[AArch64] Add FPAC feature.

Author: ahmedbougacha

llvm/lib/Target/AArch64/AArch64.td

@@ -459,6 +459,9 @@ def FeatureMatMulFP32 : SubtargetFeature<"f32mm", "HasMatMulFP32",
 def FeatureMatMulFP64 : SubtargetFeature<"f64mm", "HasMatMulFP64",
     "true", "Enable Matrix Multiply FP64 Extension (FEAT_F64MM)", [FeatureSVE]>;
 
+def FeatureFPAC : SubtargetFeature<"fpac", "HasFPAC",
+    "true", "Enable Armv8.6-A Pointer Authentication Faulting enhancement">;
+
 def FeatureXS : SubtargetFeature<"xs", "HasXS",
     "true", "Enable Armv8.7-A limited-TLB-maintenance instruction (FEAT_XS)">;
 

llvm/lib/Target/AArch64/AArch64InstrInfo.td

@@ -260,6 +260,8 @@ def HasMatMulFP32    : Predicate<"Subtarget->hasMatMulFP32()">,
                        AssemblerPredicateWithAll<(all_of FeatureMatMulFP32), "f32mm">;
 def HasMatMulFP64    : Predicate<"Subtarget->hasMatMulFP64()">,
                        AssemblerPredicateWithAll<(all_of FeatureMatMulFP64), "f64mm">;
+def HasFPAC          : Predicate<"Subtarget->hasFPAC())">,
+                       AssemblerPredicateWithAll<(all_of FeatureFPAC), "fpac">;
 def HasXS            : Predicate<"Subtarget->hasXS()">,
                        AssemblerPredicateWithAll<(all_of FeatureXS), "xs">;
 def HasWFxT          : Predicate<"Subtarget->hasWFxT()">,