[AArch64][llvm] Relax mandatory features for Armv9.6-A (#163973)

`FEAT_FPRCVT` is removed from being mandatory in Armv9.6-A
`FEAT_SVE2p2` is removed from being mandatory in Armv9.6-A

(cherry picked from commit 0e87811)

Author: jthackray

clang/test/Driver/aarch64-v96a.c

@@ -6,15 +6,15 @@
 // RUN: %clang -target aarch64 -mlittle-endian -march=armv9.6-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A %s
 // RUN: %clang -target aarch64_be -mlittle-endian -march=armv9.6a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A %s
 // RUN: %clang -target aarch64_be -mlittle-endian -march=armv9.6-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A %s
-// GENERICV96A: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic" "-target-feature" "+v9.6a"{{.*}} "-target-feature" "+cmpbr"{{.*}} "-target-feature" "+fprcvt"{{.*}} "-target-feature" "+sve2p2"
+// GENERICV96A: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-cpu" "generic" "-target-feature" "+v9.6a"{{.*}} "-target-feature" "+cmpbr"{{.*}}
 
 // RUN: %clang -target aarch64_be -march=armv9.6a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A-BE %s
 // RUN: %clang -target aarch64_be -march=armv9.6-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A-BE %s
 // RUN: %clang -target aarch64 -mbig-endian -march=armv9.6a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A-BE %s
 // RUN: %clang -target aarch64 -mbig-endian -march=armv9.6-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A-BE %s
 // RUN: %clang -target aarch64_be -mbig-endian -march=armv9.6a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A-BE %s
 // RUN: %clang -target aarch64_be -mbig-endian -march=armv9.6-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV96A-BE %s
-// GENERICV96A-BE: "-cc1"{{.*}} "-triple" "aarch64_be{{.*}}" "-target-cpu" "generic" "-target-feature" "+v9.6a"{{.*}} "-target-feature" "+cmpbr"{{.*}} "-target-feature" "+fprcvt"{{.*}} "-target-feature" "+sve2p2"
+// GENERICV96A-BE: "-cc1"{{.*}} "-triple" "aarch64_be{{.*}}" "-target-cpu" "generic" "-target-feature" "+v9.6a"{{.*}} "-target-feature" "+cmpbr"{{.*}}
 
 // ===== Features supported on aarch64 =====
 

llvm/lib/Target/AArch64/AArch64Features.td

@@ -923,8 +923,8 @@ def HasV9_5aOps : Architecture64<9, 5, "a", "v9.5a",
   [HasV9_4aOps, FeatureCPA],
   !listconcat(HasV9_4aOps.DefaultExts, [FeatureCPA,  FeatureLUT, FeatureFAMINMAX])>;
 def HasV9_6aOps : Architecture64<9, 6, "a", "v9.6a",
-  [HasV9_5aOps, FeatureCMPBR, FeatureFPRCVT, FeatureSVE2p2, FeatureLSUI, FeatureOCCMO],
-  !listconcat(HasV9_5aOps.DefaultExts, [FeatureCMPBR, FeatureFPRCVT, FeatureSVE2p2,
+  [HasV9_5aOps, FeatureCMPBR, FeatureLSUI, FeatureOCCMO],
+  !listconcat(HasV9_5aOps.DefaultExts, [FeatureCMPBR,
     FeatureLSUI, FeatureOCCMO])>;
 def HasV8_0rOps : Architecture64<8, 0, "r", "v8r",
   [ //v8.1