[AArch64] Add command-line options for ARMv8.2-A

[olista01]

Summary

This adds new values for the -march option (armv8.2a and armv8.2-a,
which are aliases of each other), and new suffixes for the -march and
-mcpu options (+fp16 and +nofp16), to allow targeting the ARMv8.2-A
architecture and it's optional half-precision floating-point extension.

[t.p.northover]

This looks good, too.

Tim.

lib/Driver/Tools.cpp

                              .Case("simd", "+neon")
                              .Case("crc", "+crc")
                              .Case("crypto", "+crypto")
+                             .Case("fp16", "+fullfp16")
                              .Case("nofp", "-fp-armv8")
                              .Case("nosimd", "-neon")
                              .Case("nocrc", "-crc")
                              .Case("nocrypto", "-crypto")
+                             .Case("nofp16", "-fullfp16")
                              .Default(nullptr);
     if (result)
       Features.push_back(result);

     // ok, no additional features.
   } else if (Split.first == "armv8.1-a" || Split.first == "armv8.1a") {
     Features.push_back("+v8.1a");
+  } else if (Split.first == "armv8.2-a" || Split.first == "armv8.2a" ) {
+    Features.push_back("+v8.2a");
   } else {
     return false;
   }

test/Driver/aarch64-cpus.c

 // RUN: %clang -target aarch64 -mbig-endian -march=armv8.1-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV81A-BE %s
 // RUN: %clang -target aarch64_be -mbig-endian -march=armv8.1a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV81A-BE %s
 // RUN: %clang -target aarch64_be -mbig-endian -march=armv8.1-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV81A-BE %s
+
+// RUN: %clang -target aarch64 -march=armv8.2a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV82A %s
+// RUN: %clang -target aarch64 -march=armv8.2-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV82A %s
+// RUN: %clang -target aarch64 -mlittle-endian -march=armv8.2a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV82A %s
+// RUN: %clang -target aarch64 -mlittle-endian -march=armv8.2-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV82A %s
+// RUN: %clang -target aarch64_be -mlittle-endian -march=armv8.2a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV82A %s
+// RUN: %clang -target aarch64_be -mlittle-endian -march=armv8.2-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV82A %s
+// GENERICV82A: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic" "-target-feature" "+neon" "-target-feature" "+v8.2a"
+
+// RUN: %clang -target aarch64 -march=armv8.2-a+fp16 -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV82A-FP16 %s
+// GENERICV82A-FP16: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic" "-target-feature" "+neon" "-target-feature" "+v8.2a" "-target-feature" "+fullfp16"
+
 // ================== Check whether -march accepts mixed-case values.
 // RUN: %clang -target aarch64_be -march=ARMV8.1A -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV81A-BE %s
 // RUN: %clang -target aarch64_be -march=ARMV8.1-A -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV81A-BE %s