[mlir] Replace LLVM_ATTRIBUTE_UNUSED with [[maybe_unused]] (NFC) (#163703)

This patch replaces LLVM_ATTRIBUTE_UNUSED with [[maybe_unused]],
introduced as part of C++17.

mlir/include/mlir/Dialect/Affine/LoopUtils.h

@@ -61,7 +61,7 @@ LogicalResult loopUnrollUpToFactor(AffineForOp forOp, uint64_t unrollFactor);
 
 /// Returns true if `loops` is a perfectly nested loop nest, where loops appear
 /// in it from outermost to innermost.
-bool LLVM_ATTRIBUTE_UNUSED isPerfectlyNested(ArrayRef<AffineForOp> loops);
+[[maybe_unused]] bool isPerfectlyNested(ArrayRef<AffineForOp> loops);
 
 /// Get perfectly nested sequence of loops starting at root of loop nest
 /// (the first op being another AffineFor, and the second op - a terminator).

mlir/lib/Analysis/FlatLinearValueConstraints.cpp

@@ -1244,8 +1244,9 @@ bool FlatLinearValueConstraints::areVarsAlignedWithOther(
 
 /// Checks if the SSA values associated with `cst`'s variables in range
 /// [start, end) are unique.
-static bool LLVM_ATTRIBUTE_UNUSED areVarsUnique(
-    const FlatLinearValueConstraints &cst, unsigned start, unsigned end) {
+[[maybe_unused]] static bool
+areVarsUnique(const FlatLinearValueConstraints &cst, unsigned start,
+              unsigned end) {
 
   assert(start <= cst.getNumDimAndSymbolVars() &&
          "Start position out of bounds");
@@ -1267,14 +1268,14 @@ static bool LLVM_ATTRIBUTE_UNUSED areVarsUnique(
 }
 
 /// Checks if the SSA values associated with `cst`'s variables are unique.
-static bool LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]] static bool
 areVarsUnique(const FlatLinearValueConstraints &cst) {
   return areVarsUnique(cst, 0, cst.getNumDimAndSymbolVars());
 }
 
 /// Checks if the SSA values associated with `cst`'s variables of kind `kind`
 /// are unique.
-static bool LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]] static bool
 areVarsUnique(const FlatLinearValueConstraints &cst, VarKind kind) {
 
   if (kind == VarKind::SetDim)

mlir/lib/Analysis/Presburger/Simplex.cpp

@@ -34,7 +34,7 @@ using Direction = Simplex::Direction;
 const int nullIndex = std::numeric_limits<int>::max();
 
 // Return a + scale*b;
-LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]]
 static SmallVector<DynamicAPInt, 8>
 scaleAndAddForAssert(ArrayRef<DynamicAPInt> a, const DynamicAPInt &scale,
                      ArrayRef<DynamicAPInt> b) {

mlir/lib/Dialect/Affine/IR/AffineOps.cpp

@@ -125,9 +125,9 @@ static bool remainsLegalAfterInline(OpTy op, Region *src, Region *dest,
 //  Use "unused attribute" marker to silence clang-tidy warning stemming from
 //  the inability to see through "llvm::TypeSwitch".
 template <>
-bool LLVM_ATTRIBUTE_UNUSED remainsLegalAfterInline(AffineApplyOp op,
-                                                   Region *src, Region *dest,
-                                                   const IRMapping &mapping) {
+[[maybe_unused]] bool remainsLegalAfterInline(AffineApplyOp op, Region *src,
+                                              Region *dest,
+                                              const IRMapping &mapping) {
   // If it's a valid dimension, we need to check that it remains so.
   if (isValidDim(op.getResult(), src))
     return remainsLegalAfterInline(
@@ -1032,8 +1032,8 @@ static void simplifyMinOrMaxExprWithOperands(AffineMap &map,
 /// Simplify the map while exploiting information on the values in `operands`.
 //  Use "unused attribute" marker to silence warning stemming from the inability
 //  to see through the template expansion.
-static void LLVM_ATTRIBUTE_UNUSED
-simplifyMapWithOperands(AffineMap &map, ArrayRef<Value> operands) {
+[[maybe_unused]] static void simplifyMapWithOperands(AffineMap &map,
+                                                     ArrayRef<Value> operands) {
   assert(map.getNumInputs() == operands.size() && "invalid operands for map");
   SmallVector<AffineExpr> newResults;
   newResults.reserve(map.getNumResults());

mlir/lib/Dialect/Affine/Utils/LoopUtils.cpp

@@ -1357,7 +1357,7 @@ bool mlir::affine::isValidLoopInterchangePermutation(
 
 /// Returns true if `loops` is a perfectly nested loop nest, where loops appear
 /// in it from outermost to innermost.
-bool LLVM_ATTRIBUTE_UNUSED
+[[maybe_unused]] bool
 mlir::affine::isPerfectlyNested(ArrayRef<AffineForOp> loops) {
   assert(!loops.empty() && "no loops provided");
 
@@ -1920,8 +1920,7 @@ generatePointWiseCopy(Location loc, Value memref, Value fastMemRef,
   return copyNestRoot;
 }
 
-static InFlightDiagnostic LLVM_ATTRIBUTE_UNUSED
-emitRemarkForBlock(Block &block) {
+[[maybe_unused]] static InFlightDiagnostic emitRemarkForBlock(Block &block) {
   return block.getParentOp()->emitRemark();
 }
 

mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp

@@ -134,10 +134,10 @@ static void printExtTypeParams(AsmPrinter &p, ArrayRef<Type> typeParams,
 
 /// These are unused for now.
 /// TODO: Move over to these once more types have been migrated to TypeDef.
-LLVM_ATTRIBUTE_UNUSED static OptionalParseResult
+[[maybe_unused]] static OptionalParseResult
 generatedTypeParser(AsmParser &parser, StringRef *mnemonic, Type &value);
-LLVM_ATTRIBUTE_UNUSED static LogicalResult
-generatedTypePrinter(Type def, AsmPrinter &printer);
+[[maybe_unused]] static LogicalResult generatedTypePrinter(Type def,
+                                                           AsmPrinter &printer);
 
 #include "mlir/Dialect/LLVMIR/LLVMTypeInterfaces.cpp.inc"
 

mlir/lib/Dialect/SparseTensor/IR/Detail/Var.cpp

@@ -143,8 +143,8 @@ void VarInfo::setNum(Var::Num n) {
 
 /// Helper function for `assertUsageConsistency` to better handle SMLoc
 /// mismatches.
-LLVM_ATTRIBUTE_UNUSED static llvm::SMLoc
-minSMLoc(AsmParser &parser, llvm::SMLoc sm1, llvm::SMLoc sm2) {
+[[maybe_unused]] static llvm::SMLoc minSMLoc(AsmParser &parser, llvm::SMLoc sm1,
+                                             llvm::SMLoc sm2) {
   const auto loc1 = dyn_cast<FileLineColLoc>(parser.getEncodedSourceLoc(sm1));
   assert(loc1 && "Could not get `FileLineColLoc` for first `SMLoc`");
   const auto loc2 = dyn_cast<FileLineColLoc>(parser.getEncodedSourceLoc(sm2));

mlir/lib/Dialect/SparseTensor/Transforms/Utils/LoopEmitter.cpp

@@ -43,8 +43,8 @@ using namespace mlir::sparse_tensor;
 //===----------------------------------------------------------------------===//
 
 #ifndef NDEBUG
-LLVM_ATTRIBUTE_UNUSED static void dumpIndexMemRef(OpBuilder &builder,
-                                                  Location loc, Value memref) {
+[[maybe_unused]] static void dumpIndexMemRef(OpBuilder &builder, Location loc,
+                                             Value memref) {
   memref = memref::CastOp::create(
       builder, loc, UnrankedMemRefType::get(builder.getIndexType(), 0), memref);
   createFuncCall(builder, loc, "printMemrefInd", TypeRange{},

mlir/lib/Dialect/Transform/IR/TransformTypes.cpp

@@ -21,10 +21,10 @@ using namespace mlir;
 
 // These are automatically generated by ODS but are not used as the Transform
 // dialect uses a different dispatch mechanism to support dialect extensions.
-LLVM_ATTRIBUTE_UNUSED static OptionalParseResult
+[[maybe_unused]] static OptionalParseResult
 generatedTypeParser(AsmParser &parser, StringRef *mnemonic, Type &value);
-LLVM_ATTRIBUTE_UNUSED static LogicalResult
-generatedTypePrinter(Type def, AsmPrinter &printer);
+[[maybe_unused]] static LogicalResult generatedTypePrinter(Type def,
+                                                           AsmPrinter &printer);
 
 #define GET_TYPEDEF_CLASSES
 #include "mlir/Dialect/Transform/IR/TransformTypes.cpp.inc"

mlir/lib/IR/MLIRContext.cpp

@@ -1204,7 +1204,7 @@ AffineMap AffineMap::getImpl(unsigned dimCount, unsigned symbolCount,
 /// present in result expressions is less than `dimCount` and the highest index
 /// of symbolic identifier present in result expressions is less than
 /// `symbolCount`.
-LLVM_ATTRIBUTE_UNUSED static bool
+[[maybe_unused]] static bool
 willBeValidAffineMap(unsigned dimCount, unsigned symbolCount,
                      ArrayRef<AffineExpr> results) {
   int64_t maxDimPosition = -1;

mlir/lib/Tools/PDLL/CodeGen/CPPGen.cpp

@@ -93,7 +93,7 @@ void CodeGen::generate(const ast::Module &astModule, ModuleOp module) {
 
   // Emit function to add the generated matchers to the pattern list.
   os << "template <typename... ConfigsT>\n"
-        "static void LLVM_ATTRIBUTE_UNUSED populateGeneratedPDLLPatterns("
+        "[[maybe_unused]] static void populateGeneratedPDLLPatterns("
         "::mlir::RewritePatternSet &patterns, ConfigsT &&...configs) {\n";
   for (const auto &name : patternNames)
     os << "  patterns.add<" << name

mlir/test/lib/Dialect/Transform/TestTransformDialectExtension.cpp

@@ -938,10 +938,10 @@ public:
 
 // These are automatically generated by ODS but are not used as the Transform
 // dialect uses a different dispatch mechanism to support dialect extensions.
-LLVM_ATTRIBUTE_UNUSED static OptionalParseResult
+[[maybe_unused]] static OptionalParseResult
 generatedTypeParser(AsmParser &parser, StringRef *mnemonic, Type &value);
-LLVM_ATTRIBUTE_UNUSED static LogicalResult
-generatedTypePrinter(Type def, AsmPrinter &printer);
+[[maybe_unused]] static LogicalResult generatedTypePrinter(Type def,
+                                                           AsmPrinter &printer);
 
 #define GET_TYPEDEF_CLASSES
 #include "TestTransformDialectExtensionTypes.cpp.inc"

mlir/test/mlir-pdll/CodeGen/CPP/general.pdll

@@ -28,7 +28,7 @@
 // CHECK:      operation "test.op3"
 // CHECK:  )mlir", context), std::forward<ConfigsT>(configs)...)
 
-// CHECK:      static void LLVM_ATTRIBUTE_UNUSED populateGeneratedPDLLPatterns(::mlir::RewritePatternSet &patterns, ConfigsT &&...configs) {
+// CHECK{LITERAL}: [[maybe_unused]] static void populateGeneratedPDLLPatterns(::mlir::RewritePatternSet &patterns, ConfigsT &&...configs) {
 // CHECK-NEXT:   patterns.add<GeneratedPDLLPattern0>(patterns.getContext(), configs...);
 // CHECK-NEXT:   patterns.add<NamedPattern>(patterns.getContext(), configs...);
 // CHECK-NEXT:   patterns.add<GeneratedPDLLPattern1>(patterns.getContext(), configs...);

mlir/tools/mlir-tblgen/LLVMIRConversionGen.cpp

@@ -416,7 +416,7 @@ static void emitOneEnumToConversion(const Record *record, raw_ostream &os) {
 
   // Emit the function converting the enum attribute to its LLVM counterpart.
   os << formatv(
-      "static LLVM_ATTRIBUTE_UNUSED {0} convert{1}ToLLVM({2}::{1} value) {{\n",
+      "[[maybe_unused]] static {0} convert{1}ToLLVM({2}::{1} value) {{\n",
       llvmClass, cppClassName, cppNamespace);
   os << "  switch (value) {\n";
 
@@ -444,7 +444,7 @@ static void emitOneCEnumToConversion(const Record *record, raw_ostream &os) {
   StringRef cppNamespace = enumAttr.getCppNamespace();
 
   // Emit the function converting the enum attribute to its LLVM counterpart.
-  os << formatv("static LLVM_ATTRIBUTE_UNUSED int64_t "
+  os << formatv("[[maybe_unused]] static int64_t "
                 "convert{0}ToLLVM({1}::{0} value) {{\n",
                 cppClassName, cppNamespace);
   os << "  switch (value) {\n";
@@ -474,7 +474,7 @@ static void emitOneEnumFromConversion(const Record *record, raw_ostream &os) {
   StringRef cppNamespace = enumInfo.getCppNamespace();
 
   // Emit the function converting the enum attribute from its LLVM counterpart.
-  os << formatv("inline LLVM_ATTRIBUTE_UNUSED {0}::{1} convert{1}FromLLVM({2} "
+  os << formatv("[[maybe_unused]] inline {0}::{1} convert{1}FromLLVM({2} "
                 "value) {{\n",
                 cppNamespace, cppClassName, llvmClass);
   os << "  switch (value) {\n";
@@ -509,10 +509,9 @@ static void emitOneCEnumFromConversion(const Record *record, raw_ostream &os) {
   StringRef cppNamespace = enumInfo.getCppNamespace();
 
   // Emit the function converting the enum attribute from its LLVM counterpart.
-  os << formatv(
-      "inline LLVM_ATTRIBUTE_UNUSED {0}::{1} convert{1}FromLLVM(int64_t "
-      "value) {{\n",
-      cppNamespace, cppClassName);
+  os << formatv("[[maybe_unused]] inline {0}::{1} convert{1}FromLLVM(int64_t "
+                "value) {{\n",
+                cppNamespace, cppClassName);
   os << "  switch (value) {\n";
 
   for (const auto &enumerant : enumInfo.getAllCases()) {

mlir/tools/mlir-tblgen/RewriterGen.cpp

@@ -2120,7 +2120,7 @@ static void emitRewriters(const RecordKeeper &records, raw_ostream &os) {
   }
 
   // Emit function to add the generated matchers to the pattern list.
-  os << "void LLVM_ATTRIBUTE_UNUSED populateWithGenerated("
+  os << "[[maybe_unused]] void populateWithGenerated("
         "::mlir::RewritePatternSet &patterns) {\n";
   for (const auto &name : rewriterNames) {
     os << "  patterns.add<" << name << ">(patterns.getContext());\n";

mlir/unittests/Dialect/SparseTensor/MergerTest.cpp

@@ -113,8 +113,7 @@ static Match tensorMatch(TensorId tid) { return Match(tid); }
 static Match synZeroMatch() { return Match(); }
 
 #define IMPL_BINOP_PATTERN(OP, KIND)                                           \
-  LLVM_ATTRIBUTE_UNUSED static Match OP##Match(const Match &e0,                \
-                                               const Match &e1) {              \
+  [[maybe_unused]] static Match OP##Match(const Match &e0, const Match &e1) {  \
     return Match(KIND, e0, e1);                                                \
   }
 FOREVERY_BINOP(IMPL_BINOP_PATTERN)