[llvm] bca1b8e - [SystemZ/ZOS] Implement computeHostNumPhysicalCores

[Kai Nacke via llvm-commits]

Author: Kai Nacke
Date: 2020-08-12T08:31:33-04:00
New Revision: bca1b8ed994336690db4775e67953aad533b0e31

URL: https://github.com/llvm/llvm-project/commit/bca1b8ed994336690db4775e67953aad533b0e31
DIFF: https://github.com/llvm/llvm-project/commit/bca1b8ed994336690db4775e67953aad533b0e31.diff

LOG: [SystemZ/ZOS] Implement computeHostNumPhysicalCores

On z/OS, the information is stored in the Common System Data Area
(CSD). It is the number of CPs allocated to the current LPAR.

Reviewers: aganea, hubert.reinterpertcast, MaskRay

Reviewed By: hubert.reinterpertcast

Differential Revision: https://reviews.llvm.org/D85531

Added: 
    

Modified: 
    llvm/lib/Support/Host.cpp
    llvm/unittests/Support/Host.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Support/Host.cpp b/llvm/lib/Support/Host.cpp
index 890b1178cbd0..bc06a7858f5b 100644
--- a/llvm/lib/Support/Host.cpp
+++ b/llvm/lib/Support/Host.cpp
@@ -1311,6 +1311,28 @@ int computeHostNumPhysicalCores() {
   }
   return count;
 }
+#elif defined(__MVS__)
+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();

diff  --git a/llvm/unittests/Support/Host.cpp b/llvm/unittests/Support/Host.cpp
index 41c7227dd94e..8029bb5830fc 100644
--- a/llvm/unittests/Support/Host.cpp
+++ b/llvm/unittests/Support/Host.cpp
@@ -36,13 +36,12 @@ class HostTest : public testing::Test {
 protected:
   bool isSupportedArchAndOS() {
     // Initially this is only testing detection of the number of
-    // physical cores, which is currently only supported/tested for
-    // x86_64 Linux and Darwin.
+    // physical cores, which is currently only supported/tested on
+    // some systems.
     return (Host.isOSWindows() && llvm_is_multithreaded()) ||
-           (Host.isX86() &&
-            (Host.isOSDarwin() || Host.getOS() == Triple::Linux)) ||
-           (Host.getOS() == Triple::Linux &&
-            (Host.isPPC64() || Host.isSystemZ()));
+           (Host.isX86() && (Host.isOSDarwin() || Host.isOSLinux())) ||
+           (Host.isPPC64() && Host.isOSLinux()) ||
+           (Host.isSystemZ() && (Host.isOSLinux() || Host.isOSzOS()));
   }
 
   HostTest() : Host(Triple::normalize(sys::getProcessTriple())) {}