[ARM][AArch64] generate subtarget feature flags [NFC]

[tmatheson]

Summary

This patch aims to reduce a lot of the boilerplate around adding new subtarget
features. From the SubtargetFeatures tablegen definitions, a series of calls to
the macro GET_SUBTARGETINFO_MACRO are generated in
ARM/AArch64GenSubtargetInfo.inc. ARMSubtarget/AArch64Subtarget can then use
this macro to define bool members and the corresponding getter methods.

Some naming inconsistencies have been fixed to allow this, and one unused
member removed.

This implementation only applies to boolean members; in future both BitVector
and enum members could also be generated.

[tmatheson]

Ping. Anyone have thoughts on this approach?

[MaskRay]

Looks great!

llvm/lib/Target/AArch64/AArch64Subtarget.h

158

Is NAME used? Or do you expect it may be used in the future?

llvm/lib/Target/ARM/ARM.td

53

It seems that you just copy comments from *Subtarget.h to the TableGen file. Seems useful to push the comment in a separate commit to make it clear this patch changes TableGen very little.

177

Previous comments use True if while this one uses If true,. Try improving consistency.

Also, end comments with a period.

llvm/utils/TableGen/SubtargetEmitter.cpp

1811

delete blank line after for

[MaskRay]

llvm/utils/TableGen/SubtargetEmitter.cpp

1812

https://llvm.org/docs/CodingStandards.html#use-auto-type-deduction-to-make-code-more-readable

String can be std::string, StringRef, or SmallString<0>. It is clearer to spell it.

1823

https://llvm.org/docs/CodingStandards.html#use-auto-type-deduction-to-make-code-more-readable

const char *

[MaskRay]

llvm/lib/Target/ARM/ARM.td

204

https://llvm.org/docs/CodingStandards.html#doxygen-use-in-documentation-comments
"Don’t duplicate function or class name at the beginning of the comment."

231–233

The two sentences now have no punctuation as a separator.

[MaskRay]

llvm/lib/Target/ARM/ARM.td

191

supports AES does not convey more information than FeatureAES. Drop the comment.

(The previous comment // If true, processor supports SHA1 and SHA256 conveys more information.)

[tmatheson]

Address review comments

[tmatheson]

llvm/lib/Target/AArch64/AArch64Subtarget.h

158

Unused so removed for now.

[skan]

llvm/utils/TableGen/SubtargetEmitter.cpp

1816

A question: Why we need to check [ here?

1817

Just checking IsBool could not handle some X86 features ...

bool hasCMov() const { return HasCMov || X86SSELevel >= SSE1 || is64Bit(); }
bool useAA() const override { return UseAA; }
bool hasLAHFSAHF() const { return HasLAHFSAHF64 || !is64Bit(); }

1821

I'm afraid this assumption is not correct. The default value is orthogonal to the value set by a feature.

1826

The comments is missing is the generated header file.

[tmatheson]

llvm/utils/TableGen/SubtargetEmitter.cpp

1816

This is to exclude BitVector fields which have attributes like ReserveRegister[i]

1817

IMO these functions should be renamed to make it clear they do more than just check a feature field.

1821

It is correct for ARM/AArch64, which I would argue is sensible.

1826

The comments have been moved to the SubtargetFeature declarations in the tablegen files. It would be better if they were available on the getter/fields but that can't be accomplished using a macro.

[skan]

llvm/utils/TableGen/SubtargetEmitter.cpp

1817

IMO these functions should be renamed to make it clear they do more than just check a feature field.

It loses the flexibility.

[skan]

In summary, this solution is good for ARM, but is not generic enough. We have to deprecate some customized interfaces and find other workarounds for X86 and AMDGPU w/ this method.
D121768 provides a more flexible approach to allow developer customize the fields and interfaces, and handle the descriptions of features in a better way. Could we consider applying D121768 first and then reducing hand-written ARM codes in this patch?

[tmatheson]

I'm going to submit this, since it has been approved for a while and covers a decent subset of the features without invasive changes. We can keep discussing any future alterations in D121768.

llvm/lib/Target/AArch64/AArch64.td

def FeatureSVE2BitPerm : SubtargetFeature<"sve2-bitperm", "HasSVE2BitPerm", "true",
   "Enable bit permutation SVE2 instructions", [FeatureSVE2]>;
 
 def FeatureZCRegMove : SubtargetFeature<"zcm", "HasZeroCycleRegMove", "true",
                                         "Has zero-cycle register moves">;
 
 def FeatureZCZeroingGP : SubtargetFeature<"zcz-gp", "HasZeroCycleZeroingGP", "true",
                                         "Has zero-cycle zeroing instructions for generic registers">;
 
+// It is generally beneficial to rewrite "fmov s0, wzr" to "movi d0, #0".
+// as movi is more efficient across all cores. Newer cores can eliminate
+// fmovs early and there is no difference with movi, but this not true for
+// all implementations.
 def FeatureNoZCZeroingFP : SubtargetFeature<"no-zcz-fp", "HasZeroCycleZeroingFP", "false",
                                         "Has no zero-cycle zeroing instructions for FP registers">;
 
 def FeatureZCZeroing : SubtargetFeature<"zcz", "HasZeroCycleZeroing", "true",
                                         "Has zero-cycle zeroing instructions",
                                         [FeatureZCZeroingGP]>;
 
 /// ... but the floating-point version doesn't quite work in rare cases on older
 /// CPUs.
 def FeatureZCZeroingFPWorkaround : SubtargetFeature<"zcz-fp-workaround",
     "HasZeroCycleZeroingFPWorkaround", "true",
     "The zero-cycle floating-point zeroing instruction has a bug">;
 
 def FeatureStrictAlign : SubtargetFeature<"strict-align",
-                                          "StrictAlign", "true",
+                                          "RequiresStrictAlign", "true",
                                           "Disallow all unaligned memory "
                                           "access">;
 
 foreach i = {1-7,9-15,18,20-28,30} in
     def FeatureReserveX#i : SubtargetFeature<"reserve-x"#i, "ReserveXRegister["#i#"]", "true",
                                              "Reserve X"#i#", making it unavailable "
                                              "as a GPR">;
 
 foreach i = {8-15,18} in
     def FeatureCallSavedX#i : SubtargetFeature<"call-saved-x"#i,
          "CustomCallSavedXRegs["#i#"]", "true", "Make X"#i#" callee saved.">;
 
 def FeatureBalanceFPOps : SubtargetFeature<"balance-fp-ops", "BalanceFPOps",
     "true",
     "balance mix of odd and even D-registers for fp multiply(-accumulate) ops">;
 
 def FeaturePredictableSelectIsExpensive : SubtargetFeature<
     "predictable-select-expensive", "PredictableSelectIsExpensive", "true",
     "Prefer likely predicted branches over selects">;
 
 def FeatureCustomCheapAsMoveHandling : SubtargetFeature<"custom-cheap-as-move",
-    "CustomAsCheapAsMove", "true",
+    "HasCustomCheapAsMoveHandling", "true",
     "Use custom handling of cheap instructions">;
 
 def FeatureExynosCheapAsMoveHandling : SubtargetFeature<"exynos-cheap-as-move",
-    "ExynosAsCheapAsMove", "true",
+    "HasExynosCheapAsMoveHandling", "true",
     "Use Exynos specific handling of cheap instructions",
     [FeatureCustomCheapAsMoveHandling]>;
 
 def FeaturePostRAScheduler : SubtargetFeature<"use-postra-scheduler",
     "UsePostRAScheduler", "true", "Schedule again after register allocation">;
 
 def FeatureSlowMisaligned128Store : SubtargetFeature<"slow-misaligned-128store",
-    "Misaligned128StoreIsSlow", "true", "Misaligned 128 bit stores are slow">;
+    "IsMisaligned128StoreSlow", "true", "Misaligned 128 bit stores are slow">;
 
 def FeatureSlowPaired128 : SubtargetFeature<"slow-paired-128",
-    "Paired128IsSlow", "true", "Paired 128 bit loads and stores are slow">;
+    "IsPaired128Slow", "true", "Paired 128 bit loads and stores are slow">;
 
-def FeatureSlowSTRQro : SubtargetFeature<"slow-strqro-store", "STRQroIsSlow",
+def FeatureSlowSTRQro : SubtargetFeature<"slow-strqro-store", "IsSTRQroSlow",
     "true", "STR of Q register with register offset is slow">;
 
 def FeatureAlternateSExtLoadCVTF32Pattern : SubtargetFeature<
     "alternate-sextload-cvt-f32-pattern", "UseAlternateSExtLoadCVTF32Pattern",
     "true", "Use alternative pattern for sextload convert to f32">;
 
 def FeatureArithmeticBccFusion : SubtargetFeature<
     "arith-bcc-fusion", "HasArithmeticBccFusion", "true",

llvm/lib/Target/AArch64/AArch64Subtarget.h

enum ARMProcFamilyEnum : uint8_t {
     ThunderX3T110,
     TSV110
   };
 
 protected:
   /// ARMProcFamily - ARM processor family: Cortex-A53, Cortex-A57, and others.
   ARMProcFamilyEnum ARMProcFamily = Others;
 
-  bool HasV8_0aOps = false;
-  bool HasV8_1aOps = false;
-  bool HasV8_2aOps = false;
-  bool HasV8_3aOps = false;
-  bool HasV8_4aOps = false;
-  bool HasV8_5aOps = false;
-  bool HasV8_6aOps = false;
-  bool HasV8_7aOps = false;
-  bool HasV8_8aOps = false;
-  bool HasV9_0aOps = false;
-  bool HasV9_1aOps = false;
-  bool HasV9_2aOps = false;
-  bool HasV9_3aOps = false;
-  bool HasV8_0rOps = false;
-
-  bool HasCONTEXTIDREL2 = false;
-  bool HasEL2VMSA = false;
-  bool HasEL3 = false;
-  bool HasFPARMv8 = false;
-  bool HasNEON = false;
-  bool HasCrypto = false;
-  bool HasDotProd = false;
-  bool HasCRC = false;
-  bool HasLSE = false;
-  bool HasLSE2 = false;
-  bool HasRAS = false;
-  bool HasRDM = false;
-  bool HasPerfMon = false;
-  bool HasFullFP16 = false;
-  bool HasFP16FML = false;
-  bool HasSPE = false;
-
-  bool FixCortexA53_835769 = false;
-
-  // ARMv8.1 extensions
-  bool HasVH = false;
-  bool HasPAN = false;
-  bool HasLOR = false;
-
-  // ARMv8.2 extensions
-  bool HasPsUAO = false;
-  bool HasPAN_RWV = false;
-  bool HasCCPP = false;
-
-  // SVE extensions
-  bool HasSVE = false;
-  bool UseExperimentalZeroingPseudos = false;
-  bool UseScalarIncVL = false;
-
-  // Armv8.2 Crypto extensions
-  bool HasSM4 = false;
-  bool HasSHA3 = false;
-  bool HasSHA2 = false;
-  bool HasAES = false;
-
-  // ARMv8.3 extensions
-  bool HasPAuth = false;
-  bool HasJS = false;
-  bool HasCCIDX = false;
-  bool HasComplxNum = false;
-
-  // ARMv8.4 extensions
-  bool HasNV = false;
-  bool HasMPAM = false;
-  bool HasDIT = false;
-  bool HasTRACEV8_4 = false;
-  bool HasAM = false;
-  bool HasSEL2 = false;
-  bool HasTLB_RMI = false;
-  bool HasFlagM = false;
-  bool HasRCPC_IMMO = false;
-
-  bool HasLSLFast = false;
-  bool HasRCPC = false;
-  bool HasAggressiveFMA = false;
-
-  // Armv8.5-A Extensions
-  bool HasAlternativeNZCV = false;
-  bool HasFRInt3264 = false;
-  bool HasSpecRestrict = false;
-  bool HasSSBS = false;
-  bool HasSB = false;
-  bool HasPredRes = false;
-  bool HasCCDP = false;
-  bool HasBTI = false;
-  bool HasRandGen = false;
-  bool HasMTE = false;
-  bool HasTME = false;
-
-  // Armv8.6-A Extensions
-  bool HasBF16 = false;
-  bool HasMatMulInt8 = false;
-  bool HasMatMulFP32 = false;
-  bool HasMatMulFP64 = false;
-  bool HasAMVS = false;
-  bool HasFineGrainedTraps = false;
-  bool HasEnhancedCounterVirtualization = false;
-
-  // Armv8.7-A Extensions
-  bool HasXS = false;
-  bool HasWFxT = false;
-  bool HasHCX = false;
-  bool HasLS64 = false;
-
-  // Armv8.8-A Extensions
-  bool HasHBC = false;
-  bool HasMOPS = false;
-
-  // Arm SVE2 extensions
-  bool HasSVE2 = false;
-  bool HasSVE2AES = false;
-  bool HasSVE2SM4 = false;
-  bool HasSVE2SHA3 = false;
-  bool HasSVE2BitPerm = false;
-
-  // Armv9-A Extensions
-  bool HasRME = false;
-
-  // Arm Scalable Matrix Extension (SME)
-  bool HasSME = false;
-  bool HasSMEF64 = false;
-  bool HasSMEI64 = false;
-  bool HasStreamingSVE = false;
-
-  // AppleA7 system register.
-  bool HasAppleA7SysReg = false;
-
-  // Future architecture extensions.
-  bool HasETE = false;
-  bool HasTRBE = false;
-  bool HasBRBE = false;
-  bool HasSPE_EEF = false;
-
-  // HasZeroCycleRegMove - Has zero-cycle register mov instructions.
-  bool HasZeroCycleRegMove = false;
-
-  // HasZeroCycleZeroing - Has zero-cycle zeroing instructions.
-  bool HasZeroCycleZeroing = false;
-  bool HasZeroCycleZeroingGP = false;
-  bool HasZeroCycleZeroingFPWorkaround = false;
-
-  // It is generally beneficial to rewrite "fmov s0, wzr" to "movi d0, #0".
-  // as movi is more efficient across all cores. Newer cores can eliminate
-  // fmovs early and there is no difference with movi, but this not true for
-  // all implementations.
-  bool HasZeroCycleZeroingFP = true;
-
-  // StrictAlign - Disallow unaligned memory accesses.
-  bool StrictAlign = false;
-
-  // NegativeImmediates - transform instructions with negative immediates
-  bool NegativeImmediates = true;
-
   // Enable 64-bit vectorization in SLP.
   unsigned MinVectorRegisterBitWidth = 64;
 
-  bool OutlineAtomics = false;
-  bool PredictableSelectIsExpensive = false;
-  bool BalanceFPOps = false;
-  bool CustomAsCheapAsMove = false;
-  bool ExynosAsCheapAsMove = false;
-  bool UsePostRAScheduler = false;
-  bool Misaligned128StoreIsSlow = false;
-  bool Paired128IsSlow = false;
-  bool STRQroIsSlow = false;
-  bool UseAlternateSExtLoadCVTF32Pattern = false;
-  bool HasArithmeticBccFusion = false;
-  bool HasArithmeticCbzFusion = false;
-  bool HasCmpBccFusion = false;
-  bool HasFuseAddress = false;
-  bool HasFuseAES = false;
-  bool HasFuseArithmeticLogic = false;
-  bool HasFuseCCSelect = false;
-  bool HasFuseCryptoEOR = false;
-  bool HasFuseLiterals = false;
-  bool DisableLatencySchedHeuristic = false;
-  bool UseRSqrt = false;
-  bool Force32BitJumpTables = false;
-  bool UseEL1ForTP = false;
-  bool UseEL2ForTP = false;
-  bool UseEL3ForTP = false;
-  bool AllowTaggedGlobals = false;
-  bool HardenSlsRetBr = false;
-  bool HardenSlsBlr = false;
-  bool HardenSlsNoComdat = false;
+// Bool members corresponding to the SubtargetFeatures defined in tablegen
+#define GET_SUBTARGETINFO_MACRO(ATTRIBUTE, DEFAULT, GETTER)                    \
+  bool ATTRIBUTE = DEFAULT;
+#include "AArch64GenSubtargetInfo.inc"
+
   uint8_t MaxInterleaveFactor = 2;
   uint8_t VectorInsertExtractBaseCost = 3;
   uint16_t CacheLineSize = 0;
   uint16_t PrefetchDistance = 0;
   uint16_t MinPrefetchStride = 1;
   unsigned MaxPrefetchIterationsAhead = UINT_MAX;
   unsigned PrefFunctionLogAlignment = 0;
   unsigned PrefLoopLogAlignment = 0;
public:
   /// This constructor initializes the data members to match that
   /// of the specified triple.
   AArch64Subtarget(const Triple &TT, const std::string &CPU,
                    const std::string &TuneCPU, const std::string &FS,
                    const TargetMachine &TM, bool LittleEndian,
                    unsigned MinSVEVectorSizeInBitsOverride = 0,
                    unsigned MaxSVEVectorSizeInBitsOverride = 0);
 
+// Getters for SubtargetFeatures defined in tablegen
+#define GET_SUBTARGETINFO_MACRO(ATTRIBUTE, DEFAULT, GETTER)                    \
+  bool GETTER() const { return ATTRIBUTE; }
+#include "AArch64GenSubtargetInfo.inc"
+
   const AArch64SelectionDAGInfo *getSelectionDAGInfo() const override {
     return &TSInfo;
   }
   const AArch64FrameLowering *getFrameLowering() const override {
     return &FrameLowering;
   }
   const AArch64TargetLowering *getTargetLowering() const override {
     return &TLInfo;
   }
   const AArch64InstrInfo *getInstrInfo() const override { return &InstrInfo; }
   const AArch64RegisterInfo *getRegisterInfo() const override {
     return &getInstrInfo()->getRegisterInfo();
   }
   const CallLowering *getCallLowering() const override;
   const InlineAsmLowering *getInlineAsmLowering() const override;
   InstructionSelector *getInstructionSelector() const override;
   const LegalizerInfo *getLegalizerInfo() const override;
   const RegisterBankInfo *getRegBankInfo() const override;
   const Triple &getTargetTriple() const { return TargetTriple; }
   bool enableMachineScheduler() const override { return true; }
-  bool enablePostRAScheduler() const override {
-    return UsePostRAScheduler;
-  }
+  bool enablePostRAScheduler() const override { return usePostRAScheduler(); }
 
   /// Returns ARM processor family.
   /// Avoid this function! CPU specifics should be kept local to this class
   /// and preferably modeled with SubtargetFeatures or properties in
   /// initializeProperties().
   ARMProcFamilyEnum getProcFamily() const {
     return ARMProcFamily;
   }
 
-  bool hasV8_0aOps() const { return HasV8_0aOps; }
-  bool hasV8_1aOps() const { return HasV8_1aOps; }
-  bool hasV8_2aOps() const { return HasV8_2aOps; }
-  bool hasV8_3aOps() const { return HasV8_3aOps; }
-  bool hasV8_4aOps() const { return HasV8_4aOps; }
-  bool hasV8_5aOps() const { return HasV8_5aOps; }
-  bool hasV9_0aOps() const { return HasV9_0aOps; }
-  bool hasV9_1aOps() const { return HasV9_1aOps; }
-  bool hasV9_2aOps() const { return HasV9_2aOps; }
-  bool hasV9_3aOps() const { return HasV9_3aOps; }
-  bool hasV8_0rOps() const { return HasV8_0rOps; }
-
-  bool hasZeroCycleRegMove() const { return HasZeroCycleRegMove; }
-
-  bool hasZeroCycleZeroingGP() const { return HasZeroCycleZeroingGP; }
-
-  bool hasZeroCycleZeroingFP() const { return HasZeroCycleZeroingFP; }
-
-  bool hasZeroCycleZeroingFPWorkaround() const {
-    return HasZeroCycleZeroingFPWorkaround;
-  }
-
-  bool requiresStrictAlign() const { return StrictAlign; }
-
   bool isXRaySupported() const override { return true; }
 
   unsigned getMinVectorRegisterBitWidth() const {
     return MinVectorRegisterBitWidth;
   }
 
   bool isXRegisterReserved(size_t i) const { return ReserveXRegister[i]; }
   unsigned getNumXRegisterReserved() const { return ReserveXRegister.count(); }
   bool isXRegCustomCalleeSaved(size_t i) const {
     return CustomCallSavedXRegs[i];
   }
   bool hasCustomCallingConv() const { return CustomCallSavedXRegs.any(); }
-  bool hasFPARMv8() const { return HasFPARMv8; }
-  bool hasNEON() const { return HasNEON; }
-  bool hasCrypto() const { return HasCrypto; }
-  bool hasDotProd() const { return HasDotProd; }
-  bool hasCRC() const { return HasCRC; }
-  bool hasLSE() const { return HasLSE; }
-  bool hasLSE2() const { return HasLSE2; }
-  bool hasRAS() const { return HasRAS; }
-  bool hasRDM() const { return HasRDM; }
-  bool hasSM4() const { return HasSM4; }
-  bool hasSHA3() const { return HasSHA3; }
-  bool hasSHA2() const { return HasSHA2; }
-  bool hasAES() const { return HasAES; }
-  bool hasCONTEXTIDREL2() const { return HasCONTEXTIDREL2; }
-  bool balanceFPOps() const { return BalanceFPOps; }
-  bool predictableSelectIsExpensive() const {
-    return PredictableSelectIsExpensive;
-  }
-  bool hasCustomCheapAsMoveHandling() const { return CustomAsCheapAsMove; }
-  bool hasExynosCheapAsMoveHandling() const { return ExynosAsCheapAsMove; }
-  bool isMisaligned128StoreSlow() const { return Misaligned128StoreIsSlow; }
-  bool isPaired128Slow() const { return Paired128IsSlow; }
-  bool isSTRQroSlow() const { return STRQroIsSlow; }
-  bool useAlternateSExtLoadCVTF32Pattern() const {
-    return UseAlternateSExtLoadCVTF32Pattern;
-  }
-  bool hasArithmeticBccFusion() const { return HasArithmeticBccFusion; }
-  bool hasArithmeticCbzFusion() const { return HasArithmeticCbzFusion; }
-  bool hasCmpBccFusion() const { return HasCmpBccFusion; }
-  bool hasFuseAddress() const { return HasFuseAddress; }
-  bool hasFuseAES() const { return HasFuseAES; }
-  bool hasFuseArithmeticLogic() const { return HasFuseArithmeticLogic; }
-  bool hasFuseCCSelect() const { return HasFuseCCSelect; }
-  bool hasFuseCryptoEOR() const { return HasFuseCryptoEOR; }
-  bool hasFuseLiterals() const { return HasFuseLiterals; }
 
   /// Return true if the CPU supports any kind of instruction fusion.
   bool hasFusion() const {
     return hasArithmeticBccFusion() || hasArithmeticCbzFusion() ||
            hasFuseAES() || hasFuseArithmeticLogic() ||
            hasFuseCCSelect() || hasFuseLiterals();
   }
 
-  bool hardenSlsRetBr() const { return HardenSlsRetBr; }
-  bool hardenSlsBlr() const { return HardenSlsBlr; }
-  bool hardenSlsNoComdat() const { return HardenSlsNoComdat; }
-
-  bool useEL1ForTP() const { return UseEL1ForTP; }
-  bool useEL2ForTP() const { return UseEL2ForTP; }
-  bool useEL3ForTP() const { return UseEL3ForTP; }
-
-  bool useRSqrt() const { return UseRSqrt; }
-  bool force32BitJumpTables() const { return Force32BitJumpTables; }
   unsigned getMaxInterleaveFactor() const { return MaxInterleaveFactor; }
   unsigned getVectorInsertExtractBaseCost() const {
     return VectorInsertExtractBaseCost;
   }
   unsigned getCacheLineSize() const override { return CacheLineSize; }
   unsigned getPrefetchDistance() const override { return PrefetchDistance; }
   unsigned getMinPrefetchStride(unsigned NumMemAccesses,
                                 unsigned NumStridedMemAccesses,
#include "AArch64GenSubtargetInfo.inc"
   unsigned getMaxBytesForLoopAlignment() const {
     return MaxBytesForLoopAlignment;
   }
 
   unsigned getMaximumJumpTableSize() const { return MaxJumpTableSize; }
 
   unsigned getWideningBaseCost() const { return WideningBaseCost; }
 
-  bool useExperimentalZeroingPseudos() const {
-    return UseExperimentalZeroingPseudos;
-  }
-
-  bool useScalarIncVL() const { return UseScalarIncVL; }
-
   /// CPU has TBI (top byte of addresses is ignored during HW address
   /// translation) and OS enables it.
   bool supportsAddressTopByteIgnored() const;
 
-  bool hasPerfMon() const { return HasPerfMon; }
-  bool hasFullFP16() const { return HasFullFP16; }
-  bool hasFP16FML() const { return HasFP16FML; }
-  bool hasSPE() const { return HasSPE; }
-  bool hasLSLFast() const { return HasLSLFast; }
-  bool hasSVE() const { return HasSVE; }
-  bool hasSVE2() const { return HasSVE2; }
-  bool hasRCPC() const { return HasRCPC; }
-  bool hasAggressiveFMA() const { return HasAggressiveFMA; }
-  bool hasAlternativeNZCV() const { return HasAlternativeNZCV; }
-  bool hasFRInt3264() const { return HasFRInt3264; }
-  bool hasSpecRestrict() const { return HasSpecRestrict; }
-  bool hasSSBS() const { return HasSSBS; }
-  bool hasSB() const { return HasSB; }
-  bool hasPredRes() const { return HasPredRes; }
-  bool hasCCDP() const { return HasCCDP; }
-  bool hasBTI() const { return HasBTI; }
-  bool hasRandGen() const { return HasRandGen; }
-  bool hasMTE() const { return HasMTE; }
-  bool hasTME() const { return HasTME; }
-  // Arm SVE2 extensions
-  bool hasSVE2AES() const { return HasSVE2AES; }
-  bool hasSVE2SM4() const { return HasSVE2SM4; }
-  bool hasSVE2SHA3() const { return HasSVE2SHA3; }
-  bool hasSVE2BitPerm() const { return HasSVE2BitPerm; }
-  bool hasMatMulInt8() const { return HasMatMulInt8; }
-  bool hasMatMulFP32() const { return HasMatMulFP32; }
-  bool hasMatMulFP64() const { return HasMatMulFP64; }
-
-  // Armv8.6-A Extensions
-  bool hasBF16() const { return HasBF16; }
-  bool hasFineGrainedTraps() const { return HasFineGrainedTraps; }
-  bool hasEnhancedCounterVirtualization() const {
-    return HasEnhancedCounterVirtualization;
-  }
-
-  // Arm Scalable Matrix Extension (SME)
-  bool hasSME() const { return HasSME; }
-  bool hasSMEF64() const { return HasSMEF64; }
-  bool hasSMEI64() const { return HasSMEI64; }
-  bool hasStreamingSVE() const { return HasStreamingSVE; }
-
   bool isLittleEndian() const { return IsLittle; }
 
   bool isTargetDarwin() const { return TargetTriple.isOSDarwin(); }
   bool isTargetIOS() const { return TargetTriple.isiOS(); }
   bool isTargetLinux() const { return TargetTriple.isOSLinux(); }
   bool isTargetWindows() const { return TargetTriple.isOSWindows(); }
   bool isTargetAndroid() const { return TargetTriple.isAndroid(); }
   bool isTargetFuchsia() const { return TargetTriple.isOSFuchsia(); }
 
   bool isTargetCOFF() const { return TargetTriple.isOSBinFormatCOFF(); }
   bool isTargetELF() const { return TargetTriple.isOSBinFormatELF(); }
   bool isTargetMachO() const { return TargetTriple.isOSBinFormatMachO(); }
 
   bool isTargetILP32() const {
     return TargetTriple.isArch32Bit() ||
            TargetTriple.getEnvironment() == Triple::GNUILP32;
   }
 
   bool useAA() const override;
 
-  bool outlineAtomics() const { return OutlineAtomics; }
-
-  bool hasVH() const { return HasVH; }
-  bool hasPAN() const { return HasPAN; }
-  bool hasLOR() const { return HasLOR; }
-
-  bool hasPsUAO() const { return HasPsUAO; }
-  bool hasPAN_RWV() const { return HasPAN_RWV; }
-  bool hasCCPP() const { return HasCCPP; }
-
-  bool hasPAuth() const { return HasPAuth; }
-  bool hasJS() const { return HasJS; }
-  bool hasCCIDX() const { return HasCCIDX; }
-  bool hasComplxNum() const { return HasComplxNum; }
-
-  bool hasNV() const { return HasNV; }
-  bool hasMPAM() const { return HasMPAM; }
-  bool hasDIT() const { return HasDIT; }
-  bool hasTRACEV8_4() const { return HasTRACEV8_4; }
-  bool hasAM() const { return HasAM; }
-  bool hasAMVS() const { return HasAMVS; }
-  bool hasXS() const { return HasXS; }
-  bool hasWFxT() const { return HasWFxT; }
-  bool hasHCX() const { return HasHCX; }
-  bool hasLS64() const { return HasLS64; }
-  bool hasSEL2() const { return HasSEL2; }
-  bool hasTLB_RMI() const { return HasTLB_RMI; }
-  bool hasFlagM() const { return HasFlagM; }
-  bool hasRCPC_IMMO() const { return HasRCPC_IMMO; }
-  bool hasEL2VMSA() const { return HasEL2VMSA; }
-  bool hasEL3() const { return HasEL3; }
-  bool hasHBC() const { return HasHBC; }
-  bool hasMOPS() const { return HasMOPS; }
-
-  bool fixCortexA53_835769() const { return FixCortexA53_835769; }
-
   bool addrSinkUsingGEPs() const override {
     // Keeping GEPs inbounds is important for exploiting AArch64
     // addressing-modes in ILP32 mode.
     return useAA() || isTargetILP32();
   }
 
   bool useSmallAddressing() const {
     switch (TLInfo.getTargetMachine().getCodeModel()) {

llvm/lib/Target/ARM/ARM.td

 //===----------------------------------------------------------------------===//
 
 include "llvm/Target/Target.td"
 
 //===----------------------------------------------------------------------===//
 // ARM Subtarget state.
 //
 
-def ModeThumb             : SubtargetFeature<"thumb-mode", "InThumbMode",
+// True if compiling for Thumb, false for ARM.
+def ModeThumb             : SubtargetFeature<"thumb-mode", "IsThumb",
                                              "true", "Thumb mode">;
 
+// True if we're using software floating point features.
 def ModeSoftFloat         : SubtargetFeature<"soft-float","UseSoftFloat",
                                              "true", "Use software floating "
                                              "point features.">;
 
 
 //===----------------------------------------------------------------------===//
 // ARM Subtarget features.
 //

 def FeatureFPRegs16       : SubtargetFeature<"fpregs16", "HasFPRegs16", "true",
                                              "Enable 16-bit FP registers",
                                              [FeatureFPRegs]>;
 
 def FeatureFPRegs64       : SubtargetFeature<"fpregs64", "HasFPRegs64", "true",
                                              "Enable 64-bit FP registers",
                                              [FeatureFPRegs]>;
 
+// True if the floating point unit supports double precision.
 def FeatureFP64           : SubtargetFeature<"fp64", "HasFP64", "true",
                                              "Floating point unit supports "
                                              "double precision",
                                              [FeatureFPRegs64]>;
 
+// True if subtarget has the full 32 double precision FP registers for VFPv3.
 def FeatureD32            : SubtargetFeature<"d32", "HasD32", "true",
                                              "Extend FP to 32 double registers">;
 
+/// Versions of the VFP flags restricted to single precision, or to
+/// 16 d-registers, or both.
 multiclass VFPver<string name, string query, string description,
                   list<SubtargetFeature> prev,
                   list<SubtargetFeature> otherimplies,
                   list<SubtargetFeature> vfp2prev = []> {
   def _D16_SP: SubtargetFeature<
     name#"d16sp", query#"D16SP", "true",
     description#" with only 16 d-registers and no double precision",
     !foreach(v, prev, !cast<SubtargetFeature>(v # "_D16_SP")) #

 
 defm FeatureVFP3: VFPver<"vfp3", "HasVFPv3", "Enable VFP3 instructions",
                          [], [], [FeatureVFP2]>;
 
 def FeatureNEON           : SubtargetFeature<"neon", "HasNEON", "true",
                                              "Enable NEON instructions",
                                              [FeatureVFP3]>;
 
+// True if subtarget supports half-precision FP conversions.
 def FeatureFP16           : SubtargetFeature<"fp16", "HasFP16", "true",
                                              "Enable half-precision "
                                              "floating point">;
 
 defm FeatureVFP4: VFPver<"vfp4", "HasVFPv4", "Enable VFP4 instructions",
                          [FeatureVFP3], [FeatureFP16]>;
 
 defm FeatureFPARMv8: VFPver<"fp-armv8", "HasFPARMv8", "Enable ARMv8 FP",
                          [FeatureVFP4], []>;
 
+// True if subtarget supports half-precision FP operations.
 def FeatureFullFP16       : SubtargetFeature<"fullfp16", "HasFullFP16", "true",
                                              "Enable full half-precision "
                                              "floating point",
                                              [FeatureFPARMv8_D16_SP, FeatureFPRegs16]>;
 
+// True if subtarget supports half-precision FP fml operations.
 def FeatureFP16FML        : SubtargetFeature<"fp16fml", "HasFP16FML", "true",
                                              "Enable full half-precision "
                                              "floating point fml instructions",
                                              [FeatureFullFP16]>;
 
+// True if subtarget supports [su]div in Thumb mode.
 def FeatureHWDivThumb     : SubtargetFeature<"hwdiv",
-                                             "HasHardwareDivideInThumb", "true",
+                                             "HasDivideInThumbMode", "true",
                                              "Enable divide instructions in Thumb">;
 
+// True if subtarget supports [su]div in ARM mode.
 def FeatureHWDivARM       : SubtargetFeature<"hwdiv-arm",
-                                             "HasHardwareDivideInARM", "true",
+                                             "HasDivideInARMMode", "true",
                                              "Enable divide instructions in ARM mode">;
 
 // Atomic Support
+
+// True if the subtarget supports DMB / DSB data barrier instructions.
 def FeatureDB             : SubtargetFeature<"db", "HasDataBarrier", "true",
                                              "Has data barrier (dmb/dsb) instructions">;
 
+// True if the subtarget supports CLREX instructions.
 def FeatureV7Clrex        : SubtargetFeature<"v7clrex", "HasV7Clrex", "true",
                                              "Has v7 clrex instruction">;
 
+// True if the subtarget supports DFB data barrier instruction.
 def FeatureDFB  : SubtargetFeature<"dfb", "HasFullDataBarrier", "true",
                                    "Has full data barrier (dfb) instruction">;
 
+// True if the subtarget supports v8 atomics (LDA/LDAEX etc) instructions.
 def FeatureAcquireRelease : SubtargetFeature<"acquire-release",
                                              "HasAcquireRelease", "true",
                                              "Has v8 acquire/release (lda/ldaex "
                                              " etc) instructions">;
 
 
-def FeatureSlowFPBrcc     : SubtargetFeature<"slow-fp-brcc", "SlowFPBrcc", "true",
+// True if floating point compare + branch is slow.
+def FeatureSlowFPBrcc     : SubtargetFeature<"slow-fp-brcc", "IsFPBrccSlow", "true",
                                              "FP compare + branch is slow">;
 
+// True if the processor supports the Performance Monitor Extensions. These
+// include a generic cycle-counter as well as more fine-grained (often
+// implementation-specific) events.
 def FeaturePerfMon        : SubtargetFeature<"perfmon", "HasPerfMon", "true",
                                              "Enable support for Performance "
                                              "Monitor extensions">;
 
 
 // TrustZone Security Extensions
+
+// True if processor supports TrustZone security extensions.
 def FeatureTrustZone      : SubtargetFeature<"trustzone", "HasTrustZone", "true",
                                              "Enable support for TrustZone "
                                              "security extensions">;
 
+// True if processor supports ARMv8-M Security Extensions.
 def Feature8MSecExt       : SubtargetFeature<"8msecext", "Has8MSecExt", "true",
                                              "Enable support for ARMv8-M "
                                              "Security Extensions">;
 
+// True if processor supports SHA1 and SHA256.
 def FeatureSHA2           : SubtargetFeature<"sha2", "HasSHA2", "true",
                                              "Enable SHA1 and SHA256 support", [FeatureNEON]>;
 
 def FeatureAES            : SubtargetFeature<"aes", "HasAES", "true",
                                              "Enable AES support", [FeatureNEON]>;
 
+// True if processor supports Cryptography extensions.
 def FeatureCrypto         : SubtargetFeature<"crypto", "HasCrypto", "true",
                                              "Enable support for "
                                              "Cryptography extensions",
                                              [FeatureNEON, FeatureSHA2, FeatureAES]>;
 
+// True if processor supports CRC instructions.
 def FeatureCRC            : SubtargetFeature<"crc", "HasCRC", "true",
                                              "Enable support for CRC instructions">;
 
+// True if the ARMv8.2A dot product instructions are supported.
 def FeatureDotProd        : SubtargetFeature<"dotprod", "HasDotProd", "true",
                                              "Enable support for dot product instructions",
                                              [FeatureNEON]>;
 
-// Not to be confused with FeatureHasRetAddrStack (return address stack)
+// True if the processor supports RAS extensions.
+// Not to be confused with FeatureHasRetAddrStack (return address stack).
 def FeatureRAS            : SubtargetFeature<"ras", "HasRAS", "true",
                                              "Enable Reliability, Availability "
                                              "and Serviceability extensions">;
 
-// Fast computation of non-negative address offsets
+// Fast computation of non-negative address offsets.
+// True if processor does positive address offset computation faster.
 def FeatureFPAO           : SubtargetFeature<"fpao", "HasFPAO", "true",
                                              "Enable fast computation of "
                                              "positive address offsets">;
 
-// Fast execution of AES crypto operations
+// Fast execution of AES crypto operations.
+// True if processor executes back to back AES instruction pairs faster.
 def FeatureFuseAES        : SubtargetFeature<"fuse-aes", "HasFuseAES", "true",
                                              "CPU fuses AES crypto operations">;
 
-// Fast execution of bottom and top halves of literal generation
+// Fast execution of bottom and top halves of literal generation.
+// True if processor executes back to back bottom and top halves of literal generation faster.
 def FeatureFuseLiterals   : SubtargetFeature<"fuse-literals", "HasFuseLiterals", "true",
                                              "CPU fuses literal generation operations">;
 
-// The way of reading thread pointer                                             
-def FeatureReadTp :  SubtargetFeature<"read-tp-hard", "ReadTPHard", "true",
+// The way of reading thread pointer.
+// True if read thread pointer from coprocessor register.
+def FeatureReadTp :  SubtargetFeature<"read-tp-hard", "IsReadTPHard", "true",
                                       "Reading thread pointer from register">;
 
 // Cyclone can zero VFP registers in 0 cycles.
+// True if the instructions "vmov.i32 d0, #0" and "vmov.i32 q0, #0" are
+// particularly effective at zeroing a VFP register.
 def FeatureZCZeroing      : SubtargetFeature<"zcz", "HasZeroCycleZeroing", "true",
                                              "Has zero-cycle zeroing instructions">;
 
-// Whether it is profitable to unpredicate certain instructions during if-conversion
+// Whether it is profitable to unpredicate certain instructions during if-conversion.
+// True if if conversion may decide to leave some instructions unpredicated.
 def FeatureProfUnpredicate : SubtargetFeature<"prof-unpr",
                                               "IsProfitableToUnpredicate", "true",
                                               "Is profitable to unpredicate">;
 
 // Some targets (e.g. Swift) have microcoded VGETLNi32.
+// True if VMOV will be favored over VGETLNi32.
 def FeatureSlowVGETLNi32  : SubtargetFeature<"slow-vgetlni32",
                                              "HasSlowVGETLNi32", "true",
                                              "Has slow VGETLNi32 - prefer VMOV">;
 
 // Some targets (e.g. Swift) have microcoded VDUP32.
+// True if VMOV will be favored over VDUP.
 def FeatureSlowVDUP32     : SubtargetFeature<"slow-vdup32", "HasSlowVDUP32",
                                              "true",
                                              "Has slow VDUP32 - prefer VMOV">;
 
 // Some targets (e.g. Cortex-A9) prefer VMOVSR to VMOVDRR even when using NEON
 // for scalar FP, as this allows more effective execution domain optimization.
+// True if VMOVSR will be favored over VMOVDRR.
 def FeaturePreferVMOVSR   : SubtargetFeature<"prefer-vmovsr", "PreferVMOVSR",
                                              "true", "Prefer VMOVSR">;
 
 // Swift has ISHST barriers compatible with Atomic Release semantics but weaker
-// than ISH
-def FeaturePrefISHSTBarrier : SubtargetFeature<"prefer-ishst", "PreferISHST",
+// than ISH.
+// True if ISHST barriers will be used for Release semantics.
+def FeaturePrefISHSTBarrier : SubtargetFeature<"prefer-ishst", "PreferISHSTBarriers",
                                                "true", "Prefer ISHST barriers">;
 
 // Some targets (e.g. Cortex-A9) have muxed AGU and NEON/FPU.
+// True if the AGU and NEON/FPU units are multiplexed.
 def FeatureMuxedUnits     : SubtargetFeature<"muxed-units", "HasMuxedUnits",
                                              "true",
                                              "Has muxed AGU and NEON/FPU">;
 
 // Whether VLDM/VSTM starting with odd register number need more microops
-// than single VLDRS
-def FeatureSlowOddRegister : SubtargetFeature<"slow-odd-reg", "SlowOddRegister",
+// than single VLDRS.
+// True if a VLDM/VSTM starting with an odd register number is considered to
+// take more microops than single VLDRS/VSTRS.
+def FeatureSlowOddRegister : SubtargetFeature<"slow-odd-reg", "HasSlowOddRegister",
                                               "true", "VLDM/VSTM starting "
                                               "with an odd register is slow">;
 
 // Some targets have a renaming dependency when loading into D subregisters.
+// True if loading into a D subregister will be penalized.
 def FeatureSlowLoadDSubreg : SubtargetFeature<"slow-load-D-subreg",
-                                              "SlowLoadDSubregister", "true",
+                                              "HasSlowLoadDSubregister", "true",
                                               "Loading into D subregs is slow">;
 
+// True if use a wider stride when allocating VFP registers.
 def FeatureUseWideStrideVFP : SubtargetFeature<"wide-stride-vfp",
                                                "UseWideStrideVFP", "true",
                                                "Use a wide stride when allocating VFP registers">;
 
 // Some targets (e.g. Cortex-A15) never want VMOVS to be widened to VMOVD.
+// True if VMOVS will never be widened to VMOVD.
 def FeatureDontWidenVMOVS : SubtargetFeature<"dont-widen-vmovs",
                                              "DontWidenVMOVS", "true",
                                              "Don't widen VMOVS to VMOVD">;
 
 // Some targets (e.g. Cortex-A15) prefer to avoid mixing operations on different
 // VFP register widths.
+// True if splat a register between VFP and NEON instructions.
 def FeatureSplatVFPToNeon : SubtargetFeature<"splat-vfp-neon",
-                                             "SplatVFPToNeon", "true",
+                                             "UseSplatVFPToNeon", "true",
                                              "Splat register from VFP to NEON",
                                              [FeatureDontWidenVMOVS]>;
 
 // Whether or not it is profitable to expand VFP/NEON MLA/MLS instructions.
+// True if run the MLx expansion pass.
 def FeatureExpandMLx      : SubtargetFeature<"expand-fp-mlx",
                                              "ExpandMLx", "true",
                                              "Expand VFP/NEON MLA/MLS instructions">;
 
 // Some targets have special RAW hazards for VFP/NEON VMLA/VMLS.
+// True if VFP/NEON VMLA/VMLS have special RAW hazards.
 def FeatureHasVMLxHazards : SubtargetFeature<"vmlx-hazards", "HasVMLxHazards",
                                              "true", "Has VMLx hazards">;
 
 // Some targets (e.g. Cortex-A9) want to convert VMOVRS, VMOVSR and VMOVS from
 // VFP to NEON, as an execution domain optimization.
+// True if VMOVRS, VMOVSR and VMOVS will be converted from VFP to NEON.
 def FeatureNEONForFPMovs  : SubtargetFeature<"neon-fpmovs",
                                              "UseNEONForFPMovs", "true",
                                              "Convert VMOVSR, VMOVRS, "
                                              "VMOVS to NEON">;
 
 // Some processors benefit from using NEON instructions for scalar
 // single-precision FP operations. This affects instruction selection and should
 // only be enabled if the handling of denormals is not important.
+// Use the method useNEONForSinglePrecisionFP() to determine if NEON should actually be used.
 def FeatureNEONForFP      : SubtargetFeature<"neonfp",
-                                             "UseNEONForSinglePrecisionFP",
+                                             "HasNEONForFP",
                                              "true",
                                              "Use NEON for single precision FP">;
 
 // On some processors, VLDn instructions that access unaligned data take one
 // extra cycle. Take that into account when computing operand latencies.
-def FeatureCheckVLDnAlign : SubtargetFeature<"vldn-align", "CheckVLDnAlign",
+// True if VLDn instructions take an extra cycle for unaligned accesses.
+def FeatureCheckVLDnAlign : SubtargetFeature<"vldn-align", "CheckVLDnAccessAlignment",
                                              "true",
                                              "Check for VLDn unaligned access">;
 
 // Some processors have a nonpipelined VFP coprocessor.
+// True if VFP instructions are not pipelined.
 def FeatureNonpipelinedVFP : SubtargetFeature<"nonpipelined-vfp",
                                               "NonpipelinedVFP", "true",
                                               "VFP instructions are not pipelined">;
 
 // Some processors have FP multiply-accumulate instructions that don't
 // play nicely with other VFP / NEON instructions, and it's generally better
 // to just not use them.
+// If the VFP2 / NEON instructions are available, indicates
+// whether the FP VML[AS] instructions are slow (if so, don't use them).
 def FeatureHasSlowFPVMLx  : SubtargetFeature<"slowfpvmlx", "SlowFPVMLx", "true",
                                              "Disable VFP / NEON MAC instructions">;
 
-// VFPv4 added VFMA instructions that can similar be fast or slow.
+// VFPv4 added VFMA instructions that can similarly be fast or slow.
+// If the VFP4 / NEON instructions are available, indicates
+// whether the FP VFM[AS] instructions are slow (if so, don't use them).
 def FeatureHasSlowFPVFMx  : SubtargetFeature<"slowfpvfmx", "SlowFPVFMx", "true",
                                              "Disable VFP / NEON FMA instructions">;
 
 // Cortex-A8 / A9 Advanced SIMD has multiplier accumulator forwarding.
+/// True if NEON has special multiplier accumulator
+/// forwarding to allow mul + mla being issued back to back.
 def FeatureVMLxForwarding : SubtargetFeature<"vmlx-forwarding",
                                              "HasVMLxForwarding", "true",
                                              "Has multiplier accumulator forwarding">;
 
 // Disable 32-bit to 16-bit narrowing for experimentation.
-def FeaturePref32BitThumb : SubtargetFeature<"32bit", "Pref32BitThumb", "true",
+// True if codegen would prefer 32-bit Thumb instructions over 16-bit ones.
+def FeaturePref32BitThumb : SubtargetFeature<"32bit", "Prefers32BitThumb", "true",
                                              "Prefer 32-bit Thumb instrs">;
 
 def FeaturePrefLoopAlign32 : SubtargetFeature<"loop-align", "PrefLoopLogAlignment","2",
                                               "Prefer 32-bit alignment for loops">;
 
 def FeatureMVEVectorCostFactor1 : SubtargetFeature<"mve1beat", "MVEVectorCostFactor", "1",
                         "Model MVE instructions as a 1 beat per tick architecture">;
 
 def FeatureMVEVectorCostFactor2 : SubtargetFeature<"mve2beat", "MVEVectorCostFactor", "2",
                         "Model MVE instructions as a 2 beats per tick architecture">;
 
 def FeatureMVEVectorCostFactor4 : SubtargetFeature<"mve4beat", "MVEVectorCostFactor", "4",
                         "Model MVE instructions as a 4 beats per tick architecture">;
 
 /// Some instructions update CPSR partially, which can add false dependency for
 /// out-of-order implementation, e.g. Cortex-A9, unless each individual bit is
 /// mapped to a separate physical register. Avoid partial CPSR update for these
 /// processors.
+/// True if codegen would avoid using instructions
+/// that partially update CPSR and add false dependency on the previous
+/// CPSR setting instruction.
 def FeatureAvoidPartialCPSR : SubtargetFeature<"avoid-partial-cpsr",
                                                "AvoidCPSRPartialUpdate", "true",
                                  "Avoid CPSR partial update for OOO execution">;
 
 /// Disable +1 predication cost for instructions updating CPSR.
 /// Enabled for Cortex-A57.
+/// True if disable +1 predication cost for instructions updating CPSR. Enabled for Cortex-A57.
 def FeatureCheapPredicableCPSR : SubtargetFeature<"cheap-predicable-cpsr",
                                                   "CheapPredicableCPSRDef",
                                                   "true",
                   "Disable +1 predication cost for instructions updating CPSR">;
 
+// True if codegen should avoid using flag setting movs with shifter operand (i.e. asr, lsl, lsr).
 def FeatureAvoidMOVsShOp  : SubtargetFeature<"avoid-movs-shop",
                                              "AvoidMOVsShifterOperand", "true",
                                              "Avoid movs instructions with "
                                              "shifter operand">;
 
 // Some processors perform return stack prediction. CodeGen should avoid issue
 // "normal" call instructions to callees which do not return.
 def FeatureHasRetAddrStack : SubtargetFeature<"ret-addr-stack",
                                               "HasRetAddrStack", "true",
                                               "Has return address stack">;
 
 // Some processors have no branch predictor, which changes the expected cost of
 // taking a branch which affects the choice of whether to use predicated
 // instructions.
+// True if the subtarget has a branch predictor. Having
+// a branch predictor or not changes the expected cost of taking a branch
+// which affects the choice of whether to use predicated instructions.
 def FeatureHasNoBranchPredictor : SubtargetFeature<"no-branch-predictor",
                                                    "HasBranchPredictor", "false",
                                                    "Has no branch predictor">;
 
 /// DSP extension.
+/// True if the subtarget supports the DSP (saturating arith and such) instructions.
 def FeatureDSP            : SubtargetFeature<"dsp", "HasDSP", "true",
                                              "Supports DSP instructions in "
                                              "ARM and/or Thumb2">;
 
-// Multiprocessing extension.
+// True if the subtarget supports Multiprocessing extension (ARMv7 only).
 def FeatureMP             : SubtargetFeature<"mp", "HasMPExtension", "true",
                                         "Supports Multiprocessing extension">;
 
 // Virtualization extension - requires HW divide (ARMv7-AR ARMARM - 4.4.8).
 def FeatureVirtualization : SubtargetFeature<"virtualization",
                                              "HasVirtualization", "true",
                                              "Supports Virtualization extension",
                                              [FeatureHWDivThumb, FeatureHWDivARM]>;
 
 // Special TRAP encoding for NaCl, which looks like a TRAP in Thumb too.
 // See ARMInstrInfo.td for details.
+// True if NaCl TRAP instruction is generated instead of the regular TRAP.
 def FeatureNaClTrap       : SubtargetFeature<"nacl-trap", "UseNaClTrap", "true",
                                              "NaCl trap">;
 
+// True if the subtarget disallows unaligned memory
+// accesses for some types.  For details, see
+// ARMTargetLowering::allowsMisalignedMemoryAccesses().
 def FeatureStrictAlign    : SubtargetFeature<"strict-align",
                                              "StrictAlign", "true",
                                              "Disallow all unaligned memory "
                                              "access">;
 
+// Generate calls via indirect call instructions.
 def FeatureLongCalls      : SubtargetFeature<"long-calls", "GenLongCalls", "true",
                                              "Generate calls via indirect call "
                                              "instructions">;
 
+// Generate code that does not contain data access to code sections.
 def FeatureExecuteOnly    : SubtargetFeature<"execute-only",
                                              "GenExecuteOnly", "true",
                                              "Enable the generation of "
                                              "execute only code.">;
 
+// True if R9 is not available as a general purpose register.
 def FeatureReserveR9      : SubtargetFeature<"reserve-r9", "ReserveR9", "true",
                                              "Reserve R9, making it unavailable"
                                              " as GPR">;
 
+// True if MOVT / MOVW pairs are not used for materialization of
+// 32-bit imms (including global addresses).
 def FeatureNoMovt         : SubtargetFeature<"no-movt", "NoMovt", "true",
                                              "Don't use movt/movw pairs for "
                                              "32-bit imms">;
 
+/// Implicitly convert an instruction to a different one if its immediates
+/// cannot be encoded. For example, ADD r0, r1, #FFFFFFFF -> SUB r0, r1, #1.
 def FeatureNoNegativeImmediates
                           : SubtargetFeature<"no-neg-immediates",
                                              "NegativeImmediates", "false",
                                              "Convert immediates and instructions "
                                              "to their negated or complemented "
                                              "equivalent when the immediate does "
                                              "not fit in the encoding.">;
 
 // Use the MachineScheduler for instruction scheduling for the subtarget.
 def FeatureUseMISched: SubtargetFeature<"use-misched", "UseMISched", "true",
                                         "Use the MachineScheduler">;
 
+// False if scheduling should happen again after register allocation.
 def FeatureNoPostRASched : SubtargetFeature<"disable-postra-scheduler",
     "DisablePostRAScheduler", "true",
     "Don't schedule again after register allocation">;
 
 // Armv8.5-A extensions
 
+// Has speculation barrier.
 def FeatureSB       : SubtargetFeature<"sb", "HasSB", "true",
   "Enable v8.5a Speculation Barrier" >;
 
 // Armv8.6-A extensions
+
+// True if subtarget supports BFloat16 floating point operations.
 def FeatureBF16     : SubtargetFeature<"bf16", "HasBF16", "true",
   "Enable support for BFloat16 instructions",  [FeatureNEON]>;
 
+// True if subtarget supports 8-bit integer matrix multiply.
 def FeatureMatMulInt8 : SubtargetFeature<"i8mm", "HasMatMulInt8",
     "true", "Enable Matrix Multiply Int8 Extension", [FeatureNEON]>;
 
 // Armv8.1-M extensions
 
+// True if the processor supports the Low Overhead Branch extension.
 def FeatureLOB            : SubtargetFeature<"lob", "HasLOB", "true",
                                              "Enable Low Overhead Branch "
                                              "extensions">;
 
+// Mitigate against the cve-2021-35465 security vulnurability.
 def FeatureFixCMSE_CVE_2021_35465 : SubtargetFeature<"fix-cmse-cve-2021-35465",
                                         "FixCMSE_CVE_2021_35465", "true",
                                         "Mitigate against the cve-2021-35465 "
                                         "security vulnurability">;
 
 def FeaturePACBTI         : SubtargetFeature<"pacbti", "HasPACBTI", "true",
                                              "Enable Pointer Authentication and Branch "
                                              "Target Identification">;
 
+/// Don't place a BTI instruction after return-twice constructs (setjmp).
 def FeatureNoBTIAtReturnTwice : SubtargetFeature<"no-bti-at-return-twice",
                                                  "NoBTIAtReturnTwice", "true",
                                                  "Don't place a BTI instruction "
                                                  "after a return-twice">;
 
 //===----------------------------------------------------------------------===//
 // ARM architecture class
 //
 
 // A-series ISA
 def FeatureAClass : SubtargetFeature<"aclass", "ARMProcClass", "AClass",
                                      "Is application profile ('A' series)">;
 
 // R-series ISA
 def FeatureRClass : SubtargetFeature<"rclass", "ARMProcClass", "RClass",
                                      "Is realtime profile ('R' series)">;
 
 // M-series ISA
 def FeatureMClass : SubtargetFeature<"mclass", "ARMProcClass", "MClass",
                                      "Is microcontroller profile ('M' series)">;
 
-
+// True if Thumb2 instructions are supported.
 def FeatureThumb2 : SubtargetFeature<"thumb2", "HasThumb2", "true",
                                      "Enable Thumb2 instructions">;
 
+// True if subtarget does not support ARM mode execution.
 def FeatureNoARM  : SubtargetFeature<"noarm", "NoARM", "true",
                                      "Does not support ARM mode execution">;
 
 //===----------------------------------------------------------------------===//
 // ARM ISAa.
 //
+// Specify whether target support specific ARM ISA variants.
 
 def HasV4TOps   : SubtargetFeature<"v4t", "HasV4TOps", "true",
                                    "Support ARM v4T instructions">;
 
 def HasV5TOps   : SubtargetFeature<"v5t", "HasV5TOps", "true",
                                    "Support ARM v5T instructions",
                                    [HasV4TOps]>;
 
def FeatureCoprocCDE#i : SubtargetFeature<"cdecp"#i,
                                               "CoprocCDE["#i#"]", "true",
                                               "Coprocessor "#i#" ISA is CDEv1",
                                               [HasCDEOps]>;
 
 //===----------------------------------------------------------------------===//
 // Control codegen mitigation against Straight Line Speculation vulnerability.
 //===----------------------------------------------------------------------===//
 
+/// Harden against Straight Line Speculation for Returns and Indirect Branches.
 def FeatureHardenSlsRetBr : SubtargetFeature<"harden-sls-retbr",
   "HardenSlsRetBr", "true",
   "Harden against straight line speculation across RETurn and BranchRegister "
   "instructions">;
+/// Harden against Straight Line Speculation for indirect calls.
 def FeatureHardenSlsBlr : SubtargetFeature<"harden-sls-blr",
   "HardenSlsBlr", "true",
   "Harden against straight line speculation across indirect calls">;
+/// Generate thunk code for SLS mitigation in the normal text section.
 def FeatureHardenSlsNoComdat : SubtargetFeature<"harden-sls-nocomdat",
   "HardenSlsNoComdat", "true",
   "Generate thunk code for SLS mitigation in the normal text section">;
 
 //===----------------------------------------------------------------------===//
 // ARM Processor subtarget features.
 //
 

llvm/lib/Target/ARM/ARMISelLowering.cpp

ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   bool isThisReturn = false;
   bool isCmseNSCall   = false;
   bool isSibCall = false;
   bool PreferIndirect = false;
   bool GuardWithBTI = false;
 
   // Lower 'returns_twice' calls to a pseudo-instruction.
   if (CLI.CB && CLI.CB->getAttributes().hasFnAttr(Attribute::ReturnsTwice) &&
-      !Subtarget->getNoBTIAtReturnTwice())
+      !Subtarget->noBTIAtReturnTwice())
     GuardWithBTI = AFI->branchTargetEnforcement();
 
   // Determine whether this is a non-secure function call.
   if (CLI.CB && CLI.CB->getAttributes().hasFnAttr("cmse_nonsecure_call"))
     isCmseNSCall = true;
 
   // Disable tail calls if they're not supported.
   if (!Subtarget->supportsTailCall())

llvm/lib/Target/ARM/ARMSubtarget.h

enum ARMLdStMultipleTiming {
     /// Can load/store 1 register/cycle.
     SingleIssue,
     /// Can load/store 1 register/cycle, but needs an extra cycle for address
     /// computation and potentially also for register writeback.
     SingleIssuePlusExtras,
   };
 
 protected:
+// Bool members corresponding to the SubtargetFeatures defined in tablegen
+#define GET_SUBTARGETINFO_MACRO(ATTRIBUTE, DEFAULT, GETTER)                    \
+  bool ATTRIBUTE = DEFAULT;
+#include "ARMGenSubtargetInfo.inc"
+
   /// ARMProcFamily - ARM processor family: Cortex-A8, Cortex-A9, and others.
   ARMProcFamilyEnum ARMProcFamily = Others;
 
   /// ARMProcClass - ARM processor class: None, AClass, RClass or MClass.
   ARMProcClassEnum ARMProcClass = None;
 
   /// ARMArch - ARM architecture
   ARMArchEnum ARMArch = ARMv4t;
 
-  /// HasV4TOps, HasV5TOps, HasV5TEOps,
-  /// HasV6Ops, HasV6MOps, HasV6KOps, HasV6T2Ops, HasV7Ops, HasV8Ops -
-  /// Specify whether target support specific ARM ISA variants.
-  bool HasV4TOps = false;
-  bool HasV5TOps = false;
-  bool HasV5TEOps = false;
-  bool HasV6Ops = false;
-  bool HasV6MOps = false;
-  bool HasV6KOps = false;
-  bool HasV6T2Ops = false;
-  bool HasV7Ops = false;
-  bool HasV8Ops = false;
-  bool HasV8_1aOps = false;
-  bool HasV8_2aOps = false;
-  bool HasV8_3aOps = false;
-  bool HasV8_4aOps = false;
-  bool HasV8_5aOps = false;
-  bool HasV8_6aOps = false;
-  bool HasV8_8aOps = false;
-  bool HasV8_7aOps = false;
-  bool HasV9_0aOps = false;
-  bool HasV9_1aOps = false;
-  bool HasV9_2aOps = false;
-  bool HasV9_3aOps = false;
-  bool HasV8MBaselineOps = false;
-  bool HasV8MMainlineOps = false;
-  bool HasV8_1MMainlineOps = false;
-  bool HasMVEIntegerOps = false;
-  bool HasMVEFloatOps = false;
-  bool HasCDEOps = false;
-
-  /// HasVFPv2, HasVFPv3, HasVFPv4, HasFPARMv8, HasNEON - Specify what
-  /// floating point ISAs are supported.
-  bool HasVFPv2 = false;
-  bool HasVFPv3 = false;
-  bool HasVFPv4 = false;
-  bool HasFPARMv8 = false;
-  bool HasNEON = false;
-  bool HasFPRegs = false;
-  bool HasFPRegs16 = false;
-  bool HasFPRegs64 = false;
-
-  /// Versions of the VFP flags restricted to single precision, or to
-  /// 16 d-registers, or both.
-  bool HasVFPv2SP = false;
-  bool HasVFPv3SP = false;
-  bool HasVFPv4SP = false;
-  bool HasFPARMv8SP = false;
-  bool HasVFPv3D16 = false;
-  bool HasVFPv4D16 = false;
-  bool HasFPARMv8D16 = false;
-  bool HasVFPv3D16SP = false;
-  bool HasVFPv4D16SP = false;
-  bool HasFPARMv8D16SP = false;
-
-  /// HasDotProd - True if the ARMv8.2A dot product instructions are supported.
-  bool HasDotProd = false;
-
-  /// UseNEONForSinglePrecisionFP - if the NEONFP attribute has been
-  /// specified. Use the method useNEONForSinglePrecisionFP() to
-  /// determine if NEON should actually be used.
-  bool UseNEONForSinglePrecisionFP = false;
-
   /// UseMulOps - True if non-microcoded fused integer multiply-add and
   /// multiply-subtract instructions should be used.
   bool UseMulOps = false;
 
-  /// SlowFPVMLx - If the VFP2 / NEON instructions are available, indicates
-  /// whether the FP VML[AS] instructions are slow (if so, don't use them).
-  bool SlowFPVMLx = false;
-
-  /// SlowFPVFMx - If the VFP4 / NEON instructions are available, indicates
-  /// whether the FP VFM[AS] instructions are slow (if so, don't use them).
-  bool SlowFPVFMx = false;
-
-  /// HasVMLxForwarding - If true, NEON has special multiplier accumulator
-  /// forwarding to allow mul + mla being issued back to back.
-  bool HasVMLxForwarding = false;
-
-  /// SlowFPBrcc - True if floating point compare + branch is slow.
-  bool SlowFPBrcc = false;
-
-  /// InThumbMode - True if compiling for Thumb, false for ARM.
-  bool InThumbMode = false;
-
-  /// UseSoftFloat - True if we're using software floating point features.
-  bool UseSoftFloat = false;
-
-  /// UseMISched - True if MachineScheduler should be used for this subtarget.
-  bool UseMISched = false;
-
-  /// DisablePostRAScheduler - False if scheduling should happen again after
-  /// register allocation.
-  bool DisablePostRAScheduler = false;
-
-  /// HasThumb2 - True if Thumb2 instructions are supported.
-  bool HasThumb2 = false;
-
-  /// NoARM - True if subtarget does not support ARM mode execution.
-  bool NoARM = false;
-
-  /// ReserveR9 - True if R9 is not available as a general purpose register.
-  bool ReserveR9 = false;
-
-  /// NoMovt - True if MOVT / MOVW pairs are not used for materialization of
-  /// 32-bit imms (including global addresses).
-  bool NoMovt = false;
-
   /// SupportsTailCall - True if the OS supports tail call. The dynamic linker
   /// must be able to synthesize call stubs for interworking between ARM and
   /// Thumb.
   bool SupportsTailCall = false;
 
-  /// HasFP16 - True if subtarget supports half-precision FP conversions
-  bool HasFP16 = false;
-
-  /// HasFullFP16 - True if subtarget supports half-precision FP operations
-  bool HasFullFP16 = false;
-
-  /// HasFP16FML - True if subtarget supports half-precision FP fml operations
-  bool HasFP16FML = false;
-
-  /// HasBF16 - True if subtarget supports BFloat16 floating point operations
-  bool HasBF16 = false;
-
-  /// HasMatMulInt8 - True if subtarget supports 8-bit integer matrix multiply
-  bool HasMatMulInt8 = false;
-
-  /// HasD32 - True if subtarget has the full 32 double precision
-  /// FP registers for VFPv3.
-  bool HasD32 = false;
-
-  /// HasHardwareDivide - True if subtarget supports [su]div in Thumb mode
-  bool HasHardwareDivideInThumb = false;
-
-  /// HasHardwareDivideInARM - True if subtarget supports [su]div in ARM mode
-  bool HasHardwareDivideInARM = false;
-
-  /// HasDataBarrier - True if the subtarget supports DMB / DSB data barrier
-  /// instructions.
-  bool HasDataBarrier = false;
-
-  /// HasFullDataBarrier - True if the subtarget supports DFB data barrier
-  /// instruction.
-  bool HasFullDataBarrier = false;
-
-  /// HasV7Clrex - True if the subtarget supports CLREX instructions
-  bool HasV7Clrex = false;
-
-  /// HasAcquireRelease - True if the subtarget supports v8 atomics (LDA/LDAEX etc)
-  /// instructions
-  bool HasAcquireRelease = false;
-
-  /// Pref32BitThumb - If true, codegen would prefer 32-bit Thumb instructions
-  /// over 16-bit ones.
-  bool Pref32BitThumb = false;
-
-  /// AvoidCPSRPartialUpdate - If true, codegen would avoid using instructions
-  /// that partially update CPSR and add false dependency on the previous
-  /// CPSR setting instruction.
-  bool AvoidCPSRPartialUpdate = false;
-
-  /// CheapPredicableCPSRDef - If true, disable +1 predication cost
-  /// for instructions updating CPSR. Enabled for Cortex-A57.
-  bool CheapPredicableCPSRDef = false;
-
-  /// AvoidMOVsShifterOperand - If true, codegen should avoid using flag setting
-  /// movs with shifter operand (i.e. asr, lsl, lsr).
-  bool AvoidMOVsShifterOperand = false;
-
-  /// HasRetAddrStack - Some processors perform return stack prediction. CodeGen should
-  /// avoid issue "normal" call instructions to callees which do not return.
-  bool HasRetAddrStack = false;
-
-  /// HasBranchPredictor - True if the subtarget has a branch predictor. Having
-  /// a branch predictor or not changes the expected cost of taking a branch
-  /// which affects the choice of whether to use predicated instructions.
-  bool HasBranchPredictor = true;
-
-  /// HasMPExtension - True if the subtarget supports Multiprocessing
-  /// extension (ARMv7 only).
-  bool HasMPExtension = false;
-
-  /// HasVirtualization - True if the subtarget supports the Virtualization
-  /// extension.
-  bool HasVirtualization = false;
-
-  /// HasFP64 - If true, the floating point unit supports double
-  /// precision.
-  bool HasFP64 = false;
-
-  /// If true, the processor supports the Performance Monitor Extensions. These
-  /// include a generic cycle-counter as well as more fine-grained (often
-  /// implementation-specific) events.
-  bool HasPerfMon = false;
-
-  /// HasTrustZone - if true, processor supports TrustZone security extensions
-  bool HasTrustZone = false;
-
-  /// Has8MSecExt - if true, processor supports ARMv8-M Security Extensions
-  bool Has8MSecExt = false;
-
-  /// HasSHA2 - if true, processor supports SHA1 and SHA256
-  bool HasSHA2 = false;
-
-  /// HasAES - if true, processor supports AES
-  bool HasAES = false;
-
-  /// HasCrypto - if true, processor supports Cryptography extensions
-  bool HasCrypto = false;
-
-  /// HasCRC - if true, processor supports CRC instructions
-  bool HasCRC = false;
-
-  /// HasRAS - if true, the processor supports RAS extensions
-  bool HasRAS = false;
-
-  /// HasLOB - if true, the processor supports the Low Overhead Branch extension
-  bool HasLOB = false;
-
-  bool HasPACBTI = false;
-
-  /// If true, the instructions "vmov.i32 d0, #0" and "vmov.i32 q0, #0" are
-  /// particularly effective at zeroing a VFP register.
-  bool HasZeroCycleZeroing = false;
-
-  /// HasFPAO - if true, processor  does positive address offset computation faster
-  bool HasFPAO = false;
-
-  /// HasFuseAES - if true, processor executes back to back AES instruction
-  /// pairs faster.
-  bool HasFuseAES = false;
-
-  /// HasFuseLiterals - if true, processor executes back to back
-  /// bottom and top halves of literal generation faster.
-  bool HasFuseLiterals = false;
-
-  /// If true, if conversion may decide to leave some instructions unpredicated.
-  bool IsProfitableToUnpredicate = false;
-
-  /// If true, VMOV will be favored over VGETLNi32.
-  bool HasSlowVGETLNi32 = false;
-
-  /// If true, VMOV will be favored over VDUP.
-  bool HasSlowVDUP32 = false;
-
-  /// If true, VMOVSR will be favored over VMOVDRR.
-  bool PreferVMOVSR = false;
-
-  /// If true, ISHST barriers will be used for Release semantics.
-  bool PreferISHST = false;
-
-  /// If true, a VLDM/VSTM starting with an odd register number is considered to
-  /// take more microops than single VLDRS/VSTRS.
-  bool SlowOddRegister = false;
-
-  /// If true, loading into a D subregister will be penalized.
-  bool SlowLoadDSubregister = false;
-
-  /// If true, use a wider stride when allocating VFP registers.
-  bool UseWideStrideVFP = false;
-
-  /// If true, the AGU and NEON/FPU units are multiplexed.
-  bool HasMuxedUnits = false;
-
-  /// If true, VMOVS will never be widened to VMOVD.
-  bool DontWidenVMOVS = false;
-
-  /// If true, splat a register between VFP and NEON instructions.
-  bool SplatVFPToNeon = false;
-
-  /// If true, run the MLx expansion pass.
-  bool ExpandMLx = false;
-
-  /// If true, VFP/NEON VMLA/VMLS have special RAW hazards.
-  bool HasVMLxHazards = false;
-
-  // If true, read thread pointer from coprocessor register.
-  bool ReadTPHard = false;
-
-  /// If true, VMOVRS, VMOVSR and VMOVS will be converted from VFP to NEON.
-  bool UseNEONForFPMovs = false;
-
-  /// If true, VLDn instructions take an extra cycle for unaligned accesses.
-  bool CheckVLDnAlign = false;
-
-  /// If true, VFP instructions are not pipelined.
-  bool NonpipelinedVFP = false;
-
-  /// StrictAlign - If true, the subtarget disallows unaligned memory
-  /// accesses for some types.  For details, see
-  /// ARMTargetLowering::allowsMisalignedMemoryAccesses().
-  bool StrictAlign = false;
-
   /// RestrictIT - If true, the subtarget disallows generation of complex IT
   ///  blocks.
   bool RestrictIT = false;
 
-  /// HasDSP - If true, the subtarget supports the DSP (saturating arith
-  /// and such) instructions.
-  bool HasDSP = false;
-
-  /// NaCl TRAP instruction is generated instead of the regular TRAP.
-  bool UseNaClTrap = false;
-
-  /// Generate calls via indirect call instructions.
-  bool GenLongCalls = false;
-
-  /// Generate code that does not contain data access to code sections.
-  bool GenExecuteOnly = false;
-
-  /// Target machine allowed unsafe FP math (such as use of NEON fp)
-  bool UnsafeFPMath = false;
-
   /// UseSjLjEH - If true, the target uses SjLj exception handling (e.g. iOS).
   bool UseSjLjEH = false;
 
-  /// Has speculation barrier
-  bool HasSB = false;
-
-  /// Implicitly convert an instruction to a different one if its immediates
-  /// cannot be encoded. For example, ADD r0, r1, #FFFFFFFF -> SUB r0, r1, #1.
-  bool NegativeImmediates = true;
-
-  /// Mitigate against the cve-2021-35465 security vulnurability.
-  bool FixCMSE_CVE_2021_35465 = false;
-
-  /// Harden against Straight Line Speculation for Returns and Indirect
-  /// Branches.
-  bool HardenSlsRetBr = false;
-
-  /// Harden against Straight Line Speculation for indirect calls.
-  bool HardenSlsBlr = false;
-
-  /// Generate thunk code for SLS mitigation in the normal text section.
-  bool HardenSlsNoComdat = false;
-
   /// stackAlignment - The minimum alignment known to hold of the stack frame on
   /// entry to the function and which must be maintained by every function.
   Align stackAlignment = Align(4);
 
   /// CPUString - String name of used CPU.
   std::string CPUString;
 
   unsigned MaxInterleaveFactor = 1;
#include "ARMGenSubtargetInfo.inc"
   Triple TargetTriple;
 
   /// SchedModel - Processor specific instruction costs.
   MCSchedModel SchedModel;
 
   /// Selected instruction itineraries (one entry per itinerary class.)
   InstrItineraryData InstrItins;
 
-  /// NoBTIAtReturnTwice - Don't place a BTI instruction after
-  /// return-twice constructs (setjmp)
-  bool NoBTIAtReturnTwice = false;
-
   /// Options passed via command line that could influence the target
   const TargetOptions &Options;
 
   const ARMBaseTargetMachine &TM;
 
 public:
   /// This constructor initializes the data members to match that
   /// of the specified triple.
private:
   std::unique_ptr<RegisterBankInfo> RegBankInfo;
 
   void initializeEnvironment();
   void initSubtargetFeatures(StringRef CPU, StringRef FS);
   ARMFrameLowering *initializeFrameLowering(StringRef CPU, StringRef FS);
 
   std::bitset<8> CoprocCDE = {};
 public:
-  void computeIssueWidth();
+// Getters for SubtargetFeatures defined in tablegen
+#define GET_SUBTARGETINFO_MACRO(ATTRIBUTE, DEFAULT, GETTER)                    \
+  bool GETTER() const { return ATTRIBUTE; }
+#include "ARMGenSubtargetInfo.inc"
 
-  bool hasV4TOps()  const { return HasV4TOps;  }
-  bool hasV5TOps()  const { return HasV5TOps;  }
-  bool hasV5TEOps() const { return HasV5TEOps; }
-  bool hasV6Ops()   const { return HasV6Ops;   }
-  bool hasV6MOps()  const { return HasV6MOps;  }
-  bool hasV6KOps()  const { return HasV6KOps; }
-  bool hasV6T2Ops() const { return HasV6T2Ops; }
-  bool hasV7Ops()   const { return HasV7Ops;  }
-  bool hasV8Ops()   const { return HasV8Ops;  }
-  bool hasV8_1aOps() const { return HasV8_1aOps; }
-  bool hasV8_2aOps() const { return HasV8_2aOps; }
-  bool hasV8_3aOps() const { return HasV8_3aOps; }
-  bool hasV8_4aOps() const { return HasV8_4aOps; }
-  bool hasV8_5aOps() const { return HasV8_5aOps; }
-  bool hasV8_6aOps() const { return HasV8_6aOps; }
-  bool hasV8_7aOps() const { return HasV8_7aOps; }
-  bool hasV8_8aOps() const { return HasV8_8aOps; }
-  bool hasV9_0aOps() const { return HasV9_0aOps; }
-  bool hasV9_1aOps() const { return HasV9_1aOps; }
-  bool hasV9_2aOps() const { return HasV9_2aOps; }
-  bool hasV9_3aOps() const { return HasV9_3aOps; }
-  bool hasV8MBaselineOps() const { return HasV8MBaselineOps; }
-  bool hasV8MMainlineOps() const { return HasV8MMainlineOps; }
-  bool hasV8_1MMainlineOps() const { return HasV8_1MMainlineOps; }
-  bool hasMVEIntegerOps() const { return HasMVEIntegerOps; }
-  bool hasMVEFloatOps() const { return HasMVEFloatOps; }
-  bool hasCDEOps() const { return HasCDEOps; }
-  bool hasFPRegs() const { return HasFPRegs; }
-  bool hasFPRegs16() const { return HasFPRegs16; }
-  bool hasFPRegs64() const { return HasFPRegs64; }
+  void computeIssueWidth();
 
   /// @{
   /// These functions are obsolete, please consider adding subtarget features
   /// or properties instead of calling them.
   bool isCortexA5() const { return ARMProcFamily == CortexA5; }
   bool isCortexA7() const { return ARMProcFamily == CortexA7; }
   bool isCortexA8() const { return ARMProcFamily == CortexA8; }
   bool isCortexA9() const { return ARMProcFamily == CortexA9; }
   bool isCortexA15() const { return ARMProcFamily == CortexA15; }
   bool isSwift()    const { return ARMProcFamily == Swift; }
   bool isCortexM3() const { return ARMProcFamily == CortexM3; }
   bool isCortexM7() const { return ARMProcFamily == CortexM7; }
   bool isLikeA9() const { return isCortexA9() || isCortexA15() || isKrait(); }
   bool isCortexR5() const { return ARMProcFamily == CortexR5; }
   bool isKrait() const { return ARMProcFamily == Krait; }
   /// @}
 
   bool hasARMOps() const { return !NoARM; }
 
-  bool hasVFP2Base() const { return HasVFPv2SP; }
-  bool hasVFP3Base() const { return HasVFPv3D16SP; }
-  bool hasVFP4Base() const { return HasVFPv4D16SP; }
-  bool hasFPARMv8Base() const { return HasFPARMv8D16SP; }
-  bool hasNEON() const { return HasNEON;  }
-  bool hasSHA2() const { return HasSHA2; }
-  bool hasAES() const { return HasAES; }
-  bool hasCrypto() const { return HasCrypto; }
-  bool hasDotProd() const { return HasDotProd; }
-  bool hasCRC() const { return HasCRC; }
-  bool hasRAS() const { return HasRAS; }
-  bool hasLOB() const { return HasLOB; }
-  bool hasPACBTI() const { return HasPACBTI; }
-  bool hasVirtualization() const { return HasVirtualization; }
-
   bool useNEONForSinglePrecisionFP() const {
-    return hasNEON() && UseNEONForSinglePrecisionFP;
+    return hasNEON() && hasNEONForFP();
   }
 
-  bool hasDivideInThumbMode() const { return HasHardwareDivideInThumb; }
-  bool hasDivideInARMMode() const { return HasHardwareDivideInARM; }
-  bool hasDataBarrier() const { return HasDataBarrier; }
-  bool hasFullDataBarrier() const { return HasFullDataBarrier; }
-  bool hasV7Clrex() const { return HasV7Clrex; }
-  bool hasAcquireRelease() const { return HasAcquireRelease; }
+  bool hasVFP2Base() const { return hasVFPv2SP(); }
+  bool hasVFP3Base() const { return hasVFPv3D16SP(); }
+  bool hasVFP4Base() const { return hasVFPv4D16SP(); }
+  bool hasFPARMv8Base() const { return hasFPARMv8D16SP(); }
 
   bool hasAnyDataBarrier() const {
     return HasDataBarrier || (hasV6Ops() && !isThumb());
   }
 
   bool useMulOps() const { return UseMulOps; }
   bool useFPVMLx() const { return !SlowFPVMLx; }
   bool useFPVFMx() const {
     return !isTargetDarwin() && hasVFP4Base() && !SlowFPVFMx;
   }
   bool useFPVFMx16() const { return useFPVFMx() && hasFullFP16(); }
   bool useFPVFMx64() const { return useFPVFMx() && hasFP64(); }
-  bool hasVMLxForwarding() const { return HasVMLxForwarding; }
-  bool isFPBrccSlow() const { return SlowFPBrcc; }
-  bool hasFP64() const { return HasFP64; }
-  bool hasPerfMon() const { return HasPerfMon; }
-  bool hasTrustZone() const { return HasTrustZone; }
-  bool has8MSecExt() const { return Has8MSecExt; }
-  bool hasZeroCycleZeroing() const { return HasZeroCycleZeroing; }
-  bool hasFPAO() const { return HasFPAO; }
-  bool isProfitableToUnpredicate() const { return IsProfitableToUnpredicate; }
-  bool hasSlowVGETLNi32() const { return HasSlowVGETLNi32; }
-  bool hasSlowVDUP32() const { return HasSlowVDUP32; }
-  bool preferVMOVSR() const { return PreferVMOVSR; }
-  bool preferISHSTBarriers() const { return PreferISHST; }
-  bool expandMLx() const { return ExpandMLx; }
-  bool hasVMLxHazards() const { return HasVMLxHazards; }
-  bool hasSlowOddRegister() const { return SlowOddRegister; }
-  bool hasSlowLoadDSubregister() const { return SlowLoadDSubregister; }
-  bool useWideStrideVFP() const { return UseWideStrideVFP; }
-  bool hasMuxedUnits() const { return HasMuxedUnits; }
-  bool dontWidenVMOVS() const { return DontWidenVMOVS; }
-  bool useSplatVFPToNeon() const { return SplatVFPToNeon; }
-  bool useNEONForFPMovs() const { return UseNEONForFPMovs; }
-  bool checkVLDnAccessAlignment() const { return CheckVLDnAlign; }
-  bool nonpipelinedVFP() const { return NonpipelinedVFP; }
-  bool prefers32BitThumb() const { return Pref32BitThumb; }
-  bool avoidCPSRPartialUpdate() const { return AvoidCPSRPartialUpdate; }
-  bool cheapPredicableCPSRDef() const { return CheapPredicableCPSRDef; }
-  bool avoidMOVsShifterOperand() const { return AvoidMOVsShifterOperand; }
-  bool hasRetAddrStack() const { return HasRetAddrStack; }
-  bool hasBranchPredictor() const { return HasBranchPredictor; }
-  bool hasMPExtension() const { return HasMPExtension; }
-  bool hasDSP() const { return HasDSP; }
-  bool useNaClTrap() const { return UseNaClTrap; }
   bool useSjLjEH() const { return UseSjLjEH; }
-  bool hasSB() const { return HasSB; }
-  bool genLongCalls() const { return GenLongCalls; }
-  bool genExecuteOnly() const { return GenExecuteOnly; }
   bool hasBaseDSP() const {
     if (isThumb())
       return hasDSP();
     else
       return hasV5TEOps();
   }
 
-  bool hasFP16() const { return HasFP16; }
-  bool hasD32() const { return HasD32; }
-  bool hasFullFP16() const { return HasFullFP16; }
-  bool hasFP16FML() const { return HasFP16FML; }
-  bool hasBF16() const { return HasBF16; }
-
-  bool hasFuseAES() const { return HasFuseAES; }
-  bool hasFuseLiterals() const { return HasFuseLiterals; }
   /// Return true if the CPU supports any kind of instruction fusion.
   bool hasFusion() const { return hasFuseAES() || hasFuseLiterals(); }
 
-  bool hasMatMulInt8() const { return HasMatMulInt8; }
-
   const Triple &getTargetTriple() const { return TargetTriple; }
 
   bool isTargetDarwin() const { return TargetTriple.isOSDarwin(); }
   bool isTargetIOS() const { return TargetTriple.isiOS(); }
   bool isTargetWatchOS() const { return TargetTriple.isWatchOS(); }
   bool isTargetWatchABI() const { return TargetTriple.isWatchABI(); }
   bool isTargetDriverKit() const { return TargetTriple.isDriverKit(); }
   bool isTargetLinux() const { return TargetTriple.isOSLinux(); }
#include "ARMGenSubtargetInfo.inc"
   bool isAPCS_ABI() const;
   bool isAAPCS_ABI() const;
   bool isAAPCS16_ABI() const;
 
   bool isROPI() const;
   bool isRWPI() const;
 
   bool useMachineScheduler() const { return UseMISched; }
-  bool disablePostRAScheduler() const { return DisablePostRAScheduler; }
-  bool useSoftFloat() const { return UseSoftFloat; }
-  bool isThumb() const { return InThumbMode; }
   bool hasMinSize() const { return OptMinSize; }
-  bool isThumb1Only() const { return InThumbMode && !HasThumb2; }
-  bool isThumb2() const { return InThumbMode && HasThumb2; }
-  bool hasThumb2() const { return HasThumb2; }
+  bool isThumb1Only() const { return isThumb() && !hasThumb2(); }
+  bool isThumb2() const { return isThumb() && hasThumb2(); }
   bool isMClass() const { return ARMProcClass == MClass; }
   bool isRClass() const { return ARMProcClass == RClass; }
   bool isAClass() const { return ARMProcClass == AClass; }
-  bool isReadTPHard() const { return ReadTPHard; }
 
   bool isR9Reserved() const {
     return isTargetMachO() ? (ReserveR9 || !HasV6Ops) : ReserveR9;
   }
 
   MCPhysReg getFramePointerReg() const {
     if (isTargetDarwin() || (!isTargetWindows() && isThumb()))
       return ARM::R7;
getMVEVectorCostFactor(TargetTransformInfo::TargetCostKind CostKind) const {
     if (CostKind == TargetTransformInfo::TCK_CodeSize)
       return 1;
     return MVEVectorCostFactor;
   }
 
   bool ignoreCSRForAllocationOrder(const MachineFunction &MF,
                                    unsigned PhysReg) const override;
   unsigned getGPRAllocationOrder(const MachineFunction &MF) const;
-
-  bool fixCMSE_CVE_2021_35465() const { return FixCMSE_CVE_2021_35465; }
-
-  bool hardenSlsRetBr() const { return HardenSlsRetBr; }
-  bool hardenSlsBlr() const { return HardenSlsBlr; }
-  bool hardenSlsNoComdat() const { return HardenSlsNoComdat; }
-
-  bool getNoBTIAtReturnTwice() const { return NoBTIAtReturnTwice; }
 };
 
 } // end namespace llvm
 
 #endif  // LLVM_LIB_TARGET_ARM_ARMSUBTARGET_H

llvm/lib/Target/ARM/ARMSubtarget.cpp

case RestrictedIT:
     RestrictIT = true;
     break;
   }
 
   // NEON f32 ops are non-IEEE 754 compliant. Darwin is ok with it by default.
   const FeatureBitset &Bits = getFeatureBits();
   if ((Bits[ARM::ProcA5] || Bits[ARM::ProcA8]) && // Where this matters
       (Options.UnsafeFPMath || isTargetDarwin()))
-    UseNEONForSinglePrecisionFP = true;
+    HasNEONForFP = true;
 
   if (isRWPI())
     ReserveR9 = true;
 
   // If MVEVectorCostFactor is still 0 (has not been set to anything else), default it to 2
   if (MVEVectorCostFactor == 0)
     MVEVectorCostFactor = 2;
 

llvm/utils/TableGen/SubtargetEmitter.cpp

void SubtargetEmitter::run(raw_ostream &OS) {
 
   DenseMap<Record *, unsigned> FeatureMap;
 
   OS << "namespace llvm {\n";
   Enumeration(OS, FeatureMap);
   OS << "} // end namespace llvm\n\n";
   OS << "#endif // GET_SUBTARGETINFO_ENUM\n\n";
 
+  OS << "\n#ifdef GET_SUBTARGETINFO_MACRO\n";
+  std::vector<Record *> FeatureList =
+      Records.getAllDerivedDefinitions("SubtargetFeature");
+  llvm::sort(FeatureList, LessRecordFieldName());
+  for (const Record *Feature : FeatureList) {
+    const StringRef Attribute = Feature->getValueAsString("Attribute");
+    const StringRef Value = Feature->getValueAsString("Value");
+
+    // Only handle boolean features for now, excluding BitVectors and enums.
+    const bool IsBool = (Value == "false" || Value == "true") &&
+                        !StringRef(Attribute).contains('[');
+    if (!IsBool)
+      continue;
+
+    // Some features default to true, with values set to false if enabled.
+    const char *Default = Value == "false" ? "true" : "false";
+
+    // Define the getter with lowercased first char: xxxYyy() { return XxxYyy; }
+    const auto Getter = Attribute.substr(0, 1).lower() + Attribute.substr(1);
+
+    OS << "GET_SUBTARGETINFO_MACRO(" << Attribute << ", " << Default << ", "
+       << Getter << ")\n";
+  }
+  OS << "#undef GET_SUBTARGETINFO_MACRO\n";
+  OS << "#endif // GET_SUBTARGETINFO_MACRO\n\n";
+
   OS << "\n#ifdef GET_SUBTARGETINFO_MC_DESC\n";
   OS << "#undef GET_SUBTARGETINFO_MC_DESC\n\n";
 
   OS << "namespace llvm {\n";
 #if 0
   OS << "namespace {\n";
 #endif
   unsigned NumFeatures = FeatureKeyValues(OS, FeatureMap);