[AArch64] Add FEAT_FPAC to Neoverse V2 (#133054)

This feature is implemented in the Neoverse V2 core, but wasn't specified
in the CPU definition.

Author: sjoerdmeijer

clang/test/Driver/aarch64-mcpu-native.c

@@ -22,6 +22,7 @@
 // CHECK-FEAT-NV2:    FEAT_FHM                                               Enable FP16 FML instructions
 // CHECK-FEAT-NV2:    FEAT_FP                                                Enable Armv8.0-A Floating Point Extensions
 // CHECK-FEAT-NV2:    FEAT_FP16                                              Enable half-precision floating-point data processing
+// CHECK-FEAT-NV2:    FEAT_FPAC                                              Enable Armv8.3-A Pointer Authentication Faulting enhancement
 // CHECK-FEAT-NV2:    FEAT_FRINTTS                                           Enable FRInt[32|64][Z|X] instructions that round a floating-point number to an integer (in FP format) forcing it to fit into a 32- or 64-bit int
 // CHECK-FEAT-NV2:    FEAT_FlagM                                             Enable Armv8.4-A Flag Manipulation instructions
 // CHECK-FEAT-NV2:    FEAT_FlagM2                                            Enable alternative NZCV format for floating point comparisons

clang/test/Driver/print-enabled-extensions/aarch64-grace.c

@@ -21,6 +21,7 @@
 // CHECK-NEXT:     FEAT_FHM                                               Enable FP16 FML instructions
 // CHECK-NEXT:     FEAT_FP                                                Enable Armv8.0-A Floating Point Extensions
 // CHECK-NEXT:     FEAT_FP16                                              Enable half-precision floating-point data processing
+// CHECK-NEXT:     FEAT_FPAC                                              Enable Armv8.3-A Pointer Authentication Faulting enhancement
 // CHECK-NEXT:     FEAT_FRINTTS                                           Enable FRInt[32|64][Z|X] instructions that round a floating-point number to an integer (in FP format) forcing it to fit into a 32- or 64-bit int
 // CHECK-NEXT:     FEAT_FlagM                                             Enable Armv8.4-A Flag Manipulation instructions
 // CHECK-NEXT:     FEAT_FlagM2                                            Enable alternative NZCV format for floating point comparisons
@@ -59,4 +60,4 @@
 // CHECK-NEXT:     FEAT_TRBE                                              Enable Trace Buffer Extension
 // CHECK-NEXT:     FEAT_TRF                                               Enable Armv8.4-A Trace extension
 // CHECK-NEXT:     FEAT_UAO                                               Enable Armv8.2-A UAO PState
-// CHECK-NEXT:     FEAT_VHE                                               Enable Armv8.1-A Virtual Host extension
+// CHECK-NEXT:     FEAT_VHE                                               Enable Armv8.1-A Virtual Host extension

clang/test/Driver/print-enabled-extensions/aarch64-neoverse-v2.c

@@ -20,6 +20,7 @@
 // CHECK-NEXT:     FEAT_FHM                                               Enable FP16 FML instructions
 // CHECK-NEXT:     FEAT_FP                                                Enable Armv8.0-A Floating Point Extensions
 // CHECK-NEXT:     FEAT_FP16                                              Enable half-precision floating-point data processing
+// CHECK-NEXT:     FEAT_FPAC                                              Enable Armv8.3-A Pointer Authentication Faulting enhancement
 // CHECK-NEXT:     FEAT_FRINTTS                                           Enable FRInt[32|64][Z|X] instructions that round a floating-point number to an integer (in FP format) forcing it to fit into a 32- or 64-bit int
 // CHECK-NEXT:     FEAT_FlagM                                             Enable Armv8.4-A Flag Manipulation instructions
 // CHECK-NEXT:     FEAT_FlagM2                                            Enable alternative NZCV format for floating point comparisons

llvm/lib/Target/AArch64/AArch64Processors.td

@@ -1015,7 +1015,7 @@ def ProcessorFeatures {
                                        FeatureCCIDX,
                                        FeatureSVE, FeatureSVE2, FeatureSSBS, FeatureFullFP16, FeatureDotProd,
                                        FeatureComplxNum, FeatureCRC, FeatureFPARMv8, FeatureJS, FeatureLSE,
-                                       FeaturePAuth, FeatureRAS, FeatureRCPC, FeatureRDM];
+                                       FeaturePAuth, FeatureRAS, FeatureRCPC, FeatureRDM, FeatureFPAC];
   list<SubtargetFeature> NeoverseV3 = [HasV9_2aOps, FeatureETE, FeatureFP16FML,
                                       FeatureFullFP16, FeatureLS64, FeatureMTE,
                                       FeaturePerfMon, FeatureRandGen, FeatureSPE,