[FMV][AArch64] Add feature CSSC and detect on linux platform. (#132727)

Also removes priority bits for unused features predres and ls64.

Added to ACLE with ARM-software/acle#390

Author: labrinea

clang/test/CodeGen/AArch64/fmv-dependencies.c

@@ -135,6 +135,9 @@ __attribute__((target_version("sve2-sm4"))) int fmv(void) { return 0; }
 // CHECK: define dso_local i32 @fmv._Mwfxt() #[[wfxt:[0-9]+]] {
 __attribute__((target_version("wfxt"))) int fmv(void) { return 0; }
 
+// CHECK: define dso_local i32 @fmv._Mcssc() #[[cssc:[0-9]+]] {
+__attribute__((target_version("cssc"))) int fmv(void) { return 0; }
+
 // CHECK-NOT: define dso_local i32 @fmv._M{{.*}}
 __attribute__((target_version("non_existent_extension"))) int fmv(void);
 
@@ -188,3 +191,4 @@ int caller() {
 // CHECK: attributes #[[sve2_sha3]] = { {{.*}} "target-features"="+fp-armv8,+fullfp16,+neon,+outline-atomics,+sha2,+sha3,+sve,+sve2,+sve2-sha3,+v8a"
 // CHECK: attributes #[[sve2_sm4]] = { {{.*}} "target-features"="+fp-armv8,+fullfp16,+neon,+outline-atomics,+sm4,+sve,+sve2,+sve2-sm4,+v8a"
 // CHECK: attributes #[[wfxt]] = { {{.*}} "target-features"="+fp-armv8,+neon,+outline-atomics,+v8a,+wfxt"
+// CHECK: attributes #[[cssc]] = { {{.*}} "target-features"="+cssc,+fp-armv8,+neon,+outline-atomics,+v8a"

clang/test/CodeGen/AArch64/fmv-detection.c

@@ -33,7 +33,7 @@ enum CPUFeatures {
   FEAT_FP,
   FEAT_SIMD,
   FEAT_CRC,
-  RESERVED_FEAT_SHA1, // previously used and now ABI legacy
+  FEAT_CSSC,
   FEAT_SHA2,
   FEAT_SHA3,
   RESERVED_FEAT_AES, // previously used and now ABI legacy

compiler-rt/lib/builtins/cpu_model/AArch64CPUFeatures.inc

@@ -81,6 +81,8 @@ static void __init_cpu_features_constructor(unsigned long hwcap,
     setCPUFeature(FEAT_SME_F64);
   if (hwcap2 & HWCAP2_MOPS)
     setCPUFeature(FEAT_MOPS);
+  if (hwcap2 & HWCAP2_CSSC)
+    setCPUFeature(FEAT_CSSC);
   if (hwcap & HWCAP_FP) {
     setCPUFeature(FEAT_FP);
     // FP and AdvSIMD fields have the same value

compiler-rt/lib/builtins/cpu_model/aarch64/fmv/mrs.inc

@@ -187,3 +187,6 @@
 #ifndef HWCAP2_LRCPC3
 #define HWCAP2_LRCPC3 (1UL << 46)
 #endif
+#ifndef HWCAP2_CSSC
+#define HWCAP2_CSSC (1UL << 34)
+#endif

compiler-rt/lib/builtins/cpu_model/aarch64/hwcap.inc

@@ -33,7 +33,7 @@ enum CPUFeatures {
   FEAT_FP,
   FEAT_SIMD,
   FEAT_CRC,
-  RESERVED_FEAT_SHA1, // previously used and now ABI legacy
+  FEAT_CSSC,
   FEAT_SHA2,
   FEAT_SHA3,
   RESERVED_FEAT_AES, // previously used and now ABI legacy

llvm/include/llvm/TargetParser/AArch64CPUFeatures.inc

@@ -52,15 +52,14 @@ enum FeatPriorities {
   PRIOR_SME,
   PRIOR_MEMTAG2,
   PRIOR_SB,
-  PRIOR_PREDRES,
   PRIOR_SSBS2,
   PRIOR_BTI,
-  PRIOR_LS64_ACCDATA,
   PRIOR_WFXT,
   PRIOR_SME_F64,
   PRIOR_SME_I64,
   PRIOR_SME2,
-  PRIOR_MOPS
+  PRIOR_MOPS,
+  PRIOR_CSSC
 };
 
 #endif

llvm/include/llvm/TargetParser/AArch64FeatPriorities.inc

@@ -82,3 +82,4 @@ def : FMVExtension<"sve2-bitperm", "SVE_BITPERM">;
 def : FMVExtension<"sve2-sha3", "SVE_SHA3">;
 def : FMVExtension<"sve2-sm4", "SVE_SM4">;
 def : FMVExtension<"wfxt", "WFXT">;
+def : FMVExtension<"cssc", "CSSC">;