[flang][debug] Improve check for global variable detection.

[abidh]

When a global variable is used in the OpenMP target region, it is passed as an argument to the function that implements target region. But the DeclareOp for this incarnation still have the original name of the variable. As some of our checks to decide if a variable is global or nor are based on the name, this can result in a local variable being treated as global. This PR hardens the check a bit. We now also check that memory ref is actually an AddrOfOp before looking at the name.

[llvmbot]

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

Author: Abid Qadeer (abidh)

Changes

When a global variable is used in the OpenMP target region, it is passed as an argument to the function that implements target region. But the DeclareOp for this incarnation still have the original name of the variable. As some of our checks to decide if a variable is global or nor are based on the name, this can result in a local variable being treated as global. This PR hardens the check a bit. We now also check that memory ref is actually an AddrOfOp before looking at the name.

---

Full diff: https://github.com/llvm/llvm-project/pull/118326.diff

1 Files Affected:

• (modified) flang/lib/Optimizer/Transforms/AddDebugInfo.cpp (+7-7)

diff --git a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
index 3a437c7a0f0137..db223e99b6c59c 100644
--- a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
+++ b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
@@ -102,15 +102,15 @@ void AddDebugInfoPass::handleDeclareOp(fir::cg::XDeclareOp declOp,
   if (result.first != fir::NameUniquer::NameKind::VARIABLE)
     return;
   // If this DeclareOp actually represents a global then treat it as such.
-  if (auto global = symbolTable->lookup<fir::GlobalOp>(declOp.getUniqName())) {
-    handleGlobalOp(global, fileAttr, scopeAttr, typeGen, symbolTable, declOp);
-    return;
+  mlir::Operation *defOp = declOp.getMemref().getDefiningOp();
+  if (defOp && llvm::isa<fir::AddrOfOp>(defOp)) {
+    if (auto global =
+            symbolTable->lookup<fir::GlobalOp>(declOp.getUniqName())) {
+      handleGlobalOp(global, fileAttr, scopeAttr, typeGen, symbolTable, declOp);
+      return;
+    }
   }
 
-  // Only accept local variables.
-  if (result.second.procs.empty())
-    return;
-
   // FIXME: There may be cases where an argument is processed a bit before
   // DeclareOp is generated. In that case, DeclareOp may point to an
   // intermediate op and not to BlockArgument.

[jeanPerier]

LGTM, I do not know much about debugging inside OpenMP contexts though.