3 files changed, 51 insertions, 3 deletions
diff --git a/llvm/lib/Support/Host.cpp b/llvm/lib/Support/Host.cpp
index 12df08c6c0c..6a5d4d28a91 100644
--- a/llvm/lib/Support/Host.cpp
+++ b/llvm/lib/Support/Host.cpp
@@ -535,6 +535,48 @@ std::string sys::getHostCPUName() {
 
   return "generic";
 }
+#elif defined(__linux__) && defined(__s390x__)
+std::string sys::getHostCPUName() {
+  // STIDP is a privileged operation, so use /proc/cpuinfo instead.
+  // Note: We cannot mmap /proc/cpuinfo here and then process the resulting
+  // memory buffer because the 'file' has 0 size (it can be read from only
+  // as a stream).
+
+  std::string Err;
+  DataStreamer *DS = getDataFileStreamer("/proc/cpuinfo", &Err);
+  if (!DS) {
+    DEBUG(dbgs() << "Unable to open /proc/cpuinfo: " << Err << "\n");
+    return "generic";
+  }
+
+  // The "processor 0:" line comes after a fair amount of other information,
+  // including a cache breakdown, but this should be plenty.
+  char buffer[2048];
+  size_t CPUInfoSize = DS->GetBytes((unsigned char*) buffer, sizeof(buffer));
+  delete DS;
+
+  StringRef Str(buffer, CPUInfoSize);
+  SmallVector<StringRef, 32> Lines;
+  Str.split(Lines, "\n");
+  for (unsigned I = 0, E = Lines.size(); I != E; ++I) {
+    if (Lines[I].startswith("processor ")) {
+      size_t Pos = Lines[I].find("machine = ");
+      if (Pos != StringRef::npos) {
+        Pos += sizeof("machine = ") - 1;
+        unsigned int Id;
+        if (!Lines[I].drop_front(Pos).getAsInteger(10, Id)) {
+          if (Id >= 2827)
+            return "zEC12";
+          if (Id >= 2817)
+            return "z196";
+        }
+      }
+      break;
+    }
+  }
+  
+  return "generic";
+}
 #else
 std::string sys::getHostCPUName() {
   return "generic";
diff --git a/llvm/lib/Target/SystemZ/SystemZProcessors.td b/llvm/lib/Target/SystemZ/SystemZProcessors.td
index 00d4338af55..f241fb0c222 100644
--- a/llvm/lib/Target/SystemZ/SystemZProcessors.td
+++ b/llvm/lib/Target/SystemZ/SystemZProcessors.td
@@ -36,8 +36,9 @@ def FeatureFPExtension : SystemZFeature<
   "Assume that the floating-point extension facility is installed"
 >;
 
-def : Processor<"z10",   NoItineraries, []>;
-def : Processor<"z196",  NoItineraries,
+def : Processor<"generic", NoItineraries, []>;
+def : Processor<"z10", NoItineraries, []>;
+def : Processor<"z196", NoItineraries,
                 [FeatureDistinctOps, FeatureLoadStoreOnCond, FeatureHighWord,
                  FeatureFPExtension]>;
 def : Processor<"zEC12", NoItineraries,
diff --git a/llvm/lib/Target/SystemZ/SystemZSubtarget.cpp b/llvm/lib/Target/SystemZ/SystemZSubtarget.cpp
index b6a63923cf5..474192099f2 100644
--- a/llvm/lib/Target/SystemZ/SystemZSubtarget.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZSubtarget.cpp
@@ -9,6 +9,7 @@
 
 #include "SystemZSubtarget.h"
 #include "llvm/IR/GlobalValue.h"
+#include "llvm/Support/Host.h"
 #include "MCTargetDesc/SystemZMCTargetDesc.h"
 
 #define GET_SUBTARGETINFO_TARGET_DESC
@@ -25,7 +26,11 @@ SystemZSubtarget::SystemZSubtarget(const std::string &TT,
     TargetTriple(TT) {
   std::string CPUName = CPU;
   if (CPUName.empty())
-    CPUName = "z10";
+    CPUName = "generic";
+#if defined(__linux__) && defined(__s390x__)
+  if (CPUName == "generic")
+    CPUName = sys::getHostCPUName();
+#endif
 
   // Parse features string.
   ParseSubtargetFeatures(CPUName, FS);