[flang] Emit argNo debug info only for func block args

[ergawy]

Fixes a bug uncovered by pr43337.f90 in the test suite.

In particular, this emits argNo debug info only if the parent op of a block is a func.func op. This avoids DI conflicts when a function contains a nested OpenMP region that itself has block arguments with DI attached to them; for example, omp.parallel with delayed privatization enabled.

[llvmbot]

@llvm/pr-subscribers-flang-openmp

@llvm/pr-subscribers-flang-fir-hlfir

Author: Kareem Ergawy (ergawy)

Changes

Fixes a bug uncovered by (pr43337.f90)[https://github.com/llvm/llvm-test-suite/blob/main/Fortran/gfortran/regression/gomp/pr43337.f90] in the test suite.

In particular, this emits argNo debug info only if the parent op of a block is a func.func op. This avoids DI conflicts when a function contains a nested OpenMP region that itself has block arguments with DI attached to them; for example, omp.parallel with delayed privatization enabled.

---

Full diff: https://github.com/llvm/llvm-project/pull/93921.diff

2 Files Affected:

• (modified) flang/lib/Optimizer/Transforms/AddDebugInfo.cpp (+3-3)
• (added) flang/test/Lower/OpenMP/debug_info_conflict.f90 (+16)

diff --git a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
index fb7c0bf0d1f97..e7a3d93a533ef 100644
--- a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
+++ b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
@@ -94,10 +94,10 @@ void AddDebugInfoPass::handleDeclareOp(fir::cg::XDeclareOp declOp,
   // DeclareOp is generated. In that case, DeclareOp may point to an
   // intermediate op and not to BlockArgument. We need to find those cases and
   // walk the chain to get to the actual argument.
-
   unsigned argNo = 0;
-  if (auto Arg = llvm::dyn_cast<mlir::BlockArgument>(declOp.getMemref()))
-    argNo = Arg.getArgNumber() + 1;
+  if (mlir::isa<mlir::func::FuncOp>(declOp->getParentOp()))
+    if (auto arg = llvm::dyn_cast<mlir::BlockArgument>(declOp.getMemref()))
+      argNo = arg.getArgNumber() + 1;
 
   auto tyAttr = typeGen.convertType(fir::unwrapRefType(declOp.getType()),
                                     fileAttr, scopeAttr, declOp.getLoc());
diff --git a/flang/test/Lower/OpenMP/debug_info_conflict.f90 b/flang/test/Lower/OpenMP/debug_info_conflict.f90
new file mode 100644
index 0000000000000..5e52db281da23
--- /dev/null
+++ b/flang/test/Lower/OpenMP/debug_info_conflict.f90
@@ -0,0 +1,16 @@
+! Tests that there no debug-info conflicts arise because of DI attached to nested
+! OMP regions arguments.
+
+! RUN: %flang -c -fopenmp -g -mmlir --openmp-enable-delayed-privatization=true \
+! RUN:   %s -o - 2>&1 | FileCheck %s
+
+subroutine bar (b)
+  integer :: a, b
+!$omp parallel
+  do a = 1, 10
+    b = a
+  end do
+!$omp end parallel
+end subroutine bar
+
+! CHECK-NOT: conflicting debug info for argument

[tblah]

Thanks for the bug fix

[tblah]

Thanks!

[abidh]

Nit: I think using %flang_fc1 -emit-llvm will also reproduce this problem and it will be more in line with the other tests in this folder instead of using %flang. You can use -debug-info-kind=standalone for -g.

[abidh]

Thanks for the fix. Looks good to me apart from the small nit.