[flang-commits] [flang] [flang][debug] Set scope of internal functions correctly. (PR #99531)

[Abid Qadeer via flang-commits]

https://github.com/abidh created https://github.com/llvm/llvm-project/pull/99531

The functions internal to subroutine should have the scope set to the parent function. This allows a user to evaluate local variables of parent function when control is stopped in the child.

Fixes #96314

>From f938ad6dc5918494fb92d915c2e5e2dbbec34056 Mon Sep 17 00:00:00 2001
From: Abid Qadeer <haqadeer at amd.com>
Date: Thu, 18 Jul 2024 18:08:09 +0100
Subject: [PATCH] [flang][debug] Set scope of internal functions correctly.

The functions internal to subroutine should have the scope set to the
parent function. This allows to evaluate variable in parent when control
is stopped in the child.

Fixes #96314
---
 .../lib/Optimizer/Transforms/AddDebugInfo.cpp | 22 +++++++++++++++-
 flang/test/Transforms/debug-96314.fir         | 26 +++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 flang/test/Transforms/debug-96314.fir

diff --git a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
index 8bb24fb6c8078..7c9555dd737ab 100644
--- a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
+++ b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
@@ -299,9 +299,29 @@ void AddDebugInfoPass::runOnOperation() {
           subprogramFlags | mlir::LLVM::DISubprogramFlags::Definition;
     }
     unsigned line = getLineFromLoc(l);
-    if (!result.second.modules.empty())
+    if (fir::isInternalProcedure(funcOp)) {
+      // For contained functions, the scope is the parent subroutine.
+      mlir::SymbolRefAttr sym = mlir::cast<mlir::SymbolRefAttr>(
+          funcOp->getAttr(fir::getHostSymbolAttrName()));
+      if (sym) {
+        if (auto func = symbolTable.lookup<mlir::func::FuncOp>(
+                sym.getLeafReference())) {
+          // FIXME: Can there be situation where we process contained function
+          // before the parent?
+          if (debugInfoIsAlreadySet(func.getLoc())) {
+            if (auto fusedLoc = mlir::cast<mlir::FusedLoc>(func.getLoc())) {
+              if (auto spAttr =
+                      mlir::dyn_cast_if_present<mlir::LLVM::DISubprogramAttr>(
+                          fusedLoc.getMetadata()))
+                Scope = spAttr;
+            }
+          }
+        }
+      }
+    } else if (!result.second.modules.empty()) {
       Scope = getOrCreateModuleAttr(result.second.modules[0], fileAttr, cuAttr,
                                     line - 1, false);
+    }
 
     auto spAttr = mlir::LLVM::DISubprogramAttr::get(
         context, id, compilationUnit, Scope, funcName, fullName, funcFileAttr,
diff --git a/flang/test/Transforms/debug-96314.fir b/flang/test/Transforms/debug-96314.fir
new file mode 100644
index 0000000000000..e2d0f24a1105c
--- /dev/null
+++ b/flang/test/Transforms/debug-96314.fir
@@ -0,0 +1,26 @@
+// RUN: fir-opt --add-debug-info --mlir-print-debuginfo %s -o - | FileCheck %s
+
+module attributes {dlti.dl_spec = #dlti.dl_spec<>} {
+  func.func @_QMhelperPmod_sub(%arg0: !fir.ref<i32> {fir.bindc_name = "a"} ) {
+    return
+  } loc(#loc1)
+  func.func private @_QMhelperFmod_subPchild1(%arg0: !fir.ref<i32> {fir.bindc_name = "b"} ) attributes {fir.host_symbol = @_QMhelperPmod_sub, llvm.linkage = #llvm.linkage<internal>} {
+    return
+  } loc(#loc2)
+  func.func @global_sub_(%arg0: !fir.ref<i32> {fir.bindc_name = "n"} ) attributes {fir.internal_name = "_QPglobal_sub"} {
+    return
+  } loc(#loc3)
+  func.func private @_QFglobal_subPchild2(%arg0: !fir.ref<i32> {fir.bindc_name = "c"}) attributes {fir.host_symbol = @global_sub_, llvm.linkage = #llvm.linkage<internal>} {
+    return
+  } loc(#loc4)
+}
+
+#loc1 = loc("test.f90":5:1)
+#loc2 = loc("test.f90":15:1)
+#loc3 = loc("test.f90":25:1)
+#loc4 = loc("test.f90":35:1)
+
+// CHECK-DAG: #[[SP1:.*]] = #llvm.di_subprogram<{{.*}}name = "mod_sub"{{.*}}>
+// CHECK-DAG: #llvm.di_subprogram<{{.*}}scope = #[[SP1]], name = "child1"{{.*}}>
+// CHECK-DAG: #[[SP2:.*]] = #llvm.di_subprogram<{{.*}}linkageName = "global_sub_"{{.*}}>
+// CHECK-DAG: #llvm.di_subprogram<{{.*}}scope = #[[SP2]], name = "child2"{{.*}}>