[flang-commits] [flang] f7420a9 - [flang][debug] Fix issue with argument numbering. (#120726)

[via flang-commits]

Author: Abid Qadeer
Date: 2025-01-03T19:41:48Z
New Revision: f7420a9dff6d09715042b60c9e26a40a1b2a3147

URL: https://github.com/llvm/llvm-project/commit/f7420a9dff6d09715042b60c9e26a40a1b2a3147
DIFF: https://github.com/llvm/llvm-project/commit/f7420a9dff6d09715042b60c9e26a40a1b2a3147.diff

LOG: [flang][debug] Fix issue with argument numbering. (#120726)

Currently fir::isDummyArgument is being used to check if a DeclareOp
represents a dummy argument. The argument passed to the function is
declOp.getMemref(). This bypasses the code in isDummyArgument that
checks for dummy_scope because the `Value` returned by the getMemref()
may not have DeclareOp as its defining op.

This bypassing mean that sometime a variable will be marked as argument
when it should not. This happened in this case where same arg was being
used for 2 different result variables with use of `entry` in the
function.

The solution is to check directly if the declOp has a dummy_scope. If
yes, we know this is dummy argument. We can now check if the memref
points to the BlockArgument and use its number. This will still miss
arguments where memref does not directly point to a BlockArgument but
that is missed currently too. Note that we can still evaluate those
variable in debugger. It is just that they are not marked as arguments.

Fixes #116525.

Added: 
    flang/test/Integration/debug-116525.f90

Modified: 
    flang/lib/Optimizer/Transforms/AddDebugInfo.cpp

Removed: 
    


################################################################################
diff  --git a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
index 3a437c7a0f0137..a8e9d198ccb97c 100644
--- a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
+++ b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
@@ -121,9 +121,9 @@ void AddDebugInfoPass::handleDeclareOp(fir::cg::XDeclareOp declOp,
   // constant attribute of [hl]fir.declare/fircg.ext_declare operation that has
   // a dummy_scope operand).
   unsigned argNo = 0;
-  if (fir::isDummyArgument(declOp.getMemref())) {
-    auto arg = llvm::cast<mlir::BlockArgument>(declOp.getMemref());
-    argNo = arg.getArgNumber() + 1;
+  if (declOp.getDummyScope()) {
+    if (auto arg = llvm::dyn_cast<mlir::BlockArgument>(declOp.getMemref()))
+      argNo = arg.getArgNumber() + 1;
   }
 
   auto tyAttr = typeGen.convertType(fir::unwrapRefType(declOp.getType()),

diff  --git a/flang/test/Integration/debug-116525.f90 b/flang/test/Integration/debug-116525.f90
new file mode 100644
index 00000000000000..1916a34df4c12c
--- /dev/null
+++ b/flang/test/Integration/debug-116525.f90
@@ -0,0 +1,12 @@
+! RUN: %flang_fc1 -fopenmp -emit-llvm -debug-info-kind=standalone %s -o -
+
+! Test that this does not cause build failure.
+function s(x)
+    character(len=2) :: x, s, ss
+
+    s = x
+
+    entry ss()
+
+end function s
+