[Mlir-commits] [mlir] [mlir][flang] Improve handling of fortran module variables. (PR #91604)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-llvm

Author: Abid Qadeer (abidh)

<details>
<summary>Changes</summary>

Currently, only those global variables which are at compile unit scope are added to the 'globals' list of the DICompileUnit. This does not work for module variables of Fortran where hierarchy can be variable -> module -> compile unit.

To fix this, if a variable scope points to a module, we walk one level up and see if module is in the compile unit scope.

This was initially part of #<!-- -->91582 which adds debug information for Fortran module variables. @<!-- -->kiranchandramohan pointed out that MLIR changes should go in separate PRs.

---
Full diff: https://github.com/llvm/llvm-project/pull/91604.diff


2 Files Affected:

- (modified) mlir/lib/Target/LLVMIR/ModuleTranslation.cpp (+8-2) 
- (modified) mlir/test/Target/LLVMIR/llvmir-debug.mlir (+23) 


``````````diff
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 669b95a9c6a5b..717a32e4f980f 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -1029,11 +1029,17 @@ LogicalResult ModuleTranslation::convertGlobals() {
           debugTranslation->translateGlobalVariableExpression(op.getDbgExpr());
       llvm::DIGlobalVariable *diGlobalVar = diGlobalExpr->getVariable();
       var->addDebugInfo(diGlobalExpr);
+      // For fortran, the scope hierarchy can be
+      // variable -> module -> compile unit
+      // If a variable scope points to Module then we get its parent scope so
+      // that globals get added to the compile unit.
+      llvm::DIScope *scope = diGlobalVar->getScope();
+      if (llvm::DIModule *mod = dyn_cast_if_present<llvm::DIModule>(scope))
+        scope = mod->getScope();
 
       // Get the compile unit (scope) of the the global variable.
       if (llvm::DICompileUnit *compileUnit =
-              dyn_cast_if_present<llvm::DICompileUnit>(
-                  diGlobalVar->getScope())) {
+              dyn_cast_if_present<llvm::DICompileUnit>(scope)) {
         // Update the compile unit with this incoming global variable expression
         // during the finalizing step later.
         allGVars[compileUnit].push_back(diGlobalExpr);
diff --git a/mlir/test/Target/LLVMIR/llvmir-debug.mlir b/mlir/test/Target/LLVMIR/llvmir-debug.mlir
index 1f0fc969364ac..b561ac5968ccc 100644
--- a/mlir/test/Target/LLVMIR/llvmir-debug.mlir
+++ b/mlir/test/Target/LLVMIR/llvmir-debug.mlir
@@ -311,6 +311,29 @@ llvm.mlir.global external @global_with_expr_2() {addr_space = 0 : i32, dbg_expr
 
 // -----
 
+// CHECK: @module_global_1 = external global i64, !dbg {{.*}}
+// CHECK: @module_global_2 = external global i64, !dbg {{.*}}
+// CHECK: !llvm.module.flags = !{{{.*}}}
+// CHECK: !llvm.dbg.cu = !{{{.*}}}
+// CHECK-DAG: ![[FILE:.*]] = !DIFile(filename: "test.f90", directory: "existence")
+// CHECK-DAG: ![[TYPE:.*]] = !DIBasicType(name: "integer", size: 64, encoding: DW_ATE_signed)
+// CHECK-DAG: ![[SCOPE:.*]] = distinct !DICompileUnit(language: DW_LANG_Fortran95, file: ![[FILE]], producer: "MLIR", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: ![[GVALS:.*]])
+// CHECK-DAG: ![[SCOPE1:.*]] = !DIModule(scope: ![[SCOPE]], name: "module2", file: ![[FILE]], line: 120)
+// CHECK-DAG: ![[GVAR0:.*]] = distinct !DIGlobalVariable(name: "module_global_1", linkageName: "module_global_1", scope: ![[SCOPE1]], file: ![[FILE]], line: 121, type: ![[TYPE]], isLocal: false, isDefinition: true)
+// CHECK-DAG: ![[GVAR1:.*]] = distinct !DIGlobalVariable(name: "module_global_2", linkageName: "module_global_2", scope: ![[SCOPE1]], file: ![[FILE]], line: 122, type: ![[TYPE]], isLocal: false, isDefinition: true)
+// CHECK-DAG: ![[GEXPR0:.*]] = !DIGlobalVariableExpression(var: ![[GVAR0]], expr: !DIExpression())
+// CHECK-DAG: ![[GEXPR1:.*]] = !DIGlobalVariableExpression(var: ![[GVAR1]], expr: !DIExpression())
+// CHECK-DAG: ![[GVALS]] = !{![[GEXPR0]], ![[GEXPR1]]}
+
+#di_file = #llvm.di_file<"test.f90" in "existence">
+#di_compile_unit = #llvm.di_compile_unit<id = distinct[0]<>, sourceLanguage = DW_LANG_Fortran95, file = #di_file, producer = "MLIR", isOptimized = true, emissionKind = Full>
+#di_basic_type = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "integer", sizeInBits = 64, encoding = DW_ATE_signed>
+#di_module = #llvm.di_module<file = #di_file, scope = #di_compile_unit, name = "module2", configMacros = "", includePath = "", apinotes = "", line = 120, isDecl = false >
+llvm.mlir.global external @module_global_1() {dbg_expr = #llvm.di_global_variable_expression<var = <scope = #di_module, name = "module_global_1", linkageName = "module_global_1", file = #di_file, line = 121, type = #di_basic_type, isLocalToUnit = false, isDefined = true>, expr = <>>} : i64
+llvm.mlir.global external @module_global_2() {dbg_expr = #llvm.di_global_variable_expression<var = <scope = #di_module, name = "module_global_2", linkageName = "module_global_2", file = #di_file, line = 122, type = #di_basic_type, isLocalToUnit = false, isDefined = true>, expr = <>>} : i64
+
+// -----
+
 // Nameless and scopeless global constant.
 
 // CHECK-LABEL: @.str.1 = external constant [10 x i8]

``````````

</details>


https://github.com/llvm/llvm-project/pull/91604