llvm · kazutakahirata · Oct 15, 2025 · Oct 13, 2025
diff --git a/llvm/include/llvm/Analysis/TargetLibraryInfo.h b/llvm/include/llvm/Analysis/TargetLibraryInfo.h
@@ -373,12 +373,10 @@ class TargetLibraryInfo {
   /// Disables all builtins.
   ///
   /// This can be used for options like -fno-builtin.
-  void disableAllFunctions() LLVM_ATTRIBUTE_UNUSED {
-    OverrideAsUnavailable.set();
-  }
+  [[maybe_unused]] void disableAllFunctions() { OverrideAsUnavailable.set(); }
 
   /// Forces a function to be marked as unavailable.
-  void setUnavailable(LibFunc F) LLVM_ATTRIBUTE_UNUSED {
+  [[maybe_unused]] void setUnavailable(LibFunc F) {
     assert(F < OverrideAsUnavailable.size() && "out-of-bounds LibFunc");
     OverrideAsUnavailable.set(F);
   }

diff --git a/llvm/include/llvm/CodeGen/LiveRangeCalc.h b/llvm/include/llvm/CodeGen/LiveRangeCalc.h
@@ -259,7 +259,7 @@ class LiveRangeCalc {
   /// jointly dominated by the blocks corresponding to the slot indices
   /// in @p Defs. This function is mainly for use in self-verification
   /// checks.
-  LLVM_ABI LLVM_ATTRIBUTE_UNUSED static bool
+  [[maybe_unused]] LLVM_ABI static bool
   isJointlyDominated(const MachineBasicBlock *MBB, ArrayRef<SlotIndex> Defs,
                      const SlotIndexes &Indexes);
 };

diff --git a/llvm/include/llvm/Support/DebugLog.h b/llvm/include/llvm/Support/DebugLog.h
@@ -221,12 +221,10 @@ constexpr ::llvm::StringRef strip_quotes(const char *Str) {
 #define LDBG_GET_DEBUG_TYPE_STR() LDBG_GET_DEBUG_TYPE_STR_(DEBUG_TYPE)
 
 /// Helper to call isCurrentDebugType with a StringRef.
-static LLVM_ATTRIBUTE_UNUSED bool ldbgIsCurrentDebugType(StringRef Type,
-                                                         int Level) {
+[[maybe_unused]] static bool ldbgIsCurrentDebugType(StringRef Type, int Level) {
   return ::llvm::isCurrentDebugType(Type.str().c_str(), Level);
 }
-static LLVM_ATTRIBUTE_UNUSED bool ldbgIsCurrentDebugType(int Level,
-                                                         StringRef Type) {
+[[maybe_unused]] static bool ldbgIsCurrentDebugType(int Level, StringRef Type) {
   return ::llvm::isCurrentDebugType(Type.str().c_str(), Level);
 }
 
@@ -302,7 +300,7 @@ class RAIINewLineStream final : public raw_ostream {
 };
 
 /// Remove the path prefix from the file name.
-static LLVM_ATTRIBUTE_UNUSED constexpr const char *
+[[maybe_unused]] static constexpr const char *
 getShortFileName(const char *path) {
   const char *filename = path;
   for (const char *p = path; *p != '\0'; ++p) {
@@ -315,7 +313,7 @@ getShortFileName(const char *path) {
 /// Compute the prefix for the debug log in the form of:
 /// "[DebugType] File:Line "
 /// Where the File is the file name without the path prefix.
-static LLVM_ATTRIBUTE_UNUSED std::string
+[[maybe_unused]] static std::string
 computePrefix(StringRef DebugType, const char *File, int Line, int Level) {
   std::string Prefix;
   raw_string_ostream OsPrefix(Prefix);
@@ -326,7 +324,7 @@ computePrefix(StringRef DebugType, const char *File, int Line, int Level) {
   return OsPrefix.str();
 }
 /// Overload allowing to swap the order of the DebugType and Level arguments.
-static LLVM_ATTRIBUTE_UNUSED std::string
+[[maybe_unused]] static std::string
 computePrefix(int Level, const char *File, int Line, StringRef DebugType) {
   return computePrefix(DebugType, File, Line, Level);
 }

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -819,7 +819,7 @@ void CodeGenPrepare::removeAllAssertingVHReferences(Value *V) {
 }
 
 // Verify BFI has been updated correctly by recomputing BFI and comparing them.
-void LLVM_ATTRIBUTE_UNUSED CodeGenPrepare::verifyBFIUpdates(Function &F) {
+[[maybe_unused]] void CodeGenPrepare::verifyBFIUpdates(Function &F) {
   DominatorTree NewDT(F);
   LoopInfo NewLI(NewDT);
   BranchProbabilityInfo NewBPI(F, NewLI, TLInfo);

diff --git a/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -1257,7 +1257,7 @@ void MachineCopyPropagation::BackwardCopyPropagateBlock(
   Tracker.clear();
 }
 
-static void LLVM_ATTRIBUTE_UNUSED printSpillReloadChain(
+[[maybe_unused]] static void printSpillReloadChain(
     DenseMap<MachineInstr *, SmallVector<MachineInstr *>> &SpillChain,
     DenseMap<MachineInstr *, SmallVector<MachineInstr *>> &ReloadChain,
     MachineInstr *Leader) {

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
@@ -181,8 +181,8 @@ DWARFDebugFrame::DWARFDebugFrame(Triple::ArchType Arch,
 
 DWARFDebugFrame::~DWARFDebugFrame() = default;
 
-static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
-                                              uint64_t Offset, int Length) {
+[[maybe_unused]] static void dumpDataAux(DataExtractor Data, uint64_t Offset,
+                                         int Length) {
   errs() << "DUMP: ";
   for (int i = 0; i < Length; ++i) {
     uint8_t c = Data.getU8(&Offset);

diff --git a/llvm/lib/ProfileData/InstrProf.cpp b/llvm/lib/ProfileData/InstrProf.cpp
@@ -302,7 +302,7 @@ void ProfOStream::patch(ArrayRef<PatchItem> P) {
 
 std::string getPGOFuncName(StringRef Name, GlobalValue::LinkageTypes Linkage,
                            StringRef FileName,
-                           uint64_t Version LLVM_ATTRIBUTE_UNUSED) {
+                           [[maybe_unused]] uint64_t Version) {
   // Value names may be prefixed with a binary '1' to indicate
   // that the backend should not modify the symbols due to any platform
   // naming convention. Do not include that '1' in the PGO profile name.

diff --git a/llvm/lib/Support/PrettyStackTrace.cpp b/llvm/lib/Support/PrettyStackTrace.cpp
@@ -141,7 +141,7 @@ extern "C" const char *__crashreporter_info__
 asm(".desc ___crashreporter_info__, 0x10");
 #endif
 
-static void setCrashLogMessage(const char *msg) LLVM_ATTRIBUTE_UNUSED;
+[[maybe_unused]] static void setCrashLogMessage(const char *msg);
 static void setCrashLogMessage(const char *msg) {
 #ifdef HAVE_CRASHREPORTERCLIENT_H
   (void)CRSetCrashLogMessage(msg);

diff --git a/llvm/lib/Target/ARM/ARMExpandPseudoInsts.cpp b/llvm/lib/Target/ARM/ARMExpandPseudoInsts.cpp
@@ -161,8 +161,8 @@ namespace {
     friend bool operator<(const NEONLdStTableEntry &TE, unsigned PseudoOpc) {
       return TE.PseudoOpc < PseudoOpc;
     }
-    friend bool LLVM_ATTRIBUTE_UNUSED operator<(unsigned PseudoOpc,
-                                                const NEONLdStTableEntry &TE) {
+    [[maybe_unused]] friend bool operator<(unsigned PseudoOpc,
+                                           const NEONLdStTableEntry &TE) {
       return PseudoOpc < TE.PseudoOpc;
     }
   };

diff --git a/llvm/lib/Target/Hexagon/HexagonBitSimplify.cpp b/llvm/lib/Target/Hexagon/HexagonBitSimplify.cpp
@@ -174,8 +174,8 @@ namespace {
     const TargetRegisterInfo *TRI;
   };
 
-  raw_ostream &operator<< (raw_ostream &OS, const PrintRegSet &P)
-    LLVM_ATTRIBUTE_UNUSED;
+  [[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS,
+                                           const PrintRegSet &P);
   raw_ostream &operator<< (raw_ostream &OS, const PrintRegSet &P) {
     OS << '{';
     for (unsigned R = P.RS.find_first(); R; R = P.RS.find_next(R))

diff --git a/llvm/lib/Target/Hexagon/HexagonCommonGEP.cpp b/llvm/lib/Target/Hexagon/HexagonCommonGEP.cpp
@@ -272,15 +272,14 @@ namespace {
       OS << *I << ' ' << **I << '\n';
   }
 
-  raw_ostream &operator<< (raw_ostream &OS,
-                           const NodeVect &S) LLVM_ATTRIBUTE_UNUSED;
+  [[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS, const NodeVect &S);
   raw_ostream &operator<< (raw_ostream &OS, const NodeVect &S) {
     dump_node_container(OS, S);
     return OS;
   }
 
-  raw_ostream &operator<< (raw_ostream &OS,
-                           const NodeToUsesMap &M) LLVM_ATTRIBUTE_UNUSED;
+  [[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS,
+                                           const NodeToUsesMap &M);
   raw_ostream &operator<< (raw_ostream &OS, const NodeToUsesMap &M){
     for (const auto &I : M) {
       const UseSet &Us = I.second;
@@ -914,9 +913,8 @@ namespace {
     const NodeToValueMap &Map;
   };
 
-  raw_ostream &operator<< (raw_ostream &OS,
-                           const LocationAsBlock &Loc) LLVM_ATTRIBUTE_UNUSED ;
-  raw_ostream &operator<< (raw_ostream &OS, const LocationAsBlock &Loc) {
+  [[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS,
+                                           const LocationAsBlock &Loc) {
     for (const auto &I : Loc.Map) {
       OS << I.first << " -> ";
       if (BasicBlock *B = cast_or_null<BasicBlock>(I.second))

diff --git a/llvm/lib/Target/Hexagon/HexagonEarlyIfConv.cpp b/llvm/lib/Target/Hexagon/HexagonEarlyIfConv.cpp
@@ -132,8 +132,7 @@ namespace {
     const TargetRegisterInfo &TRI;
     friend raw_ostream &operator<< (raw_ostream &OS, const PrintFP &P);
   };
-  raw_ostream &operator<<(raw_ostream &OS,
-                          const PrintFP &P) LLVM_ATTRIBUTE_UNUSED;
+  [[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS, const PrintFP &P);
   raw_ostream &operator<<(raw_ostream &OS, const PrintFP &P) {
     OS << "{ SplitB:" << PrintMB(P.FP.SplitB)
        << ", PredR:" << printReg(P.FP.PredR, &P.TRI)

diff --git a/llvm/lib/Target/Hexagon/HexagonGenPredicate.cpp b/llvm/lib/Target/Hexagon/HexagonGenPredicate.cpp
@@ -51,11 +51,11 @@ struct PrintRegister {
   const TargetRegisterInfo &TRI;
 };
 
-  raw_ostream &operator<< (raw_ostream &OS, const PrintRegister &PR)
-    LLVM_ATTRIBUTE_UNUSED;
-  raw_ostream &operator<< (raw_ostream &OS, const PrintRegister &PR) {
-    return OS << printReg(PR.Reg.Reg, &PR.TRI, PR.Reg.SubReg);
-  }
+[[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS,
+                                         const PrintRegister &PR);
+raw_ostream &operator<<(raw_ostream &OS, const PrintRegister &PR) {
+  return OS << printReg(PR.Reg.Reg, &PR.TRI, PR.Reg.SubReg);
+}
 
   class HexagonGenPredicate : public MachineFunctionPass {
   public:

diff --git a/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCTargetDesc.cpp b/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCTargetDesc.cpp
@@ -422,12 +422,12 @@ static MCTargetStreamer *createHexagonNullTargetStreamer(MCStreamer &S) {
   return new HexagonTargetStreamer(S);
 }
 
-static void LLVM_ATTRIBUTE_UNUSED clearFeature(MCSubtargetInfo* STI, uint64_t F) {
+[[maybe_unused]] static void clearFeature(MCSubtargetInfo *STI, uint64_t F) {
   if (STI->hasFeature(F))
     STI->ToggleFeature(F);
 }
 
-static bool LLVM_ATTRIBUTE_UNUSED checkFeature(MCSubtargetInfo* STI, uint64_t F) {
+[[maybe_unused]] static bool checkFeature(MCSubtargetInfo *STI, uint64_t F) {
   return STI->hasFeature(F);
 }
 

diff --git a/llvm/lib/Target/Sparc/SparcFrameLowering.cpp b/llvm/lib/Target/Sparc/SparcFrameLowering.cpp
@@ -246,8 +246,7 @@ SparcFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
   }
 }
 
-static bool LLVM_ATTRIBUTE_UNUSED verifyLeafProcRegUse(MachineRegisterInfo *MRI)
-{
+[[maybe_unused]] static bool verifyLeafProcRegUse(MachineRegisterInfo *MRI) {
 
   for (unsigned reg = SP::I0; reg <= SP::I7; ++reg)
     if (MRI->isPhysRegUsed(reg))

diff --git a/llvm/lib/Target/X86/X86FloatingPoint.cpp b/llvm/lib/Target/X86/X86FloatingPoint.cpp
@@ -602,8 +602,7 @@ namespace {
     friend bool operator<(const TableEntry &TE, unsigned V) {
       return TE.from < V;
     }
-    friend bool LLVM_ATTRIBUTE_UNUSED operator<(unsigned V,
-                                                const TableEntry &TE) {
+    [[maybe_unused]] friend bool operator<(unsigned V, const TableEntry &TE) {
       return V < TE.from;
     }
   };

diff --git a/llvm/lib/TargetParser/Host.cpp b/llvm/lib/TargetParser/Host.cpp
@@ -70,8 +70,8 @@
 
 using namespace llvm;
 
-static std::unique_ptr<llvm::MemoryBuffer>
-    LLVM_ATTRIBUTE_UNUSED getProcCpuinfoContent() {
+[[maybe_unused]] static std::unique_ptr<llvm::MemoryBuffer>
+getProcCpuinfoContent() {
   const char *CPUInfoFile = "/proc/cpuinfo";
   if (const char *CpuinfoIntercept = std::getenv("LLVM_CPUINFO"))
     CPUInfoFile = CpuinfoIntercept;

diff --git a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
@@ -396,9 +396,8 @@ class CHR {
 
 } // end anonymous namespace
 
-static inline
-raw_ostream LLVM_ATTRIBUTE_UNUSED &operator<<(raw_ostream &OS,
-                                              const CHRStats &Stats) {
+[[maybe_unused]] static inline raw_ostream &operator<<(raw_ostream &OS,
+                                                       const CHRStats &Stats) {
   Stats.print(OS);
   return OS;
 }
@@ -425,8 +424,8 @@ static bool shouldApply(Function &F, ProfileSummaryInfo &PSI) {
   return PSI.isFunctionEntryHot(&F);
 }
 
-static void LLVM_ATTRIBUTE_UNUSED dumpIR(Function &F, const char *Label,
-                                         CHRStats *Stats) {
+[[maybe_unused]] static void dumpIR(Function &F, const char *Label,
+                                    CHRStats *Stats) {
   StringRef FuncName = F.getName();
   StringRef ModuleName = F.getParent()->getName();
   (void)(FuncName); // Unused in release build.
@@ -1622,7 +1621,7 @@ static void insertTrivialPHIs(CHRScope *Scope,
 }
 
 // Assert that all the CHR regions of the scope have a biased branch or select.
-static void LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]] static void
 assertCHRRegionsHaveBiasedBranchOrSelect(CHRScope *Scope) {
 #ifndef NDEBUG
   auto HasBiasedBranchOrSelect = [](RegInfo &RI, CHRScope *Scope) {
@@ -1644,8 +1643,9 @@ assertCHRRegionsHaveBiasedBranchOrSelect(CHRScope *Scope) {
 
 // Assert that all the condition values of the biased branches and selects have
 // been hoisted to the pre-entry block or outside of the scope.
-static void LLVM_ATTRIBUTE_UNUSED assertBranchOrSelectConditionHoisted(
-    CHRScope *Scope, BasicBlock *PreEntryBlock) {
+[[maybe_unused]] static void
+assertBranchOrSelectConditionHoisted(CHRScope *Scope,
+                                     BasicBlock *PreEntryBlock) {
   CHR_DEBUG(dbgs() << "Biased regions condition values \n");
   for (RegInfo &RI : Scope->CHRRegions) {
     Region *R = RI.R;
@@ -2007,8 +2007,8 @@ void CHR::transformScopes(SmallVectorImpl<CHRScope *> &CHRScopes) {
   }
 }
 
-static void LLVM_ATTRIBUTE_UNUSED
-dumpScopes(SmallVectorImpl<CHRScope *> &Scopes, const char *Label) {
+[[maybe_unused]] static void dumpScopes(SmallVectorImpl<CHRScope *> &Scopes,
+                                        const char *Label) {
   dbgs() << Label << " " << Scopes.size() << "\n";
   for (CHRScope *Scope : Scopes) {
     dbgs() << *Scope << "\n";

diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -326,8 +326,7 @@ const unsigned BBState::OverflowOccurredValue = 0xffffffff;
 
 namespace llvm {
 
-raw_ostream &operator<<(raw_ostream &OS,
-                        BBState &BBState) LLVM_ATTRIBUTE_UNUSED;
+[[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS, BBState &BBState);
 
 } // end namespace llvm
 

diff --git a/llvm/lib/Transforms/ObjCARC/PtrState.h b/llvm/lib/Transforms/ObjCARC/PtrState.h
@@ -47,8 +47,7 @@ enum Sequence {
   S_MovableRelease ///< objc_release(x), !clang.imprecise_release.
 };
 
-raw_ostream &operator<<(raw_ostream &OS,
-                        const Sequence S) LLVM_ATTRIBUTE_UNUSED;
+[[maybe_unused]] raw_ostream &operator<<(raw_ostream &OS, const Sequence S);
 
 /// Unidirectional information about either a
 /// retain-decrement-use-release sequence or release-use-decrement-retain

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -551,12 +551,10 @@ class Slice {
   }
 
   /// Support comparison with a single offset to allow binary searches.
-  friend LLVM_ATTRIBUTE_UNUSED bool operator<(const Slice &LHS,
-                                              uint64_t RHSOffset) {
+  [[maybe_unused]] friend bool operator<(const Slice &LHS, uint64_t RHSOffset) {
     return LHS.beginOffset() < RHSOffset;
   }
-  friend LLVM_ATTRIBUTE_UNUSED bool operator<(uint64_t LHSOffset,
-                                              const Slice &RHS) {
+  [[maybe_unused]] friend bool operator<(uint64_t LHSOffset, const Slice &RHS) {
     return LHSOffset < RHS.beginOffset();
   }
 

diff --git a/llvm/unittests/ADT/SmallVectorTest.cpp b/llvm/unittests/ADT/SmallVectorTest.cpp
@@ -127,24 +127,24 @@ class Constructable {
     return c0.getValue() == c1.getValue();
   }
 
-  friend bool LLVM_ATTRIBUTE_UNUSED operator!=(const Constructable &c0,
-                                               const Constructable &c1) {
+  [[maybe_unused]] friend bool operator!=(const Constructable &c0,
+                                          const Constructable &c1) {
     return c0.getValue() != c1.getValue();
   }
 
   friend bool operator<(const Constructable &c0, const Constructable &c1) {
     return c0.getValue() < c1.getValue();
   }
-  friend bool LLVM_ATTRIBUTE_UNUSED operator<=(const Constructable &c0,
-                                               const Constructable &c1) {
+  [[maybe_unused]] friend bool operator<=(const Constructable &c0,
+                                          const Constructable &c1) {
     return c0.getValue() <= c1.getValue();
   }
-  friend bool LLVM_ATTRIBUTE_UNUSED operator>(const Constructable &c0,
-                                              const Constructable &c1) {
+  [[maybe_unused]] friend bool operator>(const Constructable &c0,
+                                         const Constructable &c1) {
     return c0.getValue() > c1.getValue();
   }
-  friend bool LLVM_ATTRIBUTE_UNUSED operator>=(const Constructable &c0,
-                                               const Constructable &c1) {
+  [[maybe_unused]] friend bool operator>=(const Constructable &c0,
+                                          const Constructable &c1) {
     return c0.getValue() >= c1.getValue();
   }
 };

diff --git a/llvm/utils/TableGen/Common/Types.cpp b/llvm/utils/TableGen/Common/Types.cpp
@@ -8,16 +8,12 @@
 
 #include "Types.h"
 
-// For LLVM_ATTRIBUTE_UNUSED
-#include "llvm/Support/Compiler.h"
-
 #include <cassert>
 
 using namespace llvm;
 
-const char *
-llvm::getMinimalTypeForRange(uint64_t Range,
-                             unsigned MaxSize LLVM_ATTRIBUTE_UNUSED) {
+const char *llvm::getMinimalTypeForRange(uint64_t Range,
+                                         [[maybe_unused]] unsigned MaxSize) {
   // TODO: The original callers only used 32 and 64 so these are the only
   //       values permitted. Rather than widen the supported values we should
   //       allow 64 for the callers that currently use 32 and remove the