[flang][debug] Generate correct name for external function.

[abidh]

The ExternalNameConversion will add an _ at the end of the external functions. We extract the real function name to use in the debug info. The convention is to use the real name of function in the name field and mangled name with extra _ at the end in the linkageName field.

Fixes #92391.

[llvmbot]

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

Author: Abid Qadeer (abidh)

Changes

The ExternalNameConversion will add an _ at the end of the external functions. We extract the real function name to use in the debug info. The convention is to use the real name of function in the name field and mangled name with extra _ at the end in the linkageName field.

Fixes #92391.

---

Full diff: https://github.com/llvm/llvm-project/pull/99510.diff

2 Files Affected:

• (modified) flang/lib/Optimizer/Transforms/AddDebugInfo.cpp (+6-2)
• (added) flang/test/Transforms/debug-92391.fir (+18)

diff --git a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
index 8bb24fb6c8078..685a8645fa2fc 100644
--- a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
+++ b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
@@ -262,9 +262,13 @@ void AddDebugInfoPass::runOnOperation() {
 
     mlir::StringAttr fullName =
         mlir::StringAttr::get(context, funcOp.getName());
-    auto result = fir::NameUniquer::deconstruct(funcOp.getName());
+    mlir::Attribute attr = funcOp->getAttr(fir::getInternalFuncNameAttrName());
     mlir::StringAttr funcName =
-        mlir::StringAttr::get(context, result.second.name);
+        (attr) ? mlir::cast<mlir::StringAttr>(attr)
+               : mlir::StringAttr::get(context, funcOp.getName());
+
+    auto result = fir::NameUniquer::deconstruct(funcName);
+    funcName = mlir::StringAttr::get(context, result.second.name);
 
     llvm::SmallVector<mlir::LLVM::DITypeAttr> types;
     fir::DebugTypeGenerator typeGen(module);
diff --git a/flang/test/Transforms/debug-92391.fir b/flang/test/Transforms/debug-92391.fir
new file mode 100644
index 0000000000000..2d83be995a0f6
--- /dev/null
+++ b/flang/test/Transforms/debug-92391.fir
@@ -0,0 +1,18 @@
+// RUN: fir-opt --add-debug-info --mlir-print-debuginfo %s | FileCheck %s
+
+module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<i64, dense<64> : vector<2xi64>>, #dlti.dl_entry<!llvm.ptr<272>, dense<64> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<271>, dense<32> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<270>, dense<32> : vector<4xi64>>, #dlti.dl_entry<f128, dense<128> : vector<2xi64>>, #dlti.dl_entry<f80, dense<128> : vector<2xi64>>, #dlti.dl_entry<i128, dense<128> : vector<2xi64>>, #dlti.dl_entry<i8, dense<8> : vector<2xi64>>, #dlti.dl_entry<!llvm.ptr, dense<64> : vector<4xi64>>, #dlti.dl_entry<i1, dense<8> : vector<2xi64>>, #dlti.dl_entry<f16, dense<16> : vector<2xi64>>, #dlti.dl_entry<f64, dense<64> : vector<2xi64>>, #dlti.dl_entry<i32, dense<32> : vector<2xi64>>, #dlti.dl_entry<i16, dense<16> : vector<2xi64>>, #dlti.dl_entry<"dlti.stack_alignment", 128 : i64>, #dlti.dl_entry<"dlti.endianness", "little">>, fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", llvm.data_layout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"} {
+  func.func @my_square_(%arg0: !fir.ref<i32> {fir.bindc_name = "x"} ) -> i32 attributes {fir.internal_name = "_QPmy_square"} {
+    %0 = fir.undefined !fir.dscope
+    %1 = fir.alloca i32 {bindc_name = "my_square", uniq_name = "_QFmy_squareEmy_square"}
+    %2 = fircg.ext_declare %1 {uniq_name = "_QFmy_squareEmy_square"} : (!fir.ref<i32>) -> !fir.ref<i32>
+    %3 = fircg.ext_declare %arg0 dummy_scope %0 {uniq_name = "_QFmy_squareEx"} : (!fir.ref<i32>, !fir.dscope) -> !fir.ref<i32>
+    %4 = fir.load %3 : !fir.ref<i32>
+    %5 = arith.muli %4, %4 : i32
+    fir.store %5 to %2 : !fir.ref<i32>
+    %6 = fir.load %2 : !fir.ref<i32>
+    return %6 : i32
+  } loc(#loc1)
+}
+#loc1 = loc("92391.f90":15:1)
+
+// CHECK: #di_subprogram = #llvm.di_subprogram<{{.*}}name = "my_square", linkageName = "my_square_"{{.*}}>

[DavidSpickett]

I confirmed that this fixes placing breakpoints with gdb.

(lldb is still confused but given it lacks explicit fortran support, this is not surprising)

[jeanPerier]

LGTM, thanks

[tblah]

LGTM, thanks!