[flang][debug] Don't generate debug info for compiler-generated variables.

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 '.'. 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.

Author: abidh

flang/lib/Optimizer/Transforms/AddDebugInfo.cpp

@@ -211,10 +211,13 @@ 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] == '.')
+  // Discard entries that describe a derived type. They start with either '.' or
+  // 'X'. We filter both of them out. Note that NameUniquer makes the name lower
+  // case so user variables should be safe. 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] == '.' || result.second.name[0] == 'X'))
     return;
 
   unsigned line = getLineFromLoc(globalOp.getLoc());

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

flang/test/Transforms/debug-derived-type-1.fir

@@ -8,15 +8,15 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<!llvm.ptr<272>, d
     %0 = fir.zero_bits !fir.type<_QMm_employeeTt_employee{t_person:!fir.type<_QMm_employeeTt_person{t_address:!fir.type<_QMm_employeeTt_address{house_number:i32}>,name:!fir.char<1,20>}>,hired_date:!fir.type<_QMm_employeeTt_date{year:i32,month:i32,day:i32}>,monthly_salary:f32}>
     fir.has_value %0 : !fir.type<_QMm_employeeTt_employee{t_person:!fir.type<_QMm_employeeTt_person{t_address:!fir.type<_QMm_employeeTt_address{house_number:i32}>,name:!fir.char<1,20>}>,hired_date:!fir.type<_QMm_employeeTt_date{year:i32,month:i32,day:i32}>,monthly_salary:f32}>
   } loc(#loc5)
-  fir.global @_QMt1Evar : !fir.type<_QMt1Tt_t1{age:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}> {
-    %0 = fir.zero_bits !fir.type<_QMt1Tt_t1{age:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}>
-    fir.has_value %0 : !fir.type<_QMt1Tt_t1{age:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}>
+  fir.global @_QMt1Evar : !fir.type<_QMt1Tt_t1{XcX:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}> {
+    %0 = fir.zero_bits !fir.type<_QMt1Tt_t1{XcX:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}>
+    fir.has_value %0 : !fir.type<_QMt1Tt_t1{XcX:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}>
   } loc(#loc6)
   fir.global @_QMtest_1Exyz : !fir.type<_QMtest_1Tsometype{m_array:!fir.array<3xi32>,m_vt1:!fir.box<!fir.heap<!fir.type<_QMtest_1Tt1{name:!fir.char<1,20>,height:f32}>>>,v2:i32,m_alloc:!fir.box<!fir.heap<!fir.array<?xi32>>>,v3:i32,m_first:!fir.box<!fir.heap<!fir.char<1,?>>>,v4:i32,m_p1:!fir.box<!fir.ptr<i32>>,v5:i32,m_p2:!fir.box<!fir.ptr<i32>>,v6:i32,m_p3:!fir.box<!fir.ptr<!fir.array<?xi32>>>,v7:i32}> {
     %0 = fir.zero_bits !fir.type<_QMtest_1Tsometype{m_array:!fir.array<3xi32>,m_vt1:!fir.box<!fir.heap<!fir.type<_QMtest_1Tt1{name:!fir.char<1,20>,height:f32}>>>,v2:i32,m_alloc:!fir.box<!fir.heap<!fir.array<?xi32>>>,v3:i32,m_first:!fir.box<!fir.heap<!fir.char<1,?>>>,v4:i32,m_p1:!fir.box<!fir.ptr<i32>>,v5:i32,m_p2:!fir.box<!fir.ptr<i32>>,v6:i32,m_p3:!fir.box<!fir.ptr<!fir.array<?xi32>>>,v7:i32}>
     fir.has_value %0 : !fir.type<_QMtest_1Tsometype{m_array:!fir.array<3xi32>,m_vt1:!fir.box<!fir.heap<!fir.type<_QMtest_1Tt1{name:!fir.char<1,20>,height:f32}>>>,v2:i32,m_alloc:!fir.box<!fir.heap<!fir.array<?xi32>>>,v3:i32,m_first:!fir.box<!fir.heap<!fir.char<1,?>>>,v4:i32,m_p1:!fir.box<!fir.ptr<i32>>,v5:i32,m_p2:!fir.box<!fir.ptr<i32>>,v6:i32,m_p3:!fir.box<!fir.ptr<!fir.array<?xi32>>>,v7:i32}>
   } loc(#loc12)
-  fir.type_info @_QMt1Tt_t1 noinit nodestroy nofinal : !fir.type<_QMt1Tt_t1{age:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}> loc(#loc7)
+  fir.type_info @_QMt1Tt_t1 noinit nodestroy nofinal : !fir.type<_QMt1Tt_t1{XcX:i32,points:!fir.array<3xcomplex<f32>>,cond:!fir.logical<1>,name:!fir.char<1,20>,ratio:f64}> loc(#loc7)
   fir.type_info @_QMm_employeeTt_address noinit nodestroy nofinal : !fir.type<_QMm_employeeTt_address{house_number:i32}> loc(#loc1)
   fir.type_info @_QMm_employeeTt_person noinit nodestroy nofinal extends !fir.type<_QMm_employeeTt_address{house_number:i32}> : !fir.type<_QMm_employeeTt_person{t_address:!fir.type<_QMm_employeeTt_address{house_number:i32}>,name:!fir.char<1,20>}> loc(#loc2)
   fir.type_info @_QMm_employeeTt_date noinit nodestroy nofinal : !fir.type<_QMm_employeeTt_date{year:i32,month:i32,day:i32}> loc(#loc3)
@@ -68,7 +68,7 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<!llvm.ptr<272>, d
 // CHECK-DAG: #[[ELME3:.*]] = #llvm.di_derived_type<tag = DW_TAG_member, name = "monthly_salary", baseType = #[[REAL4_TY]], sizeInBits = 32, alignInBits = 32, offsetInBits = 288>
 // CHECK-DAG: #[[EMP:.*]] = #llvm.di_composite_type<{{.*}}tag = DW_TAG_structure_type, name = "t_employee"{{.*}}line = 46, scope = #[[MOD]], sizeInBits = 320, elements = #[[ELME1]], #[[ELME2]], #[[ELME3]]>
 
-// CHECK-DAG: #[[ELM1:.*]] = #llvm.di_derived_type<tag = DW_TAG_member, name = "age", baseType = #[[INT_TY]], sizeInBits = 32, alignInBits = 32>
+// CHECK-DAG: #[[ELM1:.*]] = #llvm.di_derived_type<tag = DW_TAG_member, name = "XcX", baseType = #[[INT_TY]], sizeInBits = 32, alignInBits = 32>
 // CHECK-DAG: #[[ELM2:.*]] = #llvm.di_derived_type<tag = DW_TAG_member, name = "points", baseType = #[[CMX_ARR]], sizeInBits = 192, alignInBits = 32, offsetInBits = 32>
 // CHECK-DAG: #[[ELM3:.*]] = #llvm.di_derived_type<tag = DW_TAG_member, name = "cond", baseType = #[[LOG_TY]], sizeInBits = 8, alignInBits = 8, offsetInBits = 224>
 // CHECK-DAG: #[[ELM4:.*]] = #llvm.di_derived_type<tag = DW_TAG_member, name = "name", baseType = #[[STR_TY]], sizeInBits = 160, alignInBits = 8, offsetInBits = 232>

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