // will be zero-extended to uintptr_t.
-    FLCCVT = 16,
-    // Byte offset of the pointer to the Common System Data Area (CSD) in the
-    // CVT. The table entry is a 31-bit pointer and will be zero-extended to
-    // uintptr_t.
-    CVTCSD = 660,
-    // Byte offset to the number of live CPs in the LPAR, stored as a signed
-    // 32-bit value in the table.
-    CSD_NUMBER_ONLINE_STANDARD_CPS = 264,
-  };
-  char *PSA = 0;
-  char *CVT = reinterpret_cast<char *>(
-      static_cast<uintptr_t>(reinterpret_cast<unsigned int &>(PSA[FLCCVT])));
-  char *CSD = reinterpret_cast<char *>(
-      static_cast<uintptr_t>(reinterpret_cast<unsigned int &>(CVT[CVTCSD])));
-  return reinterpret_cast<int &>(CSD[CSD_NUMBER_ONLINE_STANDARD_CPS]);
-}
-#elif defined(_WIN32) && LLVM_ENABLE_THREADS != 0
-// Defined in llvm/lib/Support/Windows/Threading.inc
-int computeHostNumPhysicalCores();
-#else
-// On other systems, return -1 to indicate unknown.
-static int computeHostNumPhysicalCores() { return -1; }
-#endif
-
-int llvm::get_physical_cores() {
-  static int NumCores = computeHostNumPhysicalCores();
-  return NumCores;
-}