[flang-commits] [flang] [flang][hlfir] Add hlfir.maxval intrinsic (PR #65705)

Yusuke MINATO via flang-commits flang-commits at lists.llvm.org
Mon Sep 11 18:00:52 PDT 2023


https://github.com/yus3710-fj updated https://github.com/llvm/llvm-project/pull/65705:

>From a64d98d1d2784156a638ac2b9bbff4e311d9a8aa Mon Sep 17 00:00:00 2001
From: Yusuke MINATO <minato.yusuke at fujitsu.com>
Date: Wed, 30 Aug 2023 16:30:38 +0900
Subject: [PATCH 1/3] [flang][hlfir] Add hlfir.maxval intrinsic

Adds a new HLFIR operation for the MAXVAL intrinsic according to
the design set out in flang/docs/HighLevel.md.
---
 .../include/flang/Optimizer/HLFIR/HLFIROps.td |  26 ++
 flang/lib/Lower/HlfirIntrinsics.cpp           |  15 +
 flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp     |  89 ++++++
 .../HLFIR/Transforms/LowerHLFIRIntrinsics.cpp |  19 +-
 flang/test/HLFIR/invalid.fir                  |  78 ++++++
 flang/test/HLFIR/maxval-lowering.fir          | 218 +++++++++++++++
 flang/test/HLFIR/maxval.fir                   | 249 +++++++++++++++++
 flang/test/Lower/HLFIR/maxval.f90             | 262 ++++++++++++++++++
 8 files changed, 950 insertions(+), 6 deletions(-)
 create mode 100644 flang/test/HLFIR/maxval-lowering.fir
 create mode 100644 flang/test/HLFIR/maxval.fir
 create mode 100644 flang/test/Lower/HLFIR/maxval.f90

diff --git a/flang/include/flang/Optimizer/HLFIR/HLFIROps.td b/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
index 8aab44f176c0eca..d24b2b6b818c187 100644
--- a/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
+++ b/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
@@ -404,6 +404,32 @@ def hlfir_CountOp : hlfir_Op<"count", [AttrSizedOperandSegments, DeclareOpInterf
   let hasVerifier = 1;
 }
 
+def hlfir_MaxvalOp : hlfir_Op<"maxval", [AttrSizedOperandSegments,
+    DeclareOpInterfaceMethods<ArithFastMathInterface>]> {
+  let summary = "MAXVAL transformational intrinsic";
+  let description = [{
+    Maximum value(s) of an array.
+    If DIM is absent, the result is a scalar.
+    If DIM is present, the result is an array of rank n-1, where n is the rank of ARRAY.
+  }];
+
+  let arguments = (ins
+    AnyFortranArrayObject:$array,
+    Optional<AnyIntegerType>:$dim,
+    Optional<AnyFortranLogicalOrI1ArrayObject>:$mask,
+    DefaultValuedAttr<Arith_FastMathAttr,
+                      "::mlir::arith::FastMathFlags::none">:$fastmath
+  );
+
+  let results = (outs AnyFortranValue);
+
+  let assemblyFormat = [{
+    $array (`dim` $dim^)? (`mask` $mask^)? attr-dict `:` functional-type(operands, results)
+  }];
+
+  let hasVerifier = 1;
+}
+
 def hlfir_ProductOp : hlfir_Op<"product", [AttrSizedOperandSegments,
     DeclareOpInterfaceMethods<ArithFastMathInterface>,
     DeclareOpInterfaceMethods<MemoryEffectsOpInterface>]> {
diff --git a/flang/lib/Lower/HlfirIntrinsics.cpp b/flang/lib/Lower/HlfirIntrinsics.cpp
index ab569adaf6f46ff..7146b1adc0d8060 100644
--- a/flang/lib/Lower/HlfirIntrinsics.cpp
+++ b/flang/lib/Lower/HlfirIntrinsics.cpp
@@ -88,6 +88,7 @@ class HlfirReductionIntrinsic : public HlfirTransformationalIntrinsic {
 };
 using HlfirSumLowering = HlfirReductionIntrinsic<hlfir::SumOp, true>;
 using HlfirProductLowering = HlfirReductionIntrinsic<hlfir::ProductOp, true>;
+using HlfirMaxvalLowering = HlfirReductionIntrinsic<hlfir::MaxvalOp, true>;
 using HlfirAnyLowering = HlfirReductionIntrinsic<hlfir::AnyOp, false>;
 using HlfirAllLowering = HlfirReductionIntrinsic<hlfir::AllOp, false>;
 
@@ -227,6 +228,17 @@ HlfirTransformationalIntrinsic::computeResultType(mlir::Value argArray,
     mlir::Type elementType = array.getEleTy();
     return hlfir::ExprType::get(builder.getContext(), resultShape, elementType,
                                 /*polymorphic=*/false);
+  } else if (auto resCharType =
+                 mlir::dyn_cast<fir::CharacterType>(stmtResultType)) {
+    if (!resCharType.hasConstantLen()) {
+      auto argCharType = mlir::dyn_cast<fir::CharacterType>(
+          hlfir::getFortranElementType(argArray.getType()));
+      if (argCharType && argCharType.hasConstantLen())
+        resCharType = fir::CharacterType::get(
+            builder.getContext(), resCharType.getFKind(), argCharType.getLen());
+    }
+    normalisedResult = hlfir::ExprType::get(
+        builder.getContext(), hlfir::ExprType::Shape{}, resCharType, false);
   }
   return normalisedResult;
 }
@@ -348,6 +360,9 @@ std::optional<hlfir::EntityWithAttributes> Fortran::lower::lowerHlfirIntrinsic(
   if (name == "count")
     return HlfirCountLowering{builder, loc}.lower(loweredActuals, argLowering,
                                                   stmtResultType);
+  if (name == "maxval")
+    return HlfirMaxvalLowering{builder, loc}.lower(loweredActuals, argLowering,
+                                                   stmtResultType);
   if (mlir::isa<fir::CharacterType>(stmtResultType)) {
     if (name == "min")
       return HlfirCharExtremumLowering{builder, loc,
diff --git a/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp b/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
index 5bb954647fb275d..6c46f1581164124 100644
--- a/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
+++ b/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
@@ -749,6 +749,95 @@ void hlfir::ProductOp::getEffects(
   getIntrinsicEffects(getOperation(), effects);
 }
 
+//===----------------------------------------------------------------------===//
+// CharacterReductionOp
+//===----------------------------------------------------------------------===//
+
+template <typename CharacterReductionOp>
+static mlir::LogicalResult
+verifyCharacterReductionOp(CharacterReductionOp reductionOp) {
+  mlir::Operation *op = reductionOp->getOperation();
+
+  auto results = op->getResultTypes();
+  assert(results.size() == 1);
+
+  mlir::Value array = reductionOp->getArray();
+  mlir::Value dim = reductionOp->getDim();
+  mlir::Value mask = reductionOp->getMask();
+
+  fir::SequenceType arrayTy =
+      hlfir::getFortranElementOrSequenceType(array.getType())
+          .cast<fir::SequenceType>();
+  mlir::Type numTy = arrayTy.getEleTy();
+  llvm::ArrayRef<int64_t> arrayShape = arrayTy.getShape();
+
+  if (mask) {
+    fir::SequenceType maskSeq =
+        hlfir::getFortranElementOrSequenceType(mask.getType())
+            .dyn_cast<fir::SequenceType>();
+    llvm::ArrayRef<int64_t> maskShape;
+
+    if (maskSeq)
+      maskShape = maskSeq.getShape();
+
+    if (!maskShape.empty()) {
+      if (maskShape.size() != arrayShape.size())
+        return reductionOp->emitWarning("MASK must be conformable to ARRAY");
+      static_assert(fir::SequenceType::getUnknownExtent() ==
+                    hlfir::ExprType::getUnknownExtent());
+      constexpr int64_t unknownExtent = fir::SequenceType::getUnknownExtent();
+      for (std::size_t i = 0; i < arrayShape.size(); ++i) {
+        int64_t arrayExtent = arrayShape[i];
+        int64_t maskExtent = maskShape[i];
+        if ((arrayExtent != maskExtent) && (arrayExtent != unknownExtent) &&
+            (maskExtent != unknownExtent))
+          return reductionOp->emitWarning("MASK must be conformable to ARRAY");
+      }
+    }
+  }
+
+  auto resultExpr = results[0].cast<hlfir::ExprType>();
+  mlir::Type resultType = resultExpr.getEleTy();
+  assert(mlir::isa<fir::CharacterType>(resultType) &&
+         "result must be character");
+
+  // Result is of the same type as ARRAY
+  if (resultType != numTy)
+    return reductionOp->emitOpError(
+        "result must have the same element type as ARRAY argument");
+
+  if (arrayShape.size() > 1 && dim != nullptr) {
+    if (!resultExpr.isArray())
+      return reductionOp->emitOpError("result must be an array");
+    llvm::ArrayRef<int64_t> resultShape = resultExpr.getShape();
+    // Result has rank n-1
+    if (resultShape.size() != (arrayShape.size() - 1))
+      return reductionOp->emitOpError(
+          "result rank must be one less than ARRAY");
+  } else if (!resultExpr.isScalar()) {
+    return reductionOp->emitOpError("result must be scalar character");
+  }
+  return mlir::success();
+}
+
+//===----------------------------------------------------------------------===//
+// MaxvalOp
+//===----------------------------------------------------------------------===//
+
+mlir::LogicalResult hlfir::MaxvalOp::verify() {
+  mlir::Operation *op = getOperation();
+
+  auto results = op->getResultTypes();
+  assert(results.size() == 1);
+
+  auto resultExpr = mlir::dyn_cast<hlfir::ExprType>(results[0]);
+  if (resultExpr && mlir::isa<fir::CharacterType>(resultExpr.getEleTy())) {
+    return verifyCharacterReductionOp<hlfir::MaxvalOp *>(this);
+  } else {
+    return verifyNumericalReductionOp<hlfir::MaxvalOp *>(this);
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // SetLengthOp
 //===----------------------------------------------------------------------===//
diff --git a/flang/lib/Optimizer/HLFIR/Transforms/LowerHLFIRIntrinsics.cpp b/flang/lib/Optimizer/HLFIR/Transforms/LowerHLFIRIntrinsics.cpp
index f30d79ebaa9b405..b6045fdef0987c0 100644
--- a/flang/lib/Optimizer/HLFIR/Transforms/LowerHLFIRIntrinsics.cpp
+++ b/flang/lib/Optimizer/HLFIR/Transforms/LowerHLFIRIntrinsics.cpp
@@ -220,6 +220,8 @@ class HlfirReductionIntrinsicConversion : public HlfirIntrinsicConversion<OP> {
       opName = "sum";
     } else if constexpr (std::is_same_v<OP, hlfir::ProductOp>) {
       opName = "product";
+    } else if constexpr (std::is_same_v<OP, hlfir::MaxvalOp>) {
+      opName = "maxval";
     } else if constexpr (std::is_same_v<OP, hlfir::AnyOp>) {
       opName = "any";
     } else if constexpr (std::is_same_v<OP, hlfir::AllOp>) {
@@ -238,7 +240,8 @@ class HlfirReductionIntrinsicConversion : public HlfirIntrinsicConversion<OP> {
     llvm::SmallVector<fir::ExtendedValue, 0> args;
 
     if constexpr (std::is_same_v<OP, hlfir::SumOp> ||
-                  std::is_same_v<OP, hlfir::ProductOp>) {
+                  std::is_same_v<OP, hlfir::ProductOp> ||
+                  std::is_same_v<OP, hlfir::MaxvalOp>) {
       args = buildNumericalArgs(operation, i32, logicalType, rewriter, opName);
     } else {
       args = buildLogicalArgs(operation, i32, logicalType, rewriter, opName);
@@ -259,6 +262,8 @@ using SumOpConversion = HlfirReductionIntrinsicConversion<hlfir::SumOp>;
 
 using ProductOpConversion = HlfirReductionIntrinsicConversion<hlfir::ProductOp>;
 
+using MaxvalOpConversion = HlfirReductionIntrinsicConversion<hlfir::MaxvalOp>;
+
 using AnyOpConversion = HlfirReductionIntrinsicConversion<hlfir::AnyOp>;
 
 using AllOpConversion = HlfirReductionIntrinsicConversion<hlfir::AllOp>;
@@ -431,17 +436,19 @@ class LowerHLFIRIntrinsics
     mlir::ModuleOp module = this->getOperation();
     mlir::MLIRContext *context = &getContext();
     mlir::RewritePatternSet patterns(context);
-    patterns.insert<MatmulOpConversion, MatmulTransposeOpConversion,
-                    AllOpConversion, AnyOpConversion, SumOpConversion,
-                    ProductOpConversion, TransposeOpConversion,
-                    CountOpConversion, DotProductOpConversion>(context);
+    patterns
+        .insert<MatmulOpConversion, MatmulTransposeOpConversion,
+                AllOpConversion, AnyOpConversion, SumOpConversion,
+                ProductOpConversion, TransposeOpConversion, CountOpConversion,
+                DotProductOpConversion, MaxvalOpConversion>(context);
     mlir::ConversionTarget target(*context);
     target.addLegalDialect<mlir::BuiltinDialect, mlir::arith::ArithDialect,
                            mlir::func::FuncDialect, fir::FIROpsDialect,
                            hlfir::hlfirDialect>();
     target.addIllegalOp<hlfir::MatmulOp, hlfir::MatmulTransposeOp, hlfir::SumOp,
                         hlfir::ProductOp, hlfir::TransposeOp, hlfir::AnyOp,
-                        hlfir::AllOp, hlfir::DotProductOp, hlfir::CountOp>();
+                        hlfir::AllOp, hlfir::DotProductOp, hlfir::CountOp,
+                        hlfir::MaxvalOp>();
     target.markUnknownOpDynamicallyLegal(
         [](mlir::Operation *) { return true; });
     if (mlir::failed(
diff --git a/flang/test/HLFIR/invalid.fir b/flang/test/HLFIR/invalid.fir
index db16cb29c623880..00fe30988439542 100644
--- a/flang/test/HLFIR/invalid.fir
+++ b/flang/test/HLFIR/invalid.fir
@@ -392,6 +392,84 @@ func.func @bad_count4(%arg0: !hlfir.expr<?x!fir.logical<4>>, %arg1: i32) {
   %0 = hlfir.count %arg0 dim %arg1 : (!hlfir.expr<?x!fir.logical<4>>, i32) -> !fir.logical<4>
 }
 
+// -----
+func.func @bad_maxval1(%arg0: !hlfir.expr<?xi32>, %arg1: i32, %arg2: !fir.box<!fir.logical<4>>) {
+  // expected-error at +1 {{'hlfir.maxval' op result must have the same element type as ARRAY argument}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?xi32>, i32, !fir.box<!fir.logical<4>>) -> f32
+}
+
+// -----
+func.func @bad_maxval2(%arg0: !hlfir.expr<?xi32>, %arg1: i32, %arg2: !fir.box<!fir.array<?x?x?x?x?x!fir.logical<4>>>) {
+  // expected-warning at +1 {{MASK must be conformable to ARRAY}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?xi32>, i32, !fir.box<!fir.array<?x?x?x?x?x!fir.logical<4>>>) -> !hlfir.expr<i32>
+}
+
+// -----
+func.func @bad_maxval3(%arg0: !hlfir.expr<?x5x?xi32>, %arg1: i32, %arg2: !fir.box<!fir.array<2x6x?x!fir.logical<4>>>) {
+  // expected-warning at +1 {{MASK must be conformable to ARRAY}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?x5x?xi32>, i32, !fir.box<!fir.array<2x6x?x!fir.logical<4>>>) -> !hlfir.expr<i32>
+}
+
+// -----
+func.func @bad_maxval4(%arg0: !hlfir.expr<?x?xi32>, %arg1: i32, %arg2: !fir.box<!fir.logical<4>>) {
+  // expected-error at +1 {{'hlfir.maxval' op result rank must be one less than ARRAY}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?x?xi32>, i32, !fir.box<!fir.logical<4>>) -> !hlfir.expr<?x?xi32>
+}
+
+// -----
+func.func @bad_maxval5(%arg0: !hlfir.expr<?xi32>, %arg1: i32, %arg2: !fir.box<!fir.logical<4>>) {
+  // expected-error at +1 {{'hlfir.maxval' op result must be of numerical scalar type}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?xi32>, i32, !fir.box<!fir.logical<4>>) -> !fir.logical<4>
+}
+
+// -----
+func.func @bad_maxval6(%arg0: !hlfir.expr<?x?xi32>, %arg1: i32){
+  // expected-error at +1 {{'hlfir.maxval' op result must be an array}}
+  %0 = hlfir.maxval %arg0 dim %arg1 : (!hlfir.expr<?x?xi32>, i32) -> !hlfir.expr<i32>
+}
+
+// -----
+func.func @bad_maxval7(%arg0: !hlfir.expr<?xi32>){
+  // expected-error at +1 {{'hlfir.maxval' op result must be of numerical scalar type}}
+  %0 = hlfir.maxval %arg0 : (!hlfir.expr<?xi32>) -> !hlfir.expr<i32>
+}
+
+// -----
+func.func @bad_maxval8(%arg0: !hlfir.expr<?x!fir.char<1,?>>, %arg1: i32, %arg2: !fir.box<!fir.logical<4>>) {
+  // expected-error at +1 {{'hlfir.maxval' op result must have the same element type as ARRAY argument}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?x!fir.char<1,?>>, i32, !fir.box<!fir.logical<4>>) -> i32
+}
+
+// -----
+func.func @bad_maxval9(%arg0: !hlfir.expr<?x!fir.char<1,?>>, %arg1: i32, %arg2: !fir.box<!fir.array<?x?x?x?x?x!fir.logical<4>>>) {
+  // expected-warning at +1 {{MASK must be conformable to ARRAY}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?x!fir.char<1,?>>, i32, !fir.box<!fir.array<?x?x?x?x?x!fir.logical<4>>>) -> !hlfir.expr<!fir.char<1,?>>
+}
+
+// -----
+func.func @bad_maxval10(%arg0: !hlfir.expr<?x5x?x!fir.char<1,?>>, %arg1: i32, %arg2: !fir.box<!fir.array<2x6x?x!fir.logical<4>>>) {
+  // expected-warning at +1 {{MASK must be conformable to ARRAY}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?x5x?x!fir.char<1,?>>, i32, !fir.box<!fir.array<2x6x?x!fir.logical<4>>>) -> !hlfir.expr<!fir.char<1,?>>
+}
+
+// -----
+func.func @bad_maxval11(%arg0: !hlfir.expr<?x?x!fir.char<1,?>>, %arg1: i32, %arg2: !fir.box<!fir.logical<4>>) {
+  // expected-error at +1 {{'hlfir.maxval' op result rank must be one less than ARRAY}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?x?x!fir.char<1,?>>, i32, !fir.box<!fir.logical<4>>) -> !hlfir.expr<?x?x!fir.char<1,?>>
+}
+
+// -----
+func.func @bad_maxval12(%arg0: !hlfir.expr<?x!fir.char<1,?>>, %arg1: i32, %arg2: !fir.box<!fir.logical<4>>) {
+  // expected-error at +1 {{'hlfir.maxval' op result must be scalar character}}
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %arg2 : (!hlfir.expr<?x!fir.char<1,?>>, i32, !fir.box<!fir.logical<4>>) -> !hlfir.expr<?x!fir.char<1,?>>
+}
+
+// -----
+func.func @bad_maxval13(%arg0: !hlfir.expr<?x?x!fir.char<1,?>>, %arg1: i32){
+  // expected-error at +1 {{'hlfir.maxval' op result must be an array}}
+  %0 = hlfir.maxval %arg0 dim %arg1 : (!hlfir.expr<?x?x!fir.char<1,?>>, i32) -> !hlfir.expr<!fir.char<1,?>>
+}
+
 // -----
 func.func @bad_product1(%arg0: !hlfir.expr<?xi32>, %arg1: i32, %arg2: !fir.box<!fir.logical<4>>) {
   // expected-error at +1 {{'hlfir.product' op result must have the same element type as ARRAY argument}}
diff --git a/flang/test/HLFIR/maxval-lowering.fir b/flang/test/HLFIR/maxval-lowering.fir
new file mode 100644
index 000000000000000..3eb36cdef2cbfaf
--- /dev/null
+++ b/flang/test/HLFIR/maxval-lowering.fir
@@ -0,0 +1,218 @@
+// Test hlfir.maxval operation lowering to fir runtime call
+// RUN: fir-opt %s -lower-hlfir-intrinsics | FileCheck %s
+
+// simple one argument maxval
+func.func @_QPmaxval1(%arg0: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "a"}, %arg1: !fir.ref<i32> {fir.bindc_name = "s"}) {
+  %0:2 = hlfir.declare %arg0 {uniq_name = "_QFmaxval1Ea"} : (!fir.box<!fir.array<?xi32>>) -> (!fir.box<!fir.array<?xi32>>, !fir.box<!fir.array<?xi32>>)
+  %1:2 = hlfir.declare %arg1 {uniq_name = "_QFmaxval1Es"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
+  %2 = hlfir.maxval %0#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?xi32>>) -> i32
+  hlfir.assign %2 to %1#0 : i32, !fir.ref<i32>
+  return
+}
+// CHECK-LABEL: func.func @_QPmaxval1(
+// CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?xi32>>
+// CHECK:           %[[ARG1:.*]]: !fir.ref<i32>
+// CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+// CHECK-DAG:     %[[RES:.*]]:2 = hlfir.declare %[[ARG1]]
+// CHECK-DAG:     %[[MASK:.*]] = fir.absent !fir.box<i1>
+// CHECK-DAG:     %[[ARRAY_ARG:.*]] = fir.convert %[[ARRAY]]#1 : (!fir.box<!fir.array<?xi32>>) -> !fir.box<none>
+// CHECK-DAG:     %[[MASK_ARG:.*]] = fir.convert %[[MASK]] : (!fir.box<i1>) -> !fir.box<none>
+// CHECK:         %[[RET:.*]] = fir.call @_FortranAMaxvalInteger4(%[[ARRAY_ARG]], %[[LOC_STR:.*]], %[[LOC_N:.*]], %[[INT:.*]], %[[MASK_ARG]]) fastmath<contract> : (!fir.box<none>, !fir.ref<i8>, i32, i32, !fir.box<none>) -> i32
+// CHECK-NEXT:    hlfir.assign %[[RET]] to %[[RES]]#0 : i32, !fir.ref<i32>
+// CHECK-NEXT:    return
+// CHECK-NEXT:  }
+
+// maxval with a by-ref dimension of index type
+func.func @_QPmaxval2(%arg0: !fir.box<!fir.array<?x?xi32>> {fir.bindc_name = "a"}, %arg1: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "s"}, %arg2: !fir.ref<index> {fir.bindc_name = "d"}) {
+  %0:2 = hlfir.declare %arg0 {uniq_name = "_QFmaxval2Ea"} : (!fir.box<!fir.array<?x?xi32>>) -> (!fir.box<!fir.array<?x?xi32>>, !fir.box<!fir.array<?x?xi32>>)
+  %1:2 = hlfir.declare %arg2 {uniq_name = "_QFmaxval2Ed"} : (!fir.ref<index>) -> (!fir.ref<index>, !fir.ref<index>)
+  %2:2 = hlfir.declare %arg1 {uniq_name = "_QFmaxval2Es"} : (!fir.box<!fir.array<?xi32>>) -> (!fir.box<!fir.array<?xi32>>, !fir.box<!fir.array<?xi32>>)
+  %3 = fir.load %1#0 : !fir.ref<index>
+  %4 = hlfir.maxval %0#0 dim %3#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?x?xi32>>, index) -> !hlfir.expr<?xi32>
+  hlfir.assign %4 to %2#0 : !hlfir.expr<?xi32>, !fir.box<!fir.array<?xi32>>
+  hlfir.destroy %4 : !hlfir.expr<?xi32>
+  return
+}
+// CHECK-LABEL: func.func @_QPmaxval2(
+// CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?x?xi32>>
+// CHECK:           %[[ARG1:.*]]: !fir.box<!fir.array<?xi32>>
+// CHECK:           %[[ARG2:.*]]: !fir.ref<index>
+// CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+// CHECK-DAG:     %[[RES:.*]]:2 = hlfir.declare %[[ARG1]]
+// CHECK-DAG:     %[[DIM_VAR:.*]]:2 = hlfir.declare %[[ARG2]]
+
+// CHECK-DAG:     %[[RET_BOX:.*]] = fir.alloca !fir.box<!fir.heap<!fir.array<?xi32>>>
+// CHECK-DAG:     %[[RET_ADDR:.*]] = fir.zero_bits !fir.heap<!fir.array<?xi32>>
+// CHECK-DAG:     %[[C0:.*]] = arith.constant 0 : index
+// CHECK-DAG:     %[[RET_SHAPE:.*]] = fir.shape %[[C0]] : (index) -> !fir.shape<1>
+// CHECK-DAG:     %[[RET_EMBOX:.*]] = fir.embox %[[RET_ADDR]](%[[RET_SHAPE]])
+// CHECK-DAG:     fir.store %[[RET_EMBOX]] to %[[RET_BOX]]
+
+// CHECK-DAG:     %[[MASK:.*]] = fir.absent !fir.box<i1>
+// CHECK-DAG:     %[[DIM_IDX:.*]] = fir.load %[[DIM_VAR]]#0 : !fir.ref<index>
+// CHECK-DAG:     %[[DIM:.*]] = fir.convert %[[DIM_IDX]] : (index) -> i32
+
+// CHECK-DAG:     %[[RET_ARG:.*]] = fir.convert %[[RET_BOX]]
+// CHECK-DAG:     %[[ARRAY_ARG:.*]] = fir.convert %[[ARRAY]]#1 : (!fir.box<!fir.array<?x?xi32>>) -> !fir.box<none>
+// CHECK-DAG:     %[[MASK_ARG:.*]] = fir.convert %[[MASK]] : (!fir.box<i1>) -> !fir.box<none>
+// CHECK:         %[[NONE:.*]] = fir.call @_FortranAMaxvalDim(%[[RET_ARG]], %[[ARRAY_ARG]], %[[DIM]], %[[LOC_STR:.*]], %[[LOC_N:.*]], %[[MASK_ARG]]) fastmath<contract> : (!fir.ref<!fir.box<none>>, !fir.box<none>, i32, !fir.ref<i8>, i32, !fir.box<none>) -> none
+
+// CHECK:         %[[RET:.*]] = fir.load %[[RET_BOX]]
+// CHECK:         %[[BOX_DIMS:.*]]:3 = fir.box_dims %[[RET]]
+// CHECK-NEXT:    %[[ADDR:.*]] = fir.box_addr %[[RET]]
+// CHECK-NEXT:    %[[SHIFT:.*]] = fir.shape_shift %[[BOX_DIMS]]#0, %[[BOX_DIMS]]#1
+// TODO: fix alias analysis in hlfir.assign bufferization
+// CHECK-NEXT:    %[[TMP:.*]]:2 = hlfir.declare %[[ADDR]](%[[SHIFT]]) {uniq_name = ".tmp.intrinsic_result"}
+// CHECK:         %[[TRUE:.*]] = arith.constant true
+// CHECK:         %[[ASEXPR:.*]] = hlfir.as_expr %[[TMP]]#0 move %[[TRUE]] : (!fir.box<!fir.array<?xi32>>, i1) -> !hlfir.expr<?xi32>
+// CHECK:         hlfir.assign %[[ASEXPR]] to %[[RES]]#0
+// CHECK:         hlfir.destroy %[[ASEXPR]]
+// CHECK-NEXT:    return
+// CHECK-NEXT:  }
+
+// maxval with scalar mask
+func.func @_QPmaxval3(%arg0: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "a"}, %arg1: !fir.ref<i32> {fir.bindc_name = "s"}, %arg2: !fir.ref<!fir.logical<4>> {fir.bindc_name = "m"}) {
+  %0:2 = hlfir.declare %arg0 {uniq_name = "_QFmaxval3Ea"} : (!fir.box<!fir.array<?xi32>>) -> (!fir.box<!fir.array<?xi32>>, !fir.box<!fir.array<?xi32>>)
+  %1:2 = hlfir.declare %arg2 {uniq_name = "_QFmaxval3Em"} : (!fir.ref<!fir.logical<4>>) -> (!fir.ref<!fir.logical<4>>, !fir.ref<!fir.logical<4>>)
+  %2:2 = hlfir.declare %arg1 {uniq_name = "_QFmaxval3Es"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
+  %3 = hlfir.maxval %0#0 mask %1#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.logical<4>>) -> i32
+  hlfir.assign %3 to %2#0 : i32, !fir.ref<i32>
+  return
+}
+// CHECK-LABEL: func.func @_QPmaxval3(
+// CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?xi32>>
+// CHECK:           %[[ARG1:.*]]: !fir.ref<i32>
+// CHECK:           %[[ARG2:.*]]: !fir.ref<!fir.logical<4>>
+// CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+// CHECK-DAG:     %[[RES:.*]]:2 = hlfir.declare %[[ARG1]]
+// CHECK-DAG:     %[[MASK:.*]]:2 = hlfir.declare %[[ARG2]]
+// CHECK-DAG:     %[[MASK_BOX:.*]] = fir.embox %[[MASK]]#1 : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+// CHECK-DAG:     %[[ARRAY_ARG:.*]] = fir.convert %[[ARRAY]]#1 : (!fir.box<!fir.array<?xi32>>) -> !fir.box<none>
+// CHECK-DAG:     %[[MASK_ARG:.*]] = fir.convert %[[MASK_BOX]] : (!fir.box<!fir.logical<4>>) -> !fir.box<none>
+// CHECK:         %[[RET:.*]] = fir.call @_FortranAMaxvalInteger4(%[[ARRAY_ARG]], %[[LOC_STR:.*]], %[[LOC_N:.*]], %[[INT:.*]], %[[MASK_ARG]]) fastmath<contract> : (!fir.box<none>, !fir.ref<i8>, i32, i32, !fir.box<none>) -> i32
+// CHECK-NEXT:    hlfir.assign %[[RET]] to %[[RES]]#0 : i32, !fir.ref<i32>
+// CHECK-NEXT:    return
+// CHECK-NEXT:  }
+
+// maxval with array mask
+func.func @_QPmaxval4(%arg0: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "a"}, %arg1: !fir.ref<i32> {fir.bindc_name = "s"}, %arg2: !fir.box<!fir.array<?x!fir.logical<4>>> {fir.bindc_name = "m"}) {
+  %0:2 = hlfir.declare %arg0 {uniq_name = "_QFmaxval4Ea"} : (!fir.box<!fir.array<?xi32>>) -> (!fir.box<!fir.array<?xi32>>, !fir.box<!fir.array<?xi32>>)
+  %1:2 = hlfir.declare %arg2 {uniq_name = "_QFmaxval4Em"} : (!fir.box<!fir.array<?x!fir.logical<4>>>) -> (!fir.box<!fir.array<?x!fir.logical<4>>>, !fir.box<!fir.array<?x!fir.logical<4>>>)
+  %2:2 = hlfir.declare %arg1 {uniq_name = "_QFmaxval4Es"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
+  %3 = hlfir.maxval %0#0 mask %1#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?xi32>>, !fir.box<!fir.array<?x!fir.logical<4>>>) -> i32
+  hlfir.assign %3 to %2#0 : i32, !fir.ref<i32>
+  return
+}
+// CHECK-LABEL: func.func @_QPmaxval4(
+// CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?xi32>>
+// CHECK:           %[[ARG1:.*]]: !fir.ref<i32>
+// CHECK:           %[[ARG2:.*]]: !fir.box<!fir.array<?x!fir.logical<4>>>
+// CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+// CHECK-DAG:     %[[RES:.*]]:2 = hlfir.declare %[[ARG1]]
+// CHECK-DAG:     %[[MASK:.*]]:2 = hlfir.declare %[[ARG2]]
+// CHECK-DAG:     %[[ARRAY_ARG:.*]] = fir.convert %[[ARRAY]]#1 : (!fir.box<!fir.array<?xi32>>) -> !fir.box<none>
+// CHECK-DAG:     %[[MASK_ARG:.*]] = fir.convert %[[MASK]]#1 : (!fir.box<!fir.array<?x!fir.logical<4>>>) -> !fir.box<none>
+// CHECK:         %[[RET:.*]] = fir.call @_FortranAMaxvalInteger4(%[[ARRAY_ARG]], %[[LOC_STR:.*]], %[[LOC_N:.*]], %[[INT:.*]], %[[MASK_ARG]]) fastmath<contract> : (!fir.box<none>, !fir.ref<i8>, i32, i32, !fir.box<none>) -> i32
+// CHECK-NEXT:    hlfir.assign %[[RET]] to %[[RES]]#0 : i32, !fir.ref<i32>
+// CHECK-NEXT:    return
+// CHECK-NEXT:  }
+
+fir.global internal @_QFmaxval5Ea : !fir.array<2x2xi32> {
+  %0 = fir.undefined !fir.array<2x2xi32>
+  %c1_i32 = arith.constant 1 : i32
+  %1 = fir.insert_value %0, %c1_i32, [0 : index, 0 : index] : (!fir.array<2x2xi32>, i32) -> !fir.array<2x2xi32>
+  %c2_i32 = arith.constant 2 : i32
+  %2 = fir.insert_value %1, %c2_i32, [1 : index, 0 : index] : (!fir.array<2x2xi32>, i32) -> !fir.array<2x2xi32>
+  %c3_i32 = arith.constant 3 : i32
+  %3 = fir.insert_value %2, %c3_i32, [0 : index, 1 : index] : (!fir.array<2x2xi32>, i32) -> !fir.array<2x2xi32>
+  %c4_i32 = arith.constant 4 : i32
+  %4 = fir.insert_value %3, %c4_i32, [1 : index, 1 : index] : (!fir.array<2x2xi32>, i32) -> !fir.array<2x2xi32>
+  %c2 = arith.constant 2 : index
+  %c2_0 = arith.constant 2 : index
+  fir.has_value %4 : !fir.array<2x2xi32>
+}
+
+// 3 argument maxval, using local variables
+func.func @_QPmaxval5(%arg0: !fir.ref<!fir.array<2xi32>> {fir.bindc_name = "s"}) {
+  %0 = fir.address_of(@_QFmaxval5Ea) : !fir.ref<!fir.array<2x2xi32>>
+  %c2 = arith.constant 2 : index
+  %c2_0 = arith.constant 2 : index
+  %1 = fir.shape %c2, %c2_0 : (index, index) -> !fir.shape<2>
+  %2:2 = hlfir.declare %0(%1) {uniq_name = "_QFmaxval5Ea"} : (!fir.ref<!fir.array<2x2xi32>>, !fir.shape<2>) -> (!fir.ref<!fir.array<2x2xi32>>, !fir.ref<!fir.array<2x2xi32>>)
+  %c2_1 = arith.constant 2 : index
+  %3 = fir.shape %c2_1 : (index) -> !fir.shape<1>
+  %4:2 = hlfir.declare %arg0(%3) {uniq_name = "_QFmaxval5Es"} : (!fir.ref<!fir.array<2xi32>>, !fir.shape<1>) -> (!fir.ref<!fir.array<2xi32>>, !fir.ref<!fir.array<2xi32>>)
+  %c1_i32 = arith.constant 1 : i32
+  %true = arith.constant true
+  %5 = hlfir.maxval %2#0 dim %c1_i32 mask %true {fastmath = #arith.fastmath<contract>} : (!fir.ref<!fir.array<2x2xi32>>, i32, i1) -> !hlfir.expr<2xi32>
+  hlfir.assign %5 to %4#0 : !hlfir.expr<2xi32>, !fir.ref<!fir.array<2xi32>>
+  hlfir.destroy %5 : !hlfir.expr<2xi32>
+  return
+}
+// CHECK-LABEL: func.func @_QPmaxval5(
+// CHECK:           %[[ARG0:.*]]: !fir.ref<!fir.array<2xi32>>
+// CHECK-DAG:     %[[RET_BOX:.*]] = fir.alloca !fir.box<!fir.heap<!fir.array<?xi32>>>
+// CHECK-DAG:     %[[RET_ADDR:.*]] = fir.zero_bits !fir.heap<!fir.array<?xi32>>
+// CHECK-DAG:     %[[C0:.*]] = arith.constant 0 : index
+// CHECK-DAG:     %[[RET_SHAPE:.*]] = fir.shape %[[C0]] : (index) -> !fir.shape<1>
+// CHECK-DAG:     %[[RET_EMBOX:.*]] = fir.embox %[[RET_ADDR]](%[[RET_SHAPE]])
+// CHECK-DAG:     fir.store %[[RET_EMBOX]] to %[[RET_BOX]]
+
+// CHECK-DAG:     %[[RES_VAR:.*]] = hlfir.declare %[[ARG0]](%[[RES_SHAPE:.*]])
+
+// CHECK-DAG:     %[[MASK_ALLOC:.*]] = fir.alloca !fir.logical<4>
+// CHECK-DAG:     %[[TRUE:.*]] = arith.constant true
+// CHECK-DAG:     %[[MASK_VAL:.*]]  = fir.convert %[[TRUE]] : (i1) -> !fir.logical<4>
+// CHECK-DAG:     fir.store %[[MASK_VAL]] to %[[MASK_ALLOC]] : !fir.ref<!fir.logical<4>>
+// CHECK-DAG:     %[[MASK_BOX:.*]] = fir.embox %[[MASK_ALLOC]]
+
+// CHECK-DAG:     %[[ARRAY_ADDR:.*]] = fir.address_of
+// CHECK-DAG:     %[[ARRAY_VAR:.*]]:2 = hlfir.declare %[[ARRAY_ADDR]](%[[ARRAY_SHAPE:.*]])
+// CHECK-DAG:     %[[ARRAY_BOX:.*]] = fir.embox %[[ARRAY_VAR]]#1(%[[ARRAY_SHAPE:.*]])
+
+// CHECK-DAG:     %[[DIM:.*]] = arith.constant 1 : i32
+
+// CHECK-DAG:     %[[RET_ARG:.*]] = fir.convert %[[RET_BOX]]
+// CHECK-DAG:     %[[ARRAY_ARG:.*]] = fir.convert %[[ARRAY_BOX]] : (!fir.box<!fir.array<2x2xi32>>) -> !fir.box<none>
+// CHECK-DAG:     %[[MASK_ARG:.*]] = fir.convert %[[MASK_BOX]] : (!fir.box<!fir.logical<4>>) -> !fir.box<none>
+// CHECK:         %[[NONE:.*]] = fir.call @_FortranAMaxvalDim(%[[RET_ARG]], %[[ARRAY_ARG]], %[[DIM]], %[[LOC_STR:.*]], %[[LOC_N:.*]], %[[MASK_ARG]]) fastmath<contract> : (!fir.ref<!fir.box<none>>, !fir.box<none>, i32, !fir.ref<i8>, i32, !fir.box<none>) -> none
+
+// simple one argument maxval for character
+func.func @_QPmaxval6(%arg0: !fir.box<!fir.array<?x!fir.char<1,?>>> {fir.bindc_name = "a"}, %arg1: !fir.boxchar<1> {fir.bindc_name = "s"}) {
+  %0:2 = hlfir.declare %arg0 {uniq_name = "_QFmaxval6Ea"} : (!fir.box<!fir.array<?x!fir.char<1,?>>>) -> (!fir.box<!fir.array<?x!fir.char<1,?>>>, !fir.box<!fir.array<?x!fir.char<1,?>>>)
+  %1:2 = fir.unboxchar %arg1 : (!fir.boxchar<1>) -> (!fir.ref<!fir.char<1,?>>, index)
+  %2:2 = hlfir.declare %1#0 typeparams %1#1 {uniq_name = "_QFmaxval6Es"} : (!fir.ref<!fir.char<1,?>>, index) -> (!fir.boxchar<1>, !fir.ref<!fir.char<1,?>>)
+  %3 = hlfir.maxval %0#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?x!fir.char<1,?>>>) -> !hlfir.expr<!fir.char<1,?>>
+  hlfir.assign %3 to %2#0 : !hlfir.expr<!fir.char<1,?>>, !fir.boxchar<1>
+  hlfir.destroy %3 : !hlfir.expr<!fir.char<1,?>>
+  return
+}
+// CHECK-LABEL: func.func @_QPmaxval6(
+// CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?x!fir.char<1,?>>>
+// CHECK:           %[[ARG1:.*]]: !fir.boxchar<1>
+// CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+// CHECK-DAG:     %[[UNBOXED:.*]]:2 = fir.unboxchar %[[ARG1]]
+// CHECK-DAG:     %[[RES:.*]]:2 = hlfir.declare %[[UNBOXED]]#0 typeparams %[[UNBOXED]]#1
+
+// CHECK-DAG:     %[[MASK:.*]] = fir.absent !fir.box<i1>
+// CHECK-DAG:     %[[RET_BOX:.*]] = fir.alloca !fir.box<!fir.heap<!fir.char<1,?>>>
+// CHECK-DAG:     %[[RET_ADDR:.*]] = fir.zero_bits !fir.heap<!fir.char<1,?>>
+// CHECK-DAG:     %[[C0:.*]] = arith.constant 0 : index
+// CHECK-DAG:     %[[RET_EMBOX:.*]] = fir.embox %[[RET_ADDR]] typeparams %[[C0]]
+// CHECK-DAG:     fir.store %[[RET_EMBOX]] to %[[RET_BOX]]
+
+// CHECK-DAG:     %[[RET_ARG:.*]] = fir.convert %[[RET_BOX]]
+// CHECK-DAG:     %[[ARRAY_ARG:.*]] = fir.convert %[[ARRAY]]#1 : (!fir.box<!fir.array<?x!fir.char<1,?>>>) -> !fir.box<none>
+// CHECK-DAG:     %[[MASK_ARG:.*]] = fir.convert %[[MASK]] : (!fir.box<i1>) -> !fir.box<none>
+// CHECK:         %[[NONE:.*]] = fir.call @_FortranAMaxvalCharacter(%[[RET_ARG]], %[[ARRAY_ARG]], %[[LOC_STR:.*]], %[[LOC_N:.*]], %[[MASK_ARG]]) fastmath<contract> : (!fir.ref<!fir.box<none>>, !fir.box<none>, !fir.ref<i8>, i32, !fir.box<none>) -> none
+
+// CHECK:         %[[RET:.*]] = fir.load %[[RET_BOX]]
+// CHECK:         %[[BOX_ELESIZE:.*]] = fir.box_elesize %[[RET]]
+// CHECK-NEXT:    %[[ADDR:.*]] = fir.box_addr %[[RET]]
+// CHECK-NEXT:    %[[TMP:.*]]:2 = hlfir.declare %[[ADDR]] typeparams %[[BOX_ELESIZE]] {uniq_name = ".tmp.intrinsic_result"}
+// CHECK:         %[[TRUE:.*]] = arith.constant true
+// CHECK:         %[[ASEXPR:.*]] = hlfir.as_expr %[[TMP]]#0 move %[[TRUE]] : (!fir.boxchar<1>, i1) -> !hlfir.expr<!fir.char<1,?>>
+// CHECK:         hlfir.assign %[[ASEXPR]] to %[[RES]]#0
+// CHECK:         hlfir.destroy %[[ASEXPR]]
+// CHECK-NEXT:    return
+// CHECK-NEXT:  }
diff --git a/flang/test/HLFIR/maxval.fir b/flang/test/HLFIR/maxval.fir
new file mode 100644
index 000000000000000..2d1de0c33e71dec
--- /dev/null
+++ b/flang/test/HLFIR/maxval.fir
@@ -0,0 +1,249 @@
+// Test hlfir.maxval operation parse, verify (no errors), and unparse
+
+// RUN: fir-opt %s | fir-opt | FileCheck %s
+
+// array is an expression of known shape
+func.func @maxval0(%arg0: !hlfir.expr<42xi32>) {
+  %mask = fir.alloca !fir.logical<4>
+  %c_1 = arith.constant 1 : index
+  %true = arith.constant true
+  %true_logical = fir.convert %true : (i1) -> !fir.logical<4>
+  fir.store %true_logical to %mask : !fir.ref<!fir.logical<4>>
+  %mask_box = fir.embox %mask : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %mask_box : (!hlfir.expr<42xi32>, index, !fir.box<!fir.logical<4>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval0(%[[ARRAY:.*]]: !hlfir.expr<42xi32>) {
+// CHECK-NEXT:   %[[MASK:.*]] = fir.alloca !fir.logical<4>
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   %[[TRUE:.*]] = arith.constant true
+// CHECK-NEXT:   %[[LOGICAL:.*]] = fir.convert %[[TRUE]] : (i1) -> !fir.logical<4>
+// CHECK-NEXT:   fir.store %[[LOGICAL]] to %[[MASK]] : !fir.ref<!fir.logical<4>>
+// CHECK-NEXT:   %[[BOX:.*]] = fir.embox %0 : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY]] dim %[[C1]] mask %[[BOX]] : (!hlfir.expr<42xi32>, index, !fir.box<!fir.logical<4>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// array is an expression of asmaxvaled shape
+func.func @maxval1(%arg0: !hlfir.expr<?xi32>) {
+  %mask = fir.alloca !fir.logical<4>
+  %c_1 = arith.constant 1 : index
+  %true = arith.constant true
+  %true_logical = fir.convert %true : (i1) -> !fir.logical<4>
+  fir.store %true_logical to %mask : !fir.ref<!fir.logical<4>>
+  %mask_box = fir.embox %mask : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %mask_box : (!hlfir.expr<?xi32>, index, !fir.box<!fir.logical<4>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval1(%[[ARRAY:.*]]: !hlfir.expr<?xi32>) {
+// CHECK-NEXT:   %[[MASK:.*]] = fir.alloca !fir.logical<4>
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   %[[TRUE:.*]] = arith.constant true
+// CHECK-NEXT:   %[[LOGICAL:.*]] = fir.convert %[[TRUE]] : (i1) -> !fir.logical<4>
+// CHECK-NEXT:   fir.store %[[LOGICAL:.*]] to %[[MASK:.*]] : !fir.ref<!fir.logical<4>>
+// CHECK-NEXT:   %[[BOX:.*]] = fir.embox %[[MASK:.*]] : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY:.*]] dim %[[C1]] mask %[[BOX]] : (!hlfir.expr<?xi32>, index, !fir.box<!fir.logical<4>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// boxed array
+func.func @maxval2(%arg0: !fir.box<!fir.array<42xi32>>) {
+  %mask = fir.alloca !fir.logical<4>
+  %c_1 = arith.constant 1 : index
+  %true = arith.constant true
+  %true_logical = fir.convert %true : (i1) -> !fir.logical<4>
+  fir.store %true_logical to %mask : !fir.ref<!fir.logical<4>>
+  %mask_box = fir.embox %mask : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %mask_box : (!fir.box<!fir.array<42xi32>>, index, !fir.box<!fir.logical<4>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval2(%[[ARRAY:.*]]: !fir.box<!fir.array<42xi32>>) {
+// CHECK-NEXT:   %[[MASK:.*]] = fir.alloca !fir.logical<4>
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   %[[TRUE:.*]] = arith.constant true
+// CHECK-NEXT:   %[[LOGICAL:.*]] = fir.convert %[[TRUE]] : (i1) -> !fir.logical<4>
+// CHECK-NEXT:   fir.store %[[LOGICAL:.*]] to %[[MASK:.*]] : !fir.ref<!fir.logical<4>>
+// CHECK-NEXT:   %[[BOX:.*]] = fir.embox %[[MASK:.*]] : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY:.*]] dim %[[C1]] mask %[[BOX]] : (!fir.box<!fir.array<42xi32>>, index, !fir.box<!fir.logical<4>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// asmaxvaled shape boxed array
+func.func @maxval3(%arg0: !fir.box<!fir.array<?xi32>>) {
+  %mask = fir.alloca !fir.logical<4>
+  %c_1 = arith.constant 1 : index
+  %true = arith.constant true
+  %true_logical = fir.convert %true : (i1) -> !fir.logical<4>
+  fir.store %true_logical to %mask : !fir.ref<!fir.logical<4>>
+  %mask_box = fir.embox %mask : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %mask_box : (!fir.box<!fir.array<?xi32>>, index, !fir.box<!fir.logical<4>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval3(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>) {
+// CHECK-NEXT:   %[[MASK:.*]] = fir.alloca !fir.logical<4>
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   %[[TRUE:.*]] = arith.constant true
+// CHECK-NEXT:   %[[LOGICAL:.*]] = fir.convert %[[TRUE]] : (i1) -> !fir.logical<4>
+// CHECK-NEXT:   fir.store %[[LOGICAL:.*]] to %[[MASK:.*]] : !fir.ref<!fir.logical<4>>
+// CHECK-NEXT:   %[[BOX:.*]] = fir.embox %[[MASK:.*]] : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY:.*]] dim %[[C1]] mask %[[BOX]] : (!fir.box<!fir.array<?xi32>>, index, !fir.box<!fir.logical<4>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// known shape expr mask
+func.func @maxval4(%arg0: !fir.box<!fir.array<?xi32>>, %arg1: !hlfir.expr<42x!fir.logical<4>>) {
+  %c_1 = arith.constant 1 : index
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %arg1 : (!fir.box<!fir.array<?xi32>>, index, !hlfir.expr<42x!fir.logical<4>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval4(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>, %[[MASK:.*]]: !hlfir.expr<42x!fir.logical<4>>) {
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY]] dim %[[C1]] mask %[[MASK]] : (!fir.box<!fir.array<?xi32>>, index, !hlfir.expr<42x!fir.logical<4>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// asmaxvaled shape expr mask
+func.func @maxval5(%arg0: !fir.box<!fir.array<?xi32>>, %arg1: !hlfir.expr<?x!fir.logical<4>>) {
+  %c_1 = arith.constant 1 : index
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %arg1 : (!fir.box<!fir.array<?xi32>>, index, !hlfir.expr<?x!fir.logical<4>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval5(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>, %[[MASK:.*]]: !hlfir.expr<?x!fir.logical<4>>) {
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY]] dim %[[C1]] mask %[[MASK]] : (!fir.box<!fir.array<?xi32>>, index, !hlfir.expr<?x!fir.logical<4>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// known shape array mask
+func.func @maxval6(%arg0: !fir.box<!fir.array<?xi32>>, %arg1: !fir.box<!fir.array<42x!fir.logical<4>>>) {
+  %c_1 = arith.constant 1 : index
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %arg1 : (!fir.box<!fir.array<?xi32>>, index, !fir.box<!fir.array<42x!fir.logical<4>>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval6(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>, %[[MASK:.*]]: !fir.box<!fir.array<42x!fir.logical<4>>>) {
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY]] dim %[[C1]] mask %[[MASK]] : (!fir.box<!fir.array<?xi32>>, index, !fir.box<!fir.array<42x!fir.logical<4>>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// asmaxvaled shape array mask
+func.func @maxval7(%arg0: !fir.box<!fir.array<?xi32>>, %arg1: !fir.box<!fir.array<?x!fir.logical<4>>>) {
+  %c_1 = arith.constant 1 : index
+  %0 = hlfir.maxval %arg0 dim %c_1 mask %arg1 : (!fir.box<!fir.array<?xi32>>, index, !fir.box<!fir.array<?x!fir.logical<4>>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval7(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>, %[[MASK:.*]]: !fir.box<!fir.array<?x!fir.logical<4>>>) {
+// CHECK-NEXT:   %[[C1:.*]] = arith.constant 1 : index
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY]] dim %[[C1]] mask %[[MASK]] : (!fir.box<!fir.array<?xi32>>, index, !fir.box<!fir.array<?x!fir.logical<4>>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// known shape expr return
+func.func @maxval8(%arg0: !fir.box<!fir.array<2x2xi32>>, %arg1: i32) {
+  %mask = fir.alloca !fir.logical<4>
+  %true = arith.constant true
+  %true_logical = fir.convert %true : (i1) -> !fir.logical<4>
+  fir.store %true_logical to %mask : !fir.ref<!fir.logical<4>>
+  %mask_box = fir.embox %mask : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %mask_box : (!fir.box<!fir.array<2x2xi32>>, i32, !fir.box<!fir.logical<4>>) -> !hlfir.expr<2xi32>
+  return
+}
+// CHECK:      func.func @maxval8(%[[ARRAY:.*]]: !fir.box<!fir.array<2x2xi32>>, %[[DIM:.*]]: i32) {
+// CHECK-NEXT:   %[[MASK:.*]] = fir.alloca !fir.logical<4>
+// CHECK-NEXT:   %[[TRUE:.*]] = arith.constant true
+// CHECK-NEXT:   %[[LOGICAL:.*]] = fir.convert %[[TRUE]] : (i1) -> !fir.logical<4>
+// CHECK-NEXT:   fir.store %[[LOGICAL]] to %[[MASK]] : !fir.ref<!fir.logical<4>>
+// CHECK-NEXT:   %[[BOX:.*]] = fir.embox %0 : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY]] dim %[[DIM]] mask %[[BOX]] : (!fir.box<!fir.array<2x2xi32>>, i32, !fir.box<!fir.logical<4>>) -> !hlfir.expr<2xi32>
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// asmaxvaled shape expr return
+func.func @maxval9(%arg0: !fir.box<!fir.array<?x?xi32>>, %arg1: i32) {
+  %mask = fir.alloca !fir.logical<4>
+  %true = arith.constant true
+  %true_logical = fir.convert %true : (i1) -> !fir.logical<4>
+  fir.store %true_logical to %mask : !fir.ref<!fir.logical<4>>
+  %mask_box = fir.embox %mask : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+  %0 = hlfir.maxval %arg0 dim %arg1 mask %mask_box : (!fir.box<!fir.array<?x?xi32>>, i32, !fir.box<!fir.logical<4>>) -> !hlfir.expr<?xi32>
+  return
+}
+// CHECK:      func.func @maxval9(%[[ARRAY:.*]]: !fir.box<!fir.array<?x?xi32>>, %[[DIM:.*]]: i32) {
+// CHECK-NEXT:   %[[MASK:.*]] = fir.alloca !fir.logical<4>
+// CHECK-NEXT:   %[[TRUE:.*]] = arith.constant true
+// CHECK-NEXT:   %[[LOGICAL:.*]] = fir.convert %[[TRUE]] : (i1) -> !fir.logical<4>
+// CHECK-NEXT:   fir.store %[[LOGICAL]] to %[[MASK]] : !fir.ref<!fir.logical<4>>
+// CHECK-NEXT:   %[[BOX:.*]] = fir.embox %0 : (!fir.ref<!fir.logical<4>>) -> !fir.box<!fir.logical<4>>
+// CHECK-NEXT:   hlfir.maxval %[[ARRAY]] dim %[[DIM]] mask %[[BOX]] : (!fir.box<!fir.array<?x?xi32>>, i32, !fir.box<!fir.logical<4>>) -> !hlfir.expr<?xi32>
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// hlfir.maxval with only an array argument
+func.func @maxval10(%arg0: !fir.box<!fir.array<?x?xi32>>) {
+  %maxval = hlfir.maxval %arg0 : (!fir.box<!fir.array<?x?xi32>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval10(%[[ARRAY:.*]]: !fir.box<!fir.array<?x?xi32>>
+// CHECK-NEXT:   %[[maxval:.*]] = hlfir.maxval %[[ARRAY]] : (!fir.box<!fir.array<?x?xi32>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// hlfir.maxval with only a character array argument
+func.func @maxval11(%arg0: !fir.box<!fir.array<?x?x!fir.char<1,?>>>) {
+  %maxval = hlfir.maxval %arg0 : (!fir.box<!fir.array<?x?x!fir.char<1,?>>>) -> !hlfir.expr<!fir.char<1,?>>
+  return
+}
+// CHECK:      func.func @maxval11(%[[ARRAY:.*]]: !fir.box<!fir.array<?x?x!fir.char<1,?>>>
+// CHECK-NEXT:   %[[maxval:.*]] = hlfir.maxval %[[ARRAY]] : (!fir.box<!fir.array<?x?x!fir.char<1,?>>>) -> !hlfir.expr<!fir.char<1,?>>
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// hlfir.maxval with array and dim argument
+func.func @maxval12(%arg0: !fir.box<!fir.array<?x?xi32>>, %arg1: i32) {
+  %maxval = hlfir.maxval %arg0 dim %arg1 : (!fir.box<!fir.array<?x?xi32>>, i32) -> !hlfir.expr<?xi32>
+  return
+}
+// CHECK:      func.func @maxval12(%[[ARRAY:.*]]: !fir.box<!fir.array<?x?xi32>>, %[[DIM:.*]]: i32
+// CHECK-NEXT:   %[[maxval:.*]] = hlfir.maxval %[[ARRAY]] dim %[[DIM]] : (!fir.box<!fir.array<?x?xi32>>, i32) -> !hlfir.expr<?xi32>
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// hlfir.maxval with array and mask argument
+func.func @maxval13(%arg0: !fir.box<!fir.array<?xi32>>, %arg1: !fir.logical<4>) {
+  %maxval = hlfir.maxval %arg0 mask %arg1 : (!fir.box<!fir.array<?xi32>>, !fir.logical<4>) -> i32
+  return
+}
+// CHECK:      func.func @maxval13(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>, %[[MASK:.*]]: !fir.logical<4>
+// CHECK-NEXT:   %[[maxval:.*]] = hlfir.maxval %[[ARRAY]] mask %[[MASK]] : (!fir.box<!fir.array<?xi32>>, !fir.logical<4>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// hlfir.maxval with dim argument with an unusual type
+func.func @maxval14(%arg0: !fir.box<!fir.array<?x?xi32>>, %arg1: index) {
+  %maxval = hlfir.maxval %arg0 dim %arg1 : (!fir.box<!fir.array<?x?xi32>>, index) -> !hlfir.expr<?xi32>
+  return
+}
+// CHECK:      func.func @maxval14(%[[ARRAY:.*]]: !fir.box<!fir.array<?x?xi32>>, %[[DIM:.*]]: index
+// CHECK-NEXT:   %[[maxval:.*]] = hlfir.maxval %[[ARRAY]] dim %[[DIM]] : (!fir.box<!fir.array<?x?xi32>>, index) -> !hlfir.expr<?xi32>
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// hlfir.maxval with mask argument of unusual type
+func.func @maxval15(%arg0: !fir.box<!fir.array<?xi32>>, %arg1: i1) {
+  %maxval = hlfir.maxval %arg0 mask %arg1 : (!fir.box<!fir.array<?xi32>>, i1) -> i32
+  return
+}
+// CHECK:      func.func @maxval15(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>, %[[MASK:.*]]: i1
+// CHECK-NEXT:   %[[maxval:.*]] = hlfir.maxval %[[ARRAY]] mask %[[MASK]] : (!fir.box<!fir.array<?xi32>>, i1) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
+
+// hlfir.maxval with mask argument of ref<array<>> type
+func.func @maxval16(%arg0: !fir.box<!fir.array<?xi32>>, %arg1: !fir.ref<!fir.array<?x!fir.logical<4>>>) {
+  %maxval = hlfir.maxval %arg0 mask %arg1 : (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.array<?x!fir.logical<4>>>) -> i32
+  return
+}
+// CHECK:      func.func @maxval16(%[[ARRAY:.*]]: !fir.box<!fir.array<?xi32>>, %[[MASK:.*]]: !fir.ref<!fir.array<?x!fir.logical<4>>>
+// CHECK-NEXT:   %[[maxval:.*]] = hlfir.maxval %[[ARRAY]] mask %[[MASK]] : (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.array<?x!fir.logical<4>>>) -> i32
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
diff --git a/flang/test/Lower/HLFIR/maxval.f90 b/flang/test/Lower/HLFIR/maxval.f90
new file mode 100644
index 000000000000000..5adad286a77d28b
--- /dev/null
+++ b/flang/test/Lower/HLFIR/maxval.f90
@@ -0,0 +1,262 @@
+! Test lowering of MAXVAL intrinsic to HLFIR
+! RUN: bbc -emit-hlfir -o - %s 2>&1 | FileCheck %s
+
+! simple 1 argument MAXVAL
+subroutine maxval1(a, s)
+  integer :: a(:), s
+  s = MAXVAL(a)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval1(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "a"}, %[[ARG1:.*]]: !fir.ref<i32>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?xi32>>) -> i32
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : i32, !fir.ref<i32>
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+! maxval with by-ref DIM argument
+subroutine maxval2(a, s, d)
+  integer :: a(:,:), s(:), d
+  s = MAXVAL(a, d)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval2(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?x?xi32>> {fir.bindc_name = "a"}, %[[ARG1:.*]]: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "s"}, %[[ARG2:.*]]: !fir.ref<i32>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-DAG:     %[[DIM_REF:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-NEXT:    %[[DIM:.*]] = fir.load %[[DIM_REF]]#0 : !fir.ref<i32>
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 dim %[[DIM]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?x?xi32>>, i32) -> !hlfir.expr<?xi32>
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : !hlfir.expr<?xi32>, !fir.box<!fir.array<?xi32>>
+! CHECK-NEXT:    hlfir.destroy %[[EXPR]]
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+! maxval with scalar mask argument
+subroutine maxval3(a, s, m)
+  integer :: a(:), s
+  logical :: m
+  s = MAXVAL(a, m)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval3(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "a"}, %[[ARG1:.*]]: !fir.ref<i32> {fir.bindc_name = "s"}, %[[ARG2:.*]]: !fir.ref<!fir.logical<4>>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-DAG:     %[[MASK:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 mask %[[MASK]]#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?xi32>>, !fir.ref<!fir.logical<4>>) -> i32
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : i32, !fir.ref<i32>
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+! maxval with array mask argument
+subroutine maxval4(a, s, m)
+  integer :: a(:), s
+  logical :: m(:)
+  s = MAXVAL(a, m)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval4(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "a"}, %[[ARG1:.*]]: !fir.ref<i32> {fir.bindc_name = "s"}, %[[ARG2:.*]]: !fir.box<!fir.array<?x!fir.logical<4>>>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-DAG:     %[[MASK:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 mask %[[MASK]]#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?xi32>>, !fir.box<!fir.array<?x!fir.logical<4>>>) -> i32
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : i32, !fir.ref<i32>
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+! maxval with all 3 arguments, dim is by-val, array isn't boxed
+subroutine maxval5(s)
+  integer :: s(2)
+  integer :: a(2,2) = reshape((/1, 2, 3, 4/), [2,2])
+  s = maxval(a, 1, .true.)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval5
+! CHECK:           %[[ARG0:.*]]: !fir.ref<!fir.array<2xi32>>
+! CHECK-DAG:     %[[ADDR:.*]] = fir.address_of({{.*}}) : !fir.ref<!fir.array<2x2xi32>>
+! CHECK-DAG:     %[[ARRAY_SHAPE:.*]] = fir.shape {{.*}} -> !fir.shape<2>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ADDR]](%[[ARRAY_SHAPE]])
+! CHECK-DAG:     %[[OUT_SHAPE:.*]] = fir.shape {{.*}} -> !fir.shape<1>
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[ARG0]](%[[OUT_SHAPE]])
+! CHECK-DAG:     %[[TRUE:.*]] = arith.constant true
+! CHECK-DAG:     %[[C1:.*]] = arith.constant 1 : i32
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 dim %[[C1]] mask %[[TRUE]] {fastmath = #arith.fastmath<contract>} : (!fir.ref<!fir.array<2x2xi32>>, i32, i1) -> !hlfir.expr<2xi32>
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : !hlfir.expr<2xi32>, !fir.ref<!fir.array<2xi32>>
+! CHECK-NEXT:    hlfir.destroy %[[EXPR]] : !hlfir.expr<2xi32>
+! CHECK-NEXT:    return
+! CHECK-nEXT:  }
+
+subroutine maxval6(a, s, d)
+  integer, pointer :: d
+  real :: a(:,:), s(:)
+  s = maxval(a, (d))
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval6(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?x?xf32>>
+! CHECK:           %[[ARG1:.*]]: !fir.box<!fir.array<?xf32>>
+! CHECK:           %[[ARG2:.*]]: !fir.ref<!fir.box<!fir.ptr<i32>>>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-DAG:     %[[DIM_VAR:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-NEXT:     %[[DIM_BOX:.*]] = fir.load %[[DIM_VAR]]#0 : !fir.ref<!fir.box<!fir.ptr<i32>>>
+! CHECK-NEXT:    %[[DIM_ADDR:.*]] = fir.box_addr %[[DIM_BOX]] : (!fir.box<!fir.ptr<i32>>) -> !fir.ptr<i32>
+! CHECK-NEXT:    %[[DIM0:.*]] = fir.load %[[DIM_ADDR]] : !fir.ptr<i32>
+! CHECK-NEXT:    %[[DIM1:.*]] = hlfir.no_reassoc %[[DIM0]] : i32
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 dim %[[DIM1]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?x?xf32>>, i32) -> !hlfir.expr<?xf32>
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : !hlfir.expr<?xf32>, !fir.box<!fir.array<?xf32>>
+! CHECK-NEXT:    hlfir.destroy %[[EXPR]]
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+! simple 1 argument MAXVAL for character
+subroutine maxval7(a, s)
+  character(*) :: a(:), s
+  s = MAXVAL(a)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval7(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?x!fir.char<1,?>>> {fir.bindc_name = "a"}, %[[ARG1:.*]]: !fir.boxchar<1>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[UNBOXED:.*]]:2 = fir.unboxchar %[[ARG1]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[UNBOXED]]#0 typeparams %[[UNBOXED]]#1
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?x!fir.char<1,?>>>) -> !hlfir.expr<!fir.char<1,?>>
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : !hlfir.expr<!fir.char<1,?>>, !fir.boxchar<1>
+! CHECK-NEXT:    hlfir.destroy %[[EXPR]]
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+! maxval for character with by-ref DIM argument
+subroutine maxval8(a, s, d)
+  character(*) :: a(:,:), s(:)
+  integer :: d
+  s = MAXVAL(a, d)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval8(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?x?x!fir.char<1,?>>> {fir.bindc_name = "a"}, %[[ARG1:.*]]: !fir.box<!fir.array<?x!fir.char<1,?>>> {fir.bindc_name = "s"}, %[[ARG2:.*]]: !fir.ref<i32>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-DAG:     %[[DIM_REF:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-NEXT:    %[[DIM:.*]] = fir.load %[[DIM_REF]]#0 : !fir.ref<i32>
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 dim %[[DIM]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?x?x!fir.char<1,?>>>, i32) -> !hlfir.expr<?x!fir.char<1,?>>
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : !hlfir.expr<?x!fir.char<1,?>>, !fir.box<!fir.array<?x!fir.char<1,?>>>
+! CHECK-NEXT:    hlfir.destroy %[[EXPR]]
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+! maxval for character with scalar mask argument
+subroutine maxval9(a, s, m)
+  character(*) :: a(:), s
+  logical :: m
+  s = MAXVAL(a, m)
+end subroutine
+! CHECK-LABEL: func.func @_QPmaxval9(
+! CHECK:           %[[ARG0:.*]]: !fir.box<!fir.array<?x!fir.char<1,?>>> {fir.bindc_name = "a"}, %[[ARG1:.*]]: !fir.boxchar<1> {fir.bindc_name = "s"}, %[[ARG2:.*]]: !fir.ref<!fir.logical<4>>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[UNBOXED:.*]]:2 = fir.unboxchar %[[ARG1]]
+! CHECK-DAG:     %[[MASK:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-DAG:     %[[OUT:.*]]:2 = hlfir.declare %[[UNBOXED]]#0 typeparams %[[UNBOXED]]#1
+! CHECK-NEXT:    %[[EXPR:.*]] = hlfir.maxval %[[ARRAY]]#0 mask %[[MASK]]#0 {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<?x!fir.char<1,?>>>, !fir.ref<!fir.logical<4>>) -> !hlfir.expr<!fir.char<1,?>>
+! CHECK-NEXT:    hlfir.assign %[[EXPR]] to %[[OUT]]#0 : !hlfir.expr<!fir.char<1,?>>, !fir.boxchar<1>
+! CHECK-NEXT:    hlfir.destroy %[[EXPR]]
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+subroutine testDynamicallyOptionalMask(array, mask, res)
+  integer :: array(:), res
+  logical, allocatable :: mask(:)
+  res = MAXVAL(array, mask=mask)
+end subroutine
+! CHECK-LABEL: func.func @_QPtestdynamicallyoptionalmask(
+! CHECK-SAME:      %[[ARG0:.*]]: !fir.box<!fir.array<?xi32>>
+! CHECK-SAME:      %[[ARG1:.*]]: !fir.ref<!fir.box<!fir.heap<!fir.array<?x!fir.logical<4>>>>>
+! CHECK-SAME:      %[[ARG2:.*]]: !fir.ref<i32>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[MASK:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-DAG:     %[[RES:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-NEXT:    %[[MASK_LOAD:.*]] = fir.load %[[MASK]]#1
+! CHECK-NEXT:    %[[MASK_ADDR:.*]] = fir.box_addr %[[MASK_LOAD]]
+! CHECK-NEXT:    %[[MASK_ADDR_INT:.*]] = fir.convert %[[MASK_ADDR]]
+! CHECK-NEXT:    %[[C0:.*]] = arith.constant 0 : i64
+! CHECK-NEXT:    %[[CMP:.*]] = arith.cmpi ne, %[[MASK_ADDR_INT]], %[[C0]] : i64
+! it is a shame there is a second load here. The first is generated for
+! PreparedActualArgument::isPresent, the second is for optional handling
+! CHECK-NEXT:    %[[MASK_LOAD2:.*]] = fir.load %[[MASK]]#1
+! CHECK-NEXT:    %[[ABSENT:.*]] = fir.absent !fir.box<!fir.heap<!fir.array<?x!fir.logical<4>>>>
+! CHECK-NEXT:    %[[SELECT:.*]] = arith.select %[[CMP]], %[[MASK_LOAD2]], %[[ABSENT]]
+! CHECK-NEXT:    %[[MAXVAL:.*]] = hlfir.maxval %[[ARRAY]]#0 mask %[[SELECT]]
+! CHECK-NEXT:    hlfir.assign %[[MAXVAL]] to %[[RES]]#0
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+subroutine testAllocatableArray(array, mask, res)
+  integer, allocatable :: array(:)
+  integer :: res
+  logical :: mask(:)
+  res = MAXVAL(array, mask=mask)
+end subroutine
+! CHECK-LABEL: func.func @_QPtestallocatablearray(
+! CHECK-SAME:      %[[ARG0:.*]]: !fir.ref<!fir.box<!fir.heap<!fir.array<?xi32>>>>
+! CHECK-SAME:      %[[ARG1:.*]]: !fir.box<!fir.array<?x!fir.logical<4>>>
+! CHECK-SAME:      %[[ARG2:.*]]: !fir.ref<i32>
+! CHECK-DAG:     %[[ARRAY:.*]]:2 = hlfir.declare %[[ARG0]]
+! CHECK-DAG:     %[[MASK:.*]]:2 = hlfir.declare %[[ARG1]]
+! CHECK-DAG:     %[[RES:.*]]:2 = hlfir.declare %[[ARG2]]
+! CHECK-NEXT:    %[[LOADED_ARRAY:.*]] = fir.load %[[ARRAY]]#0
+! CHECK-NEXT:    %[[MAXVAL:.*]] = hlfir.maxval %[[LOADED_ARRAY]] mask %[[MASK]]#0
+! CHECK-NEXT:    hlfir.assign %[[MAXVAL]] to %[[RES]]#0
+! CHECK-NEXT:    return
+! CHECK-NEXT:  }
+
+function testOptionalScalar(array, mask)
+  integer :: array(:)
+  logical, optional :: mask
+  integer :: testOptionalScalar
+  testOptionalScalar = maxval(array, mask)
+end function
+! CHECK-LABEL:   func.func @_QPtestoptionalscalar(
+! CHECK-SAME:                                     %[[ARRAY_ARG:.*]]: !fir.box<!fir.array<?xi32>> {fir.bindc_name = "array"},
+! CHECK-SAME:                                     %[[MASK_ARG:.*]]: !fir.ref<!fir.logical<4>> {fir.bindc_name = "mask", fir.optional}) -> i32
+! CHECK:           %[[ARRAY_VAR:.*]]:2 = hlfir.declare %[[ARRAY_ARG]]
+! CHECK:           %[[MASK_VAR:.*]]:2 = hlfir.declare %[[MASK_ARG]]
+! CHECK:           %[[RET_ALLOC:.*]] = fir.alloca i32 {bindc_name = "testoptionalscalar", uniq_name = "_QFtestoptionalscalarEtestoptionalscalar"}
+! CHECK:           %[[RET_VAR:.*]]:2 = hlfir.declare %[[RET_ALLOC]]
+! CHECK:           %[[MASK_IS_PRESENT:.*]] = fir.is_present %[[MASK_VAR]]#0 : (!fir.ref<!fir.logical<4>>) -> i1
+! CHECK:           %[[MASK_BOX:.*]] = fir.embox %[[MASK_VAR]]#1
+! CHECK:           %[[ABSENT:.*]] = fir.absent !fir.box<!fir.logical<4>>
+! CHECK:           %[[MASK_SELECT:.*]] = arith.select %[[MASK_IS_PRESENT]], %[[MASK_BOX]], %[[ABSENT]]
+! CHECK:           %[[RES:.*]] = hlfir.maxval %[[ARRAY_VAR]]#0 mask %[[MASK_SELECT]] {{.*}}: (!fir.box<!fir.array<?xi32>>, !fir.box<!fir.logical<4>>) -> i32
+! CHECK:           hlfir.assign %[[RES]] to %[[RET_VAR]]#0
+! CHECK:           %[[RET:.*]] = fir.load %[[RET_VAR]]#1 : !fir.ref<i32>
+! CHECK:           return %[[RET]] : i32
+! CHECK:         }
+
+! Test that hlfir.maxval lowering inherits constant
+! character length from the argument, when the length
+! is unknown from the Fortran::evaluate expression type.
+subroutine test_unknown_char_len_result
+  character(len=3) :: array(3,3), res
+  res = maxval(array(:,:)(:))
+end subroutine test_unknown_char_len_result
+! CHECK-LABEL:   func.func @_QPtest_unknown_char_len_result() {
+! CHECK-DAG:       %[[C3:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[C3_0:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[C3_1:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[ARRAY_ALLOC:.*]] = fir.alloca !fir.array<3x3x!fir.char<1,3>>
+! CHECK-DAG:       %[[ARRAY_SHAPE:.*]] = fir.shape %[[C3_0]], %[[C3_1]] : (index, index) -> !fir.shape<2>
+! CHECK-DAG:       %[[ARRAY:.*]]:2 = hlfir.declare %[[ARRAY_ALLOC]](%[[ARRAY_SHAPE]]) typeparams %[[C3]]
+! CHECK-DAG:       %[[C3_2:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[RES_ALLOC:.*]] = fir.alloca !fir.char<1,3>
+! CHECK-DAG:       %[[RES:.*]]:2 = hlfir.declare %[[RES_ALLOC]] typeparams %[[C3_2]]
+! CHECK-DAG:       %[[C1:.*]] = arith.constant 1 : index
+! CHECK-DAG:       %[[C1_3:.*]] = arith.constant 1 : index
+! CHECK-DAG:       %[[C3_4:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[C1_5:.*]] = arith.constant 1 : index
+! CHECK-DAG:       %[[C3_6:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[SHAPE:.*]] = fir.shape %[[C3_4]], %[[C3_6]] : (index, index) -> !fir.shape<2>
+! CHECK-DAG:       %[[C1_7:.*]] = arith.constant 1 : index
+! CHECK-DAG:       %[[C3_8:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[C3_9:.*]] = arith.constant 3 : index
+! CHECK-DAG:       %[[ARRAY_BOX:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]]  shape %[[SHAPE]] typeparams %[[C3_9]]
+! CHECK:           %[[EXPR:.*]] = hlfir.maxval %[[ARRAY_BOX]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<!fir.char<1,3>>
+! CHECK-NEXT:      hlfir.assign %[[EXPR]] to %[[RES]]#0 : !hlfir.expr<!fir.char<1,3>>, !fir.ref<!fir.char<1,3>>
+! CHECK-NEXT:      hlfir.destroy %[[EXPR]]
+! CHECK-NEXT:      return
+! CHECK-NEXT:    }

>From 653e94955eed00dbcf94ca6a0a7aca499fa9191b Mon Sep 17 00:00:00 2001
From: Yusuke MINATO <minato.yusuke at fujitsu.com>
Date: Mon, 11 Sep 2023 15:43:15 +0900
Subject: [PATCH 2/3] fixup! [flang][hlfir] Add hlfir.maxval intrinsic

---
 flang/include/flang/Optimizer/HLFIR/HLFIROps.td |  3 ++-
 flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp       |  7 +++++++
 flang/test/HLFIR/memory-effects.fir             | 15 +++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/flang/include/flang/Optimizer/HLFIR/HLFIROps.td b/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
index d24b2b6b818c187..aef3b1d976f16d9 100644
--- a/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
+++ b/flang/include/flang/Optimizer/HLFIR/HLFIROps.td
@@ -405,7 +405,8 @@ def hlfir_CountOp : hlfir_Op<"count", [AttrSizedOperandSegments, DeclareOpInterf
 }
 
 def hlfir_MaxvalOp : hlfir_Op<"maxval", [AttrSizedOperandSegments,
-    DeclareOpInterfaceMethods<ArithFastMathInterface>]> {
+    DeclareOpInterfaceMethods<ArithFastMathInterface>,
+    DeclareOpInterfaceMethods<MemoryEffectsOpInterface>]> {
   let summary = "MAXVAL transformational intrinsic";
   let description = [{
     Maximum value(s) of an array.
diff --git a/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp b/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
index 6c46f1581164124..531a40c8dd4f920 100644
--- a/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
+++ b/flang/lib/Optimizer/HLFIR/IR/HLFIROps.cpp
@@ -838,6 +838,13 @@ mlir::LogicalResult hlfir::MaxvalOp::verify() {
   }
 }
 
+void hlfir::MaxvalOp::getEffects(
+    llvm::SmallVectorImpl<
+        mlir::SideEffects::EffectInstance<mlir::MemoryEffects::Effect>>
+        &effects) {
+  getIntrinsicEffects(getOperation(), effects);
+}
+
 //===----------------------------------------------------------------------===//
 // SetLengthOp
 //===----------------------------------------------------------------------===//
diff --git a/flang/test/HLFIR/memory-effects.fir b/flang/test/HLFIR/memory-effects.fir
index a49dc1678116362..f30d1b86c4d862a 100644
--- a/flang/test/HLFIR/memory-effects.fir
+++ b/flang/test/HLFIR/memory-effects.fir
@@ -92,6 +92,21 @@ func.func @sum_effects(%arg0: !fir.ref<!fir.array<2x2xf32>>, %arg1: i32) {
   return
 }
 
+func.func @maxval_no_effects(%arg0: !hlfir.expr<?xf32>) {
+// expected-remark at +1 {{operation has no memory effects}}
+  %maxval = hlfir.maxval %arg0 : (!hlfir.expr<?xf32>) -> f32
+// expected-remark at +1 {{operation has no memory effects}}
+  return
+}
+
+func.func @maxval_effects(%arg0: !fir.ref<!fir.array<2x2xf32>>, %arg1: i32) {
+// expected-remark at +2 {{found an instance of 'allocate' on a value, on resource '<Default>'}}
+// expected-remark at +1 {{found an instance of 'read' on a value, on resource '<Default>'}}
+  %maxval = hlfir.maxval %arg0 dim %arg1 : (!fir.ref<!fir.array<2x2xf32>>, i32) -> !hlfir.expr<2xf32>
+// expected-remark at +1 {{operation has no memory effects}}
+  return
+}
+
 func.func @dot_product_no_effects(%arg0: !hlfir.expr<?xf32>, %arg1: !hlfir.expr<?xf32>) {
 // expected-remark at +1 {{operation has no memory effects}}
   %0 = hlfir.dot_product %arg0 %arg1 : (!hlfir.expr<?xf32>, !hlfir.expr<?xf32>) -> f32

>From 52ce3f92070f755c930d0a6676914e21ae6e3616 Mon Sep 17 00:00:00 2001
From: Yusuke MINATO <minato.yusuke at fujitsu.com>
Date: Tue, 12 Sep 2023 09:26:08 +0900
Subject: [PATCH 3/3] fixup! [flang][hlfir] Add hlfir.maxval intrinsic

---
 flang/lib/Lower/HlfirIntrinsics.cpp | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/flang/lib/Lower/HlfirIntrinsics.cpp b/flang/lib/Lower/HlfirIntrinsics.cpp
index 7146b1adc0d8060..4d25c59bf79ca6c 100644
--- a/flang/lib/Lower/HlfirIntrinsics.cpp
+++ b/flang/lib/Lower/HlfirIntrinsics.cpp
@@ -230,13 +230,6 @@ HlfirTransformationalIntrinsic::computeResultType(mlir::Value argArray,
                                 /*polymorphic=*/false);
   } else if (auto resCharType =
                  mlir::dyn_cast<fir::CharacterType>(stmtResultType)) {
-    if (!resCharType.hasConstantLen()) {
-      auto argCharType = mlir::dyn_cast<fir::CharacterType>(
-          hlfir::getFortranElementType(argArray.getType()));
-      if (argCharType && argCharType.hasConstantLen())
-        resCharType = fir::CharacterType::get(
-            builder.getContext(), resCharType.getFKind(), argCharType.getLen());
-    }
     normalisedResult = hlfir::ExprType::get(
         builder.getContext(), hlfir::ExprType::Shape{}, resCharType, false);
   }



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