[flang] Add debug information for module variables. (llvm#91582)

abidh · web-flow · commit f156b9ce7aae · 2024-05-22T10:59:29.000+01:00
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.
diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -2716,6 +2716,18 @@ 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);
@@ -2724,8 +2736,11 @@ 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
@@ -54,6 +54,16 @@ class AddDebugInfoPass : public fir::impl::AddDebugInfoBase<AddDebugInfoPass> {
 public:
   AddDebugInfoPass(fir::AddDebugInfoOptions options) : Base(options) {}
   void runOnOperation() override;
+
+private:
+  llvm::StringMap<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) {
@@ -99,6 +109,70 @@ void AddDebugInfoPass::handleDeclareOp(fir::cg::XDeclareOp declOp,
   declOp->setLoc(builder.getFusedLoc({declOp->getLoc()}, localVarAttr));
 }
 
+// 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->getValue();
+  } else {
+    modAttr = mlir::LLVM::DIModuleAttr::get(
+        context, fileAttr, scope, mlir::StringAttr::get(context, name),
+        /* configMacros */ mlir::StringAttr(),
+        /* includePath */ mlir::StringAttr(),
+        /* apinotes */ 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);
+
+  std::pair 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 isInitialized() 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())
+    return;
+
+  scope = getOrCreateModuleAttr(result.second.modules[0], fileAttr, scope,
+                                line - 1, !globalOp.isInitialized());
+
+  mlir::LLVM::DITypeAttr 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.isInitialized(), /* alignInBits*/ 0);
+  globalOp->setLoc(builder.getFusedLoc({globalOp->getLoc()}, gvAttr));
+}
+
 void AddDebugInfoPass::runOnOperation() {
   mlir::ModuleOp module = getOperation();
   mlir::MLIRContext *context = &getContext();
@@ -138,6 +212,12 @@ void AddDebugInfoPass::runOnOperation() {
       llvm::dwarf::getLanguage("DW_LANG_Fortran95"), fileAttr, producer,
       isOptimized, debugLevel);
 
+  if (debugLevel == mlir::LLVM::DIEmissionKind::Full) {
+    // Process 'GlobalOp' only if full debug info is requested.
+    for (auto globalOp : module.getOps<fir::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
@@ -180,6 +260,7 @@ void AddDebugInfoPass::runOnOperation() {
 
     // 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{};
@@ -192,9 +273,13 @@ void AddDebugInfoPass::runOnOperation() {
           subprogramFlags | mlir::LLVM::DISubprogramFlags::Definition;
     }
     unsigned line = getLineFromLoc(l);
+    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));
 
     // Don't process variables if user asked for line tables only.
diff --git a/flang/test/Integration/debug-module-2.f90 b/flang/test/Integration/debug-module-2.f90
@@ -0,0 +1,39 @@
+! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o - | FileCheck %s
+! RUN: %flang_fc1 -emit-llvm -debug-info-kind=line-tables-only %s -o - | FileCheck --check-prefix=LINEONLY %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]]}
+! LINEONLY-NOT: DIGlobalVariable
diff --git a/flang/test/Transforms/debug-module-1.fir b/flang/test/Transforms/debug-module-1.fir
@@ -0,0 +1,40 @@
+// RUN: fir-opt --add-debug-info --mlir-print-debuginfo %s | FileCheck %s
+
+
+module attributes {} {
+  fir.global @_QMhelperEgli : i32 {
+    %0 = fir.zero_bits i32
+    fir.has_value %0 : i32
+  } loc(#loc1)
+  fir.global @_QMhelperEglr : f32 {
+    %0 = fir.zero_bits f32
+    fir.has_value %0 : f32
+  } loc(#loc2)
+  func.func @_QMhelperPtest() {
+    %c67_i32 = arith.constant 67 : i32
+    %cst = arith.constant 1.234000e+01 : f32
+    %0 = fir.address_of(@_QMhelperEgli) : !fir.ref<i32>
+    %1 = fir.address_of(@_QMhelperEglr) : !fir.ref<f32>
+    fir.store %cst to %1 : !fir.ref<f32>
+    fir.store %c67_i32 to %0 : !fir.ref<i32>
+    return
+  } loc(#loc3)
+}
+#loc1 = loc("test.f90":12:11)
+#loc2 = loc("test.f90":15:8)
+#loc3 = loc("test.f90":20:5)
+
+// 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: #[[CU:.*]] = #llvm.di_compile_unit<{{.*}}>
+// CHECK-DAG: #[[MOD:.*]] = #llvm.di_module<{{.*}}scope = #[[CU]], name = "helper"{{.*}}>
+// CHECK-DAG: #[[LOC1:.*]] = loc("{{.*}}test.f90":12{{.*}})
+// CHECK-DAG: #[[GLI:.*]] = #llvm.di_global_variable<scope = #[[MOD]], name = "gli", linkageName = "_QMhelperEgli"{{.*}}line = 12, type = #[[I4]], isDefined = true>
+// CHECK-DAG: #[[LOC2:.*]] = loc("{{.*}}test.f90":15{{.*}})
+// CHECK-DAG: #[[GLR:.*]] = #llvm.di_global_variable<scope = #[[MOD]], name = "glr", linkageName = "_QMhelperEglr"{{.*}}line = 15, type = #[[R4]], isDefined = true>
+// CHECK-DAG: #[[LOC3:.*]] = loc("{{.*}}test.f90":20{{.*}})
+// CHECK-DAG: #[[TEST:.*]] = #llvm.di_subprogram<{{.*}}compileUnit = #[[CU]], scope = #[[MOD]], name = "test", linkageName = "_QMhelperPtest"{{.*}}line = 20, scopeLine = 20{{.*}}>
+// CHECK-DAG: loc(fused<#[[GLI]]>[#[[LOC1]]])
+// CHECK-DAG: loc(fused<#[[GLR]]>[#[[LOC2]]])
+// CHECK-DAG: loc(fused<#[[TEST]]>[#[[LOC3]]])
+
diff --git a/flang/test/Transforms/debug-module-2.fir b/flang/test/Transforms/debug-module-2.fir
@@ -0,0 +1,35 @@
+// RUN: fir-opt --fir-to-llvm-ir="target=x86_64-unknown-linux-gnu" --mlir-print-debuginfo %s | FileCheck %s
+
+module {
+  fir.global @_QMhelperEgli : i32 {
+    %0 = fir.zero_bits i32
+    fir.has_value %0 : i32
+  } loc(#loc3)
+  fir.global @_QMhelperEglr : f32 {
+    %0 = fir.zero_bits f32
+    fir.has_value %0 : f32
+  } loc(#loc4)
+}
+#di_basic_type = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "integer", sizeInBits = 32, encoding = DW_ATE_signed>
+#di_basic_type1 = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "real", sizeInBits = 32, encoding = DW_ATE_float>
+
+#di_file = #llvm.di_file<"test.f90" in "">
+#di_subroutine_type = #llvm.di_subroutine_type<callingConvention = DW_CC_normal>
+
+#di_compile_unit = #llvm.di_compile_unit<id = distinct[0]<>, sourceLanguage = DW_LANG_Fortran95, file = #di_file, producer = "flang version 19.0.0 (/home/haqadeer/work/llvm-project/flang 5d5c73cad421bdca6e43e1cc10704ff160f1a33e)", isOptimized = false, emissionKind = Full>
+#di_module = #llvm.di_module<file = #di_file, scope = #di_compile_unit, name = "helper", line = 11>
+#di_global_variable = #llvm.di_global_variable<scope = #di_module, name = "gli", linkageName = "_QMhelperEgli", file = #di_file, line = 12, type = #di_basic_type, isDefined = true>
+#di_global_variable1 = #llvm.di_global_variable<scope = #di_module, name = "glr", linkageName = "_QMhelperEglr", file = #di_file, line = 15, type = #di_basic_type1, isDefined = true>
+
+#loc1 = loc("test.f90":12:11)
+#loc2 = loc("test.f90":15:8)
+#loc3 = loc(fused<#di_global_variable>[#loc1])
+#loc4 = loc(fused<#di_global_variable1>[#loc2])
+
+
+// CHECK-DAG: #[[GLI:.*]] = #llvm.di_global_variable<{{.*}}name = "gli", linkageName = "_QMhelperEgli"{{.*}}>
+// CHECK-DAG: #[[GLR:.*]] = #llvm.di_global_variable<{{.*}}name = "glr", linkageName = "_QMhelperEglr"{{.*}}>
+// CHECK-DAG: #[[GLIE:.*]] = #llvm.di_global_variable_expression<var = #[[GLI]]>
+// CHECK-DAG: #[[GLRE:.*]] = #llvm.di_global_variable_expression<var = #[[GLR]]>
+// CHECK-DAG: llvm.mlir.global{{.*}}@_QMhelperEgli() {{{.*}}dbg_expr = #[[GLIE]]}
+// CHECK-DAG: llvm.mlir.global{{.*}}@_QMhelperEglr() {{{.*}}dbg_expr = #[[GLRE]]}
