[NFC][clang][FMV][TargetInfo] Refactor API for FMV feature priority. (#116257)

Currently we have code with target hooks in CodeGenModule shared between
X86 and AArch64 for sorting MultiVersionResolverOptions. Those are used
when generating IFunc resolvers for FMV. The RISCV target has different
criteria for sorting, therefore it repeats sorting after calling
CodeGenFunction::EmitMultiVersionResolver.

I am moving the FMV priority logic in TargetInfo, so that it can be
implemented by the TargetParser which then makes it possible to query it
from llvm. Here is an example why this is handy:
https://github.com/llvm/llvm-project/pull/87939

10 files changed, 155 insertions, 193 deletions

diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index eb8a3ad..4efc184 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -705,18 +705,8 @@ AArch64TargetInfo::getVScaleRange(const LangOptions &LangOpts) const {
   return std::nullopt;
 }
 
-unsigned AArch64TargetInfo::multiVersionSortPriority(StringRef Name) const {
-  if (Name == "default")
-    return 0;
-  if (auto Ext = llvm::AArch64::parseFMVExtension(Name))
-    return Ext->Priority;
-  return 0;
-}
-
-unsigned AArch64TargetInfo::multiVersionFeatureCost() const {
-  // Take the maximum priority as per feature cost, so more features win.
-  constexpr unsigned MaxFMVPriority = 1000;
-  return MaxFMVPriority;
+unsigned AArch64TargetInfo::getFMVPriority(ArrayRef<StringRef> Features) const {
+  return llvm::AArch64::getFMVPriority(Features);
 }
 
 bool AArch64TargetInfo::doesFeatureAffectCodeGen(StringRef Name) const {
diff --git a/clang/lib/Basic/Targets/AArch64.h b/clang/lib/Basic/Targets/AArch64.h
index 4c25bdb..68a8b1e 100644
--- a/clang/lib/Basic/Targets/AArch64.h
+++ b/clang/lib/Basic/Targets/AArch64.h
@@ -137,8 +137,7 @@ public:
   void fillValidCPUList(SmallVectorImpl<StringRef> &Values) const override;
   bool setCPU(const std::string &Name) override;
 
-  unsigned multiVersionSortPriority(StringRef Name) const override;
-  unsigned multiVersionFeatureCost() const override;
+  unsigned getFMVPriority(ArrayRef<StringRef> Features) const override;
 
   bool useFP16ConversionIntrinsics() const override {
     return false;
diff --git a/clang/lib/Basic/Targets/RISCV.cpp b/clang/lib/Basic/Targets/RISCV.cpp
index 0f8607c..a541dfed 100644
--- a/clang/lib/Basic/Targets/RISCV.cpp
+++ b/clang/lib/Basic/Targets/RISCV.cpp
@@ -423,6 +423,24 @@ ParsedTargetAttr RISCVTargetInfo::parseTargetAttr(StringRef Features) const {
   Features.split(AttrFeatures, ";");
   bool FoundArch = false;
 
+  auto handleArchExtension = [](StringRef AttrString,
+                                std::vector<std::string> &Features) {
+    SmallVector<StringRef, 1> Exts;
+    AttrString.split(Exts, ",");
+    for (auto Ext : Exts) {
+      if (Ext.empty())
+        continue;
+
+      StringRef ExtName = Ext.substr(1);
+      std::string TargetFeature =
+          llvm::RISCVISAInfo::getTargetFeatureForExtension(ExtName);
+      if (!TargetFeature.empty())
+        Features.push_back(Ext.front() + TargetFeature);
+      else
+        Features.push_back(Ext.str());
+    }
+  };
+
   for (auto &Feature : AttrFeatures) {
     Feature = Feature.trim();
     StringRef AttrString = Feature.split("=").second.trim();
@@ -436,20 +454,7 @@ ParsedTargetAttr RISCVTargetInfo::parseTargetAttr(StringRef Features) const {
 
       if (AttrString.starts_with("+")) {
         // EXTENSION like arch=+v,+zbb
-        SmallVector<StringRef, 1> Exts;
-        AttrString.split(Exts, ",");
-        for (auto Ext : Exts) {
-          if (Ext.empty())
-            continue;
-
-          StringRef ExtName = Ext.substr(1);
-          std::string TargetFeature =
-              llvm::RISCVISAInfo::getTargetFeatureForExtension(ExtName);
-          if (!TargetFeature.empty())
-            Ret.Features.push_back(Ext.front() + TargetFeature);
-          else
-            Ret.Features.push_back(Ext.str());
-        }
+        handleArchExtension(AttrString, Ret.Features);
       } else {
         // full-arch-string like arch=rv64gcv
         handleFullArchString(AttrString, Ret.Features);
@@ -475,11 +480,35 @@ ParsedTargetAttr RISCVTargetInfo::parseTargetAttr(StringRef Features) const {
       Ret.Tune = AttrString;
     } else if (Feature.starts_with("priority")) {
       // Skip because it only use for FMV.
+    } else if (Feature.starts_with("+")) {
+      // Handle target_version/target_clones attribute strings
+      // that are already delimited by ','
+      handleArchExtension(Feature, Ret.Features);
     }
   }
   return Ret;
 }
 
+unsigned RISCVTargetInfo::getFMVPriority(ArrayRef<StringRef> Features) const {
+  // Priority is explicitly specified on RISC-V unlike on other targets, where
+  // it is derived by all the features of a specific version. Therefore if a
+  // feature contains the priority string, then return it immediately.
+  for (StringRef Feature : Features) {
+    auto [LHS, RHS] = Feature.rsplit(';');
+    if (LHS.consume_front("priority="))
+      Feature = LHS;
+    else if (RHS.consume_front("priority="))
+      Feature = RHS;
+    else
+      continue;
+    unsigned Priority;
+    if (!Feature.getAsInteger(0, Priority))
+      return Priority;
+  }
+  // Default Priority is zero.
+  return 0;
+}
+
 TargetInfo::CallingConvCheckResult
 RISCVTargetInfo::checkCallingConvention(CallingConv CC) const {
   switch (CC) {
diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
index 3544ea6..68f10e7 100644
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -122,6 +122,7 @@ public:
   void fillValidTuneCPUList(SmallVectorImpl<StringRef> &Values) const override;
   bool supportsTargetAttributeTune() const override { return true; }
   ParsedTargetAttr parseTargetAttr(StringRef Str) const override;
+  unsigned getFMVPriority(ArrayRef<StringRef> Features) const override;
 
   std::pair<unsigned, unsigned> hardwareInterferenceSizes() const override {
     return std::make_pair(32, 32);
diff --git a/clang/lib/Basic/Targets/X86.cpp b/clang/lib/Basic/Targets/X86.cpp
index 5993257..38714d0 100644
--- a/clang/lib/Basic/Targets/X86.cpp
+++ b/clang/lib/Basic/Targets/X86.cpp
@@ -1364,19 +1364,26 @@ static llvm::X86::ProcessorFeatures getFeature(StringRef Name) {
   // correct, so it asserts if the value is out of range.
 }
 
-unsigned X86TargetInfo::multiVersionSortPriority(StringRef Name) const {
-  // Valid CPUs have a 'key feature' that compares just better than its key
-  // feature.
-  using namespace llvm::X86;
-  CPUKind Kind = parseArchX86(Name);
-  if (Kind != CK_None) {
-    ProcessorFeatures KeyFeature = getKeyFeature(Kind);
-    return (getFeaturePriority(KeyFeature) << 1) + 1;
-  }
-
-  // Now we know we have a feature, so get its priority and shift it a few so
-  // that we have sufficient room for the CPUs (above).
-  return getFeaturePriority(getFeature(Name)) << 1;
+unsigned X86TargetInfo::getFMVPriority(ArrayRef<StringRef> Features) const {
+  auto getPriority = [this](StringRef Feature) -> unsigned {
+    // Valid CPUs have a 'key feature' that compares just better than its key
+    // feature.
+    using namespace llvm::X86;
+    CPUKind Kind = parseArchX86(Feature);
+    if (Kind != CK_None) {
+      ProcessorFeatures KeyFeature = getKeyFeature(Kind);
+      return (getFeaturePriority(KeyFeature) << 1) + 1;
+    }
+    // Now we know we have a feature, so get its priority and shift it a few so
+    // that we have sufficient room for the CPUs (above).
+    return getFeaturePriority(getFeature(Feature)) << 1;
+  };
+
+  unsigned Priority = 0;
+  for (StringRef Feature : Features)
+    if (!Feature.empty())
+      Priority = std::max(Priority, getPriority(Feature));
+  return Priority;
 }
 
 bool X86TargetInfo::validateCPUSpecificCPUDispatch(StringRef Name) const {
diff --git a/clang/lib/Basic/Targets/X86.h b/clang/lib/Basic/Targets/X86.h
index 06a7eed8..3ed36c8 100644
--- a/clang/lib/Basic/Targets/X86.h
+++ b/clang/lib/Basic/Targets/X86.h
@@ -384,7 +384,7 @@ public:
     return CPU != llvm::X86::CK_None;
   }
 
-  unsigned multiVersionSortPriority(StringRef Name) const override;
+  unsigned getFMVPriority(ArrayRef<StringRef> Features) const override;
 
   bool setFPMath(StringRef Name) override;
 
diff --git a/clang/lib/CodeGen/ABIInfo.cpp b/clang/lib/CodeGen/ABIInfo.cpp
index edd7146..8e76cf1 100644
--- a/clang/lib/CodeGen/ABIInfo.cpp
+++ b/clang/lib/CodeGen/ABIInfo.cpp
@@ -218,8 +218,8 @@ void ABIInfo::appendAttributeMangling(StringRef AttrStr,
     // only have "+" prefixes here.
     assert(LHS.starts_with("+") && RHS.starts_with("+") &&
            "Features should always have a prefix.");
-    return TI.multiVersionSortPriority(LHS.substr(1)) >
-           TI.multiVersionSortPriority(RHS.substr(1));
+    return TI.getFMVPriority({LHS.substr(1)}) >
+           TI.getFMVPriority({RHS.substr(1)});
   });
 
   bool IsFirst = true;
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index ef6bb4f..f8138e9 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -2828,23 +2828,17 @@ void CodeGenFunction::EmitKCFIOperandBundle(
     Bundles.emplace_back("kcfi", CGM.CreateKCFITypeId(FP->desugar()));
 }
 
-llvm::Value *CodeGenFunction::FormAArch64ResolverCondition(
-    const MultiVersionResolverOption &RO) {
-  llvm::SmallVector<StringRef, 8> CondFeatures;
-  for (const StringRef &Feature : RO.Conditions.Features)
-    CondFeatures.push_back(Feature);
-  if (!CondFeatures.empty()) {
-    return EmitAArch64CpuSupports(CondFeatures);
-  }
-  return nullptr;
+llvm::Value *
+CodeGenFunction::FormAArch64ResolverCondition(const FMVResolverOption &RO) {
+  return RO.Features.empty() ? nullptr : EmitAArch64CpuSupports(RO.Features);
 }
 
-llvm::Value *CodeGenFunction::FormX86ResolverCondition(
-    const MultiVersionResolverOption &RO) {
+llvm::Value *
+CodeGenFunction::FormX86ResolverCondition(const FMVResolverOption &RO) {
   llvm::Value *Condition = nullptr;
 
-  if (!RO.Conditions.Architecture.empty()) {
-    StringRef Arch = RO.Conditions.Architecture;
+  if (RO.Architecture) {
+    StringRef Arch = *RO.Architecture;
     // If arch= specifies an x86-64 micro-architecture level, test the feature
     // with __builtin_cpu_supports, otherwise use __builtin_cpu_is.
     if (Arch.starts_with("x86-64"))
@@ -2853,8 +2847,8 @@ llvm::Value *CodeGenFunction::FormX86ResolverCondition(
       Condition = EmitX86CpuIs(Arch);
   }
 
-  if (!RO.Conditions.Features.empty()) {
-    llvm::Value *FeatureCond = EmitX86CpuSupports(RO.Conditions.Features);
+  if (!RO.Features.empty()) {
+    llvm::Value *FeatureCond = EmitX86CpuSupports(RO.Features);
     Condition =
         Condition ? Builder.CreateAnd(Condition, FeatureCond) : FeatureCond;
   }
@@ -2884,7 +2878,7 @@ static void CreateMultiVersionResolverReturn(CodeGenModule &CGM,
 }
 
 void CodeGenFunction::EmitMultiVersionResolver(
-    llvm::Function *Resolver, ArrayRef<MultiVersionResolverOption> Options) {
+    llvm::Function *Resolver, ArrayRef<FMVResolverOption> Options) {
 
   llvm::Triple::ArchType ArchType =
       getContext().getTargetInfo().getTriple().getArch();
@@ -2907,26 +2901,8 @@ void CodeGenFunction::EmitMultiVersionResolver(
   }
 }
 
-static unsigned getPriorityFromAttrString(StringRef AttrStr) {
-  SmallVector<StringRef, 8> Attrs;
-
-  AttrStr.split(Attrs, ';');
-
-  // Default Priority is zero.
-  unsigned Priority = 0;
-  for (auto Attr : Attrs) {
-    if (Attr.consume_front("priority=")) {
-      unsigned Result;
-      if (!Attr.getAsInteger(0, Result))
-        Priority = Result;
-    }
-  }
-
-  return Priority;
-}
-
 void CodeGenFunction::EmitRISCVMultiVersionResolver(
-    llvm::Function *Resolver, ArrayRef<MultiVersionResolverOption> Options) {
+    llvm::Function *Resolver, ArrayRef<FMVResolverOption> Options) {
 
   if (getContext().getTargetInfo().getTriple().getOS() !=
       llvm::Triple::OSType::Linux) {
@@ -2942,20 +2918,10 @@ void CodeGenFunction::EmitRISCVMultiVersionResolver(
   bool HasDefault = false;
   unsigned DefaultIndex = 0;
 
-  SmallVector<CodeGenFunction::MultiVersionResolverOption, 10> CurrOptions(
-      Options);
-
-  llvm::stable_sort(
-      CurrOptions, [](const CodeGenFunction::MultiVersionResolverOption &LHS,
-                      const CodeGenFunction::MultiVersionResolverOption &RHS) {
-        return getPriorityFromAttrString(LHS.Conditions.Features[0]) >
-               getPriorityFromAttrString(RHS.Conditions.Features[0]);
-      });
-
   // Check the each candidate function.
-  for (unsigned Index = 0; Index < CurrOptions.size(); Index++) {
+  for (unsigned Index = 0; Index < Options.size(); Index++) {
 
-    if (CurrOptions[Index].Conditions.Features[0].starts_with("default")) {
+    if (Options[Index].Features.empty()) {
       HasDefault = true;
       DefaultIndex = Index;
       continue;
@@ -2963,15 +2929,6 @@ void CodeGenFunction::EmitRISCVMultiVersionResolver(
 
     Builder.SetInsertPoint(CurBlock);
 
-    std::vector<std::string> TargetAttrFeats =
-        getContext()
-            .getTargetInfo()
-            .parseTargetAttr(CurrOptions[Index].Conditions.Features[0])
-            .Features;
-
-    if (TargetAttrFeats.empty())
-      continue;
-
     // FeaturesCondition: The bitmask of the required extension has been
     // enabled by the runtime object.
     // (__riscv_feature_bits.features[i] & REQUIRED_BITMASK) ==
@@ -2994,20 +2951,32 @@ void CodeGenFunction::EmitRISCVMultiVersionResolver(
     // Without checking the length first, we may access an incorrect memory
     // address when using different versions.
     llvm::SmallVector<StringRef, 8> CurrTargetAttrFeats;
+    llvm::SmallVector<std::string, 8> TargetAttrFeats;
 
-    for (auto &Feat : TargetAttrFeats) {
-      StringRef CurrFeat = Feat;
-      if (CurrFeat.starts_with('+'))
-        CurrTargetAttrFeats.push_back(CurrFeat.substr(1));
+    for (StringRef Feat : Options[Index].Features) {
+      std::vector<std::string> FeatStr =
+          getContext().getTargetInfo().parseTargetAttr(Feat).Features;
+
+      assert(FeatStr.size() == 1 && "Feature string not delimited");
+
+      std::string &CurrFeat = FeatStr.front();
+      if (CurrFeat[0] == '+')
+        TargetAttrFeats.push_back(CurrFeat.substr(1));
     }
 
+    if (TargetAttrFeats.empty())
+      continue;
+
+    for (std::string &Feat : TargetAttrFeats)
+      CurrTargetAttrFeats.push_back(Feat);
+
     Builder.SetInsertPoint(CurBlock);
     llvm::Value *FeatsCondition = EmitRISCVCpuSupports(CurrTargetAttrFeats);
 
     llvm::BasicBlock *RetBlock = createBasicBlock("resolver_return", Resolver);
     CGBuilderTy RetBuilder(*this, RetBlock);
-    CreateMultiVersionResolverReturn(
-        CGM, Resolver, RetBuilder, CurrOptions[Index].Function, SupportsIFunc);
+    CreateMultiVersionResolverReturn(CGM, Resolver, RetBuilder,
+                                     Options[Index].Function, SupportsIFunc);
     llvm::BasicBlock *ElseBlock = createBasicBlock("resolver_else", Resolver);
 
     Builder.SetInsertPoint(CurBlock);
@@ -3019,9 +2988,8 @@ void CodeGenFunction::EmitRISCVMultiVersionResolver(
   // Finally, emit the default one.
   if (HasDefault) {
     Builder.SetInsertPoint(CurBlock);
-    CreateMultiVersionResolverReturn(CGM, Resolver, Builder,
-                                     CurrOptions[DefaultIndex].Function,
-                                     SupportsIFunc);
+    CreateMultiVersionResolverReturn(
+        CGM, Resolver, Builder, Options[DefaultIndex].Function, SupportsIFunc);
     return;
   }
 
@@ -3035,17 +3003,16 @@ void CodeGenFunction::EmitRISCVMultiVersionResolver(
 }
 
 void CodeGenFunction::EmitAArch64MultiVersionResolver(
-    llvm::Function *Resolver, ArrayRef<MultiVersionResolverOption> Options) {
+    llvm::Function *Resolver, ArrayRef<FMVResolverOption> Options) {
   assert(!Options.empty() && "No multiversion resolver options found");
-  assert(Options.back().Conditions.Features.size() == 0 &&
-         "Default case must be last");
+  assert(Options.back().Features.size() == 0 && "Default case must be last");
   bool SupportsIFunc = getContext().getTargetInfo().supportsIFunc();
   assert(SupportsIFunc &&
          "Multiversion resolver requires target IFUNC support");
   bool AArch64CpuInitialized = false;
   llvm::BasicBlock *CurBlock = createBasicBlock("resolver_entry", Resolver);
 
-  for (const MultiVersionResolverOption &RO : Options) {
+  for (const FMVResolverOption &RO : Options) {
     Builder.SetInsertPoint(CurBlock);
     llvm::Value *Condition = FormAArch64ResolverCondition(RO);
 
@@ -3081,7 +3048,7 @@ void CodeGenFunction::EmitAArch64MultiVersionResolver(
 }
 
 void CodeGenFunction::EmitX86MultiVersionResolver(
-    llvm::Function *Resolver, ArrayRef<MultiVersionResolverOption> Options) {
+    llvm::Function *Resolver, ArrayRef<FMVResolverOption> Options) {
 
   bool SupportsIFunc = getContext().getTargetInfo().supportsIFunc();
 
@@ -3090,7 +3057,7 @@ void CodeGenFunction::EmitX86MultiVersionResolver(
   Builder.SetInsertPoint(CurBlock);
   EmitX86CpuInit();
 
-  for (const MultiVersionResolverOption &RO : Options) {
+  for (const FMVResolverOption &RO : Options) {
     Builder.SetInsertPoint(CurBlock);
     llvm::Value *Condition = FormX86ResolverCondition(RO);
 
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 5c4d76c..eaea0d8 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -5334,35 +5334,27 @@ public:
 
   void EmitSanitizerStatReport(llvm::SanitizerStatKind SSK);
 
-  struct MultiVersionResolverOption {
+  struct FMVResolverOption {
     llvm::Function *Function;
-    struct Conds {
-      StringRef Architecture;
-      llvm::SmallVector<StringRef, 8> Features;
+    llvm::SmallVector<StringRef, 8> Features;
+    std::optional<StringRef> Architecture;
 
-      Conds(StringRef Arch, ArrayRef<StringRef> Feats)
-          : Architecture(Arch), Features(Feats) {}
-    } Conditions;
-
-    MultiVersionResolverOption(llvm::Function *F, StringRef Arch,
-                               ArrayRef<StringRef> Feats)
-        : Function(F), Conditions(Arch, Feats) {}
+    FMVResolverOption(llvm::Function *F, ArrayRef<StringRef> Feats,
+                      std::optional<StringRef> Arch = std::nullopt)
+        : Function(F), Features(Feats), Architecture(Arch) {}
   };
 
   // Emits the body of a multiversion function's resolver. Assumes that the
   // options are already sorted in the proper order, with the 'default' option
   // last (if it exists).
   void EmitMultiVersionResolver(llvm::Function *Resolver,
-                                ArrayRef<MultiVersionResolverOption> Options);
-  void
-  EmitX86MultiVersionResolver(llvm::Function *Resolver,
-                              ArrayRef<MultiVersionResolverOption> Options);
-  void
-  EmitAArch64MultiVersionResolver(llvm::Function *Resolver,
-                                  ArrayRef<MultiVersionResolverOption> Options);
-  void
-  EmitRISCVMultiVersionResolver(llvm::Function *Resolver,
-                                ArrayRef<MultiVersionResolverOption> Options);
+                                ArrayRef<FMVResolverOption> Options);
+  void EmitX86MultiVersionResolver(llvm::Function *Resolver,
+                                   ArrayRef<FMVResolverOption> Options);
+  void EmitAArch64MultiVersionResolver(llvm::Function *Resolver,
+                                       ArrayRef<FMVResolverOption> Options);
+  void EmitRISCVMultiVersionResolver(llvm::Function *Resolver,
+                                     ArrayRef<FMVResolverOption> Options);
 
 private:
   QualType getVarArgType(const Expr *Arg);
@@ -5381,10 +5373,9 @@ private:
   llvm::Value *EmitX86CpuSupports(ArrayRef<StringRef> FeatureStrs);
   llvm::Value *EmitX86CpuSupports(std::array<uint32_t, 4> FeatureMask);
   llvm::Value *EmitX86CpuInit();
-  llvm::Value *FormX86ResolverCondition(const MultiVersionResolverOption &RO);
+  llvm::Value *FormX86ResolverCondition(const FMVResolverOption &RO);
   llvm::Value *EmitAArch64CpuInit();
-  llvm::Value *
-  FormAArch64ResolverCondition(const MultiVersionResolverOption &RO);
+  llvm::Value *FormAArch64ResolverCondition(const FMVResolverOption &RO);
   llvm::Value *EmitAArch64CpuSupports(const CallExpr *E);
   llvm::Value *EmitAArch64CpuSupports(ArrayRef<StringRef> FeatureStrs);
 };
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 716c434..7189a46 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -4223,23 +4223,12 @@ void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD, llvm::GlobalValue *GV) {
 static void ReplaceUsesOfNonProtoTypeWithRealFunction(llvm::GlobalValue *Old,
                                                       llvm::Function *NewFn);
 
-static unsigned
-TargetMVPriority(const TargetInfo &TI,
-                 const CodeGenFunction::MultiVersionResolverOption &RO) {
-  unsigned Priority = 0;
-  unsigned NumFeatures = 0;
-  for (StringRef Feat : RO.Conditions.Features) {
-    Priority = std::max(Priority, TI.multiVersionSortPriority(Feat));
-    NumFeatures++;
-  }
-
-  if (!RO.Conditions.Architecture.empty())
-    Priority = std::max(
-        Priority, TI.multiVersionSortPriority(RO.Conditions.Architecture));
-
-  Priority += TI.multiVersionFeatureCost() * NumFeatures;
-
-  return Priority;
+static unsigned getFMVPriority(const TargetInfo &TI,
+                               const CodeGenFunction::FMVResolverOption &RO) {
+  llvm::SmallVector<StringRef, 8> Features{RO.Features};
+  if (RO.Architecture)
+    Features.push_back(*RO.Architecture);
+  return TI.getFMVPriority(Features);
 }
 
 // Multiversion functions should be at most 'WeakODRLinkage' so that a different
@@ -4285,7 +4274,7 @@ void CodeGenModule::emitMultiVersionFunctions() {
     // target_version("default")) or target_clones() is present and defined
     // in this TU. For other architectures it is always emitted.
     bool ShouldEmitResolver = !getTarget().getTriple().isAArch64();
-    SmallVector<CodeGenFunction::MultiVersionResolverOption, 10> Options;
+    SmallVector<CodeGenFunction::FMVResolverOption, 10> Options;
 
     getContext().forEachMultiversionedFunctionVersion(
         FD, [&](const FunctionDecl *CurFD) {
@@ -4293,20 +4282,17 @@ void CodeGenModule::emitMultiVersionFunctions() {
           bool IsDefined = CurFD->doesThisDeclarationHaveABody();
 
           if (const auto *TA = CurFD->getAttr<TargetAttr>()) {
-            TA->getAddedFeatures(Feats);
+            assert(getTarget().getTriple().isX86() && "Unsupported target");
+            TA->getX86AddedFeatures(Feats);
             llvm::Function *Func = createFunction(CurFD);
-            Options.emplace_back(Func, TA->getArchitecture(), Feats);
+            Options.emplace_back(Func, Feats, TA->getX86Architecture());
           } else if (const auto *TVA = CurFD->getAttr<TargetVersionAttr>()) {
             if (TVA->isDefaultVersion() && IsDefined)
               ShouldEmitResolver = true;
             llvm::Function *Func = createFunction(CurFD);
-            if (getTarget().getTriple().isRISCV()) {
-              Feats.push_back(TVA->getName());
-            } else {
-              assert(getTarget().getTriple().isAArch64());
-              TVA->getFeatures(Feats);
-            }
-            Options.emplace_back(Func, /*Architecture*/ "", Feats);
+            char Delim = getTarget().getTriple().isAArch64() ? '+' : ',';
+            TVA->getFeatures(Feats, Delim);
+            Options.emplace_back(Func, Feats);
           } else if (const auto *TC = CurFD->getAttr<TargetClonesAttr>()) {
             if (IsDefined)
               ShouldEmitResolver = true;
@@ -4315,21 +4301,15 @@ void CodeGenModule::emitMultiVersionFunctions() {
                 continue;
 
               llvm::Function *Func = createFunction(CurFD, I);
-              StringRef Architecture;
               Feats.clear();
-              if (getTarget().getTriple().isAArch64())
-                TC->getFeatures(Feats, I);
-              else if (getTarget().getTriple().isRISCV()) {
-                StringRef Version = TC->getFeatureStr(I);
-                Feats.push_back(Version);
+              if (getTarget().getTriple().isX86()) {
+                TC->getX86Feature(Feats, I);
+                Options.emplace_back(Func, Feats, TC->getX86Architecture(I));
               } else {
-                StringRef Version = TC->getFeatureStr(I);
-                if (Version.starts_with("arch="))
-                  Architecture = Version.drop_front(sizeof("arch=") - 1);
-                else if (Version != "default")
-                  Feats.push_back(Version);
+                char Delim = getTarget().getTriple().isAArch64() ? '+' : ',';
+                TC->getFeatures(Feats, I, Delim);
+                Options.emplace_back(Func, Feats);
               }
-              Options.emplace_back(Func, Architecture, Feats);
             }
           } else
             llvm_unreachable("unexpected MultiVersionKind");
@@ -4368,9 +4348,9 @@ void CodeGenModule::emitMultiVersionFunctions() {
 
     const TargetInfo &TI = getTarget();
     llvm::stable_sort(
-        Options, [&TI](const CodeGenFunction::MultiVersionResolverOption &LHS,
-                       const CodeGenFunction::MultiVersionResolverOption &RHS) {
-          return TargetMVPriority(TI, LHS) > TargetMVPriority(TI, RHS);
+        Options, [&TI](const CodeGenFunction::FMVResolverOption &LHS,
+                       const CodeGenFunction::FMVResolverOption &RHS) {
+          return getFMVPriority(TI, LHS) > getFMVPriority(TI, RHS);
         });
     CodeGenFunction CGF(*this);
     CGF.EmitMultiVersionResolver(ResolverFunc, Options);
@@ -4429,7 +4409,7 @@ void CodeGenModule::emitCPUDispatchDefinition(GlobalDecl GD) {
     ResolverFunc->setComdat(
         getModule().getOrInsertComdat(ResolverFunc->getName()));
 
-  SmallVector<CodeGenFunction::MultiVersionResolverOption, 10> Options;
+  SmallVector<CodeGenFunction::FMVResolverOption, 10> Options;
   const TargetInfo &Target = getTarget();
   unsigned Index = 0;
   for (const IdentifierInfo *II : DD->cpus()) {
@@ -4463,25 +4443,23 @@ void CodeGenModule::emitCPUDispatchDefinition(GlobalDecl GD) {
     llvm::erase_if(Features, [&Target](StringRef Feat) {
       return !Target.validateCpuSupports(Feat);
     });
-    Options.emplace_back(cast<llvm::Function>(Func), StringRef{}, Features);
+    Options.emplace_back(cast<llvm::Function>(Func), Features);
     ++Index;
   }
 
-  llvm::stable_sort(
-      Options, [](const CodeGenFunction::MultiVersionResolverOption &LHS,
-                  const CodeGenFunction::MultiVersionResolverOption &RHS) {
-        return llvm::X86::getCpuSupportsMask(LHS.Conditions.Features) >
-               llvm::X86::getCpuSupportsMask(RHS.Conditions.Features);
-      });
+  llvm::stable_sort(Options, [](const CodeGenFunction::FMVResolverOption &LHS,
+                                const CodeGenFunction::FMVResolverOption &RHS) {
+    return llvm::X86::getCpuSupportsMask(LHS.Features) >
+           llvm::X86::getCpuSupportsMask(RHS.Features);
+  });
 
   // If the list contains multiple 'default' versions, such as when it contains
   // 'pentium' and 'generic', don't emit the call to the generic one (since we
   // always run on at least a 'pentium'). We do this by deleting the 'least
   // advanced' (read, lowest mangling letter).
-  while (Options.size() > 1 &&
-         llvm::all_of(llvm::X86::getCpuSupportsMask(
-                          (Options.end() - 2)->Conditions.Features),
-                      [](auto X) { return X == 0; })) {
+  while (Options.size() > 1 && llvm::all_of(llvm::X86::getCpuSupportsMask(
+                                                (Options.end() - 2)->Features),
+                                            [](auto X) { return X == 0; })) {
     StringRef LHSName = (Options.end() - 2)->Function->getName();
     StringRef RHSName = (Options.end() - 1)->Function->getName();
     if (LHSName.compare(RHSName) < 0)