Add ras/noras flag to enable/disable RAS in clang

[rogfer01]

Summary

RAS extensions are part of ARMv8.2.

This patch enables +ras +noras to AArch64 in clang.

[rogfer01]

Update test from mrasext to mras

[t.p.northover]

Looks pretty straightforward, go for it.

Tim.

[rogfer01]

I think this has become obsolete as of

http://llvm.org/viewvc/llvm-project?view=revision&revision=270688

[rogfer01]

Well, seems that Renato reverted the changes, so this still holds.

lib/Driver/Tools.cpp

static bool DecodeAArch64Features(const Driver &D, StringRef text,
   for (StringRef Feature : Split) {
     const char *result = llvm::StringSwitch<const char *>(Feature)
                              .Case("fp", "+fp-armv8")
                              .Case("simd", "+neon")
                              .Case("crc", "+crc")
                              .Case("crypto", "+crypto")
                              .Case("fp16", "+fullfp16")
                              .Case("profile", "+spe")
+                             .Case("ras", "+ras")
                              .Case("nofp", "-fp-armv8")
                              .Case("nosimd", "-neon")
                              .Case("nocrc", "-crc")
                              .Case("nocrypto", "-crypto")
                              .Case("nofp16", "-fullfp16")
                              .Case("noprofile", "-spe")
+                             .Case("noras", "-ras")
                              .Default(nullptr);
     if (result)
       Features.push_back(result);
     else if (Feature == "neon" || Feature == "noneon")
       D.Diag(diag::err_drv_no_neon_modifier);
     else
       return false;
   }

test/Driver/aarch64-ras.c

+// RUN: %clang -target aarch64-none-none-eabi -march=armv8a+ras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-RAS %s
+// RUN: %clang -target aarch64-none-none-eabi -mcpu=generic+ras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-RAS %s
+// CHECK-RAS: "-target-feature" "+ras"
+
+// RUN: %clang -target aarch64-none-none-eabi -march=armv8a+noras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-NORAS %s
+// RUN: %clang -target aarch64-none-none-eabi -mcpu=generic+noras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-NORAS %s
+// CHECK-NORAS: "-target-feature" "-ras"

test/Driver/arm-ras.c

+// RUN: %clang -target arm-none-none-eabi -march=armv8a+ras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-RAS %s
+// RUN: %clang -target arm-none-none-eabi -mcpu=generic+ras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-RAS %s
+// CHECK-RAS: "-target-feature" "+rasext"
+
+// RUN: %clang -target arm-none-none-eabi -march=armv8a+noras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-NORAS %s
+// RUN: %clang -target arm-none-none-eabi -mcpu=generic+noras -### -c %s 2>&1 | FileCheck --check-prefix=CHECK-NORAS %s
+// CHECK-NORAS: "-target-feature" "-rasext"