[Mlir-commits] [flang] [mlir] [mlir][OpenMP] Fix update of linear iteration variables (PR #183800)

llvmlistbot at llvm.org llvmlistbot at llvm.org
Fri Feb 27 10:55:35 PST 2026


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir

Author: Leandro Lupori (luporl)

<details>
<summary>Changes</summary>

The final value of a linear iteration variable must be the loop
limit_value + 1. Before this patch it was limit_value.

This fixes the second issue reported in #<!-- -->170784.

NOTE only the second commit should be reviewed, as the first was submitted as PR #<!-- -->183794

TODO add a new test and adapt the failing MLIR tests.

---

Patch is 22.68 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/183800.diff


8 Files Affected:

- (modified) flang/lib/Lower/OpenMP/DataSharingProcessor.cpp (+9-6) 
- (modified) flang/lib/Lower/OpenMP/OpenMP.cpp (+4-1) 
- (modified) flang/test/Lower/OpenMP/composite_simd_linear.f90 (+8-7) 
- (modified) flang/test/Lower/OpenMP/distribute-parallel-do-simd.f90 (+6-7) 
- (modified) flang/test/Lower/OpenMP/distribute-simd.f90 (+3-3) 
- (modified) flang/test/Lower/OpenMP/loop-pointer-variable.f90 (+5-5) 
- (modified) flang/test/Lower/OpenMP/wsloop-simd.f90 (+5-5) 
- (modified) mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp (+91-38) 


``````````diff
diff --git a/flang/lib/Lower/OpenMP/DataSharingProcessor.cpp b/flang/lib/Lower/OpenMP/DataSharingProcessor.cpp
index fcf2ae9337295..a2379aa194277 100644
--- a/flang/lib/Lower/OpenMP/DataSharingProcessor.cpp
+++ b/flang/lib/Lower/OpenMP/DataSharingProcessor.cpp
@@ -235,11 +235,6 @@ void DataSharingProcessor::collectSymbolsForPrivatization() {
   // Such cases are suggested to be clearly documented and explained
   // instead of being silently skipped
   auto isException = [&](const Fortran::semantics::Symbol *sym) -> bool {
-    // `OmpPreDetermined` symbols cannot be exceptions since
-    // their privatized symbols are heavily used in FIR.
-    if (sym->test(Fortran::semantics::Symbol::Flag::OmpPreDetermined))
-      return false;
-
     // The handling of linear clause is deferred to the OpenMP
     // IRBuilder which is responsible for all its aspects,
     // including privatization. Privatizing linear variables at this point would
@@ -263,6 +258,11 @@ void DataSharingProcessor::collectSymbolsForPrivatization() {
     // draw a relation between %linear and %arg0. Hence skip.
     if (sym->test(Fortran::semantics::Symbol::Flag::OmpLinear))
       return true;
+
+    // `OmpPreDetermined` symbols cannot be exceptions since
+    // their privatized symbols are heavily used in FIR.
+    if (sym->test(Fortran::semantics::Symbol::Flag::OmpPreDetermined))
+      return false;
     return false;
   };
 
@@ -508,7 +508,10 @@ void DataSharingProcessor::collectSymbols(
            !sym.GetUltimate().has<semantics::DerivedTypeDetails>() &&
            !sym.GetUltimate().has<semantics::NamelistDetails>() &&
            !semantics::IsImpliedDoIndex(sym.GetUltimate()) &&
-           !semantics::IsStmtFunction(sym);
+           !semantics::IsStmtFunction(sym) &&
+           // Linear symbols are privatized by OpenMP IRBuilder. See comments
+           // in collectSymbolsForPrivatization() for more details.
+           !sym.test(semantics::Symbol::Flag::OmpLinear);
   };
 
   auto shouldCollectSymbol = [&](const semantics::Symbol *sym) {
diff --git a/flang/lib/Lower/OpenMP/OpenMP.cpp b/flang/lib/Lower/OpenMP/OpenMP.cpp
index 6d93f245228a8..254cd4880c539 100644
--- a/flang/lib/Lower/OpenMP/OpenMP.cpp
+++ b/flang/lib/Lower/OpenMP/OpenMP.cpp
@@ -716,7 +716,10 @@ static mlir::Operation *
 createAndSetPrivatizedLoopVar(lower::AbstractConverter &converter,
                               mlir::Location loc, mlir::Value indexVal,
                               const semantics::Symbol *sym) {
-  assert(converter.isPresentShallowLookup(*sym) &&
+  // The handling of linear symbols is deferred to the OpenMP IRBuilder,
+  // which is responsible for all its aspects, including privatization.
+  assert((converter.isPresentShallowLookup(*sym) ||
+          sym->test(semantics::Symbol::Flag::OmpLinear)) &&
          "Expected symbol to be in symbol table.");
   return setLoopVar(converter, loc, indexVal, sym);
 }
diff --git a/flang/test/Lower/OpenMP/composite_simd_linear.f90 b/flang/test/Lower/OpenMP/composite_simd_linear.f90
index 706b09d378db4..d976afd6c0f5e 100644
--- a/flang/test/Lower/OpenMP/composite_simd_linear.f90
+++ b/flang/test/Lower/OpenMP/composite_simd_linear.f90
@@ -8,7 +8,7 @@ subroutine do_simd
 !CHECK: %{{.*}} = arith.constant 1 : i32
 !CHECK: %[[IV_STEP:.*]] = arith.constant 1 : i32
 !CHECK: omp.wsloop {
-!CHECK: omp.simd linear(%[[X]]#0 = %[[CONST]] : !fir.ref<i32>, %[[I]]#0 = %[[IV_STEP]] : !fir.ref<i32>) private(@_QFdo_simdEi_private_i32 {{.*}} -> %arg0 : !fir.ref<i32>) {
+!CHECK: omp.simd linear(%[[X]]#0 = %[[CONST]] : !fir.ref<i32>, %[[I]]#0 = %[[IV_STEP]] : !fir.ref<i32>) {
 !CHECK: }
 !CHECK: } {linear_var_types = [i32, i32], omp.composite}
 !CHECK: } {omp.composite}
@@ -21,9 +21,10 @@ end subroutine do_simd
 
 
 subroutine distribute_simd
+!CHECK: %[[I:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "_QFdistribute_simdEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
 !CHECK: omp.teams {
-!CHECK: omp.distribute private(@_QFdistribute_simdEi_private_i32 {{.*}} -> %[[ARG0:.*]] : !fir.ref<i32>) {
-!CHECK: omp.simd linear(%[[ARG0]] = %c1_i32 : !fir.ref<i32>) private(@_QFdistribute_simdEi_private_i32 %[[ARG0]] -> {{.*}} : !fir.ref<i32>) {
+!CHECK: omp.distribute {
+!CHECK: omp.simd linear(%[[I]]#0 = %c1_i32 : !fir.ref<i32>) {
 !CHECK: } {linear_var_types = [i32], omp.composite}
 !CHECK: } {omp.composite}
     integer :: i
@@ -44,7 +45,7 @@ subroutine distribute_parallel_do
 !CHECK: %[[CONST]] = arith.constant 1 : i32
 !CHECK: omp.distribute {
 !CHECK: omp.wsloop {
-!CHECK: omp.simd linear(%[[I]]#0 = %[[CONST]] : !fir.ref<i32>) private(@_QFdistribute_parallel_doEi_private_i32 %[[I]]#0 -> %arg0 : !fir.ref<i32>) { 
+!CHECK: omp.simd linear(%[[I]]#0 = %[[CONST]] : !fir.ref<i32>)  {
     !$omp teams
     !$omp distribute parallel do simd linear(i:1)
     do i = 1, N
@@ -62,7 +63,7 @@ subroutine parallel_do
 !CHECK: %{{.*}} = arith.constant 1 : i32
 !CHECK: %[[IV_STEP:.*]] = arith.constant 1 : i32
 !CHECK: omp.wsloop {
-!CHECK: omp.simd linear(%[[X]]#0 = %[[LINEAR_STEP]] : !fir.ref<i32>, %[[I]]#0 = %[[IV_STEP]] : !fir.ref<i32>) private(@_QFparallel_doEi_private_i32 %[[I]]#0 -> %arg0 : !fir.ref<i32>) {
+!CHECK: omp.simd linear(%[[X]]#0 = %[[LINEAR_STEP]] : !fir.ref<i32>, %[[I]]#0 = %[[IV_STEP]] : !fir.ref<i32>) {
     integer :: x
     !$omp parallel do simd linear(x:2)
     do i = 1, N
@@ -79,7 +80,7 @@ subroutine teams_distribute
 !CHECK: {{.*}} = arith.constant 1 : i32
 !CHECK: %[[IV_STEP:.*]] = arith.constant 1 : i32
 !CHECK: omp.distribute {
-!CHECK: omp.simd linear(%[[X]]#0 = %[[LINEAR_STEP]] : !fir.ref<i32>, %[[I]]#0 = %[[IV_STEP]] : !fir.ref<i32>) private(@_QFteams_distributeEi_private_i32 %[[I]]#0 -> %arg0 : !fir.ref<i32>) {
+!CHECK: omp.simd linear(%[[X]]#0 = %[[LINEAR_STEP]] : !fir.ref<i32>, %[[I]]#0 = %[[IV_STEP]] : !fir.ref<i32>) {
     integer :: x
     !$omp teams distribute simd linear(x)
     do i = 1, N
@@ -98,7 +99,7 @@ subroutine teams_distribute_parallel_do
 !CHECK: %[[IV_STEP:.*]] = arith.constant 1 : i32
 !CHECK: omp.distribute {
 !CHECK: omp.wsloop {
-!CHECK: omp.simd linear(%[[X]]#0 = %c1_i32 : !fir.ref<i32>, %[[I]]#0 = %c1_i32_1 : !fir.ref<i32>) private(@_QFteams_distribute_parallel_doEi_private_i32 %[[I]]#0 -> %arg0 : !fir.ref<i32>) {
+!CHECK: omp.simd linear(%[[X]]#0 = %c1_i32 : !fir.ref<i32>, %[[I]]#0 = %c1_i32_1 : !fir.ref<i32>) {
     integer :: x
     !$omp teams distribute parallel do simd linear(x)
     do i = 1, N
diff --git a/flang/test/Lower/OpenMP/distribute-parallel-do-simd.f90 b/flang/test/Lower/OpenMP/distribute-parallel-do-simd.f90
index 120177a0420bf..7f91177cc3311 100644
--- a/flang/test/Lower/OpenMP/distribute-parallel-do-simd.f90
+++ b/flang/test/Lower/OpenMP/distribute-parallel-do-simd.f90
@@ -11,7 +11,7 @@ subroutine distribute_parallel_do_simd_num_threads()
   ! CHECK:      omp.parallel num_threads({{.*}}) {
   ! CHECK:      omp.distribute {
   ! CHECK-NEXT: omp.wsloop {
-  ! CHECK-NEXT: omp.simd linear({{.*}}) private({{.*}}) {
+  ! CHECK-NEXT: omp.simd linear({{.*}}) {
   ! CHECK-NEXT: omp.loop_nest
   !$omp distribute parallel do simd num_threads(10)
   do index_ = 1, 10
@@ -28,7 +28,7 @@ subroutine distribute_parallel_do_simd_dist_schedule()
   ! CHECK:      omp.parallel  {
   ! CHECK:      omp.distribute dist_schedule_static dist_schedule_chunk_size({{.*}}) {
   ! CHECK-NEXT: omp.wsloop {
-  ! CHECK-NEXT: omp.simd linear({{.*}}) private({{.*}}) {
+  ! CHECK-NEXT: omp.simd linear({{.*}}) {
   ! CHECK-NEXT: omp.loop_nest
   !$omp distribute parallel do simd dist_schedule(static, 4)
   do index_ = 1, 10
@@ -45,7 +45,7 @@ subroutine distribute_parallel_do_simd_schedule()
   ! CHECK:      omp.parallel {
   ! CHECK:      omp.distribute {
   ! CHECK-NEXT: omp.wsloop schedule(static = {{.*}}) {
-  ! CHECK-NEXT: omp.simd linear({{.*}}) private({{.*}}) {
+  ! CHECK-NEXT: omp.simd linear({{.*}}) {
   ! CHECK-NEXT: omp.loop_nest
   !$omp distribute parallel do simd schedule(static, 4)
   do index_ = 1, 10
@@ -62,7 +62,7 @@ subroutine distribute_parallel_do_simd_simdlen()
   ! CHECK:      omp.parallel {
   ! CHECK:      omp.distribute {
   ! CHECK-NEXT: omp.wsloop {
-  ! CHECK-NEXT: omp.simd linear({{.*}}) simdlen(4) private({{.*}}) {
+  ! CHECK-NEXT: omp.simd linear({{.*}}) simdlen(4) {
   ! CHECK-NEXT: omp.loop_nest
   !$omp distribute parallel do simd simdlen(4)
   do index_ = 1, 10
@@ -86,11 +86,10 @@ subroutine distribute_parallel_do_simd_private()
   ! CHECK:      omp.parallel {
   ! CHECK:      omp.distribute {
   ! CHECK-NEXT: omp.wsloop {
-  ! CHECK-NEXT: omp.simd linear(%{{.*}}) private(@{{.*}} %[[X]]#0 -> %[[X_ARG:[^,]+]],
-  ! CHECK-SAME:                  @{{.*}} %[[INDEX]]#0 -> %[[INDEX_ARG:.*]] : !fir.ref<i64>, !fir.ref<i32>) {
+  ! CHECK-NEXT: omp.simd linear(%{{.*}}) private(@{{.*}} %[[X]]#0 -> %[[X_ARG:[^:]+]]
+  ! CHECK-SAME:                  : !fir.ref<i64>) {
   ! CHECK-NEXT: omp.loop_nest
   ! CHECK:      %[[X_PRIV:.*]]:2 = hlfir.declare %[[X_ARG]]
-  ! CHECK:      %[[INDEX_PRIV:.*]]:2 = hlfir.declare %[[INDEX_ARG]]
   !$omp distribute parallel do simd private(x)
   do index_ = 1, 10
   end do
diff --git a/flang/test/Lower/OpenMP/distribute-simd.f90 b/flang/test/Lower/OpenMP/distribute-simd.f90
index d0316d1a136ab..f06282a10d9f0 100644
--- a/flang/test/Lower/OpenMP/distribute-simd.f90
+++ b/flang/test/Lower/OpenMP/distribute-simd.f90
@@ -61,17 +61,17 @@ end subroutine distribute_simd_simdlen
 ! CHECK-LABEL: func.func @_QPdistribute_simd_private(
 subroutine distribute_simd_private()
   integer, allocatable :: tmp
+  ! CHECK: %[[INDEX:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "_QFdistribute_simd_privateEindex_"}
   ! CHECK:      omp.teams
   !$omp teams
   ! CHECK:      omp.distribute
   ! CHECK:      omp.simd
-  ! CHECK-SAME: private(@[[PRIV_BOX_SYM:.*]] %{{.*}} -> %[[PRIV_BOX:.*]], @[[PRIV_IVAR_SYM:.*]] %{{.*}} -> %[[PRIV_IVAR:.*]] : !fir.ref<!fir.box<!fir.heap<i32>>>, !fir.ref<i32>)
+  ! CHECK-SAME: private(@[[PRIV_BOX_SYM:.*]] %{{.*}} -> %[[PRIV_BOX:.*]] : !fir.ref<!fir.box<!fir.heap<i32>>>)
   ! CHECK-NEXT: omp.loop_nest (%[[IVAR:.*]]) : i32
   !$omp distribute simd private(tmp)
   do index_ = 1, 10
   ! CHECK:      %[[PRIV_BOX_DECL:.*]]:2 = hlfir.declare %[[PRIV_BOX]]
-  ! CHECK:      %[[PRIV_IVAR_DECL:.*]]:2 = hlfir.declare %[[PRIV_IVAR]]
-  ! CHECK:      hlfir.assign %[[IVAR]] to %[[PRIV_IVAR_DECL]]#0
+  ! CHECK:      hlfir.assign %[[IVAR]] to %[[INDEX]]#0
   end do
   !$omp end distribute simd
   !$omp end teams
diff --git a/flang/test/Lower/OpenMP/loop-pointer-variable.f90 b/flang/test/Lower/OpenMP/loop-pointer-variable.f90
index 0ca5d3a197dc5..5a2ca05be7ccf 100644
--- a/flang/test/Lower/OpenMP/loop-pointer-variable.f90
+++ b/flang/test/Lower/OpenMP/loop-pointer-variable.f90
@@ -8,6 +8,7 @@ program loop_var
   integer, pointer :: ip1, ip2
   integer, allocatable :: ia1
 
+!CHECK:  %[[IA1:.*]]:2 = hlfir.declare %{{.*}} {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFEia1"}
 !CHECK:  omp.wsloop private(@_QFEip1_private_box_ptr_i32 %{{.*}}#0 -> %[[IP1_PVT:.*]], @_QFEip2_private_box_ptr_i32 %{{.*}}#0 -> %[[IP2_PVT:.*]] : !fir.ref<!fir.box<!fir.ptr<i32>>>, !fir.ref<!fir.box<!fir.ptr<i32>>>)
 !CHECK:  omp.loop_nest (%[[IP1_INDX:.*]], %[[IP2_INDX:.*]]) : i64 = ({{.*}}) to ({{.*}}) inclusive step ({{.*}})
 !CHECK:    %[[IP1_PVT_DECL:.*]]:2 = hlfir.declare %[[IP1_PVT]] {fortran_attrs = #fir.var_attrs<pointer>, uniq_name = "_QFEip1"} : (!fir.ref<!fir.box<!fir.ptr<i32>>>) -> (!fir.ref<!fir.box<!fir.ptr<i32>>>, !fir.ref<!fir.box<!fir.ptr<i32>>>)
@@ -28,13 +29,12 @@ program loop_var
   end do
   !$omp end do
 
-!CHECK:    omp.simd private(@_QFEia1_private_box_heap_i32 %{{.*}}#0 -> %[[IA1_PVT:.*]] : !fir.ref<!fir.box<!fir.heap<i32>>>)
+!CHECK:    omp.simd
 !CHECK:      omp.loop_nest (%[[IA1_INDX:.*]]) : i64 = ({{.*}}) to ({{.*}}) inclusive step ({{.*}})
-!CHECK:        %[[IA1_PVT_DECL:.*]]:2 = hlfir.declare %[[IA1_PVT]] {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFEia1"} : (!fir.ref<!fir.box<!fir.heap<i32>>>) -> (!fir.ref<!fir.box<!fir.heap<i32>>>, !fir.ref<!fir.box<!fir.heap<i32>>>)
-!CHECK:        %[[IA1:.*]] = fir.convert %[[IA1_INDX]] : (i64) -> i32
-!CHECK:        %[[IA1_BOX:.*]] = fir.load %[[IA1_PVT_DECL]]#0 : !fir.ref<!fir.box<!fir.heap<i32>>>
+!CHECK:        %[[IA1_INDX_I32:.*]] = fir.convert %[[IA1_INDX]] : (i64) -> i32
+!CHECK:        %[[IA1_BOX:.*]] = fir.load %[[IA1]]#0 : !fir.ref<!fir.box<!fir.heap<i32>>>
 !CHECK:        %[[IA1_ADDR:.*]] = fir.box_addr %[[IA1_BOX]] : (!fir.box<!fir.heap<i32>>) -> !fir.heap<i32>
-!CHECK:        hlfir.assign %[[IA1]] to %[[IA1_ADDR]] : i32, !fir.heap<i32>
+!CHECK:        hlfir.assign %[[IA1_INDX_I32]] to %[[IA1_ADDR]] : i32, !fir.heap<i32>
 !CHECK:        omp.yield
   !$omp simd
   do ia1 = 1, 10
diff --git a/flang/test/Lower/OpenMP/wsloop-simd.f90 b/flang/test/Lower/OpenMP/wsloop-simd.f90
index 03e35de04cace..1b8ac68dad765 100644
--- a/flang/test/Lower/OpenMP/wsloop-simd.f90
+++ b/flang/test/Lower/OpenMP/wsloop-simd.f90
@@ -70,15 +70,15 @@ end subroutine do_simd_reduction
 ! CHECK-LABEL: func.func @_QPdo_simd_private(
 subroutine do_simd_private()
   integer, allocatable :: tmp
+  ! CHECK:      %[[I_DECL:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "_QFdo_simd_privateEi"}
   ! CHECK:      omp.wsloop
   ! CHECK-NEXT: omp.simd
-  ! CHECK-SAME: private(@[[PRIV_BOX_SYM:.*]] %{{.*}} -> %[[PRIV_BOX:.*]], @[[PRIV_IVAR_SYM:.*]] %{{.*}} -> %[[PRIV_IVAR:.*]] : !fir.ref<!fir.box<!fir.heap<i32>>>, !fir.ref<i32>)
+  ! CHECK-SAME: private(@[[PRIV_BOX_SYM:.*]] %{{.*}} -> %[[PRIV_BOX:.*]] : !fir.ref<!fir.box<!fir.heap<i32>>>)
   ! CHECK-NEXT: omp.loop_nest (%[[IVAR:.*]]) : i32
   !$omp do simd private(tmp)
   do i=1, 10
   ! CHECK:      %[[PRIV_BOX_DECL:.*]]:2 = hlfir.declare %[[PRIV_BOX]]
-  ! CHECK:      %[[PRIV_IVAR_DECL:.*]]:2 = hlfir.declare %[[PRIV_IVAR]]
-  ! CHECK:      hlfir.assign %[[IVAR]] to %[[PRIV_IVAR_DECL]]#0
+  ! CHECK:      hlfir.assign %[[IVAR]] to %[[I_DECL]]#0
   ! CHECK:      %[[PRIV_BOX_LOAD:.*]] = fir.load %[[PRIV_BOX_DECL]]
   ! CHECK:      hlfir.assign %{{.*}} to %[[PRIV_BOX_DECL]]#0
   ! CHECK:      omp.yield
@@ -92,12 +92,12 @@ subroutine do_simd_lastprivate_firstprivate()
   ! CHECK:      omp.wsloop
   ! CHECK-SAME: private(@[[FIRSTPRIVATE_A_SYM:.*]] %{{.*}} -> %[[FIRSTPRIVATE_A:.*]] : !fir.ref<i32>)
   ! CHECK-NEXT: omp.simd
-  ! CHECK-SAME: private(@[[PRIVATE_A_SYM:.*]] %{{.*}} -> %[[PRIVATE_A:.*]], @[[PRIVATE_I_SYM:.*]] %{{.*}} -> %[[PRIVATE_I:.*]] : !fir.ref<i32>, !fir.ref<i32>)
+  ! CHECK-SAME: linear({{.*}}#0 = %{{[^:]*}} : !fir.ref<i32>)
+  ! CHECK-SAME: private(@[[PRIVATE_A_SYM:.*]] %{{.*}} -> %[[PRIVATE_A:.*]] : !fir.ref<i32>)
   !$omp do simd lastprivate(a) firstprivate(a)
   do i = 1, 10
     ! CHECK: %[[FIRSTPRIVATE_A_DECL:.*]]:2 = hlfir.declare %[[FIRSTPRIVATE_A]]
     ! CHECK: %[[PRIVATE_A_DECL:.*]]:2 = hlfir.declare %[[PRIVATE_A]]
-    ! CHECK: %[[PRIVATE_I_DECL:.*]]:2 = hlfir.declare %[[PRIVATE_I]]
     a = a + 1
   end do
   !$omp end do simd
diff --git a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
index 38c5802ed60ed..f223649b25a85 100644
--- a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
@@ -143,6 +143,37 @@ class LinearClauseProcessor {
   llvm::BasicBlock *linearFinalizationBB;
   llvm::BasicBlock *linearExitBB;
   llvm::BasicBlock *linearLastIterExitBB;
+  Value linearLoopIV;
+  Value linearLoopIVStart;
+
+  void updateLinearVar(llvm::IRBuilderBase &builder, llvm::Type *varType,
+                       llvm::Value *var, llvm::Value *varStart,
+                       llvm::Value *step, llvm::Value *iv) {
+    if (!iv->getType()->isIntegerTy())
+      llvm_unreachable("OpenMP loop induction variable must be an integer "
+                       "type");
+
+    if (varType->isIntegerTy()) {
+      // Integer path: normalize all arithmetic to linearVarType
+      iv = builder.CreateSExtOrTrunc(iv, varType);
+      step = builder.CreateSExtOrTrunc(step, varType);
+
+      llvm::Value *mulInst = builder.CreateMul(iv, step);
+      llvm::Value *addInst = builder.CreateAdd(varStart, mulInst);
+      builder.CreateStore(addInst, var);
+    } else if (varType->isFloatingPointTy()) {
+      // Float path: perform multiply in integer, then convert to float
+      step = builder.CreateSExtOrTrunc(step, iv->getType());
+
+      llvm::Value *mulInst = builder.CreateMul(iv, step);
+      llvm::Value *mulFp = builder.CreateSIToFP(mulInst, varType);
+      llvm::Value *addInst = builder.CreateFAdd(varStart, mulFp);
+      builder.CreateStore(addInst, var);
+    } else {
+      llvm_unreachable(
+          "Linear variable must be of integer or floating-point type");
+    }
+  }
 
 public:
   // Register type for the linear variables
@@ -182,46 +213,63 @@ class LinearClauseProcessor {
     }
   }
 
+  // Find linear iteration variable and save it for later updates
+  void initLinearIV(omp::SimdOp simdOp) {
+    auto loopOp = cast<omp::LoopNestOp>(simdOp.getWrappedLoop());
+    // NOTE iteration variables can only be linear in non-nested loops.
+    if (loopOp.getIVs().size() != 1)
+      return;
+    // The linear IV is the loop IV's store address.
+    BlockArgument arg = loopOp.getIVs().front();
+    for (const Operation *user : arg.getUsers()) {
+      if (auto storeOp = dyn_cast<LLVM::StoreOp>(user)) {
+        for (Value linearVar : simdOp.getLinearVars()) {
+          if (linearVar == storeOp.getAddr()) {
+            linearLoopIV = linearVar;
+            linearLoopIVStart = loopOp.getLoopLowerBounds().front();
+            break;
+          }
+        }
+      }
+    }
+  }
+
   // Emit IR for updating Linear variables
-  void updateLinearVar(llvm::IRBuilderBase &builder, llvm::BasicBlock *loopBody,
-                       llvm::Value *loopInductionVar) {
+  void updateLinearVars(llvm::IRBuilderBase &builder,
+                        llvm::BasicBlock *loopBody,
+                        llvm::Value *loopInductionVar) {
     builder.SetInsertPoint(loopBody->getTerminator());
     for (size_t index = 0; index < linearPreconditionVars.size(); index++) {
-      llvm::Type *linearVarType = linearVarTypes[index];
-      llvm::Value *iv = loopInductionVar;
-      llvm::Value *step = linearSteps[index];
-
-      if (!iv->getType()->isIntegerTy())
-        llvm_unreachable("OpenMP loop induction variable must be an integer "
-                         "type");
-
-      if (linearVarType->isIntegerTy()) {
-        // Integer path: normalize all arithmetic to linearVarType
-        iv = builder.CreateSExtOrTrunc(iv, linearVarType);
-        step = builder.CreateSExtOrTrunc(step, linearVarType);
-
-        llvm::LoadInst *linearVarStart =
-            builder.CreateLoad(linearVarType, linearPreconditionVars[index]);
-        llvm::Value *mulInst = builder.CreateMul(iv, step);
-        llvm::Value *addInst = builder.CreateAdd(linearVarStart, mulInst);
-        builder.CreateStore(addInst, linearLoopBodyTemps[index]);
-      } else if (linearVarType->isFloatingPointTy()) {
-        // Float path: perform multiply in integer, then convert to float
-        step = builder.CreateSExtOrTrunc(step, iv->getType());
-        llvm::Value *mulInst = builder.CreateMul(iv, step);
-
-        llvm::LoadInst *linearVarStart =
-            builder.CreateLoad(linearVarType, linearPreconditionVars[index]);
-        llvm::Value *mulFp = builder.CreateSIToFP(mulInst, linearVarType);
-        llvm::Value *addInst = builder.CreateFAdd(linearVarStart, mulFp);
-        builder.CreateStore(addInst, linearLoopBodyTemps[index]);
-      } else {
-        llvm_unreachable(
-            "Linear variable must be of integer or floating-point type");
-      }
+      llvm::LoadInst *linearVarStart = builder.CreateLoad(
+          linearVarTypes[index], linearPreconditionVars[index]);
+      updateLinearVar(builder, linearVarTypes[index],
+                      linearLoopBodyTemps[index], linearVarStart,
+                      linearSteps[index], loopInductionVar);
     }
   }
 
+  // Emit IR for updating linear iteration variables on loop exit
+  void updateLinearIV(llvm::IRBuilderBase &builder,
+                      LLVM::ModuleTranslation &moduleTranslation,
+                      llvm::Value *loopIV) {
+    if (!linearLoopIV)
+      return;
+    llvm::Value *linearIV = moduleTranslation.lookupV...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/183800


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