reland "[DebugInfo] Support to emit debugInfo for extern variables"

Commit d77ae15 ("[DebugInfo] Support to emit debugInfo for extern variables") added deebugInfo for extern variables for BPF target. The commit is reverted by 891e25b as the committed tests using %clang instead of %clang_cc1 causing test failed in certain scenarios as reported by Reid Kleckner. This patch fixed the tests by using %clang_cc1. Differential Revision: https://reviews.llvm.org/D71818
draperlaboratory · Dec 23, 2019 · e3d8ee3 · e3d8ee3
1 parent fb53396
commit e3d8ee3
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Showing 20 changed files with 166 additions and 7 deletions.
diff --git a/clang/include/clang/AST/ASTConsumer.h b/clang/include/clang/AST/ASTConsumer.h
@@ -102,6 +102,11 @@ class ASTConsumer {
   /// modified by the introduction of an implicit zero initializer.
   virtual void CompleteTentativeDefinition(VarDecl *D) {}
 
+  /// CompleteExternalDeclaration - Callback invoked at the end of a translation
+  /// unit to notify the consumer that the given external declaration should be
+  /// completed.
+  virtual void CompleteExternalDeclaration(VarDecl *D) {}
+
   /// Callback invoked when an MSInheritanceAttr has been attached to a
   /// CXXRecordDecl.
   virtual void AssignInheritanceModel(CXXRecordDecl *RD) {}

diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h
@@ -1389,6 +1389,9 @@ class TargetInfo : public virtual TransferrableTargetInfo,
 
   virtual void setAuxTarget(const TargetInfo *Aux) {}
 
+  /// Whether target allows debuginfo types for decl only variables.
+  virtual bool allowDebugInfoForExternalVar() const { return false; }
+
 protected:
   /// Copy type and layout related info.
   void copyAuxTarget(const TargetInfo *Aux);

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
@@ -668,6 +668,9 @@ class Sema final {
   /// All the tentative definitions encountered in the TU.
   TentativeDefinitionsType TentativeDefinitions;
 
+  /// All the external declarations encoutered and used in the TU.
+  SmallVector<VarDecl *, 4> ExternalDeclarations;
+
   typedef LazyVector<const DeclaratorDecl *, ExternalSemaSource,
                      &ExternalSemaSource::ReadUnusedFileScopedDecls, 2, 2>
     UnusedFileScopedDeclsType;

diff --git a/clang/lib/Basic/Targets/BPF.h b/clang/lib/Basic/Targets/BPF.h
@@ -76,6 +76,8 @@ class LLVM_LIBRARY_VISIBILITY BPFTargetInfo : public TargetInfo {
     return None;
   }
 
+  bool allowDebugInfoForExternalVar() const override { return true; }
+
   CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
     switch (CC) {
     default:

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -4485,7 +4485,7 @@ void CGDebugInfo::EmitGlobalVariable(llvm::GlobalVariable *Var,
 
     GVE = DBuilder.createGlobalVariableExpression(
         DContext, DeclName, LinkageName, Unit, LineNo, getOrCreateType(T, Unit),
-        Var->hasLocalLinkage(),
+        Var->hasLocalLinkage(), true,
         Expr.empty() ? nullptr : DBuilder.createExpression(Expr),
         getOrCreateStaticDataMemberDeclarationOrNull(D), TemplateParameters,
         Align);
@@ -4588,10 +4588,29 @@ void CGDebugInfo::EmitGlobalVariable(const ValueDecl *VD, const APValue &Init) {
 
   GV.reset(DBuilder.createGlobalVariableExpression(
       DContext, Name, StringRef(), Unit, getLineNumber(VD->getLocation()), Ty,
-      true, InitExpr, getOrCreateStaticDataMemberDeclarationOrNull(VarD),
+      true, true, InitExpr, getOrCreateStaticDataMemberDeclarationOrNull(VarD),
       TemplateParameters, Align));
 }
 
+void CGDebugInfo::EmitExternalVariable(llvm::GlobalVariable *Var,
+                                       const VarDecl *D) {
+  assert(DebugKind >= codegenoptions::LimitedDebugInfo);
+  if (D->hasAttr<NoDebugAttr>())
+    return;
+
+  auto Align = getDeclAlignIfRequired(D, CGM.getContext());
+  llvm::DIFile *Unit = getOrCreateFile(D->getLocation());
+  StringRef Name = D->getName();
+  llvm::DIType *Ty = getOrCreateType(D->getType(), Unit);
+
+  llvm::DIScope *DContext = getDeclContextDescriptor(D);
+  llvm::DIGlobalVariableExpression *GVE =
+      DBuilder.createGlobalVariableExpression(
+          DContext, Name, StringRef(), Unit, getLineNumber(D->getLocation()),
+          Ty, false, false, nullptr, nullptr, nullptr, Align);
+  Var->addDebugInfo(GVE);
+}
+
 llvm::DIScope *CGDebugInfo::getCurrentContextDescriptor(const Decl *D) {
   if (!LexicalBlockStack.empty())
     return LexicalBlockStack.back();

diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
@@ -478,6 +478,9 @@ class CGDebugInfo {
   /// Emit a constant global variable's debug info.
   void EmitGlobalVariable(const ValueDecl *VD, const APValue &Init);
 
+  /// Emit information about an external variable.
+  void EmitExternalVariable(llvm::GlobalVariable *GV, const VarDecl *Decl);
+
   /// Emit C++ using directive.
   void EmitUsingDirective(const UsingDirectiveDecl &UD);
 

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -336,6 +336,10 @@ namespace clang {
       Gen->CompleteTentativeDefinition(D);
     }
 
+    void CompleteExternalDeclaration(VarDecl *D) override {
+      Gen->CompleteExternalDeclaration(D);
+    }
+
     void AssignInheritanceModel(CXXRecordDecl *RD) override {
       Gen->AssignInheritanceModel(RD);
     }

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3730,6 +3730,10 @@ void CodeGenModule::EmitTentativeDefinition(const VarDecl *D) {
   EmitGlobalVarDefinition(D);
 }
 
+void CodeGenModule::EmitExternalDeclaration(const VarDecl *D) {
+  EmitExternalVarDeclaration(D);
+}
+
 CharUnits CodeGenModule::GetTargetTypeStoreSize(llvm::Type *Ty) const {
   return Context.toCharUnitsFromBits(
       getDataLayout().getTypeStoreSizeInBits(Ty));
@@ -4113,6 +4117,19 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
       DI->EmitGlobalVariable(GV, D);
 }
 
+void CodeGenModule::EmitExternalVarDeclaration(const VarDecl *D) {
+  if (CGDebugInfo *DI = getModuleDebugInfo())
+    if (getCodeGenOpts().getDebugInfo() >= codegenoptions::LimitedDebugInfo) {
+      QualType ASTTy = D->getType();
+      llvm::Type *Ty = getTypes().ConvertTypeForMem(D->getType());
+      llvm::PointerType *PTy =
+          llvm::PointerType::get(Ty, getContext().getTargetAddressSpace(ASTTy));
+      llvm::Constant *GV = GetOrCreateLLVMGlobal(D->getName(), PTy, D);
+      DI->EmitExternalVariable(
+          cast<llvm::GlobalVariable>(GV->stripPointerCasts()), D);
+    }
+}
+
 static bool isVarDeclStrongDefinition(const ASTContext &Context,
                                       CodeGenModule &CGM, const VarDecl *D,
                                       bool NoCommon) {

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
@@ -1170,6 +1170,8 @@ class CodeGenModule : public CodeGenTypeCache {
 
   void EmitTentativeDefinition(const VarDecl *D);
 
+  void EmitExternalDeclaration(const VarDecl *D);
+
   void EmitVTable(CXXRecordDecl *Class);
 
   void RefreshTypeCacheForClass(const CXXRecordDecl *Class);
@@ -1405,6 +1407,7 @@ class CodeGenModule : public CodeGenTypeCache {
   void EmitMultiVersionFunctionDefinition(GlobalDecl GD, llvm::GlobalValue *GV);
 
   void EmitGlobalVarDefinition(const VarDecl *D, bool IsTentative = false);
+  void EmitExternalVarDeclaration(const VarDecl *D);
   void EmitAliasDefinition(GlobalDecl GD);
   void emitIFuncDefinition(GlobalDecl GD);
   void emitCPUDispatchDefinition(GlobalDecl GD);

diff --git a/clang/lib/CodeGen/ModuleBuilder.cpp b/clang/lib/CodeGen/ModuleBuilder.cpp
@@ -290,6 +290,10 @@ namespace {
       Builder->EmitTentativeDefinition(D);
     }
 
+    void CompleteExternalDeclaration(VarDecl *D) override {
+      Builder->EmitExternalDeclaration(D);
+    }
+
     void HandleVTable(CXXRecordDecl *RD) override {
       if (Diags.hasErrorOccurred())
         return;

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
@@ -1136,6 +1136,13 @@ void Sema::ActOnEndOfTranslationUnit() {
       Consumer.CompleteTentativeDefinition(VD);
   }
 
+  for (auto D : ExternalDeclarations) {
+    if (!D || D->isInvalidDecl() || D->getPreviousDecl() || !D->isUsed())
+      continue;
+
+    Consumer.CompleteExternalDeclaration(D);
+  }
+
   // If there were errors, disable 'unused' warnings since they will mostly be
   // noise. Don't warn for a use from a module: either we should warn on all
   // file-scope declarations in modules or not at all, but whether the

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
@@ -12220,6 +12220,10 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
         Diag(Var->getLocation(), diag::note_private_extern);
       }
 
+      if (Context.getTargetInfo().allowDebugInfoForExternalVar() &&
+          !Var->isInvalidDecl() && !getLangOpts().CPlusPlus)
+        ExternalDeclarations.push_back(Var);
+
       return;
 
     case VarDecl::TentativeDefinition:

diff --git a/clang/test/CodeGen/debug-info-extern-basic.c b/clang/test/CodeGen/debug-info-extern-basic.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -x c -debug-info-kind=limited -triple bpf-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+extern char ch;
+int test() {
+  return ch;
+}
+
+int test2() {
+  extern char ch2;
+  return ch2;
+}
+
+extern int (*foo)(int);
+int test3() {
+  return foo(0);
+}
+
+// CHECK: distinct !DIGlobalVariable(name: "ch",{{.*}} type: ![[CHART:[0-9]+]], isLocal: false, isDefinition: false
+// CHECK: distinct !DIGlobalVariable(name: "ch2",{{.*}} type: ![[CHART]], isLocal: false, isDefinition: false
+// CHECK: ![[CHART]] = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+
+// CHECK: distinct !DIGlobalVariable(name: "foo",{{.*}} type: ![[FUNC:[0-9]+]], isLocal: false, isDefinition: false)
+// CHECK: ![[FUNC]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[SUB:[0-9]+]], size: 64)
+// CHECK: ![[SUB]] = !DISubroutineType(types: ![[TYPES:[0-9]+]])
+// CHECK: ![[TYPES]] = !{![[BASET:[0-9]+]], ![[BASET]]}
+// CHECK: ![[BASET]] = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
diff --git a/clang/test/CodeGen/debug-info-extern-duplicate.c b/clang/test/CodeGen/debug-info-extern-duplicate.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -x c -debug-info-kind=limited -triple bpf-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+extern char ch;
+extern char ch;
+int test() {
+  return ch;
+}
+
+// CHECK: distinct !DIGlobalVariable(name: "ch",{{.*}} type: ![[T:[0-9]+]], isLocal: false, isDefinition: false
+// CHECK-NOT: distinct !DIGlobalVariable(name: "ch"
diff --git a/clang/test/CodeGen/debug-info-extern-multi.c b/clang/test/CodeGen/debug-info-extern-multi.c
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -x c -debug-info-kind=limited -triple bpf-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+extern char ch;
+int test() {
+  extern short sh;
+  return ch + sh;
+}
+
+extern char (*foo)(char);
+int test2() {
+  return foo(0) + ch;
+}
+
+// CHECK: distinct !DIGlobalVariable(name: "ch",{{.*}} type: ![[Tch:[0-9]+]], isLocal: false, isDefinition: false
+// CHECK: distinct !DIGlobalVariable(name: "sh",{{.*}} type: ![[Tsh:[0-9]+]], isLocal: false, isDefinition: false
+// CHECK: ![[Tsh]] = !DIBasicType(name: "short", size: 16, encoding: DW_ATE_signed)
+
+// CHECK: distinct !DIGlobalVariable(name: "foo",{{.*}} type: ![[Tptr:[0-9]+]], isLocal: false, isDefinition: false
+// ![[Tptr]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[Tsub:[0-9]+]], size: 64)
+// ![[Tsub]] = !DISubroutineType(types: ![[Tproto:[0-9]+]])
+// ![[Tproto]] = !{![[Tch]], ![[Tch]]}
+// CHECK: ![[Tch]] = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
diff --git a/clang/test/CodeGen/debug-info-extern-unused.c b/clang/test/CodeGen/debug-info-extern-unused.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -x c -debug-info-kind=limited -triple bpf-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+extern char ch;
+int test() {
+  return 0;
+}
+
+int test2() {
+  extern char ch2;
+  return 0;
+}
+
+extern int (*foo)(int);
+int test3() {
+  return 0;
+}
+
+int test4() {
+  extern int (*foo2)(int);
+  return 0;
+}
+
+// CHECK-NOT: distinct !DIGlobalVariable(name: "ch"
+// CHECK-NOT: distinct !DIGlobalVariable(name: "ch2"
+// CHECK-NOT: distinct !DIGlobalVariable(name: "foo"
+// CHECK-NOT: distinct !DIGlobalVariable(name: "foo2"
diff --git a/llvm/include/llvm/IR/DIBuilder.h b/llvm/include/llvm/IR/DIBuilder.h
@@ -583,7 +583,7 @@ namespace llvm {
     ///                    specified)
     DIGlobalVariableExpression *createGlobalVariableExpression(
         DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *File,
-        unsigned LineNo, DIType *Ty, bool isLocalToUnit,
+        unsigned LineNo, DIType *Ty, bool isLocalToUnit, bool isDefined = true,
         DIExpression *Expr = nullptr, MDNode *Decl = nullptr,
         MDTuple *templateParams = nullptr, uint32_t AlignInBits = 0);
 

diff --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp
@@ -640,13 +640,14 @@ static void checkGlobalVariableScope(DIScope *Context) {
 
 DIGlobalVariableExpression *DIBuilder::createGlobalVariableExpression(
     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *F,
-    unsigned LineNumber, DIType *Ty, bool isLocalToUnit, DIExpression *Expr,
+    unsigned LineNumber, DIType *Ty, bool isLocalToUnit,
+    bool isDefined, DIExpression *Expr,
     MDNode *Decl, MDTuple *templateParams, uint32_t AlignInBits) {
   checkGlobalVariableScope(Context);
 
   auto *GV = DIGlobalVariable::getDistinct(
       VMContext, cast_or_null<DIScope>(Context), Name, LinkageName, F,
-      LineNumber, Ty, isLocalToUnit, true, cast_or_null<DIDerivedType>(Decl),
+      LineNumber, Ty, isLocalToUnit, isDefined, cast_or_null<DIDerivedType>(Decl),
       templateParams, AlignInBits);
   if (!Expr)
     Expr = createExpression();

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
@@ -1289,7 +1289,7 @@ LLVMMetadataRef LLVMDIBuilderCreateGlobalVariableExpression(
   return wrap(unwrap(Builder)->createGlobalVariableExpression(
       unwrapDI<DIScope>(Scope), {Name, NameLen}, {Linkage, LinkLen},
       unwrapDI<DIFile>(File), LineNo, unwrapDI<DIType>(Ty), LocalToUnit,
-      unwrap<DIExpression>(Expr), unwrapDI<MDNode>(Decl),
+      true, unwrap<DIExpression>(Expr), unwrapDI<MDNode>(Decl),
       nullptr, AlignInBits));
 }
 

diff --git a/llvm/unittests/Transforms/Utils/CloningTest.cpp b/llvm/unittests/Transforms/Utils/CloningTest.cpp
@@ -764,7 +764,7 @@ class CloneModule : public ::testing::Test {
 
     DBuilder.createGlobalVariableExpression(
         Subprogram, "unattached", "unattached", File, 1,
-        DBuilder.createNullPtrType(), false, Expr);
+        DBuilder.createNullPtrType(), false, true, Expr);
 
     auto *Entry = BasicBlock::Create(C, "", F);
     IBuilder.SetInsertPoint(Entry);