Extend sys::getHostCPUFeatures to work on AArch64 platforms

[bsmith]

Summary

This change extends the existing ARM version of the function sys::getHostCPUFeatures to correctly recognize the AArch64 kernel features. Unfortunately there is no testcase for this patch since I can't see how to reasonably write one (nor is this function used anywhere in the codebase), the result of any testcase for this would differ depending on what platform it was run on.

[t.p.northover]

Hi Bradley,

Just one comment here:

lib/Support/Host.cpp

719–723

Could we have a local enum for this?

[bsmith]

Update patch to use a local enum in place of hardcoded bit values.

[t.p.northover]

Thanks Bradley. This looks fine now.

Tim.

lib/Support/Host.cpp

StringRef sys::getHostCPUName() {
   return "generic";
 }
 #else
 StringRef sys::getHostCPUName() {
   return "generic";
 }
 #endif
 
-#if defined(__linux__) && defined(__arm__)
+#if defined(__linux__) && (defined(__arm__) || defined(__aarch64__))
 bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
   std::string Err;
   DataStreamer *DS = getDataFileStreamer("/proc/cpuinfo", &Err);
   if (!DS) {
     DEBUG(dbgs() << "Unable to open /proc/cpuinfo: " << Err << "\n");
     return false;
   }
 
bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
 
   // Look for the CPU features.
   for (unsigned I = 0, E = Lines.size(); I != E; ++I)
     if (Lines[I].startswith("Features")) {
       Lines[I].split(CPUFeatures, " ");
       break;
     }
 
+#if defined(__aarch64__)
+  // Keep track of which crypto features we have seen
+  // 0001 = aes
+  // 0010 = pmull
+  // 0100 = sha1
+  // 1000 = sha2
+  uint32_t crypto = 0;
+#endif
+
   for (unsigned I = 0, E = CPUFeatures.size(); I != E; ++I) {
     StringRef LLVMFeatureStr = StringSwitch<StringRef>(CPUFeatures[I])
+#if defined(__aarch64__)
+      .Case("asimd", "neon")
+      .Case("fp", "fp-armv8")
+      .Case("crc32", "crc")
+#else
       .Case("half", "fp16")
       .Case("neon", "neon")
       .Case("vfpv3", "vfp3")
       .Case("vfpv3d16", "d16")
       .Case("vfpv4", "vfp4")
       .Case("idiva", "hwdiv-arm")
       .Case("idivt", "hwdiv")
+#endif
       .Default("");
 
+#if defined(__aarch64__)
+    // We need to check crypto seperately since we need all of the crypto
+    // extensions to enable the subtarget feature
+    if (CPUFeatures[I] == "aes")
+      crypto |= 0x1;
+    else if (CPUFeatures[I] == "pmull")
+      crypto |= 0x2;
+    else if (CPUFeatures[I] == "sha1")
+      crypto |= 0x4;
+    else if (CPUFeatures[I] == "sha2")
+      crypto |= 0x8;
+#endif
+
     if (LLVMFeatureStr != "")
       Features.GetOrCreateValue(LLVMFeatureStr).setValue(true);
   }
 
+#if defined(__aarch64__)
+  // If we have all crypto bits we can add the feature
+  if (crypto == 0xf)
+    Features.GetOrCreateValue("crypto").setValue(true);
+#endif
+
   return true;
 }
 #else
 bool sys::getHostCPUFeatures(StringMap<bool> &Features){
   return false;
 }
 #endif