[flang] Replace LLVM_ATTRIBUTE_UNUSED with [[maybe_unused]] (NFC)

[kazutakahirata]

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

[llvmbot]

@llvm/pr-subscribers-flang-fir-hlfir

Author: Kazu Hirata (kazutakahirata)

Changes

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

---

Full diff: https://github.com/llvm/llvm-project/pull/163916.diff

6 Files Affected:

• (modified) flang/lib/Lower/Bridge.cpp (+1-1)
• (modified) flang/lib/Lower/ConvertExpr.cpp (+1-1)
• (modified) flang/lib/Optimizer/Builder/Character.cpp (+1-1)
• (modified) flang/lib/Optimizer/HLFIR/Transforms/ScheduleOrderedAssignments.cpp (+34-28)
• (modified) flang/lib/Optimizer/Transforms/AffinePromotion.cpp (+1-1)
• (modified) flang/lib/Optimizer/Transforms/StackArrays.cpp (+1-1)

diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index 525fb0e9997b7..0595ca063f407 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -6076,7 +6076,7 @@ class FirConverter : public Fortran::lower::AbstractConverter {
         if (resTy != wrappedSymTy) {
           // check size of the pointed to type so we can't overflow by writing
           // double precision to a single precision allocation, etc
-          LLVM_ATTRIBUTE_UNUSED auto getBitWidth = [this](mlir::Type ty) {
+          [[maybe_unused]] auto getBitWidth = [this](mlir::Type ty) {
             // 15.6.2.6.3: differering result types should be integer, real,
             // complex or logical
             if (auto cmplx = mlir::dyn_cast_or_null<mlir::ComplexType>(ty))
diff --git a/flang/lib/Lower/ConvertExpr.cpp b/flang/lib/Lower/ConvertExpr.cpp
index d7f94e1f7ca6a..a46d219ba4b2c 100644
--- a/flang/lib/Lower/ConvertExpr.cpp
+++ b/flang/lib/Lower/ConvertExpr.cpp
@@ -5603,7 +5603,7 @@ class ArrayExprLowering {
                     return newIters;
                   };
                   if (useTripsForSlice) {
-                    LLVM_ATTRIBUTE_UNUSED auto vectorSubscriptShape =
+                    [[maybe_unused]] auto vectorSubscriptShape =
                         getShape(arrayOperands.back());
                     auto undef = fir::UndefOp::create(builder, loc, idxTy);
                     trips.push_back(undef);
diff --git a/flang/lib/Optimizer/Builder/Character.cpp b/flang/lib/Optimizer/Builder/Character.cpp
index a096099a04fe8..155bc0fbd19ce 100644
--- a/flang/lib/Optimizer/Builder/Character.cpp
+++ b/flang/lib/Optimizer/Builder/Character.cpp
@@ -92,7 +92,7 @@ getCompileTimeLength(const fir::CharBoxValue &box) {
 
 /// Detect the precondition that the value `str` does not reside in memory. Such
 /// values will have a type `!fir.array<...x!fir.char<N>>` or `!fir.char<N>`.
-LLVM_ATTRIBUTE_UNUSED static bool needToMaterialize(mlir::Value str) {
+[[maybe_unused]] static bool needToMaterialize(mlir::Value str) {
   return mlir::isa<fir::SequenceType>(str.getType()) ||
          fir::isa_char(str.getType());
 }
diff --git a/flang/lib/Optimizer/HLFIR/Transforms/ScheduleOrderedAssignments.cpp b/flang/lib/Optimizer/HLFIR/Transforms/ScheduleOrderedAssignments.cpp
index a48b7ba8a77df..63a5803878a2d 100644
--- a/flang/lib/Optimizer/HLFIR/Transforms/ScheduleOrderedAssignments.cpp
+++ b/flang/lib/Optimizer/HLFIR/Transforms/ScheduleOrderedAssignments.cpp
@@ -21,24 +21,27 @@
 //===----------------------------------------------------------------------===//
 
 /// Log RAW or WAW conflict.
-static void LLVM_ATTRIBUTE_UNUSED logConflict(llvm::raw_ostream &os,
-                                              mlir::Value writtenOrReadVarA,
-                                              mlir::Value writtenVarB);
+[[maybe_unused]] static void logConflict(llvm::raw_ostream &os,
+                                         mlir::Value writtenOrReadVarA,
+                                         mlir::Value writtenVarB);
 /// Log when an expression evaluation must be saved.
-static void LLVM_ATTRIBUTE_UNUSED logSaveEvaluation(llvm::raw_ostream &os,
-                                                    unsigned runid,
-                                                    mlir::Region &yieldRegion,
-                                                    bool anyWrite);
+[[maybe_unused]] static void logSaveEvaluation(llvm::raw_ostream &os,
+                                               unsigned runid,
+                                               mlir::Region &yieldRegion,
+                                               bool anyWrite);
 /// Log when an assignment is scheduled.
-static void LLVM_ATTRIBUTE_UNUSED logAssignmentEvaluation(
-    llvm::raw_ostream &os, unsigned runid, hlfir::RegionAssignOp assign);
+[[maybe_unused]] static void
+logAssignmentEvaluation(llvm::raw_ostream &os, unsigned runid,
+                        hlfir::RegionAssignOp assign);
 /// Log when starting to schedule an order assignment tree.
-static void LLVM_ATTRIBUTE_UNUSED logStartScheduling(
-    llvm::raw_ostream &os, hlfir::OrderedAssignmentTreeOpInterface root);
+[[maybe_unused]] static void
+logStartScheduling(llvm::raw_ostream &os,
+                   hlfir::OrderedAssignmentTreeOpInterface root);
 /// Log op if effect value is not known.
-static void LLVM_ATTRIBUTE_UNUSED logIfUnkownEffectValue(
-    llvm::raw_ostream &os, mlir::MemoryEffects::EffectInstance effect,
-    mlir::Operation &op);
+[[maybe_unused]] static void
+logIfUnkownEffectValue(llvm::raw_ostream &os,
+                       mlir::MemoryEffects::EffectInstance effect,
+                       mlir::Operation &op);
 
 //===----------------------------------------------------------------------===//
 // Scheduling Implementation
@@ -701,23 +704,24 @@ static llvm::raw_ostream &printRegionPath(llvm::raw_ostream &os,
   return printRegionId(os, yieldRegion);
 }
 
-static void LLVM_ATTRIBUTE_UNUSED logSaveEvaluation(llvm::raw_ostream &os,
-                                                    unsigned runid,
-                                                    mlir::Region &yieldRegion,
-                                                    bool anyWrite) {
+[[maybe_unused]] static void logSaveEvaluation(llvm::raw_ostream &os,
+                                               unsigned runid,
+                                               mlir::Region &yieldRegion,
+                                               bool anyWrite) {
   os << "run " << runid << " save  " << (anyWrite ? "(w)" : "  ") << ": ";
   printRegionPath(os, yieldRegion) << "\n";
 }
 
-static void LLVM_ATTRIBUTE_UNUSED logAssignmentEvaluation(
-    llvm::raw_ostream &os, unsigned runid, hlfir::RegionAssignOp assign) {
+[[maybe_unused]] static void
+logAssignmentEvaluation(llvm::raw_ostream &os, unsigned runid,
+                        hlfir::RegionAssignOp assign) {
   os << "run " << runid << " evaluate: ";
   printNodePath(os, assign.getOperation()) << "\n";
 }
 
-static void LLVM_ATTRIBUTE_UNUSED logConflict(llvm::raw_ostream &os,
-                                              mlir::Value writtenOrReadVarA,
-                                              mlir::Value writtenVarB) {
+[[maybe_unused]] static void logConflict(llvm::raw_ostream &os,
+                                         mlir::Value writtenOrReadVarA,
+                                         mlir::Value writtenVarB) {
   auto printIfValue = [&](mlir::Value var) -> llvm::raw_ostream & {
     if (!var)
       return os << "<unknown>";
@@ -728,8 +732,9 @@ static void LLVM_ATTRIBUTE_UNUSED logConflict(llvm::raw_ostream &os,
   printIfValue(writtenVarB) << "\n";
 }
 
-static void LLVM_ATTRIBUTE_UNUSED logStartScheduling(
-    llvm::raw_ostream &os, hlfir::OrderedAssignmentTreeOpInterface root) {
+[[maybe_unused]] static void
+logStartScheduling(llvm::raw_ostream &os,
+                   hlfir::OrderedAssignmentTreeOpInterface root) {
   os << "------------ scheduling ";
   printNodePath(os, root.getOperation());
   if (auto funcOp = root->getParentOfType<mlir::func::FuncOp>())
@@ -737,9 +742,10 @@ static void LLVM_ATTRIBUTE_UNUSED logStartScheduling(
   os << "------------\n";
 }
 
-static void LLVM_ATTRIBUTE_UNUSED logIfUnkownEffectValue(
-    llvm::raw_ostream &os, mlir::MemoryEffects::EffectInstance effect,
-    mlir::Operation &op) {
+[[maybe_unused]] static void
+logIfUnkownEffectValue(llvm::raw_ostream &os,
+                       mlir::MemoryEffects::EffectInstance effect,
+                       mlir::Operation &op) {
   if (effect.getValue() != nullptr)
     return;
   os << "unknown effected value (";
diff --git a/flang/lib/Optimizer/Transforms/AffinePromotion.cpp b/flang/lib/Optimizer/Transforms/AffinePromotion.cpp
index 061a7d201edd3..bdc34186a713b 100644
--- a/flang/lib/Optimizer/Transforms/AffinePromotion.cpp
+++ b/flang/lib/Optimizer/Transforms/AffinePromotion.cpp
@@ -474,7 +474,7 @@ class AffineLoopConversion : public mlir::OpRewritePattern<fir::DoLoopOp> {
                   mlir::PatternRewriter &rewriter) const override {
     LLVM_DEBUG(llvm::dbgs() << "AffineLoopConversion: rewriting loop:\n";
                loop.dump(););
-    LLVM_ATTRIBUTE_UNUSED auto loopAnalysis =
+    [[maybe_unused]] auto loopAnalysis =
         functionAnalysis.getChildLoopAnalysis(loop);
     if (!loopAnalysis.canPromoteToAffine())
       return rewriter.notifyMatchFailure(loop, "cannot promote to affine");
diff --git a/flang/lib/Optimizer/Transforms/StackArrays.cpp b/flang/lib/Optimizer/Transforms/StackArrays.cpp
index 80b3f689efa39..860149942a5c1 100644
--- a/flang/lib/Optimizer/Transforms/StackArrays.cpp
+++ b/flang/lib/Optimizer/Transforms/StackArrays.cpp
@@ -561,7 +561,7 @@ static mlir::Value convertAllocationType(mlir::PatternRewriter &rewriter,
     return stack;
 
   fir::HeapType firHeapTy = mlir::cast<fir::HeapType>(heapTy);
-  LLVM_ATTRIBUTE_UNUSED fir::ReferenceType firRefTy =
+  [[maybe_unused]] fir::ReferenceType firRefTy =
       mlir::cast<fir::ReferenceType>(stackTy);
   assert(firHeapTy.getElementType() == firRefTy.getElementType() &&
          "Allocations must have the same type");