[flang-commits] [flang] [flang] Emit `argNo` debug info only for `func` block args (PR #93921)

[Kareem Ergawy via flang-commits]

https://github.com/ergawy created https://github.com/llvm/llvm-project/pull/93921

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.

>From ca959a85850ba7bbda566fd685b2284fe4f0593e Mon Sep 17 00:00:00 2001
From: ergawy <kareem.ergawy at amd.com>
Date: Fri, 31 May 2024 00:09:40 -0500
Subject: [PATCH] [flang] Emit `argNo` debug info only for `func` block args

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.
---
 flang/lib/Optimizer/Transforms/AddDebugInfo.cpp |  6 +++---
 flang/test/Lower/OpenMP/debug_info_conflict.f90 | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)
 create mode 100644 flang/test/Lower/OpenMP/debug_info_conflict.f90

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