[flang-commits] [flang] [flang][debug] Handle allocatable strings. (PR #95906)

[Abid Qadeer via flang-commits]

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@@ -205,16 +205,38 @@ mlir::LLVM::DITypeAttr DebugTypeGenerator::convertCharacterType(
   if (charTy.getFKind() != 1)
     encoding = llvm::dwarf::DW_ATE_UCS;
 
+  uint64_t sizeInBits = 0;
+  mlir::LLVM::DIExpressionAttr lenExpr = nullptr;
+  mlir::LLVM::DIExpressionAttr locExpr = nullptr;
+
+  if (allocatable) {
+    llvm::SmallVector<mlir::LLVM::DIExpressionElemAttr> ops;
+    auto addOp = [&](unsigned opc, llvm::ArrayRef<uint64_t> vals) {
+      ops.push_back(mlir::LLVM::DIExpressionElemAttr::get(context, opc, vals));
+    };
+    addOp(llvm::dwarf::DW_OP_push_object_address, {});
+    addOp(llvm::dwarf::DW_OP_plus_uconst, {lenOffset});
+    lenExpr = mlir::LLVM::DIExpressionAttr::get(context, ops);
+    ops.clear();
+
+    addOp(llvm::dwarf::DW_OP_push_object_address, {});
+    addOp(llvm::dwarf::DW_OP_deref, {});
+    locExpr = mlir::LLVM::DIExpressionAttr::get(context, ops);
+  } else if (charTy.hasConstantLen()) {
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abidh wrote:

When descriptor is in use, we have to use the dwarf expression approach even if the length is fixed. This is because the location of the array content is *(object_address). If we try to treat it as fixed size array here, the debugger will treat descriptor bytes as array contents.

https://github.com/llvm/llvm-project/pull/95906