r188576 - DebugInfo: Omit debug info for dynamic classes in TUs that do not have the vtable for that class

David Blaikie dblaikie at gmail.com
Fri Aug 16 13:46:50 PDT 2013


On Fri, Aug 16, 2013 at 1:40 PM, David Blaikie <dblaikie at gmail.com> wrote:
> Author: dblaikie
> Date: Fri Aug 16 15:40:29 2013
> New Revision: 188576
>
> URL: http://llvm.org/viewvc/llvm-project?rev=188576&view=rev
> Log:
> DebugInfo: Omit debug info for dynamic classes in TUs that do not have the vtable for that class

This hopefully addresses the major issue in PR7554.

>
> This reduces Clang's .dwo (fission debug info) size by 23% over
> Clang+LLVM.
>
> Modified:
>     cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
>     cfe/trunk/lib/CodeGen/CGDebugInfo.h
>     cfe/trunk/lib/CodeGen/CGVTables.cpp
>     cfe/trunk/test/CodeGenCXX/debug-info-class.cpp
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=188576&r1=188575&r2=188576&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Fri Aug 16 15:40:29 2013
> @@ -865,7 +865,7 @@ CollectRecordLambdaFields(const CXXRecor
>    }
>  }
>
> -/// CollectRecordStaticField - Helper for CollectRecordFields.
> +/// Helper for CollectRecordFields.
>  llvm::DIDerivedType
>  CGDebugInfo::CreateRecordStaticField(const VarDecl *Var,
>                                       llvm::DIType RecordTy) {
> @@ -951,7 +951,7 @@ void CGDebugInfo::CollectRecordFields(co
>      for (RecordDecl::decl_iterator I = record->decls_begin(),
>             E = record->decls_end(); I != E; ++I)
>        if (const VarDecl *V = dyn_cast<VarDecl>(*I))
> -        elements.push_back(CreateRecordStaticField(V, RecordTy));
> +        elements.push_back(getOrCreateStaticDataMemberDeclaration(V, RecordTy));
>        else if (FieldDecl *field = dyn_cast<FieldDecl>(*I)) {
>          CollectRecordNormalField(field, layout.getFieldOffset(fieldNo),
>                                   tunit, elements, RecordTy);
> @@ -1122,8 +1122,14 @@ CollectCXXMemberFunctions(const CXXRecor
>      if (D->isImplicit())
>        continue;
>
> -    if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D))
> -      EltTys.push_back(CreateCXXMemberFunction(Method, Unit, RecordTy));
> +    if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
> +      llvm::DenseMap<const FunctionDecl *, llvm::WeakVH>::iterator MI =
> +          SPCache.find(Method->getCanonicalDecl());
> +      if (MI == SPCache.end())
> +        EltTys.push_back(CreateCXXMemberFunction(Method, Unit, RecordTy));
> +      else
> +        EltTys.push_back(MI->second);
> +    }
>    }
>  }
>
> @@ -1408,10 +1414,18 @@ void CGDebugInfo::completeType(const Rec
>  }
>
>  void CGDebugInfo::completeRequiredType(const RecordDecl *RD) {
> +  if (const CXXRecordDecl *CXXDecl = dyn_cast<CXXRecordDecl>(RD))
> +    if (CXXDecl->isDynamicClass())
> +      return;
> +
>    QualType Ty = CGM.getContext().getRecordType(RD);
>    llvm::DIType T = getTypeOrNull(Ty);
> -  if (!T || !T.isForwardDecl())
> -    return;
> +  if (T && T.isForwardDecl())
> +    completeClassData(RD);
> +}
> +
> +void CGDebugInfo::completeClassData(const RecordDecl *RD) {
> +  QualType Ty = CGM.getContext().getRecordType(RD);
>    void* TyPtr = Ty.getAsOpaquePtr();
>    if (CompletedTypeCache.count(TyPtr))
>      return;
> @@ -1424,14 +1438,23 @@ void CGDebugInfo::completeRequiredType(c
>  /// CreateType - get structure or union type.
>  llvm::DIType CGDebugInfo::CreateType(const RecordType *Ty, bool Declaration) {
>    RecordDecl *RD = Ty->getDecl();
> +  const CXXRecordDecl *CXXDecl = dyn_cast<CXXRecordDecl>(RD);
>    // Limited debug info should only remove struct definitions that can
>    // safely be replaced by a forward declaration in the source code.
> -  if (DebugKind <= CodeGenOptions::LimitedDebugInfo && Declaration &&
> -      !RD->isCompleteDefinitionRequired() && CGM.getLangOpts().CPlusPlus) {
> +  if ((DebugKind <= CodeGenOptions::LimitedDebugInfo && Declaration &&
> +       !RD->isCompleteDefinitionRequired() && CGM.getLangOpts().CPlusPlus) ||
> +      (CXXDecl && CXXDecl->hasDefinition() && CXXDecl->isDynamicClass())) {
>      llvm::DIDescriptor FDContext =
>        getContextDescriptor(cast<Decl>(RD->getDeclContext()));
>      llvm::DIType RetTy = getOrCreateRecordFwdDecl(RD, FDContext);
> -    return RetTy;
> +    // FIXME: This is conservatively correct. If we return a non-forward decl
> +    // that's not a full definition (such as those created by
> +    // createContextChain) then getOrCreateType will record is as a complete
> +    // type and we'll never record all its members. But this means we're
> +    // emitting full debug info in TUs where GCC successfully emits a partial
> +    // definition of the type.
> +    if (RetTy.isForwardDecl())
> +      return RetTy;
>    }
>
>    return CreateTypeDefinition(Ty);
> @@ -1466,6 +1489,13 @@ llvm::DIType CGDebugInfo::CreateTypeDefi
>
>    // Convert all the elements.
>    SmallVector<llvm::Value *, 16> EltTys;
> +  llvm::DIArray PrevMem = FwdDecl.getTypeArray();
> +  unsigned NumElements = PrevMem.getNumElements();
> +  if (NumElements == 1 && !PrevMem.getElement(0))
> +    NumElements = 0;
> +  EltTys.reserve(NumElements);
> +  for (unsigned i = 0; i != NumElements; ++i)
> +    EltTys.push_back(PrevMem.getElement(i));
>
>    // Note: The split of CXXDecl information here is intentional, the
>    // gdb tests will depend on a certain ordering at printout. The debug
> @@ -2291,7 +2321,7 @@ llvm::DISubprogram CGDebugInfo::getFunct
>    llvm::DenseMap<const FunctionDecl *, llvm::WeakVH>::iterator
>      MI = SPCache.find(FD->getCanonicalDecl());
>    if (MI == SPCache.end()) {
> -    if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
> +    if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD->getCanonicalDecl())) {
>        llvm::DICompositeType T(S);
>        llvm::DISubprogram SP = CreateCXXMemberFunction(MD, getOrCreateFile(MD->getLocation()), T);
>        T.addMember(SP);
> @@ -2997,19 +3027,35 @@ void CGDebugInfo::EmitDeclareOfBlockLite
>    DbgDecl->setDebugLoc(llvm::DebugLoc::get(line, column, scope));
>  }
>
> -/// getStaticDataMemberDeclaration - If D is an out-of-class definition of
> -/// a static data member of a class, find its corresponding in-class
> -/// declaration.
> -llvm::DIDerivedType CGDebugInfo::getStaticDataMemberDeclaration(const VarDecl *D) {
> -  if (D->isStaticDataMember()) {
> -    llvm::DenseMap<const Decl *, llvm::WeakVH>::iterator
> -      MI = StaticDataMemberCache.find(D->getCanonicalDecl());
> -    if (MI != StaticDataMemberCache.end())
> -      // Verify the info still exists.
> -      if (llvm::Value *V = MI->second)
> -        return llvm::DIDerivedType(cast<llvm::MDNode>(V));
> +/// If D is an out-of-class definition of a static data member of a class, find
> +/// its corresponding in-class declaration.
> +llvm::DIDerivedType
> +CGDebugInfo::getOrCreateStaticDataMemberDeclarationOrNull(const VarDecl *D) {
> +  if (!D->isStaticDataMember())
> +    return llvm::DIDerivedType();
> +  llvm::DenseMap<const Decl *, llvm::WeakVH>::iterator MI =
> +      StaticDataMemberCache.find(D->getCanonicalDecl());
> +  if (MI != StaticDataMemberCache.end()) {
> +    assert(MI->second && "Static data member declaration should still exist");
> +    return llvm::DIDerivedType(cast<llvm::MDNode>(MI->second));
> +  }
> +  llvm::DICompositeType Ctxt(
> +      getContextDescriptor(cast<Decl>(D->getDeclContext())));
> +  llvm::DIDerivedType T = CreateRecordStaticField(D, Ctxt);
> +  Ctxt.addMember(T);
> +  return T;
> +}
> +
> +llvm::DIDerivedType
> +CGDebugInfo::getOrCreateStaticDataMemberDeclaration(const VarDecl *D,
> +                                            llvm::DICompositeType Ctxt) {
> +  llvm::DenseMap<const Decl *, llvm::WeakVH>::iterator MI =
> +      StaticDataMemberCache.find(D->getCanonicalDecl());
> +  if (MI != StaticDataMemberCache.end()) {
> +    assert(MI->second && "Static data member declaration should still exist");
> +    return llvm::DIDerivedType(cast<llvm::MDNode>(MI->second));
>    }
> -  return llvm::DIDerivedType();
> +  return CreateRecordStaticField(D, Ctxt);
>  }
>
>  /// EmitGlobalVariable - Emit information about a global variable.
> @@ -3041,11 +3087,10 @@ void CGDebugInfo::EmitGlobalVariable(llv
>      LinkageName = StringRef();
>    llvm::DIDescriptor DContext =
>      getContextDescriptor(dyn_cast<Decl>(D->getDeclContext()));
> -  llvm::DIGlobalVariable GV =
> -      DBuilder.createStaticVariable(DContext, DeclName, LinkageName, Unit,
> -                                    LineNo, getOrCreateType(T, Unit),
> -                                    Var->hasInternalLinkage(), Var,
> -                                    getStaticDataMemberDeclaration(D));
> +  llvm::DIGlobalVariable GV = DBuilder.createStaticVariable(
> +      DContext, DeclName, LinkageName, Unit, LineNo, getOrCreateType(T, Unit),
> +      Var->hasInternalLinkage(), Var,
> +      getOrCreateStaticDataMemberDeclarationOrNull(D));
>    DeclCache.insert(std::make_pair(D->getCanonicalDecl(), llvm::WeakVH(GV)));
>  }
>
> @@ -3093,7 +3138,7 @@ void CGDebugInfo::EmitGlobalVariable(con
>      return;
>    llvm::DIGlobalVariable GV = DBuilder.createStaticVariable(
>        Unit, Name, Name, Unit, getLineNumber(VD->getLocation()), Ty, true, Init,
> -      getStaticDataMemberDeclaration(cast<VarDecl>(VD)));
> +      getOrCreateStaticDataMemberDeclarationOrNull(cast<VarDecl>(VD)));
>    DeclCache.insert(std::make_pair(VD->getCanonicalDecl(), llvm::WeakVH(GV)));
>  }
>
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.h?rev=188576&r1=188575&r2=188576&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.h (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.h Fri Aug 16 15:40:29 2013
> @@ -290,7 +290,7 @@ public:
>
>    void completeType(const RecordDecl *RD);
>    void completeRequiredType(const RecordDecl *RD);
> -
> +  void completeClassData(const RecordDecl *RD);
>
>  private:
>    /// EmitDeclare - Emit call to llvm.dbg.declare for a variable declaration.
> @@ -353,10 +353,13 @@ private:
>    /// declaration for the given method definition.
>    llvm::DISubprogram getFunctionDeclaration(const Decl *D);
>
> -  /// getStaticDataMemberDeclaration - Return debug info descriptor to
> -  /// describe in-class static data member declaration for the given
> -  /// out-of-class definition.
> -  llvm::DIDerivedType getStaticDataMemberDeclaration(const VarDecl *D);
> +  /// Return debug info descriptor to describe in-class static data member
> +  /// declaration for the given out-of-class definition.
> +  llvm::DIDerivedType
> +  getOrCreateStaticDataMemberDeclarationOrNull(const VarDecl *D);
> +  llvm::DIDerivedType
> +  getOrCreateStaticDataMemberDeclaration(const VarDecl *D,
> +                                         llvm::DICompositeType Ctxt);
>
>    /// getFunctionName - Get function name for the given FunctionDecl. If the
>    /// name is constructred on demand (e.g. C++ destructor) then the name
>
> Modified: cfe/trunk/lib/CodeGen/CGVTables.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGVTables.cpp?rev=188576&r1=188575&r2=188576&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGVTables.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGVTables.cpp Fri Aug 16 15:40:29 2013
> @@ -828,6 +828,9 @@ CodeGenVTables::GenerateClassData(const
>      VFTContext->getVFPtrOffsets(RD);
>    }
>
> +  if (CGDebugInfo *DI = CGM.getModuleDebugInfo())
> +    DI->completeClassData(RD);
> +
>    // First off, check whether we've already emitted the v-table and
>    // associated stuff.
>    llvm::GlobalVariable *VTable = GetAddrOfVTable(RD);
>
> Modified: cfe/trunk/test/CodeGenCXX/debug-info-class.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/debug-info-class.cpp?rev=188576&r1=188575&r2=188576&view=diff
> ==============================================================================
> --- cfe/trunk/test/CodeGenCXX/debug-info-class.cpp (original)
> +++ cfe/trunk/test/CodeGenCXX/debug-info-class.cpp Fri Aug 16 15:40:29 2013
> @@ -12,6 +12,32 @@ class B {
>  public:
>    virtual ~B();
>  };
> +
> +B::~B() {
> +}
> +
> +struct C {
> +  static int s;
> +  virtual ~C();
> +};
> +
> +C::~C() {
> +}
> +
> +struct D {
> +  D();
> +  virtual ~D();
> +  void func() {
> +  }
> +};
> +
> +struct E {
> +  E();
> +  virtual ~E();
> +  virtual void func() {
> +  }
> +};
> +
>  struct A {
>    int one;
>    static const int HdrSize = 52;
> @@ -21,6 +47,11 @@ struct A {
>    }
>  };
>
> +void f1() {
> +  D x;
> +  x.func();
> +  E y;
> +}
>
>  int main(int argc, char **argv) {
>    B b;
> @@ -40,9 +71,20 @@ int main(int argc, char **argv) {
>  // CHECK: DW_TAG_structure_type ] [foo]
>  // CHECK: DW_TAG_class_type ] [bar]
>  // CHECK: DW_TAG_union_type ] [baz]
> -// CHECK: DW_TAG_structure_type ] [A]
> -// CHECK: HdrSize
>  // CHECK: DW_TAG_class_type ] [B]
>  // CHECK: metadata !"_vptr$B", {{.*}}, i32 64, metadata !{{.*}}} ; [ DW_TAG_member ]
> -// CHECK: ![[EXCEPTLOC]] = metadata !{i32 31,
> -// CHECK: ![[RETLOC]] = metadata !{i32 30,
> +
> +// CHECK: [[C:![0-9]*]] = {{.*}} metadata [[C_MEM:![0-9]*]], i32 0, metadata [[C]], null} ; [ DW_TAG_structure_type ] [C] {{.*}} [def]
> +// CHECK: [[C_MEM]] = metadata !{metadata [[C_VPTR:![0-9]*]], metadata [[C_S:![0-9]*]], metadata [[C_DTOR:![0-9]*]]}
> +// CHECK: [[C_VPTR]] = {{.*}} ; [ DW_TAG_member ] [_vptr$C] {{.*}} [artificial]
> +// CHECK: [[C_S]] = {{.*}} ; [ DW_TAG_member ] [s] {{.*}} [static] [from int]
> +// CHECK: [[C_DTOR]] = {{.*}} ; [ DW_TAG_subprogram ] {{.*}} [~C]
> +
> +// CHECK: ; [ DW_TAG_structure_type ] [A]
> +// CHECK: HdrSize
> +// CHECK: metadata [[D_MEM:![0-9]*]], i32 0, null} ; [ DW_TAG_structure_type ] [D] {{.*}} [decl]
> +// CHECK: [[D_MEM]] = metadata !{metadata [[D_FUNC:![0-9]*]]}
> +// CHECK: [[D_FUNC]] = {{.*}} ; [ DW_TAG_subprogram ] {{.*}} [func]
> +// CHECK: null, i32 0, null} ; [ DW_TAG_structure_type ] [E] {{.*}} [decl]
> +// CHECK: ![[EXCEPTLOC]] = metadata !{i32 62,
> +// CHECK: ![[RETLOC]] = metadata !{i32 61,
>
>
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