[AIX][llvm][support] Implement getHostCPUName

We implement getHostCPUName() for AIX via systemcfg interfaces since access to the processor version register is a privileged operation. We return a value based on the  current processor implementation mode.

This fixes the cpu detection used by clang for `-mcpu=native`.

Reviewed By: hubert.reinterpretcast

Differential Revision: https://reviews.llvm.org/D95966

lib/Support/Host.cpp

@@ -43,6 +43,9 @@
 #include <mach/mach_host.h>
 #include <mach/machine.h>
 #endif
+#ifdef _AIX
+#include <sys/systemcfg.h>
+#endif
 
 #define DEBUG_TYPE "host-detection"
 
@@ -1217,6 +1220,38 @@ StringRef sys::getHostCPUName() {
 
   return "generic";
 }
+#elif defined(_AIX)
+StringRef sys::getHostCPUName() {
+  switch (_system_configuration.implementation) {
+  case POWER_4:
+    if (_system_configuration.version == PV_4_3)
+      return "970";
+    return "pwr4";
+  case POWER_5:
+    if (_system_configuration.version == PV_5)
+      return "pwr5";
+    return "pwr5x";
+  case POWER_6:
+    if (_system_configuration.version == PV_6_Compat)
+      return "pwr6";
+    return "pwr6x";
+  case POWER_7:
+    return "pwr7";
+  case POWER_8:
+    return "pwr8";
+  case POWER_9:
+    return "pwr9";
+// TODO: simplify this once the macro is available in all OS levels.
+#ifdef POWER_10
+  case POWER_10:
+#else
+  case 0x40000:
+#endif
+    return "pwr10";
+  default:
+    return "generic";
+  }
+}
 #else
 StringRef sys::getHostCPUName() { return "generic"; }
 #endif

unittests/Support/Host.cpp

@@ -431,4 +431,33 @@ TEST_F(HostTest, AIXVersionDetect) {
   ASSERT_EQ(std::tie(SystemMajor, SystemMinor),
             std::tie(TargetMajor, TargetMinor));
 }
+
+TEST_F(HostTest, AIXHostCPUDetect) {
+  // Return a value based on the current processor implementation mode.
+  const char *ExePath = "/usr/sbin/getsystype";
+  StringRef argv[] = {ExePath, "-i"};
+  std::unique_ptr<char[]> Buffer;
+  off_t Size;
+  ASSERT_EQ(runAndGetCommandOutput(ExePath, argv, Buffer, Size), true);
+  StringRef CPU(Buffer.get(), Size);
+  StringRef MCPU = StringSwitch<const char *>(CPU)
+                       .Case("POWER 4\n", "pwr4")
+                       .Case("POWER 5\n", "pwr5")
+                       .Case("POWER 6\n", "pwr6")
+                       .Case("POWER 7\n", "pwr7")
+                       .Case("POWER 8\n", "pwr8")
+                       .Case("POWER 9\n", "pwr9")
+                       .Case("POWER 10\n", "pwr10")
+                       .Default("unknown");
+
+  StringRef HostCPU = sys::getHostCPUName();
+
+  // Just do the comparison on the base implementation mode.
+  if (HostCPU == "970")
+    HostCPU = StringRef("pwr4");
+  else
+    HostCPU = HostCPU.rtrim('x');
+
+  EXPECT_EQ(HostCPU, MCPU);
+}
 #endif