[fir] Add fir.select_case conversion

[clementval]

Summary

The fir.select_case operation is converted to a if-then-else ladder.

Conversion of fir.select_case operation with character is not
implemented yet.

This patch is part of the upstreaming effort from fir-dev branch.

Co-authored-by: Eric Schweitz <[e-mail]>

[mehdi_amini]

flang/lib/Optimizer/CodeGen/CodeGen.cpp

395

Can you expand a bit on the doc here? This isn't a 1-1 conversion, so it seems worth spelling it out.

417

The & reference hear is misleading, I don't think it ever gets modified and Attribute is a value type

458

Many types to spell out instead of auto in there, can you update please?

[clementval]

Address review comments

[clementval]

flang/lib/Optimizer/CodeGen/CodeGen.cpp

458

Sorry, I forgot to go through the auto in this pattern. Should be done.

[mehdi_amini]

LGTM, would be nice if someone else would also have a look at it.

[pmccormick]

In D113484#3120018, @mehdi_amini wrote:

LGTM, would be nice if someone else would also have a look at it.

Agree with @mehdi_amini -- looks good. One minor typo in the fir.select_casefirst comments: "A a point value..."

[clementval]

In D113484#3120057, @pmccormick wrote:

In D113484#3120018, @mehdi_amini wrote:

LGTM, would be nice if someone else would also have a look at it.

Agree with @mehdi_amini -- looks good. One minor typo in the fir.select_casefirst comments: "A a point value..."

Thanks I'll fix that. Can someone approve it then?

[clementval]

Typo

[kiranchandramohan]

flang/lib/Optimizer/CodeGen/CodeGen.cpp

376

Nit: Should we have a notify failure for the character case?

378

No change requested: Would using this same location for branches of individual cases be correct?

379

Nit: Should this be part of the verifier (also)?

[clementval]

flang/lib/Optimizer/CodeGen/CodeGen.cpp

378

Not sure what do mean here. We are using the same location right now.

[kiranchandramohan]

LGTM. Accepting since others are Nit comments.

flang/lib/Optimizer/CodeGen/CodeGen.cpp

378

I meant that the individual cases (for e.g case 1, case 2 below) have different locations in the source file. So the comparisons corresponding to the cases should ideally use the location of the individual cases.

select case
case 1:
case 2:
end select

[clementval]

flang/lib/Optimizer/CodeGen/CodeGen.cpp

378

Ok I get it. Will check if I can update that easily

379

This is checked in the verifier in a slightly different way. I'll just drop it here.

[clementval]

flang/lib/Optimizer/CodeGen/CodeGen.cpp

378

I have tried to retrieved the loc from the case arg but it seems to be null. It's probably something taht will take more time to be fined tune.

[clementval]

Rebase

[kiranchandramohan]

flang/lib/Optimizer/CodeGen/CodeGen.cpp

378

OK. We can work on it a separate patch.

flang/include/flang/Optimizer/Dialect/FIROps.td

string extraSwitchClassDeclaration = [{
     }
 
     // The number of blocks that may be branched to
     unsigned getNumDest() { return (*this)->getNumSuccessors(); }
 
     llvm::Optional<mlir::OperandRange> getCompareOperands(unsigned cond);
     llvm::Optional<llvm::ArrayRef<mlir::Value>> getCompareOperands(
         llvm::ArrayRef<mlir::Value> operands, unsigned cond);
+    llvm::Optional<mlir::ValueRange> getCompareOperands(
+        mlir::ValueRange operands, unsigned cond);
 
     llvm::Optional<llvm::ArrayRef<mlir::Value>> getSuccessorOperands(
         llvm::ArrayRef<mlir::Value> operands, unsigned cond);
     llvm::Optional<mlir::ValueRange> getSuccessorOperands(
         mlir::ValueRange operands, unsigned cond);
     using BranchOpInterfaceTrait::getSuccessorOperands;
 
     // Helper function to deal with Optional operand forms

flang/lib/Optimizer/CodeGen/CodeGen.cpp

 //===-- CodeGen.cpp -- bridge to lower to LLVM ----------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Coding style: https://mlir.llvm.org/getting_started/DeveloperGuide/
 //
 //===----------------------------------------------------------------------===//
 
 #include "flang/Optimizer/CodeGen/CodeGen.h"
 #include "PassDetail.h"
+#include "flang/Optimizer/Dialect/FIRAttr.h"
 #include "flang/Optimizer/Dialect/FIROps.h"
 #include "flang/Optimizer/Dialect/FIRType.h"
 #include "flang/Optimizer/Support/FIRContext.h"
 #include "mlir/Conversion/ArithmeticToLLVM/ArithmeticToLLVM.h"
 #include "mlir/Conversion/LLVMCommon/Pattern.h"
 #include "mlir/Conversion/LLVMCommon/TypeConverter.h"
 #include "mlir/Conversion/StandardToLLVM/ConvertStandardToLLVM.h"
 #include "mlir/IR/BuiltinTypes.h"
 #include "mlir/IR/Matchers.h"
 #include "mlir/Pass/Pass.h"
 #include "llvm/ADT/ArrayRef.h"
 
 #define DEBUG_TYPE "flang-codegen"
 
 // fir::LLVMTypeConverter for converting to LLVM IR dialect types.
 #include "TypeConverter.h"
 
+static Block *createBlock(mlir::ConversionPatternRewriter &rewriter,
+                          mlir::Block *insertBefore) {
+  assert(insertBefore && "expected valid insertion block");
+  return rewriter.createBlock(insertBefore->getParent(),
+                              mlir::Region::iterator(insertBefore));
+}
+
 namespace {
 /// FIR conversion pattern template
 template <typename FromOp>
 class FIROpConversion : public mlir::ConvertOpToLLVMPattern<FromOp> {
 public:
   explicit FIROpConversion(fir::LLVMTypeConverter &lowering)
       : mlir::ConvertOpToLLVMPattern<FromOp>(lowering) {}
 
if (optLinkage.hasValue()) {
         return mlir::LLVM::Linkage::Common;
       if (name == "weak")
         return mlir::LLVM::Linkage::Weak;
     }
     return mlir::LLVM::Linkage::External;
   }
 };
 
+void genCondBrOp(mlir::Location loc, mlir::Value cmp, mlir::Block *dest,
+                 Optional<mlir::ValueRange> destOps,
+                 mlir::ConversionPatternRewriter &rewriter,
+                 mlir::Block *newBlock) {
+  if (destOps.hasValue())
+    rewriter.create<mlir::LLVM::CondBrOp>(loc, cmp, dest, destOps.getValue(),
+                                          newBlock, mlir::ValueRange());
+  else
+    rewriter.create<mlir::LLVM::CondBrOp>(loc, cmp, dest, newBlock);
+}
+
+template <typename A, typename B>
+void genBrOp(A caseOp, mlir::Block *dest, Optional<B> destOps,
+             mlir::ConversionPatternRewriter &rewriter) {
+  if (destOps.hasValue())
+    rewriter.replaceOpWithNewOp<mlir::LLVM::BrOp>(caseOp, destOps.getValue(),
+                                                  dest);
+  else
+    rewriter.replaceOpWithNewOp<mlir::LLVM::BrOp>(caseOp, llvm::None, dest);
+}
+
+void genCaseLadderStep(mlir::Location loc, mlir::Value cmp, mlir::Block *dest,
+                       Optional<mlir::ValueRange> destOps,
+                       mlir::ConversionPatternRewriter &rewriter) {
+  auto *thisBlock = rewriter.getInsertionBlock();
+  auto *newBlock = createBlock(rewriter, dest);
+  rewriter.setInsertionPointToEnd(thisBlock);
+  genCondBrOp(loc, cmp, dest, destOps, rewriter, newBlock);
+  rewriter.setInsertionPointToEnd(newBlock);
+}
+
+/// Conversion of `fir.select_case`
+///
+/// The `fir.select_case` operation is converted to a if-then-else ladder.
+/// Depending on the case condition type, one or several comparison and
+/// conditional branching can be generated.
+///
+/// A a point value case such as `case(4)`, a lower bound case such as
+/// `case(5:)` or an upper bound case such as `case(:3)` are converted to a
+/// simple comparison between the selector value and the constant value in the
+/// case. The block associated with the case condition is then executed if
+/// the comparison succeed otherwise it branch to the next block with the
+/// comparison for the the next case conditon.
+///
+/// A closed interval case condition such as `case(7:10)` is converted with a
+/// first comparison and conditional branching for the lower bound. If
+/// successful, it branch to a second block with the comparison for the
+/// upper bound in the same case condition.
+///
+/// TODO: lowering of CHARACTER type cases is not handled yet.
+struct SelectCaseOpConversion : public FIROpConversion<fir::SelectCaseOp> {
+  using FIROpConversion::FIROpConversion;
+
+  mlir::LogicalResult
+  matchAndRewrite(fir::SelectCaseOp caseOp, OpAdaptor adaptor,
+                  mlir::ConversionPatternRewriter &rewriter) const override {
+    unsigned conds = caseOp.getNumConditions();
+    llvm::ArrayRef<mlir::Attribute> cases = caseOp.getCases().getValue();
+    // Type can be CHARACTER, INTEGER, or LOGICAL (C1145)
+    LLVM_ATTRIBUTE_UNUSED auto ty = caseOp.getSelector().getType();
+    mlir::Value selector = caseOp.getSelector(adaptor.getOperands());
+    auto loc = caseOp.getLoc();
+    assert(conds > 0 && "fir.selectcase must have cases");
+    for (unsigned t = 0; t != conds; ++t) {
+      mlir::Block *dest = caseOp.getSuccessor(t);
+      llvm::Optional<mlir::ValueRange> destOps =
+          caseOp.getSuccessorOperands(adaptor.getOperands(), t);
+      llvm::Optional<mlir::ValueRange> cmpOps =
+          *caseOp.getCompareOperands(adaptor.getOperands(), t);
+      mlir::Value caseArg = *(cmpOps.getValue().begin());
+      mlir::Attribute attr = cases[t];
+      if (attr.isa<fir::PointIntervalAttr>()) {
+        auto cmp = rewriter.create<mlir::LLVM::ICmpOp>(
+            loc, mlir::LLVM::ICmpPredicate::eq, selector, caseArg);
+        genCaseLadderStep(loc, cmp, dest, destOps, rewriter);
+        continue;
+      }
+      if (attr.isa<fir::LowerBoundAttr>()) {
+        auto cmp = rewriter.create<mlir::LLVM::ICmpOp>(
+            loc, mlir::LLVM::ICmpPredicate::sle, caseArg, selector);
+        genCaseLadderStep(loc, cmp, dest, destOps, rewriter);
+        continue;
+      }
+      if (attr.isa<fir::UpperBoundAttr>()) {
+        auto cmp = rewriter.create<mlir::LLVM::ICmpOp>(
+            loc, mlir::LLVM::ICmpPredicate::sle, selector, caseArg);
+        genCaseLadderStep(loc, cmp, dest, destOps, rewriter);
+        continue;
+      }
+      if (attr.isa<fir::ClosedIntervalAttr>()) {
+        auto cmp = rewriter.create<mlir::LLVM::ICmpOp>(
+            loc, mlir::LLVM::ICmpPredicate::sle, caseArg, selector);
+        auto *thisBlock = rewriter.getInsertionBlock();
+        auto *newBlock1 = createBlock(rewriter, dest);
+        auto *newBlock2 = createBlock(rewriter, dest);
+        rewriter.setInsertionPointToEnd(thisBlock);
+        rewriter.create<mlir::LLVM::CondBrOp>(loc, cmp, newBlock1, newBlock2);
+        rewriter.setInsertionPointToEnd(newBlock1);
+        mlir::Value caseArg0 = *(cmpOps.getValue().begin() + 1);
+        auto cmp0 = rewriter.create<mlir::LLVM::ICmpOp>(
+            loc, mlir::LLVM::ICmpPredicate::sle, selector, caseArg0);
+        genCondBrOp(loc, cmp0, dest, destOps, rewriter, newBlock2);
+        rewriter.setInsertionPointToEnd(newBlock2);
+        continue;
+      }
+      assert(attr.isa<mlir::UnitAttr>());
+      assert((t + 1 == conds) && "unit must be last");
+      genBrOp(caseOp, dest, destOps, rewriter);
+    }
+    return success();
+  }
+};
+
 template <typename OP>
 void selectMatchAndRewrite(fir::LLVMTypeConverter &lowering, OP select,
                            typename OP::Adaptor adaptor,
                            mlir::ConversionPatternRewriter &rewriter) {
   unsigned conds = select.getNumConditions();
   auto cases = select.getCases().getValue();
   mlir::Value selector = adaptor.selector();
   auto loc = select.getLoc();
for (unsigned t = 0; t != conds; ++t) {
     if (auto intAttr = attr.template dyn_cast<mlir::IntegerAttr>()) {
       destinations.push_back(dest);
       destinationsOperands.push_back(destOps.hasValue() ? *destOps
                                                         : ValueRange());
       caseValues.push_back(intAttr.getInt());
       continue;
     }
     assert(attr.template dyn_cast_or_null<mlir::UnitAttr>());
     assert((t + 1 == conds) && "unit must be last");
     defaultDestination = dest;
     defaultOperands = destOps.hasValue() ? *destOps : ValueRange();
   }
 
   // LLVM::SwitchOp takes a i32 type for the selector.
   if (select.getSelector().getType() != rewriter.getI32Type())
     selector =
         rewriter.create<LLVM::TruncOp>(loc, rewriter.getI32Type(), selector);
void runOnOperation() override final {
     auto mod = getModule();
     if (!forcedTargetTriple.empty()) {
       fir::setTargetTriple(mod, forcedTargetTriple);
     }
 
     auto *context = getModule().getContext();
     fir::LLVMTypeConverter typeConverter{getModule()};
     mlir::OwningRewritePatternList pattern(context);
-    pattern.insert<AddcOpConversion, AddrOfOpConversion, CallOpConversion,
-                   ConvertOpConversion, DivcOpConversion,
-                   ExtractValueOpConversion, HasValueOpConversion,
-                   GlobalOpConversion, InsertOnRangeOpConversion,
-                   InsertValueOpConversion, LoadOpConversion, NegcOpConversion,
-                   MulcOpConversion, SelectOpConversion, SelectRankOpConversion,
-                   StoreOpConversion, SubcOpConversion, UndefOpConversion,
-                   UnreachableOpConversion, ZeroOpConversion>(typeConverter);
+    pattern.insert<
+        AddcOpConversion, AddrOfOpConversion, CallOpConversion,
+        ConvertOpConversion, DivcOpConversion, ExtractValueOpConversion,
+        HasValueOpConversion, GlobalOpConversion, InsertOnRangeOpConversion,
+        MulcOpConversion, SelectCaseOpConversion, SelectOpConversion,
+        SelectRankOpConversion, StoreOpConversion, SubcOpConversion,
+        UndefOpConversion, UnreachableOpConversion, ZeroOpConversion>(
+        typeConverter);
     mlir::populateStdToLLVMConversionPatterns(typeConverter, pattern);
     mlir::arith::populateArithmeticToLLVMConversionPatterns(typeConverter,
                                                             pattern);
     mlir::ConversionTarget target{*context};
     target.addLegalDialect<mlir::LLVM::LLVMDialect>();
 
     // required NOPs for applying a full conversion
     target.addLegalOp<mlir::ModuleOp>();

flang/lib/Optimizer/Dialect/FIROps.cpp

fir::SelectCaseOp::getCompareOperands(llvm::ArrayRef<mlir::Value> operands,
                                       unsigned cond) {
   auto a = (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(
       getCompareOffsetAttr());
   auto segments = (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(
       getOperandSegmentSizeAttr());
   return {getSubOperands(cond, getSubOperands(1, operands, segments), a)};
 }
 
+llvm::Optional<mlir::ValueRange>
+fir::SelectCaseOp::getCompareOperands(mlir::ValueRange operands,
+                                      unsigned cond) {
+  auto a = (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(
+      getCompareOffsetAttr());
+  auto segments = (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(
+      getOperandSegmentSizeAttr());
+  return {getSubOperands(cond, getSubOperands(1, operands, segments), a)};
+}
+
 llvm::Optional<mlir::MutableOperandRange>
 fir::SelectCaseOp::getMutableSuccessorOperands(unsigned oper) {
   return ::getMutableSuccessorOperands(oper, targetArgsMutable(),
                                        getTargetOffsetAttr());
 }
 
 llvm::Optional<llvm::ArrayRef<mlir::Value>>
 fir::SelectCaseOp::getSuccessorOperands(llvm::ArrayRef<mlir::Value> operands,
                                         unsigned oper) {
   auto a =
       (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(getTargetOffsetAttr());
   auto segments = (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(
       getOperandSegmentSizeAttr());
   return {getSubOperands(oper, getSubOperands(2, operands, segments), a)};
 }
 
+llvm::Optional<mlir::ValueRange>
+fir::SelectCaseOp::getSuccessorOperands(mlir::ValueRange operands,
+                                        unsigned oper) {
+  auto a =
+      (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(getTargetOffsetAttr());
+  auto segments = (*this)->getAttrOfType<mlir::DenseIntElementsAttr>(
+      getOperandSegmentSizeAttr());
+  return {getSubOperands(oper, getSubOperands(2, operands, segments), a)};
+}
+
 // parser for fir.select_case Op
 static mlir::ParseResult parseSelectCase(mlir::OpAsmParser &parser,
                                          mlir::OperationState &result) {
   mlir::OpAsmParser::OperandType selector;
   mlir::Type type;
   if (parseSelector(parser, result, selector, type))
     return mlir::failure();
 

flang/test/Fir/convert-to-llvm.fir

func @test_load_box(%addr : !fir.ref<!fir.box<!fir.array<10xf32>>>) {
   return
 }
 
 // Loading a `fir.ref<!fir.box>> is a no-op
 // CHECK-LABEL: llvm.func @test_load_box
 // CHECK-SAME: (%{{.*}}: !llvm.ptr<struct<(ptr<array<10 x f{{.*}}>>, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, array<1 x array<3 x i{{.*}}>>)>>) {
 // CHECK-NEXT:  llvm.return
 // CHECK-NEXT:  }
+
+// -----
+
+// Test `fir.select_case` operation conversion with INTEGER.
+
+func @select_case_integer(%arg0: !fir.ref<i32>) -> i32 {
+  %2 = fir.load %arg0 : !fir.ref<i32>
+  %c1_i32 = arith.constant 1 : i32
+  %c2_i32 = arith.constant 2 : i32
+  %c4_i32 = arith.constant 4 : i32
+  %c5_i32 = arith.constant 5 : i32
+  %c7_i32 = arith.constant 7 : i32
+  %c8_i32 = arith.constant 8 : i32
+  %c15_i32 = arith.constant 15 : i32
+  %c21_i32 = arith.constant 21 : i32
+  fir.select_case %2 : i32 [#fir.upper, %c1_i32, ^bb1,
+                            #fir.point, %c2_i32, ^bb2,
+                            #fir.interval, %c4_i32, %c5_i32, ^bb4,
+                            #fir.point, %c7_i32, ^bb5,
+                            #fir.interval, %c8_i32, %c15_i32, ^bb5,
+                            #fir.lower, %c21_i32, ^bb5,
+                            unit, ^bb3]
+^bb1:  // pred: ^bb0
+  %c1_i32_0 = arith.constant 1 : i32
+  fir.store %c1_i32_0 to %arg0 : !fir.ref<i32>
+  br ^bb6
+^bb2:  // pred: ^bb0
+  %c2_i32_1 = arith.constant 2 : i32
+  fir.store %c2_i32_1 to %arg0 : !fir.ref<i32>
+  br ^bb6
+^bb3:  // pred: ^bb0
+  %c0_i32 = arith.constant 0 : i32
+  fir.store %c0_i32 to %arg0 : !fir.ref<i32>
+  br ^bb6
+^bb4:  // pred: ^bb0
+  %c4_i32_2 = arith.constant 4 : i32
+  fir.store %c4_i32_2 to %arg0 : !fir.ref<i32>
+  br ^bb6
+^bb5:  // 3 preds: ^bb0, ^bb0, ^bb0
+  %c7_i32_3 = arith.constant 7 : i32
+  fir.store %c7_i32_3 to %arg0 : !fir.ref<i32>
+  br ^bb6
+^bb6:  // 5 preds: ^bb1, ^bb2, ^bb3, ^bb4, ^bb5
+  %3 = fir.load %arg0 : !fir.ref<i32>
+  return %3 : i32
+}
+
+// CHECK-LABEL: llvm.func @select_case_integer(
+// CHECK-SAME:                         %[[ARG0:.*]]: !llvm.ptr<i32>) -> i32 {
+// CHECK:         %[[SELECT_VALUE:.*]] = llvm.load %[[ARG0]] : !llvm.ptr<i32>
+// CHECK:         %[[CST1:.*]] = llvm.mlir.constant(1 : i32) : i32
+// CHECK:         %[[CST2:.*]] = llvm.mlir.constant(2 : i32) : i32
+// CHECK:         %[[CST4:.*]] = llvm.mlir.constant(4 : i32) : i32
+// CHECK:         %[[CST5:.*]] = llvm.mlir.constant(5 : i32) : i32
+// CHECK:         %[[CST7:.*]] = llvm.mlir.constant(7 : i32) : i32
+// CHECK:         %[[CST8:.*]] = llvm.mlir.constant(8 : i32) : i32
+// CHECK:         %[[CST15:.*]] = llvm.mlir.constant(15 : i32) : i32
+// CHECK:         %[[CST21:.*]] = llvm.mlir.constant(21 : i32) : i32
+// Check for upper bound `case (:1)`
+// CHECK:         %[[CMP_SLE:.*]] = llvm.icmp "sle" %[[SELECT_VALUE]], %[[CST1]] : i32
+// CHECK:         llvm.cond_br %[[CMP_SLE]], ^bb2, ^bb1
+// CHECK-LABEL: ^bb1:
+// Check for point value `case (2)`
+// CHECK:         %[[CMP_EQ:.*]] = llvm.icmp "eq" %[[SELECT_VALUE]], %[[CST2]] : i32
+// CHECK:         llvm.cond_br %[[CMP_EQ]], ^bb4, ^bb3
+// Block ^bb1 in original FIR code.
+// CHECK-LABEL: ^bb2:
+// CHECK:         llvm.br ^bb{{.*}}
+// CHECK-LABEL: ^bb3:
+// Check for the lower bound for the interval `case (4:5)`
+// CHECK:        %[[CMP_SLE:.*]] = llvm.icmp "sle" %[[CST4]], %[[SELECT_VALUE]] : i32
+// CHECK:        llvm.cond_br %[[CMP_SLE]], ^bb[[UPPERBOUND5:.*]], ^bb7
+// Block ^bb2 in original FIR code.
+// CHECK-LABEL: ^bb4:
+// CHECK:        llvm.br ^bb{{.*}}
+// Block ^bb3 in original FIR code.
+// CHECK-LABEL: ^bb5:
+// CHECK:        llvm.br ^bb{{.*}}
+// CHECK:       ^bb[[UPPERBOUND5]]:
+// Check for the upper bound for the interval `case (4:5)`
+// CHECK:        %[[CMP_SLE:.*]] = llvm.icmp "sle" %[[SELECT_VALUE]], %[[CST5]] : i32
+// CHECK:        llvm.cond_br %[[CMP_SLE]], ^bb8, ^bb7
+// CHECK-LABEL: ^bb7:
+// Check for the point value 7 in `case (7,8:15,21:)`
+// CHECK: %[[CMP_EQ:.*]] = llvm.icmp "eq" %[[SELECT_VALUE]], %[[CST7]] : i32
+// CHECK: llvm.cond_br %[[CMP_EQ]], ^bb13, ^bb9
+// Block ^bb4 in original FIR code.
+// CHECK-LABEL: ^bb8:
+// CHECK:        llvm.br ^bb{{.*}}
+// CHECK-LABEL: ^bb9:
+// Check for lower bound 8 in `case (7,8:15,21:)`
+// CHECK:        %[[CMP_SLE:.*]] = llvm.icmp "sle" %[[CST8]], %[[SELECT_VALUE]] : i32
+// CHECK:        llvm.cond_br %[[CMP_SLE]], ^bb[[INTERVAL8_15:.*]], ^bb11
+// CHECK:       ^bb[[INTERVAL8_15]]:
+// Check for upper bound 15 in `case (7,8:15,21:)`
+// CHECK:        %[[CMP_SLE:.*]] = llvm.icmp "sle" %[[SELECT_VALUE]], %[[CST15]] : i32
+// CHECK:        llvm.cond_br %[[CMP_SLE]], ^bb13, ^bb11
+// CHECK-LABEL: ^bb11:
+// Check for lower bound 21 in `case (7,8:15,21:)`
+// CHECK:        %[[CMP_SLE:.*]]  = llvm.icmp "sle" %[[CST21]], %[[SELECT_VALUE]] : i32
+// CHECK:        llvm.cond_br %[[CMP_SLE]], ^bb13, ^bb12
+// CHECK-LABEL: ^bb12:
+// CHECK:         llvm.br ^bb5
+// Block ^bb5 in original FIR code.
+// CHECK-LABEL: ^bb13:
+// CHECK:        llvm.br ^bb14
+// Block ^bb6 in original FIR code.
+// CHECK-LABEL: ^bb14:
+// CHECK:        %[[RET:.*]] = llvm.load %[[ARG0:.*]] : !llvm.ptr<i32>
+// CHECK:        llvm.return %[[RET]] : i32
+
+// -----
+
+// Test `fir.select_case` operation conversion with LOGICAL.
+
+func @select_case_logical(%arg0: !fir.ref<!fir.logical<4>>) {
+  %1 = fir.load %arg0 : !fir.ref<!fir.logical<4>>
+  %2 = fir.convert %1 : (!fir.logical<4>) -> i1
+  %false = arith.constant false
+  %true = arith.constant true
+  fir.select_case %2 : i1 [#fir.point, %false, ^bb1,
+                           #fir.point, %true, ^bb2,
+                            unit, ^bb3]
+^bb1:
+  %c1_i32 = arith.constant 1 : i32
+  br ^bb3
+^bb2:
+  %c2_i32 = arith.constant 2 : i32
+  br ^bb3
+^bb3:
+  return
+}
+
+// CHECK-LABEL: llvm.func @select_case_logical(
+// CHECK-SAME:                                 %[[ARG0:.*]]: !llvm.ptr<i32>
+// CHECK:         %[[LOAD_ARG0:.*]] = llvm.load %[[ARG0]] : !llvm.ptr<i32>
+// CHECK:         %[[SELECT_VALUE:.*]] = llvm.trunc %[[LOAD_ARG0]] : i32 to i1
+// CHECK:         %[[CST_FALSE:.*]] = llvm.mlir.constant(false) : i1
+// CHECK:         %[[CST_TRUE:.*]] = llvm.mlir.constant(true) : i1
+// CHECK:         %[[CMPEQ:.*]] = llvm.icmp "eq" %[[SELECT_VALUE]], %[[CST_FALSE]] : i1
+// CHECK:         llvm.cond_br %[[CMPEQ]], ^bb2, ^bb1
+// CHECK-LABEL: ^bb1:
+// CHECK:         %[[CMPEQ:.*]] = llvm.icmp "eq" %[[SELECT_VALUE]], %[[CST_TRUE]] : i1
+// CHECK:         llvm.cond_br %[[CMPEQ]], ^bb4, ^bb3
+// CHECK-LABEL: ^bb2:
+// CHECK:         llvm.br ^bb5
+// CHECK-LABEL: ^bb3:
+// CHECK:         llvm.br ^bb5
+// CHECK-LABEL: ^bb4:
+// CHECK:         llvm.br ^bb5
+// CHECK-LABEL: ^bb5:
+// CHECK:        llvm.return