Add Macro for CSSC Feature (llvm#143148)

Add a new __ARM_FEATURE_CSSC macro that can be utilized during the
preprocessing stage.

__ARM_FEATURE_CSSC is defined to 1 if there is hardware support for
CSSC.

Implements the ACLE change:
ARM-software/acle#394

Author: MartinWehking

clang/lib/Basic/Targets/AArch64.cpp

@@ -625,6 +625,9 @@ void AArch64TargetInfo::getTargetDefines(const LangOptions &Opts,
   if (HasCRC)
     Builder.defineMacro("__ARM_FEATURE_CRC32", "1");
 
+  if (HasCSSC)
+    Builder.defineMacro("__ARM_FEATURE_CSSC", "1");
+
   if (HasRCPC3)
     Builder.defineMacro("__ARM_FEATURE_RCPC", "3");
   else if (HasRCPC)
@@ -874,6 +877,7 @@ bool AArch64TargetInfo::hasFeature(StringRef Feature) const {
       .Case("rdm", HasRDM)
       .Case("lse", HasLSE)
       .Case("crc", HasCRC)
+      .Case("cssc", HasCSSC)
       .Case("sha2", HasSHA2)
       .Case("sha3", HasSHA3)
       .Cases("aes", "pmull", HasAES)
@@ -1249,6 +1253,8 @@ bool AArch64TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
       HasPAuthLR = true;
       HasPAuth = true;
     }
+    if (Feature == "+cssc")
+      HasCSSC = true;
   }
 
   // Check features that are manually disabled by command line options.

clang/lib/Basic/Targets/AArch64.h

@@ -66,6 +66,7 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
 
   unsigned FPU = FPUMode;
   bool HasCRC = false;
+  bool HasCSSC = false;
   bool HasAES = false;
   bool HasSHA2 = false;
   bool HasSHA3 = false;

clang/test/Preprocessor/aarch64-target-features.c

@@ -744,7 +744,10 @@
 // CHECK-SMEB16B16: __ARM_FEATURE_SME2 1
 // CHECK-SMEB16B16: __ARM_FEATURE_SME_B16B16 1
 // CHECK-SMEB16B16: __ARM_FEATURE_SVE_B16B16 1
-//
+
+// RUN: %clang --target=aarch64 -march=armv9-a+cssc -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-CSSC %s
+// CHECK-CSSC: __ARM_FEATURE_CSSC 1
+
 //  RUN: %clang --target=aarch64 -march=armv9-a+fp8 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FP8 %s
 // CHECK-FP8: __ARM_FEATURE_FP8 1