[flang-commits] [flang] 95b4128 - [flang][debug] Don't generate debug for compiler-generated variables (#112423)

[via flang-commits]

Author: Abid Qadeer
Date: 2024-10-21T11:27:34+01:00
New Revision: 95b4128c6a87e9b894aa75524e63be147cca790b

URL: https://github.com/llvm/llvm-project/commit/95b4128c6a87e9b894aa75524e63be147cca790b
DIFF: https://github.com/llvm/llvm-project/commit/95b4128c6a87e9b894aa75524e63be147cca790b.diff

LOG: [flang][debug] Don't generate debug for compiler-generated variables (#112423)

Flang generates many globals to handle derived types. There was a check
in debug info to filter them based on the information that their names
start with a period. This changed since PR#104859 where 'X' is being
used instead of '.'.

This PR fixes this issue by also adding 'X' in that list. As user
variables gets lower cased by the NameUniquer, there is no risk that
those will be filtered out. I added a test for that to be sure.

Added: 
    flang/test/Integration/debug-extra-global-2.f90
    flang/test/Integration/debug-extra-global.f90
    flang/test/Transforms/debug-extra-global.fir

Modified: 
    flang/include/flang/Optimizer/Support/InternalNames.h
    flang/lib/Optimizer/Support/InternalNames.cpp
    flang/lib/Optimizer/Transforms/AddDebugInfo.cpp

Removed: 
    


################################################################################
diff  --git a/flang/include/flang/Optimizer/Support/InternalNames.h b/flang/include/flang/Optimizer/Support/InternalNames.h
index 67ab36cf8da7ff..41f2cb9842dc76 100644
--- a/flang/include/flang/Optimizer/Support/InternalNames.h
+++ b/flang/include/flang/Optimizer/Support/InternalNames.h
@@ -184,6 +184,10 @@ struct NameUniquer {
 
   static std::string replaceSpecialSymbols(const std::string &name);
 
+  /// Returns true if the passed name denotes a special symbol (e.g. global
+  /// symbol generated for derived type description).
+  static bool isSpecialSymbol(llvm::StringRef name);
+
 private:
   static std::string intAsString(std::int64_t i);
   static std::string doKind(std::int64_t kind);

diff  --git a/flang/lib/Optimizer/Support/InternalNames.cpp b/flang/lib/Optimizer/Support/InternalNames.cpp
index 58a5da5de79720..011021c9f0350f 100644
--- a/flang/lib/Optimizer/Support/InternalNames.cpp
+++ b/flang/lib/Optimizer/Support/InternalNames.cpp
@@ -411,3 +411,7 @@ fir::NameUniquer::dropTypeConversionMarkers(llvm::StringRef mangledTypeName) {
 std::string fir::NameUniquer::replaceSpecialSymbols(const std::string &name) {
   return std::regex_replace(name, std::regex{"\\."}, "X");
 }
+
+bool fir::NameUniquer::isSpecialSymbol(llvm::StringRef name) {
+  return !name.empty() && (name[0] == '.' || name[0] == 'X');
+}

diff  --git a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
index 400a8648dd7e07..3a437c7a0f0137 100644
--- a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
+++ b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
@@ -211,10 +211,7 @@ void AddDebugInfoPass::handleGlobalOp(fir::GlobalOp globalOp,
   if (result.first != fir::NameUniquer::NameKind::VARIABLE)
     return;
 
-  // Discard entries that describe a derived type. Usually start with '.c.',
-  // '.dt.' or '.n.'. It would be better if result of the deconstruct had a flag
-  // for such values so that we dont have to look at string values.
-  if (!result.second.name.empty() && result.second.name[0] == '.')
+  if (fir::NameUniquer::isSpecialSymbol(result.second.name))
     return;
 
   unsigned line = getLineFromLoc(globalOp.getLoc());

diff  --git a/flang/test/Integration/debug-extra-global-2.f90 b/flang/test/Integration/debug-extra-global-2.f90
new file mode 100644
index 00000000000000..59cb4b66def507
--- /dev/null
+++ b/flang/test/Integration/debug-extra-global-2.f90
@@ -0,0 +1,8 @@
+! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o - | FileCheck  %s
+
+module m
+  integer XcX
+end
+
+! Test that global starting with 'X' don't get filtered.
+! CHECK: !DIGlobalVariable(name: "xcx", linkageName: "_QMmExcx"{{.*}})

diff  --git a/flang/test/Integration/debug-extra-global.f90 b/flang/test/Integration/debug-extra-global.f90
new file mode 100644
index 00000000000000..c0ad2e306386da
--- /dev/null
+++ b/flang/test/Integration/debug-extra-global.f90
@@ -0,0 +1,14 @@
+! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o - | FileCheck  %s
+
+program test
+ type t1
+   integer :: XcX
+   integer :: xdtx
+ end type
+  type(t1) :: var
+  var%XcX = 2
+  var%xdtx = 3
+end
+
+! Test that there is no debug info for compiler generated globals.
+! CHECK-NOT: DIGlobalVariable

diff  --git a/flang/test/Transforms/debug-extra-global.fir b/flang/test/Transforms/debug-extra-global.fir
new file mode 100644
index 00000000000000..d3bc22ad0c59b0
--- /dev/null
+++ b/flang/test/Transforms/debug-extra-global.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<>} {
+  fir.global linkonce_odr @_QFEXnXxcx constant target : !fir.char<1,3> {
+    %0 = fir.string_lit "xcx"(3) : !fir.char<1,3>
+    fir.has_value %0 : !fir.char<1,3>
+  } loc(#loc1)
+  fir.global linkonce_odr @_QFEXnXxdtx constant target : !fir.char<1,4> {
+    %0 = fir.string_lit "xdtx"(4) : !fir.char<1,4>
+    fir.has_value %0 : !fir.char<1,4>
+  } loc(#loc1)
+}
+#loc1 = loc("derived.f90":24:1)
+
+// Test that no di_global_variable gets created for these compile generated
+// globals.
+
+// CHECK-NOT: #di_global_variable