[flang-commits] [flang] [mlir] [flang] Add debug information for module variables. (PR #91582)

Abid Qadeer via flang-commits flang-commits at lists.llvm.org
Thu May 9 03:57:58 PDT 2024


https://github.com/abidh created https://github.com/llvm/llvm-project/pull/91582

This PR add debug info for module variables. The module variables are added as global variables but their scope is set to module instead of compile unit. The scope of function declared inside a module is also set accordingly.

After this patch, a module variable could be evaluated in the GDB as `p helper::gli` where helper is name of the module and gli is the name of the variable. A future patch will add the import module functionality which will remove the need to prefix the name with helper::.

The line number where is module is declared is a best guess at the moment as this information is not part of the GlobalOp.

>From 94682e62a4f29f6c094944a8f06196ebb2d7b3b3 Mon Sep 17 00:00:00 2001
From: Abid Qadeer <haqadeer at amd.com>
Date: Fri, 26 Apr 2024 16:21:36 +0100
Subject: [PATCH] [flang] Add initial implementation of module variables.

This PR add supports for module variables and function. The module
variables are added as global variables but their scope is set to
module instead of compile unit. The scope of function declared inside
a module is also set accordingly.

After this patch, a module variable could be evaluated in the GDB as
`p helper::gli` where helper is name of the module and gli is the name
of the variable. A future patch will add the import module functionality
which will remove the need to prefix the name with helper::.

The line number where is module is declared is a best guess at the
moment as this information is not part of the GlobalOp.
---
 flang/lib/Optimizer/CodeGen/CodeGen.cpp       | 17 +++-
 .../lib/Optimizer/Transforms/AddDebugInfo.cpp | 96 ++++++++++++++++++-
 flang/test/Transforms/debug-module-1.f90      | 39 ++++++++
 flang/test/Transforms/debug-module-2.f90      | 37 +++++++
 mlir/lib/Target/LLVMIR/ModuleTranslation.cpp  |  9 +-
 5 files changed, 190 insertions(+), 8 deletions(-)
 create mode 100644 flang/test/Transforms/debug-module-1.f90
 create mode 100644 flang/test/Transforms/debug-module-2.f90

diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
index b4705aa479925..4618643f22479 100644
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -2694,6 +2694,18 @@ struct GlobalOpConversion : public fir::FIROpConversion<fir::GlobalOp> {
   mlir::LogicalResult
   matchAndRewrite(fir::GlobalOp global, OpAdaptor adaptor,
                   mlir::ConversionPatternRewriter &rewriter) const override {
+
+    mlir::LLVM::DIGlobalVariableExpressionAttr dbgExpr;
+
+    if (auto fusedLoc = mlir::dyn_cast<mlir::FusedLoc>(global.getLoc())) {
+      if (auto gvAttr =
+              mlir::dyn_cast_or_null<mlir::LLVM::DIGlobalVariableAttr>(
+                  fusedLoc.getMetadata())) {
+        dbgExpr = mlir::LLVM::DIGlobalVariableExpressionAttr::get(
+            global.getContext(), gvAttr, mlir::LLVM::DIExpressionAttr());
+      }
+    }
+
     auto tyAttr = convertType(global.getType());
     if (auto boxType = mlir::dyn_cast<fir::BaseBoxType>(global.getType()))
       tyAttr = this->lowerTy().convertBoxTypeAsStruct(boxType);
@@ -2702,8 +2714,11 @@ struct GlobalOpConversion : public fir::FIROpConversion<fir::GlobalOp> {
     assert(attributeTypeIsCompatible(global.getContext(), initAttr, tyAttr));
     auto linkage = convertLinkage(global.getLinkName());
     auto isConst = global.getConstant().has_value();
+    mlir::SymbolRefAttr comdat;
+    llvm::ArrayRef<mlir::NamedAttribute> attrs;
     auto g = rewriter.create<mlir::LLVM::GlobalOp>(
-        loc, tyAttr, isConst, linkage, global.getSymName(), initAttr);
+        loc, tyAttr, isConst, linkage, global.getSymName(), initAttr, 0, 0,
+        false, false, comdat, attrs, dbgExpr);
 
     auto module = global->getParentOfType<mlir::ModuleOp>();
     // Add comdat if necessary
diff --git a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
index 908c8fc96f633..0a1acb8b39372 100644
--- a/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
+++ b/flang/lib/Optimizer/Transforms/AddDebugInfo.cpp
@@ -34,6 +34,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include <map>
 
 namespace fir {
 #define GEN_PASS_DEF_ADDDEBUGINFO
@@ -48,10 +49,87 @@ class AddDebugInfoPass : public fir::impl::AddDebugInfoBase<AddDebugInfoPass> {
 public:
   AddDebugInfoPass(fir::AddDebugInfoOptions options) : Base(options) {}
   void runOnOperation() override;
+
+private:
+  std::map<std::string, mlir::LLVM::DIModuleAttr> moduleMap;
+
+  mlir::LLVM::DIModuleAttr getOrCreateModuleAttr(
+      const std::string &name, mlir::LLVM::DIFileAttr fileAttr,
+      mlir::LLVM::DIScopeAttr scope, unsigned line, bool decl);
+
+  void handleGlobalOp(fir::GlobalOp glocalOp, mlir::LLVM::DIFileAttr fileAttr,
+                      mlir::LLVM::DIScopeAttr scope);
 };
 
+static uint32_t getLineFromLoc(mlir::Location loc) {
+  uint32_t line = 1;
+  if (auto fileLoc = mlir::dyn_cast<mlir::FileLineColLoc>(loc))
+    line = fileLoc.getLine();
+  return line;
+}
+
 } // namespace
 
+// The `module` does not have a first class representation in the `FIR`. We
+// extract information about it from the name of the identifiers and keep a
+// map to avoid duplication.
+mlir::LLVM::DIModuleAttr AddDebugInfoPass::getOrCreateModuleAttr(
+    const std::string &name, mlir::LLVM::DIFileAttr fileAttr,
+    mlir::LLVM::DIScopeAttr scope, unsigned line, bool decl) {
+  mlir::MLIRContext *context = &getContext();
+  mlir::LLVM::DIModuleAttr modAttr;
+  if (auto iter{moduleMap.find(name)}; iter != moduleMap.end())
+    modAttr = iter->second;
+  else {
+    modAttr = mlir::LLVM::DIModuleAttr::get(
+        context, fileAttr, scope, mlir::StringAttr::get(context, name),
+        mlir::StringAttr(), mlir::StringAttr(), mlir::StringAttr(), line, decl);
+    moduleMap[name] = modAttr;
+  }
+  return modAttr;
+}
+
+void AddDebugInfoPass::handleGlobalOp(fir::GlobalOp globalOp,
+                                      mlir::LLVM::DIFileAttr fileAttr,
+                                      mlir::LLVM::DIScopeAttr scope) {
+  mlir::ModuleOp module = getOperation();
+  mlir::MLIRContext *context = &getContext();
+  fir::DebugTypeGenerator typeGen(module);
+  mlir::OpBuilder builder(context);
+
+  auto result = fir::NameUniquer::deconstruct(globalOp.getSymName());
+  if (result.first != fir::NameUniquer::NameKind::VARIABLE)
+    return;
+
+  unsigned line = getLineFromLoc(globalOp.getLoc());
+
+  // DWARF5 says following about the fortran modules:
+  // A Fortran 90 module may also be represented by a module entry
+  // (but no declaration attribute is warranted because Fortran has no concept
+  // of a corresponding module body).
+  // But in practice, compilers use declaration attribute with a module in cases
+  // where module was defined in another source file (only being used in this
+  // one). The hasInitializationBody() seems to provide the right information
+  // but inverted. It is true where module is actually defined but false where
+  // it is used.
+  // FIXME: Currently we don't have the line number on which a module was
+  // declared. We are using a best guess of line - 1 where line is the source
+  // line of the first member of the module that we encounter.
+
+  if (!result.second.modules.empty())
+    scope = getOrCreateModuleAttr(result.second.modules[0], fileAttr, scope,
+                                  line - 1, !globalOp.hasInitializationBody());
+
+  auto diType = typeGen.convertType(globalOp.getType(), fileAttr, scope,
+                                    globalOp.getLoc());
+  auto gvAttr = mlir::LLVM::DIGlobalVariableAttr::get(
+      context, scope, mlir::StringAttr::get(context, result.second.name),
+      mlir::StringAttr::get(context, globalOp.getName()), fileAttr, line,
+      diType, /*isLocalToUnit*/ false,
+      /*isDefinition*/ globalOp.hasInitializationBody(), /* alignInBits*/ 0);
+  globalOp->setLoc(builder.getFusedLoc({globalOp->getLoc()}, gvAttr));
+}
+
 void AddDebugInfoPass::runOnOperation() {
   mlir::ModuleOp module = getOperation();
   mlir::MLIRContext *context = &getContext();
@@ -91,6 +169,10 @@ void AddDebugInfoPass::runOnOperation() {
       llvm::dwarf::getLanguage("DW_LANG_Fortran95"), fileAttr, producer,
       isOptimized, debugLevel);
 
+  module.walk([&](fir::GlobalOp globalOp) {
+    handleGlobalOp(globalOp, fileAttr, cuAttr);
+  });
+
   module.walk([&](mlir::func::FuncOp funcOp) {
     mlir::Location l = funcOp->getLoc();
     // If fused location has already been created then nothing to do
@@ -131,8 +213,12 @@ void AddDebugInfoPass::runOnOperation() {
     mlir::LLVM::DIFileAttr funcFileAttr =
         mlir::LLVM::DIFileAttr::get(context, fileName, filePath);
 
+    unsigned line = 1;
+    if (auto funcLoc = mlir::dyn_cast<mlir::FileLineColLoc>(l))
+      line = funcLoc.getLine();
     // Only definitions need a distinct identifier and a compilation unit.
     mlir::DistinctAttr id;
+    mlir::LLVM::DIScopeAttr Scope = fileAttr;
     mlir::LLVM::DICompileUnitAttr compilationUnit;
     mlir::LLVM::DISubprogramFlags subprogramFlags =
         mlir::LLVM::DISubprogramFlags{};
@@ -144,13 +230,13 @@ void AddDebugInfoPass::runOnOperation() {
       subprogramFlags =
           subprogramFlags | mlir::LLVM::DISubprogramFlags::Definition;
     }
-    unsigned line = 1;
-    if (auto funcLoc = mlir::dyn_cast<mlir::FileLineColLoc>(l))
-      line = funcLoc.getLine();
+    if (!result.second.modules.empty())
+      Scope = getOrCreateModuleAttr(result.second.modules[0], fileAttr, cuAttr,
+                                    line - 1, false);
 
     auto spAttr = mlir::LLVM::DISubprogramAttr::get(
-        context, id, compilationUnit, fileAttr, funcName, fullName,
-        funcFileAttr, line, line, subprogramFlags, subTypeAttr);
+        context, id, compilationUnit, Scope, funcName, fullName, funcFileAttr,
+        line, line, subprogramFlags, subTypeAttr);
     funcOp->setLoc(builder.getFusedLoc({funcOp->getLoc()}, spAttr));
   });
 }
diff --git a/flang/test/Transforms/debug-module-1.f90 b/flang/test/Transforms/debug-module-1.f90
new file mode 100644
index 0000000000000..2321c7093f422
--- /dev/null
+++ b/flang/test/Transforms/debug-module-1.f90
@@ -0,0 +1,39 @@
+! RUN: %flang_fc1 -emit-fir -debug-info-kind=standalone -mmlir --mlir-print-debuginfo %s -o - | \
+! RUN: fir-opt --cg-rewrite --mlir-print-debuginfo | fir-opt --add-debug-info --mlir-print-debuginfo | FileCheck %s
+
+! CHECK-DAG: #[[I4:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "integer", sizeInBits = 32, encoding = DW_ATE_signed>
+! CHECK-DAG: #[[R4:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "real", sizeInBits = 32, encoding = DW_ATE_float>
+! CHECK-DAG: #[[FILE:.*]] = #llvm.di_file<"debug-module-1.f90" {{.*}}>
+! CHECK-DAG: #[[CU:.*]] = #llvm.di_compile_unit<{{.*}}, file = #[[FILE]], {{.*}}>
+! CHECK-DAG: #[[MOD:.*]] = #llvm.di_module<file = #[[FILE]], scope = #[[CU]], name = "helper", {{.*}}>
+module helper
+! CHECK-DAG: #[[LOC1:.*]] = loc("{{.*}}debug-module-1.f90":[[@LINE+2]]{{.*}})
+! CHECK-DAG: #[[GLR:.*]] = #llvm.di_global_variable<scope = #[[MOD]], name = "glr", linkageName = "_QMhelperEglr", file = #[[FILE]], line = [[@LINE+1]], type = #[[R4]], isDefined = true>
+  real glr
+! CHECK-DAG: #[[LOC2:.*]] = loc("{{.*}}debug-module-1.f90":[[@LINE+2]]{{.*}})
+! CHECK-DAG: #[[GLI:.*]] = #llvm.di_global_variable<scope = #[[MOD]], name = "gli", linkageName = "_QMhelperEgli", file = #[[FILE]], line = [[@LINE+1]], type = #[[I4]], isDefined = true>
+  integer gli
+
+  contains
+! CHECK-DAG: #[[LOC3:.*]] = loc("{{.*}}debug-module-1.f90":[[@LINE+2]]{{.*}})
+! CHECK-DAG: #[[TEST:.*]] = #llvm.di_subprogram<{{.*}}compileUnit = #[[CU]], scope = #[[MOD]], name = "test", linkageName = "_QMhelperPtest", file = #[[FILE]], line = [[@LINE+1]], scopeLine = [[@LINE+1]]{{.*}}>
+    subroutine test()
+    glr = 12.34
+    gli = 67
+
+    end subroutine
+end module helper
+
+program test
+use helper
+implicit none
+
+  glr = 3.14
+  gli = 2
+  call test()
+
+end program test
+
+! CHECK-DAG: loc(fused<#[[GLR]]>[#[[LOC1]]])
+! CHECK-DAG: loc(fused<#[[GLI]]>[#[[LOC2]]])
+! CHECK-DAG: loc(fused<#[[TEST]]>[#[[LOC3]]])
\ No newline at end of file
diff --git a/flang/test/Transforms/debug-module-2.f90 b/flang/test/Transforms/debug-module-2.f90
new file mode 100644
index 0000000000000..9f6bba3ef0470
--- /dev/null
+++ b/flang/test/Transforms/debug-module-2.f90
@@ -0,0 +1,37 @@
+! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o - | FileCheck %s
+
+! CHECK-DAG: ![[FILE:.*]] = !DIFile(filename: {{.*}}debug-module-2.f90{{.*}})
+! CHECK-DAG: ![[FILE2:.*]] = !DIFile(filename: {{.*}}debug-module-2.f90{{.*}})
+! CHECK-DAG: ![[CU:.*]] = distinct !DICompileUnit({{.*}}file: ![[FILE]]{{.*}} globals: ![[GLOBALS:.*]])
+! CHECK-DAG: ![[MOD:.*]] = !DIModule(scope: ![[CU]], name: "helper", file: ![[FILE]]{{.*}})
+! CHECK-DAG: ![[R4:.*]] = !DIBasicType(name: "real", size: 32, encoding: DW_ATE_float)
+! CHECK-DAG: ![[I4:.*]] = !DIBasicType(name: "integer", size: 32, encoding: DW_ATE_signed)
+module helper
+! CHECK-DAG: ![[GLR:.*]] = distinct !DIGlobalVariable(name: "glr", linkageName: "_QMhelperEglr", scope: ![[MOD]], file: ![[FILE]], line: [[@LINE+2]], type: ![[R4]], isLocal: false, isDefinition: true)
+! CHECK-DAG: ![[GLRX:.*]] = !DIGlobalVariableExpression(var: ![[GLR]], expr: !DIExpression())
+  real glr
+
+! CHECK-DAG: ![[GLI:.*]] = distinct !DIGlobalVariable(name: "gli", linkageName: "_QMhelperEgli", scope: ![[MOD]], file: ![[FILE]], line: [[@LINE+2]], type: ![[I4]], isLocal: false, isDefinition: true)
+! CHECK-DAG: ![[GLIX:.*]] = !DIGlobalVariableExpression(var: ![[GLI]], expr: !DIExpression())
+  integer gli
+
+  contains
+!CHECK-DAG: !DISubprogram(name: "test", linkageName: "_QMhelperPtest", scope: ![[MOD]], file: ![[FILE2]], line: [[@LINE+1]]{{.*}}unit: ![[CU]])
+    subroutine test()
+    glr = 12.34
+    gli = 67
+
+    end subroutine
+end module helper
+
+program test
+use helper
+implicit none
+
+  glr = 3.14
+  gli = 2
+  call test()
+
+end program test
+
+! CHECK-DAG: ![[GLOBALS]] = !{![[GLIX]], ![[GLRX]]}
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 669b95a9c6a5b..4f4a3ea046241 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -1030,10 +1030,15 @@ LogicalResult ModuleTranslation::convertGlobals() {
       llvm::DIGlobalVariable *diGlobalVar = diGlobalExpr->getVariable();
       var->addDebugInfo(diGlobalExpr);
 
+      // For fortran, the scope hierarchy can be
+      // variable -> module -> 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);



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