diff --git a/flang/include/flang/Optimizer/Dialect/FIROps.td b/flang/include/flang/Optimizer/Dialect/FIROps.td
index fc6eedc6ed4c6..86502c6271d23 100644
--- a/flang/include/flang/Optimizer/Dialect/FIROps.td
+++ b/flang/include/flang/Optimizer/Dialect/FIROps.td
@@ -1249,6 +1249,41 @@ def fir_IsAssumedSizeOp : fir_SimpleOp<"is_assumed_size", [NoMemoryEffect]> {
   let results = (outs BoolLike);
 }
 
+def fir_AssumedSizeExtentOp : fir_SimpleOneResultOp<"assumed_size_extent", [NoMemoryEffect]> {
+  let summary = "get the assumed-size last extent sentinel";
+
+  let description = [{
+    Returns the special extent value representing the last dimension of an
+    assumed-size array. This is used to model the semantics in FIR without
+    directly materializing the sentinel value. The concrete encoding is
+    introduced during FIR to LLVM lowering.
+
+    ```
+      %e = fir.assumed_size_extent : index
+    ```
+  }];
+
+  let results = (outs Index);
+  let assemblyFormat = "attr-dict `:` type(results)";
+}
+
+def fir_IsAssumedSizeExtentOp : fir_SimpleOp<"is_assumed_size_extent", [NoMemoryEffect]> {
+  let summary = "is value the assumed-size last extent sentinel";
+
+  let description = [{
+    Returns true iff the given integer equals the assumed-size extent sentinel.
+
+    ```
+      %t = fir.is_assumed_size_extent %v : (index) -> i1
+      %c = fir.is_assumed_size_extent %x : (i32) -> i1
+    ```
+  }];
+
+  let arguments = (ins AnyIntegerLike:$val);
+  let results = (outs BoolLike);
+  let hasCanonicalizer = 1;
+}
+
 def fir_BoxIsPtrOp : fir_SimpleOp<"box_isptr", [NoMemoryEffect]> {
   let summary = "is the boxed value a POINTER?";
 
diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index 3b711ccbe786a..238a623dc6c5d 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -4010,8 +4010,8 @@ class FirConverter : public Fortran::lower::AbstractConverter {
       // parameters and dynamic type. The selector cannot be a
       // POINTER/ALLOCATBLE as per F'2023 C1160.
       fir::ExtendedValue newExv;
-      llvm::SmallVector assumeSizeExtents{
-          builder->createMinusOneInteger(loc, builder->getIndexType())};
+      llvm::SmallVector<mlir::Value> assumeSizeExtents{
+          fir::AssumedSizeExtentOp::create(*builder, loc)};
       mlir::Value baseAddr =
           hlfir::genVariableRawAddress(loc, *builder, selector);
       const bool isVolatile = fir::isa_volatile_type(selector.getType());
diff --git a/flang/lib/Lower/ConvertVariable.cpp b/flang/lib/Lower/ConvertVariable.cpp
index 00ec1b51e5400..2517ab35d4ff0 100644
--- a/flang/lib/Lower/ConvertVariable.cpp
+++ b/flang/lib/Lower/ConvertVariable.cpp
@@ -1711,7 +1711,7 @@ static void lowerExplicitLowerBounds(
 /// CFI_desc_t requirements in 18.5.3 point 5.).
 static mlir::Value getAssumedSizeExtent(mlir::Location loc,
                                         fir::FirOpBuilder &builder) {
-  return builder.createMinusOneInteger(loc, builder.getIndexType());
+  return fir::AssumedSizeExtentOp::create(builder, loc);
 }
 
 /// Lower explicit extents into \p result if this is an explicit-shape or
diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
index 70bb43a2510ba..e71f4e3cee49c 100644
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -749,6 +749,44 @@ struct VolatileCastOpConversion
   }
 };
 
+/// Lower `fir.assumed_size_extent` to constant -1 of index type.
+struct AssumedSizeExtentOpConversion
+    : public fir::FIROpConversion<fir::AssumedSizeExtentOp> {
+  using FIROpConversion::FIROpConversion;
+
+  llvm::LogicalResult
+  matchAndRewrite(fir::AssumedSizeExtentOp op, OpAdaptor,
+                  mlir::ConversionPatternRewriter &rewriter) const override {
+    mlir::Location loc = op.getLoc();
+    mlir::Type ity = lowerTy().indexType();
+    auto cst = fir::genConstantIndex(loc, ity, rewriter, -1);
+    rewriter.replaceOp(op, cst.getResult());
+    return mlir::success();
+  }
+};
+
+/// Lower `fir.is_assumed_size_extent` to integer equality with -1.
+struct IsAssumedSizeExtentOpConversion
+    : public fir::FIROpConversion<fir::IsAssumedSizeExtentOp> {
+  using FIROpConversion::FIROpConversion;
+
+  llvm::LogicalResult
+  matchAndRewrite(fir::IsAssumedSizeExtentOp op, OpAdaptor adaptor,
+                  mlir::ConversionPatternRewriter &rewriter) const override {
+    mlir::Location loc = op.getLoc();
+    mlir::Value val = adaptor.getVal();
+    mlir::Type valTy = val.getType();
+    // Create constant -1 of the operand type.
+    auto negOneAttr = rewriter.getIntegerAttr(valTy, -1);
+    auto negOne =
+        mlir::LLVM::ConstantOp::create(rewriter, loc, valTy, negOneAttr);
+    auto cmp = mlir::LLVM::ICmpOp::create(
+        rewriter, loc, mlir::LLVM::ICmpPredicate::eq, val, negOne);
+    rewriter.replaceOp(op, cmp.getResult());
+    return mlir::success();
+  }
+};
+
 /// convert value of from-type to value of to-type
 struct ConvertOpConversion : public fir::FIROpConversion<fir::ConvertOp> {
   using FIROpConversion::FIROpConversion;
@@ -4360,6 +4398,7 @@ void fir::populateFIRToLLVMConversionPatterns(
       AllocaOpConversion, AllocMemOpConversion, BoxAddrOpConversion,
       BoxCharLenOpConversion, BoxDimsOpConversion, BoxEleSizeOpConversion,
       BoxIsAllocOpConversion, BoxIsArrayOpConversion, BoxIsPtrOpConversion,
+      AssumedSizeExtentOpConversion, IsAssumedSizeExtentOpConversion,
       BoxOffsetOpConversion, BoxProcHostOpConversion, BoxRankOpConversion,
       BoxTypeCodeOpConversion, BoxTypeDescOpConversion, CallOpConversion,
       CmpcOpConversion, VolatileCastOpConversion, ConvertOpConversion,
diff --git a/flang/lib/Optimizer/Dialect/FIROps.cpp b/flang/lib/Optimizer/Dialect/FIROps.cpp
index 1712af1d1eba7..d0164f32d9b6a 100644
--- a/flang/lib/Optimizer/Dialect/FIROps.cpp
+++ b/flang/lib/Optimizer/Dialect/FIROps.cpp
@@ -5142,6 +5142,34 @@ void fir::BoxTotalElementsOp::getCanonicalizationPatterns(
   patterns.add<SimplifyBoxTotalElementsOp>(context);
 }
 
+//===----------------------------------------------------------------------===//
+// IsAssumedSizeExtentOp and AssumedSizeExtentOp
+//===----------------------------------------------------------------------===//
+
+namespace {
+struct FoldIsAssumedSizeExtentOnCtor
+    : public mlir::OpRewritePattern<fir::IsAssumedSizeExtentOp> {
+  using mlir::OpRewritePattern<fir::IsAssumedSizeExtentOp>::OpRewritePattern;
+  mlir::LogicalResult
+  matchAndRewrite(fir::IsAssumedSizeExtentOp op,
+                  mlir::PatternRewriter &rewriter) const override {
+    if (llvm::isa_and_nonnull<fir::AssumedSizeExtentOp>(
+            op.getVal().getDefiningOp())) {
+      mlir::Type i1 = rewriter.getI1Type();
+      rewriter.replaceOpWithNewOp<mlir::arith::ConstantOp>(
+          op, i1, rewriter.getIntegerAttr(i1, 1));
+      return mlir::success();
+    }
+    return mlir::failure();
+  }
+};
+} // namespace
+
+void fir::IsAssumedSizeExtentOp::getCanonicalizationPatterns(
+    mlir::RewritePatternSet &patterns, mlir::MLIRContext *context) {
+  patterns.add<FoldIsAssumedSizeExtentOnCtor>(context);
+}
+
 //===----------------------------------------------------------------------===//
 // LocalitySpecifierOp
 //===----------------------------------------------------------------------===//
diff --git a/flang/lib/Optimizer/Transforms/ArrayValueCopy.cpp b/flang/lib/Optimizer/Transforms/ArrayValueCopy.cpp
index ed9a2ae11f0d9..5bf783db92bf3 100644
--- a/flang/lib/Optimizer/Transforms/ArrayValueCopy.cpp
+++ b/flang/lib/Optimizer/Transforms/ArrayValueCopy.cpp
@@ -832,8 +832,8 @@ static mlir::Type getEleTy(mlir::Type ty) {
 static bool isAssumedSize(llvm::SmallVectorImpl<mlir::Value> &extents) {
   if (extents.empty())
     return false;
-  auto cstLen = fir::getIntIfConstant(extents.back());
-  return cstLen.has_value() && *cstLen == -1;
+  return llvm::isa_and_nonnull<fir::AssumedSizeExtentOp>(
+      extents.back().getDefiningOp());
 }
 
 // Extract extents from the ShapeOp/ShapeShiftOp into the result vector.
diff --git a/flang/test/Fir/assumed-size-ops-codegen.fir b/flang/test/Fir/assumed-size-ops-codegen.fir
new file mode 100644
index 0000000000000..54e9b3c8f30f4
--- /dev/null
+++ b/flang/test/Fir/assumed-size-ops-codegen.fir
@@ -0,0 +1,19 @@
+// RUN: fir-opt --fir-to-llvm-ir="target=x86_64-unknown-linux-gnu" %s | FileCheck %s
+
+// CHECK-LABEL: @assumed_size_extent(
+// CHECK: %[[CNEG1:.*]] = llvm.mlir.constant(-1 : i64)
+// CHECK: llvm.return %[[CNEG1]] : i64
+func.func @assumed_size_extent() -> index {
+  %e = fir.assumed_size_extent : index
+  return %e : index
+}
+
+// CHECK-LABEL:  @is_assumed_size_extent(
+// CHECK: %[[NEG1:.*]] = llvm.mlir.constant(-1 : i64)
+// CHECK: %[[CMP:.*]] = llvm.icmp "eq"
+// CHECK: llvm.return %[[CMP]] : i1
+func.func @is_assumed_size_extent(%x: index) -> i1 {
+  %c = fir.is_assumed_size_extent %x : (index) -> i1
+  return %c : i1
+}
+
diff --git a/flang/test/Fir/assumed-size-ops-folding.fir b/flang/test/Fir/assumed-size-ops-folding.fir
new file mode 100644
index 0000000000000..9fd5fabb7290b
--- /dev/null
+++ b/flang/test/Fir/assumed-size-ops-folding.fir
@@ -0,0 +1,13 @@
+// RUN: fir-opt --canonicalize %s | FileCheck %s
+
+// Verify: fir.is_assumed_size_extent(fir.assumed_size_extent) folds to i1 true.
+
+// CHECK-LABEL: func.func @fold(
+func.func @fold() -> i1 {
+  %e = fir.assumed_size_extent : index
+  // CHECK: %[[C:.*]] = arith.constant true
+  %t = fir.is_assumed_size_extent %e : (index) -> i1
+  return %t : i1
+}
+
+
diff --git a/flang/test/Fir/assumed-size-ops-roundtrip.fir b/flang/test/Fir/assumed-size-ops-roundtrip.fir
new file mode 100644
index 0000000000000..c3c1883a2b7c0
--- /dev/null
+++ b/flang/test/Fir/assumed-size-ops-roundtrip.fir
@@ -0,0 +1,13 @@
+// RUN: fir-opt %s | fir-opt | FileCheck %s
+
+func.func @roundtrip() {
+  // CHECK: %[[E:.*]] = fir.assumed_size_extent : index
+  %e = fir.assumed_size_extent : index
+
+  // CHECK: %[[T:.*]] = fir.is_assumed_size_extent %[[E]] : (index) -> i1
+  %t = fir.is_assumed_size_extent %e : (index) -> i1
+
+  return
+}
+
+
diff --git a/flang/test/HLFIR/assumed-type-actual-args.f90 b/flang/test/HLFIR/assumed-type-actual-args.f90
index 42e9ed27340e7..aaac98ba3c79d 100644
--- a/flang/test/HLFIR/assumed-type-actual-args.f90
+++ b/flang/test/HLFIR/assumed-type-actual-args.f90
@@ -113,7 +113,7 @@ subroutine s5b(x)
 ! CHECK-LABEL:   func.func @_QPtest2(
 ! CHECK-SAME:                        %[[VAL_0:.*]]: !fir.ref<!fir.array<?xnone>> {fir.bindc_name = "x"}) {
 ! CHECK:           %[[DSCOPE:.*]] = fir.dummy_scope : !fir.dscope
-! CHECK:           %[[VAL_1:.*]] = arith.constant -1 : index
+! CHECK:           %[[VAL_1:.*]] = fir.assumed_size_extent : index
 ! CHECK:           %[[VAL_2:.*]] = fir.shape %[[VAL_1]] : (index) -> !fir.shape<1>
 ! CHECK:           %[[VAL_3:.*]]:2 = hlfir.declare %[[VAL_0]](%[[VAL_2]]) dummy_scope %[[DSCOPE]] {uniq_name = "_QFtest2Ex"} : (!fir.ref<!fir.array<?xnone>>, !fir.shape<1>, !fir.dscope) -> (!fir.box<!fir.array<?xnone>>, !fir.ref<!fir.array<?xnone>>)
 ! CHECK:           fir.call @_QPs2(%[[VAL_3]]#1) fastmath<contract> : (!fir.ref<!fir.array<?xnone>>) -> ()
diff --git a/flang/test/Lower/HLFIR/assumed-rank-iface.f90 b/flang/test/Lower/HLFIR/assumed-rank-iface.f90
index 9ecbb7c9e5b94..ffb36fa4b7003 100644
--- a/flang/test/Lower/HLFIR/assumed-rank-iface.f90
+++ b/flang/test/Lower/HLFIR/assumed-rank-iface.f90
@@ -145,7 +145,7 @@ subroutine int_r2_assumed_size_to_assumed_rank(x)
 ! CHECK:           %[[VAL_3:.*]] = arith.constant 0 : index
 ! CHECK:           %[[VAL_4:.*]] = arith.cmpi sgt, %[[VAL_2]], %[[VAL_3]] : index
 ! CHECK:           %[[VAL_5:.*]] = arith.select %[[VAL_4]], %[[VAL_2]], %[[VAL_3]] : index
-! CHECK:           %[[VAL_6:.*]] = arith.constant -1 : index
+! CHECK:           %[[VAL_6:.*]] = fir.assumed_size_extent : index
 ! CHECK:           %[[VAL_7:.*]] = fir.shape %[[VAL_5]], %[[VAL_6]] : (index, index) -> !fir.shape<2>
 ! CHECK:           %[[VAL_8:.*]]:2 = hlfir.declare %[[VAL_0]](%[[VAL_7]]) dummy_scope %{{[0-9]+}} {uniq_name = "_QFint_r2_assumed_size_to_assumed_rankEx"} : (!fir.ref<!fir.array<10x?xi32>>, !fir.shape<2>, !fir.dscope) -> (!fir.box<!fir.array<10x?xi32>>, !fir.ref<!fir.array<10x?xi32>>)
 ! CHECK:           %[[VAL_9:.*]] = fir.convert %[[VAL_8]]#0 : (!fir.box<!fir.array<10x?xi32>>) -> !fir.box<!fir.array<*:i32>>
diff --git a/flang/test/Lower/HLFIR/select-rank.f90 b/flang/test/Lower/HLFIR/select-rank.f90
index 0f80c723e468f..f1f968decd412 100644
--- a/flang/test/Lower/HLFIR/select-rank.f90
+++ b/flang/test/Lower/HLFIR/select-rank.f90
@@ -371,7 +371,7 @@ subroutine test_branching(x)
 ! CHECK:           fir.call @_QPr1(%[[VAL_11]]#0) fastmath<contract> : (!fir.box<!fir.array<?xf32>>) -> ()
 ! CHECK:           cf.br ^bb6
 ! CHECK:         ^bb5:
-! CHECK:           %[[VAL_12:.*]] = arith.constant -1 : index
+! CHECK:           %[[VAL_12:.*]] = fir.assumed_size_extent : index
 ! CHECK:           %[[VAL_13:.*]] = fir.box_addr %[[VAL_2]]#1 : (!fir.box<!fir.array<*:f32>>) -> !fir.ref<!fir.array<*:f32>>
 ! CHECK:           %[[VAL_14:.*]] = fir.convert %[[VAL_13]] : (!fir.ref<!fir.array<*:f32>>) -> !fir.ref<!fir.array<?xf32>>
 ! CHECK:           %[[VAL_15:.*]] = fir.shape %[[VAL_12]] : (index) -> !fir.shape<1>
@@ -435,7 +435,7 @@ subroutine test_branching(x)
 ! CHECK:           fir.call @_QPrdefault(%[[VAL_8]]#0) fastmath<contract> : (!fir.box<!fir.array<*:f32>>) -> ()
 ! CHECK:           cf.br ^bb5
 ! CHECK:         ^bb4:
-! CHECK:           %[[VAL_9:.*]] = arith.constant -1 : index
+! CHECK:           %[[VAL_9:.*]] = fir.assumed_size_extent : index
 ! CHECK:           %[[VAL_10:.*]] = fir.box_addr %[[VAL_2]]#1 : (!fir.box<!fir.array<*:f32>>) -> !fir.ref<!fir.array<*:f32>>
 ! CHECK:           %[[VAL_11:.*]] = fir.convert %[[VAL_10]] : (!fir.ref<!fir.array<*:f32>>) -> !fir.ref<!fir.array<?xf32>>
 ! CHECK:           %[[VAL_12:.*]] = fir.shape %[[VAL_9]] : (index) -> !fir.shape<1>
@@ -482,7 +482,7 @@ subroutine test_branching(x)
 ! CHECK:           fir.call @_QPr1_implicit(%[[VAL_21]]#1) fastmath<contract> : (!fir.ref<!fir.array<?xf32>>) -> ()
 ! CHECK:           cf.br ^bb6
 ! CHECK:         ^bb5:
-! CHECK:           %[[VAL_22:.*]] = arith.constant -1 : index
+! CHECK:           %[[VAL_22:.*]] = fir.assumed_size_extent : index
 ! CHECK:           %[[VAL_23:.*]] = fir.box_addr %[[VAL_2]]#1 : (!fir.box<!fir.array<*:f32>>) -> !fir.ref<!fir.array<*:f32>>
 ! CHECK:           %[[VAL_24:.*]] = fir.convert %[[VAL_23]] : (!fir.ref<!fir.array<*:f32>>) -> !fir.ref<!fir.array<?xf32>>
 ! CHECK:           %[[VAL_25:.*]] = fir.shape %[[VAL_22]] : (index) -> !fir.shape<1>
@@ -534,7 +534,7 @@ subroutine test_branching(x)
 ! CHECK:           fir.call @_QPrc1_implicit(%[[VAL_26]]) fastmath<contract> : (!fir.boxchar<1>) -> ()
 ! CHECK:           cf.br ^bb6
 ! CHECK:         ^bb5:
-! CHECK:           %[[VAL_27:.*]] = arith.constant -1 : index
+! CHECK:           %[[VAL_27:.*]] = fir.assumed_size_extent : index
 ! CHECK:           %[[VAL_28:.*]] = fir.box_addr %[[VAL_8]]#1 : (!fir.box<!fir.array<*:!fir.char<1,?>>>) -> !fir.ref<!fir.array<*:!fir.char<1,?>>>
 ! CHECK:           %[[VAL_29:.*]] = fir.convert %[[VAL_28]] : (!fir.ref<!fir.array<*:!fir.char<1,?>>>) -> !fir.ref<!fir.array<?x!fir.char<1,?>>>
 ! CHECK:           %[[VAL_30:.*]] = fir.shape %[[VAL_27]] : (index) -> !fir.shape<1>
diff --git a/flang/test/Lower/Intrinsics/lbound.f90 b/flang/test/Lower/Intrinsics/lbound.f90
index a5ca2d39a5ee4..75c11ff8bc95f 100644
--- a/flang/test/Lower/Intrinsics/lbound.f90
+++ b/flang/test/Lower/Intrinsics/lbound.f90
@@ -40,7 +40,7 @@ subroutine lbound_test_2(a, dim, res)
 subroutine lbound_test_3(a, dim, res)
   real, dimension(2:10, 3:*) :: a
   integer(8):: dim, res
-! CHECK:  %[[VAL_0:.*]] = arith.constant -1 : index
+! CHECK:  %[[VAL_0:.*]] = fir.assumed_size_extent : index
 ! CHECK:  %[[VAL_1:.*]] = fir.load %arg1 : !fir.ref<i64>
 ! CHECK:  %[[VAL_2:.*]] = fir.shape_shift %{{.*}}, %{{.*}}, %{{.*}}, %[[VAL_0]] : (index, index, index, index) -> !fir.shapeshift<2>
 ! CHECK:         %[[VAL_3:.*]] = fir.embox %arg0(%[[VAL_2]]) : (!fir.ref<!fir.array<9x?xf32>>, !fir.shapeshift<2>) -> !fir.box<!fir.array<9x?xf32>>
diff --git a/flang/test/Lower/Intrinsics/ubound.f90 b/flang/test/Lower/Intrinsics/ubound.f90
index dae21acda170d..bc8cff8982542 100644
--- a/flang/test/Lower/Intrinsics/ubound.f90
+++ b/flang/test/Lower/Intrinsics/ubound.f90
@@ -48,7 +48,7 @@ subroutine ubound_test_2(a, dim, res)
 subroutine ubound_test_3(a, dim, res)
   real, dimension(10, 20, *) :: a
   integer(8):: dim, res
-! CHECK:         %[[VAL_0:.*]] = arith.constant -1 : index
+! CHECK:         %[[VAL_0:.*]] = fir.assumed_size_extent : index
 ! CHECK:         %[[VAL_1:.*]] = fir.shape %{{.*}}, %{{.*}}, %[[VAL_0]] : (index, index, index) -> !fir.shape<3>
 ! CHECK:         %[[VAL_2:.*]] = fir.embox %{{.*}}(%[[VAL_1]]) : (!fir.ref<!fir.array<10x20x?xf32>>, !fir.shape<3>) -> !fir.box<!fir.array<10x20x?xf32>>
 ! CHECK:         %[[VAL_3:.*]] = fir.load %{{.*}} : !fir.ref<i64>
diff --git a/flang/test/Lower/array-expression-assumed-size.f90 b/flang/test/Lower/array-expression-assumed-size.f90
index 2fbf315aff114..a498148d07fc7 100644
--- a/flang/test/Lower/array-expression-assumed-size.f90
+++ b/flang/test/Lower/array-expression-assumed-size.f90
@@ -19,7 +19,7 @@ end subroutine assumed_size_forall_test
 ! CHECK:         %[[VAL_1A:.*]] = fir.convert %c10{{.*}} : (i64) -> index 
 ! CHECK:         %[[VAL_1B:.*]] = arith.cmpi sgt, %[[VAL_1A]], %c0{{.*}} : index 
 ! CHECK:         %[[VAL_1:.*]] = arith.select %[[VAL_1B]], %[[VAL_1A]], %c0{{.*}} : index
-! CHECK:         %[[VAL_2:.*]] = arith.constant -1 : index
+! CHECK:         %[[VAL_2:.*]] = fir.assumed_size_extent : index
 ! CHECK:         %[[VAL_3:.*]] = arith.constant 1 : index
 ! CHECK:         %[[VAL_4:.*]] = arith.constant 1 : i64
 ! CHECK:         %[[VAL_5:.*]] = fir.convert %[[VAL_4]] : (i64) -> index
@@ -82,7 +82,7 @@ end subroutine assumed_size_forall_test
 ! CHECK:         %[[VAL_2A:.*]] = fir.convert %c10{{.*}} : (i64) -> index 
 ! CHECK:         %[[VAL_2B:.*]] = arith.cmpi sgt, %[[VAL_2A]], %c0{{.*}} : index 
 ! CHECK:         %[[VAL_2:.*]] = arith.select %[[VAL_2B]], %[[VAL_2A]], %c0{{.*}} : index
-! CHECK:         %[[VAL_3:.*]] = arith.constant -1 : index
+! CHECK:         %[[VAL_3:.*]] = fir.assumed_size_extent : index
 ! CHECK:         %[[VAL_4:.*]] = arith.constant 2 : i32
 ! CHECK:         %[[VAL_5:.*]] = fir.convert %[[VAL_4]] : (i32) -> index
 ! CHECK:         %[[VAL_6:.*]] = arith.constant 6 : i32
@@ -149,7 +149,7 @@ end subroutine assumed_size_forall_test
 ! PostOpt-DAG:         %[[VAL_4:.*]] = arith.constant 0 : index
 ! PostOpt-DAG:         %[[VAL_5:.*]] = arith.constant 3 : index
 ! PostOpt-DAG:         %[[VAL_6:.*]] = arith.constant 4 : index
-! PostOpt-DAG:         %[[VAL_7:.*]] = arith.constant -1 : index
+! PostOpt-DAG:         %[[VAL_7:.*]] = fir.assumed_size_extent : index
 ! PostOpt:         %[[VAL_8:.*]] = fir.shape %[[VAL_1]], %[[VAL_7]] : (index, index) -> !fir.shape<2>
 ! PostOpt:         %[[VAL_9:.*]] = fir.slice %[[VAL_2]], %[[VAL_1]], %[[VAL_2]], %[[VAL_2]], %[[VAL_3]], %[[VAL_2]] : (index, index, index, index, index, index) -> !fir.slice<2>
 ! PostOpt:         %[[VAL_10:.*]] = fir.allocmem !fir.array<10x?xi32>, %[[VAL_3]]
@@ -227,8 +227,8 @@ end subroutine assumed_size_forall_test
 ! PostOpt-DAG:         %[[VAL_4:.*]] = arith.constant 1 : index
 ! PostOpt-DAG:         %[[VAL_5:.*]] = arith.constant 0 : index
 ! PostOpt-DAG:         %[[VAL_6:.*]] = arith.constant 5 : index
-! PostOpt-DAG:         %[[VAL_8:.*]] = arith.constant -1 : index
 ! PostOpt:         %[[VAL_7:.*]] = fir.alloca i32 {adapt.valuebyref, bindc_name = "i"}
+! PostOpt:         %[[VAL_8:.*]] = fir.assumed_size_extent : index
 ! PostOpt:         %[[VAL_9:.*]] = fir.shape %[[VAL_2]], %[[VAL_8]] : (index, index) -> !fir.shape<2>
 ! PostOpt:         %[[VAL_10:.*]] = fir.allocmem !fir.array<10x?xi32>, %[[VAL_4]]
 ! PostOpt:         br ^bb1(%[[VAL_5]], %[[VAL_4]] : index, index)
diff --git a/flang/test/Lower/entry-statement.f90 b/flang/test/Lower/entry-statement.f90
index 83d2d324aed87..f1e535a2bd3a1 100644
--- a/flang/test/Lower/entry-statement.f90
+++ b/flang/test/Lower/entry-statement.f90
@@ -491,7 +491,7 @@ subroutine assumed_size()
 ! CHECK-LABEL:   func.func @_QPentry_with_assumed_size(
 ! CHECK-SAME:                                          %[[VAL_0:.*]]: !fir.ref<!fir.array<?xf32>> {fir.bindc_name = "x"}) {
 ! CHECK:           %[[VAL_1:.*]] = fir.dummy_scope : !fir.dscope
-! CHECK:           %[[VAL_2:.*]] = arith.constant -1 : index
+! CHECK:           %[[VAL_2:.*]] = fir.assumed_size_extent : index
 ! CHECK:           %[[VAL_3:.*]] = fir.shape %[[VAL_2]] : (index) -> !fir.shape<1>
 ! CHECK:           %[[VAL_4:.*]]:2 = hlfir.declare %[[VAL_0]](%[[VAL_3]]) dummy_scope %[[VAL_1]] {uniq_name = "_QFassumed_sizeEx"} : (!fir.ref<!fir.array<?xf32>>, !fir.shape<1>, !fir.dscope) -> (!fir.box<!fir.array<?xf32>>, !fir.ref<!fir.array<?xf32>>)
 ! CHECK:           cf.br ^bb1