[NFC][clang][FMV][TargetInfo] Refactor API for FMV feature priority.

clang/include/clang/Basic/Attr.td

@@ -3260,33 +3260,28 @@ def Target : InheritableAttr {
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [TargetDocs];
   let AdditionalMembers = [{
-    StringRef getArchitecture() const {
+    std::optional<StringRef> getX86Architecture() const {
       StringRef Features = getFeaturesStr();
-      if (Features == "default") return {};
-
-      SmallVector<StringRef, 1> AttrFeatures;
-      Features.split(AttrFeatures, ",");
-
-      for (auto &Feature : AttrFeatures) {
+      SmallVector<StringRef, 4> AttrFeatures;
+      Features.split(AttrFeatures, ',');
+      for (StringRef Feature : AttrFeatures) {
         Feature = Feature.trim();
         if (Feature.starts_with("arch="))
           return Feature.drop_front(sizeof("arch=") - 1);
       }
-      return "";
+      return std::nullopt;
     }
 
     // Gets the list of features as simple string-refs with no +/- or 'no-'.
     // Only adds the items to 'Out' that are additions.
-    void getAddedFeatures(llvm::SmallVectorImpl<StringRef> &Out) const {
+    void getX86AddedFeatures(llvm::SmallVectorImpl<StringRef> &Out) const {
+      if (isDefaultVersion())
+        return;
       StringRef Features = getFeaturesStr();
-      if (Features == "default") return;
-
-      SmallVector<StringRef, 1> AttrFeatures;
-      Features.split(AttrFeatures, ",");
-
+      SmallVector<StringRef, 4> AttrFeatures;
+      Features.split(AttrFeatures, ',');
       for (auto &Feature : AttrFeatures) {
         Feature = Feature.trim();
-
         if (!Feature.starts_with("no-") && !Feature.starts_with("arch=") &&
             !Feature.starts_with("fpmath=") && !Feature.starts_with("tune="))
           Out.push_back(Feature);
@@ -3304,17 +3299,17 @@ def TargetVersion : InheritableAttr, TargetSpecificAttr<TargetArch<!listconcat(T
   let Documentation = [TargetVersionDocs];
   let AdditionalMembers = [{
     StringRef getName() const { return getNamesStr().trim(); }
-    bool isDefaultVersion() const {
-      return getName() == "default";
-    }
-    void getFeatures(llvm::SmallVectorImpl<StringRef> &Out) const {
-      if (isDefaultVersion()) return;
-      StringRef Features = getName();
 
-      SmallVector<StringRef, 8> AttrFeatures;
-      Features.split(AttrFeatures, "+");
+    bool isDefaultVersion() const { return getName() == "default"; }
 
-      for (auto &Feature : AttrFeatures) {
+    void getFeatures(llvm::SmallVectorImpl<StringRef> &Out,
+                     char Delim = '+') const {
+      if (isDefaultVersion())
+        return;
+      StringRef Features = getName();
+      SmallVector<StringRef, 4> AttrFeatures;
+      Features.split(AttrFeatures, Delim);
+      for (StringRef Feature : AttrFeatures) {
         Feature = Feature.trim();
         Out.push_back(Feature);
       }
@@ -3331,20 +3326,40 @@ def TargetClones : InheritableAttr {
     StringRef getFeatureStr(unsigned Index) const {
       return *(featuresStrs_begin() + Index);
     }
+
     bool isDefaultVersion(unsigned Index) const {
       return getFeatureStr(Index) == "default";
     }
+
     void getFeatures(llvm::SmallVectorImpl<StringRef> &Out,
-                     unsigned Index) const {
-      if (isDefaultVersion(Index)) return;
+                     unsigned Index, char Delim = '+') const {
+      if (isDefaultVersion(Index))
+        return;
       StringRef Features = getFeatureStr(Index);
-      SmallVector<StringRef, 8> AttrFeatures;
-      Features.split(AttrFeatures, "+");
-      for (auto &Feature : AttrFeatures) {
+      SmallVector<StringRef, 4> AttrFeatures;
+      Features.split(AttrFeatures, Delim);
+      for (StringRef Feature : AttrFeatures) {
         Feature = Feature.trim();
         Out.push_back(Feature);
       }
     }
+
+    std::optional<StringRef> getX86Architecture(unsigned Index) const {
+      StringRef Feature = getFeatureStr(Index);
+      if (Feature.starts_with("arch="))
+        return Feature.drop_front(sizeof("arch=") - 1);
+      return std::nullopt;
+    }
+
+    void getX86Feature(llvm::SmallVectorImpl<StringRef> &Out,
+                       unsigned Index) const {
+      if (isDefaultVersion(Index))
+        return;
+      if (getX86Architecture(Index))
+        return;
+      Out.push_back(getFeatureStr(Index));
+    }
+
     // Given an index into the 'featuresStrs' sequence, compute a unique
     // ID to be used with function name mangling for the associated variant.
     // This mapping is necessary due to a requirement that the mangling ID

clang/include/clang/Basic/TargetInfo.h

@@ -1525,14 +1525,10 @@ class TargetInfo : public TransferrableTargetInfo,
 
   // Return the target-specific priority for features/cpus/vendors so
   // that they can be properly sorted for checking.
-  virtual unsigned multiVersionSortPriority(StringRef Name) const {
+  virtual unsigned getFMVPriority(ArrayRef<StringRef> Features) const {
     return 0;
   }
 
-  // Return the target-specific cost for feature
-  // that taken into account in priority sorting.
-  virtual unsigned multiVersionFeatureCost() const { return 0; }
-
   // Validate the contents of the __builtin_cpu_is(const char*)
   // argument.
   virtual bool validateCpuIs(StringRef Name) const { return false; }

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 {

clang/lib/Basic/Targets/AArch64.h

@@ -137,8 +137,7 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
   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;

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) {

clang/lib/Basic/Targets/RISCV.h

@@ -122,6 +122,7 @@ class RISCVTargetInfo : public TargetInfo {
   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);

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 {

clang/lib/Basic/Targets/X86.h

@@ -384,7 +384,7 @@ class LLVM_LIBRARY_VISIBILITY X86TargetInfo : public TargetInfo {
     return CPU != llvm::X86::CK_None;
   }
 
-  unsigned multiVersionSortPriority(StringRef Name) const override;
+  unsigned getFMVPriority(ArrayRef<StringRef> Features) const override;
 
   bool setFPMath(StringRef Name) override;
 

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;