[llvm] f276d8f - [OMPIRBuilder] Don't leak a foreign debug loc into the taskwait call (#222586)

[via llvm-commits]

Author: Abid Qadeer
Date: 2026-09-11T10:36:37+01:00
New Revision: f276d8f00313f593ab9d8f3a1d242b6754f0a436

URL: https://github.com/llvm/llvm-project/commit/f276d8f00313f593ab9d8f3a1d242b6754f0a436
DIFF: https://github.com/llvm/llvm-project/commit/f276d8f00313f593ab9d8f3a1d242b6754f0a436.diff

LOG: [OMPIRBuilder] Don't leak a foreign debug loc into the taskwait call (#222586)

A kmp_depend_info array is hoisted to the entry block of the enclosing
function. Pointing the builder into that block also adopts the location
of what is already there, which belongs to whichever construct put it
there rather than to the construct being emitted. restoreIP does not put
the location back either, since it adopts the location of the
instruction it lands on, so in createTaskwait the leak outlives the
excursion and reaches the __kmpc_omp_taskwait_deps_51 call.

Use InsertPointGuard, which restores the location along with the
insertion point.

Fixes https://github.com/llvm/llvm-project/issues/222044

Co-authored-by: Cursor <cursoragent at cursor.com>

Added: 
    mlir/test/Target/LLVMIR/openmp-task-depend-loc.mlir

Modified: 
    llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
index 6d2732165b695..07bd542ae571c 100644
--- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
+++ b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
@@ -2404,14 +2404,15 @@ static Value *emitTaskDependencies(
   Type *DependInfo = OMPBuilder.DependInfo;
 
   Value *DepArray = nullptr;
-  OpenMPIRBuilder::InsertPointTy OldIP = Builder.saveIP();
-  Builder.SetInsertPoint(
-      OldIP.getBlock()->getParent()->getEntryBlock().getTerminator());
-
   Type *DepArrayTy = ArrayType::get(DependInfo, Dependencies.size());
-  DepArray = Builder.CreateAlloca(DepArrayTy, nullptr, ".dep.arr.addr");
-
-  Builder.restoreIP(OldIP);
+  {
+    // Use a InsertPointGuard to restore the location back along with the
+    // insertion point.
+    IRBuilderBase::InsertPointGuard IPGuard(Builder);
+    Builder.SetInsertPoint(
+        Builder.GetInsertBlock()->getParent()->getEntryBlock().getTerminator());
+    DepArray = Builder.CreateAlloca(DepArrayTy, nullptr, ".dep.arr.addr");
+  }
 
   for (const auto &[DepIdx, Dep] : enumerate(Dependencies)) {
     Value *Base =
@@ -2446,16 +2447,16 @@ void OpenMPIRBuilder::createTaskwait(const LocationDescription &Loc,
     DepArray = Dependencies.DepArray;
     NumDeps = Dependencies.NumDeps;
   } else if (!Dependencies.Deps.empty()) {
-    InsertPointTy OldIP = Builder.saveIP();
-    BasicBlock &entryBB =
-        Builder.GetInsertBlock()->getParent()->getEntryBlock();
-    Builder.SetInsertPoint(&entryBB, entryBB.getFirstInsertionPt());
-
     DepArrayTy = ArrayType::get(DependInfo, Dependencies.Deps.size());
-    DepArray = Builder.CreateAlloca(DepArrayTy, nullptr, ".dep.arr.addr");
     NumDeps = Builder.getInt32(Dependencies.Deps.size());
+    {
+      IRBuilderBase::InsertPointGuard IPGuard(Builder);
+      BasicBlock &entryBB =
+          Builder.GetInsertBlock()->getParent()->getEntryBlock();
+      Builder.SetInsertPoint(&entryBB, entryBB.getFirstInsertionPt());
+      DepArray = Builder.CreateAlloca(DepArrayTy, nullptr, ".dep.arr.addr");
+    }
 
-    Builder.restoreIP(OldIP);
     for (const auto &[DepIdx, Dep] : enumerate(Dependencies.Deps)) {
       Value *Base =
           Builder.CreateConstInBoundsGEP2_64(DepArrayTy, DepArray, 0, DepIdx);

diff  --git a/mlir/test/Target/LLVMIR/openmp-task-depend-loc.mlir b/mlir/test/Target/LLVMIR/openmp-task-depend-loc.mlir
new file mode 100644
index 0000000000000..2a6c5801a233a
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/openmp-task-depend-loc.mlir
@@ -0,0 +1,37 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+llvm.func @task_then_taskwait(%x: !llvm.ptr, %y: !llvm.ptr) {
+  omp.task depend(taskdependout -> %x : !llvm.ptr) {
+    omp.terminator
+  } loc(#loc_task)
+  omp.taskwait depend(taskdependin -> %y : !llvm.ptr) loc(#loc_wait)
+  llvm.return
+} loc(#loc_fn)
+
+// The task is on line 7 and the taskwait on line 11. Each runtime call must
+// carry its own line.
+
+// CHECK: define void @task_then_taskwait
+// CHECK: call i32 @__kmpc_omp_task_with_deps({{.*}}), !dbg ![[TASK:[0-9]+]]
+// CHECK: call void @__kmpc_omp_taskwait_deps_51({{.*}}), !dbg ![[WAIT:[0-9]+]]
+// CHECK-DAG: ![[TASK]] = !DILocation(line: 7, column: 9
+// CHECK-DAG: ![[WAIT]] = !DILocation(line: 11, column: 9
+
+#di_file = #llvm.di_file<"test.f90" in "">
+#di_null_type = #llvm.di_null_type
+#di_compile_unit = #llvm.di_compile_unit<id = distinct[0]<>,
+  sourceLanguage = DW_LANG_Fortran95, file = #di_file, producer = "flang",
+  isOptimized = false, emissionKind = LineTablesOnly>
+#di_subroutine_type = #llvm.di_subroutine_type<
+  callingConvention = DW_CC_normal, types = #di_null_type>
+#di_subprogram = #llvm.di_subprogram<id = distinct[1]<>,
+  compileUnit = #di_compile_unit, scope = #di_file, name = "sub1",
+  file = #di_file, subprogramFlags = "Definition", type = #di_subroutine_type>
+
+#loc1 = loc("test.f90":3:1)
+#loc2 = loc("test.f90":7:9)
+#loc3 = loc("test.f90":11:9)
+
+#loc_fn = loc(fused<#di_subprogram>[#loc1])
+#loc_task = loc(fused<#di_subprogram>[#loc2])
+#loc_wait = loc(fused<#di_subprogram>[#loc3])