r205999 - Debug info: (Bugfix) Make sure artificial functions like _GLOBAL__I_a

Eric Christopher echristo at gmail.com
Fri Apr 11 15:24:50 PDT 2014


So from looking at this it doesn't appear that we have any address
range or location information for _GLOBAL__I_a anymore which is
exactly what I was worried about:

0x000000d0:   DW_TAG_subprogram [13]
                DW_AT_MIPS_linkage_name [DW_FORM_strp]  (
.debug_str[0x00000099] = "_GLOBAL__I_a")
                DW_AT_artificial [DW_FORM_flag_present] (true)
                DW_AT_accessibility [DW_FORM_data1]     (0x01)

versus before:

0x000000d0:   DW_TAG_subprogram [13]
                DW_AT_MIPS_linkage_name [DW_FORM_strp]  (
.debug_str[0x00000099] = "_GLOBAL__I_a")
                DW_AT_decl_file [DW_FORM_data1] (0x03)
                DW_AT_decl_line [DW_FORM_data1] (0x66)
                DW_AT_artificial [DW_FORM_flag_present] (true)
                DW_AT_accessibility [DW_FORM_data1]     (0x01)
                DW_AT_low_pc [DW_FORM_addr]     (0x0000000000000020)
                DW_AT_high_pc [DW_FORM_data4]   (0x0000000b)
                DW_AT_frame_base [DW_FORM_exprloc]      (<0x1> 56 )

Now we don't have any note that this code belongs to this compile
unit, etc. I think this part is incorrect. We should have scope and
line information for this - even if it's line 0 etc. (Though I think
the location of the variable would be a better one).

-eric


On Thu, Apr 10, 2014 at 4:21 PM, Adrian Prantl <aprantl at apple.com> wrote:
> Author: adrian
> Date: Thu Apr 10 18:21:53 2014
> New Revision: 205999
>
> URL: http://llvm.org/viewvc/llvm-project?rev=205999&view=rev
> Log:
> Debug info: (Bugfix) Make sure artificial functions like _GLOBAL__I_a
> are not associated with any source lines.
>
> Previously, if the Location of a Decl was empty, EmitFunctionStart would
> just keep using CurLoc, which would sometimes be correct (e.g., thunks)
> but in other cases would just point to a hilariously random location.
>
> This patch fixes this by completely eliminating all uses of CurLoc from
> EmitFunctionStart and rather have clients explicitly pass in a
> SourceLocation for the function header and the function body.
>
> rdar://problem/14985269
>
> Added:
>     cfe/trunk/test/CodeGenCXX/globalinit-loc.cpp
> Modified:
>     cfe/trunk/lib/CodeGen/CGBlocks.cpp
>     cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
>     cfe/trunk/lib/CodeGen/CGDebugInfo.h
>     cfe/trunk/lib/CodeGen/CGDeclCXX.cpp
>     cfe/trunk/lib/CodeGen/CGObjC.cpp
>     cfe/trunk/lib/CodeGen/CGStmt.cpp
>     cfe/trunk/lib/CodeGen/CGVTables.cpp
>     cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
>     cfe/trunk/lib/CodeGen/CodeGenFunction.h
>
> Modified: cfe/trunk/lib/CodeGen/CGBlocks.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBlocks.cpp?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGBlocks.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGBlocks.cpp Thu Apr 10 18:21:53 2014
> @@ -1135,6 +1135,7 @@ CodeGenFunction::GenerateBlockFunction(G
>
>    // Begin generating the function.
>    StartFunction(blockDecl, fnType->getReturnType(), fn, fnInfo, args,
> +                blockDecl->getLocation(),
>                  blockInfo.getBlockExpr()->getBody()->getLocStart());
>
>    // Okay.  Undo some of what StartFunction did.
> @@ -1306,7 +1307,7 @@ CodeGenFunction::GenerateCopyHelperFunct
>                                            false);
>    // Create a scope with an artificial location for the body of this function.
>    ArtificialLocation AL(*this, Builder);
> -  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
> +  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation(), SourceLocation());
>    AL.Emit();
>
>    llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
> @@ -1476,7 +1477,7 @@ CodeGenFunction::GenerateDestroyHelperFu
>                                            false, false);
>    // Create a scope with an artificial location for the body of this function.
>    ArtificialLocation AL(*this, Builder);
> -  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
> +  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation(), SourceLocation());
>    AL.Emit();
>
>    llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
> @@ -1765,7 +1766,7 @@ generateByrefCopyHelper(CodeGenFunction
>                                            SC_Static,
>                                            false, false);
>
> -  CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
> +  CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation(), SourceLocation());
>
>    if (byrefInfo.needsCopy()) {
>      llvm::Type *byrefPtrType = byrefType.getPointerTo(0);
> @@ -1834,7 +1835,7 @@ generateByrefDisposeHelper(CodeGenFuncti
>                                            SourceLocation(), II, R, 0,
>                                            SC_Static,
>                                            false, false);
> -  CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation());
> +  CGF.StartFunction(FD, R, Fn, FI, args, SourceLocation(), SourceLocation());
>
>    if (byrefInfo.needsDispose()) {
>      llvm::Value *V = CGF.GetAddrOfLocalVar(&src);
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Thu Apr 10 18:21:53 2014
> @@ -2504,7 +2504,10 @@ llvm::DICompositeType CGDebugInfo::getOr
>  }
>
>  /// EmitFunctionStart - Constructs the debug code for entering a function.
> -void CGDebugInfo::EmitFunctionStart(GlobalDecl GD, QualType FnType,
> +void CGDebugInfo::EmitFunctionStart(GlobalDecl GD,
> +                                    SourceLocation Loc,
> +                                    SourceLocation ScopeLoc,
> +                                    QualType FnType,
>                                      llvm::Function *Fn,
>                                      CGBuilderTy &Builder) {
>
> @@ -2514,24 +2517,7 @@ void CGDebugInfo::EmitFunctionStart(Glob
>    FnBeginRegionCount.push_back(LexicalBlockStack.size());
>
>    const Decl *D = GD.getDecl();
> -
> -  // Use the location of the start of the function to determine where
> -  // the function definition is located. By default use the location
> -  // of the declaration as the location for the subprogram. A function
> -  // may lack a declaration in the source code if it is created by code
> -  // gen. (examples: _GLOBAL__I_a, __cxx_global_array_dtor, thunk).
>    bool HasDecl = (D != 0);
> -  SourceLocation Loc;
> -  if (HasDecl) {
> -    Loc = D->getLocation();
> -
> -    // If this is a function specialization then use the pattern body
> -    // as the location for the function.
> -    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
> -      if (const FunctionDecl *SpecDecl = FD->getTemplateInstantiationPattern())
> -        if (SpecDecl->hasBody(SpecDecl))
> -          Loc = SpecDecl->getLocation();
> -  }
>
>    unsigned Flags = 0;
>    llvm::DIFile Unit = getOrCreateFile(Loc);
> @@ -2591,9 +2577,14 @@ void CGDebugInfo::EmitFunctionStart(Glob
>    if (!Name.empty() && Name[0] == '\01')
>      Name = Name.substr(1);
>
> -  unsigned LineNo = getLineNumber(Loc);
> -  if (!HasDecl || D->isImplicit())
> +  if (!HasDecl || D->isImplicit()) {
>      Flags |= llvm::DIDescriptor::FlagArtificial;
> +    // Artificial functions without a location should not silently reuse CurLoc.
> +    if (Loc.isInvalid())
> +      CurLoc = SourceLocation();
> +  }
> +  unsigned LineNo = getLineNumber(Loc);
> +  unsigned ScopeLine = getLineNumber(ScopeLoc);
>
>    // FIXME: The function declaration we're constructing here is mostly reusing
>    // declarations from CXXMethodDecl and not constructing new ones for arbitrary
> @@ -2604,7 +2595,7 @@ void CGDebugInfo::EmitFunctionStart(Glob
>        DBuilder.createFunction(FDContext, Name, LinkageName, Unit, LineNo,
>                                getOrCreateFunctionType(D, FnType, Unit),
>                                Fn->hasInternalLinkage(), true /*definition*/,
> -                              getLineNumber(CurLoc), Flags,
> +                              ScopeLine, Flags,
>                                CGM.getLangOpts().Optimize, Fn, TParamsArray,
>                                getFunctionDeclaration(D));
>    if (HasDecl)
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.h?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.h (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.h Thu Apr 10 18:21:53 2014
> @@ -220,8 +220,12 @@ public:
>
>    /// EmitFunctionStart - Emit a call to llvm.dbg.function.start to indicate
>    /// start of a new function.
> -  void EmitFunctionStart(GlobalDecl GD, QualType FnType,
> -                         llvm::Function *Fn, CGBuilderTy &Builder);
> +  /// \param Loc       The location of the function header.
> +  /// \param ScopeLoc  The location of the function body.
> +  void EmitFunctionStart(GlobalDecl GD,
> +                         SourceLocation Loc, SourceLocation ScopeLoc,
> +                         QualType FnType, llvm::Function *Fn,
> +                         CGBuilderTy &Builder);
>
>    /// EmitFunctionEnd - Constructs the debug code for exiting a function.
>    void EmitFunctionEnd(CGBuilderTy &Builder);
>
> Modified: cfe/trunk/lib/CodeGen/CGDeclCXX.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDeclCXX.cpp?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDeclCXX.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGDeclCXX.cpp Thu Apr 10 18:21:53 2014
> @@ -179,7 +179,7 @@ static llvm::Constant *createAtExitStub(
>
>    CGF.StartFunction(&VD, CGM.getContext().VoidTy, fn,
>                      CGM.getTypes().arrangeNullaryFunction(), FunctionArgList(),
> -                    SourceLocation());
> +                    SourceLocation(), SourceLocation());
>
>    llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
>
> @@ -412,7 +412,8 @@ void CodeGenFunction::GenerateCXXGlobalV
>
>    StartFunction(GlobalDecl(D), getContext().VoidTy, Fn,
>                  getTypes().arrangeNullaryFunction(),
> -                FunctionArgList(), D->getInit()->getExprLoc());
> +                FunctionArgList(), D->getLocation(),
> +                D->getInit()->getExprLoc());
>
>    // Use guarded initialization if the global variable is weak. This
>    // occurs for, e.g., instantiated static data members and
> @@ -433,7 +434,7 @@ CodeGenFunction::GenerateCXXGlobalInitFu
>                                             llvm::GlobalVariable *Guard) {
>    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
>                  getTypes().arrangeNullaryFunction(),
> -                FunctionArgList(), SourceLocation());
> +                FunctionArgList(), SourceLocation(), SourceLocation());
>
>    llvm::BasicBlock *ExitBlock = 0;
>    if (Guard) {
> @@ -479,7 +480,7 @@ void CodeGenFunction::GenerateCXXGlobalD
>                                                  &DtorsAndObjects) {
>    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
>                  getTypes().arrangeNullaryFunction(),
> -                FunctionArgList(), SourceLocation());
> +                FunctionArgList(), SourceLocation(), SourceLocation());
>
>    // Emit the dtors, in reverse order from construction.
>    for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
> @@ -509,7 +510,8 @@ llvm::Function *CodeGenFunction::generat
>    llvm::Function *fn =
>      CreateGlobalInitOrDestructFunction(CGM, FTy, "__cxx_global_array_dtor");
>
> -  StartFunction(VD, getContext().VoidTy, fn, FI, args, SourceLocation());
> +  StartFunction(VD, getContext().VoidTy, fn, FI, args,
> +                SourceLocation(), SourceLocation());
>
>    emitDestroy(addr, type, destroyer, useEHCleanupForArray);
>
>
> Modified: cfe/trunk/lib/CodeGen/CGObjC.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGObjC.cpp?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGObjC.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGObjC.cpp Thu Apr 10 18:21:53 2014
> @@ -481,7 +481,8 @@ void CodeGenFunction::StartObjCMethod(co
>
>    CurGD = OMD;
>
> -  StartFunction(OMD, OMD->getReturnType(), Fn, FI, args, StartLoc);
> +  StartFunction(OMD, OMD->getReturnType(), Fn, FI, args,
> +                OMD->getLocation(), StartLoc);
>
>    // In ARC, certain methods get an extra cleanup.
>    if (CGM.getLangOpts().ObjCAutoRefCount &&
> @@ -2915,7 +2916,7 @@ CodeGenFunction::GenerateObjCAtomicSette
>                             "__assign_helper_atomic_property_",
>                             &CGM.getModule());
>
> -  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
> +  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation(), SourceLocation());
>
>    DeclRefExpr DstExpr(&dstDecl, false, DestTy,
>                        VK_RValue, SourceLocation());
> @@ -2993,7 +2994,7 @@ CodeGenFunction::GenerateObjCAtomicGette
>    llvm::Function::Create(LTy, llvm::GlobalValue::InternalLinkage,
>                           "__copy_helper_atomic_property_", &CGM.getModule());
>
> -  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation());
> +  StartFunction(FD, C.VoidTy, Fn, FI, args, SourceLocation(), SourceLocation());
>
>    DeclRefExpr SrcExpr(&srcDecl, false, SrcTy,
>                        VK_RValue, SourceLocation());
>
> Modified: cfe/trunk/lib/CodeGen/CGStmt.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGStmt.cpp?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGStmt.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGStmt.cpp Thu Apr 10 18:21:53 2014
> @@ -1944,7 +1944,9 @@ CodeGenFunction::GenerateCapturedStmtFun
>    CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
>
>    // Generate the function.
> -  StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args, CD->getBody()->getLocStart());
> +  StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args,
> +                CD->getLocation(),
> +                CD->getBody()->getLocStart());
>
>    // Set the context parameter in CapturedStmtInfo.
>    llvm::Value *DeclPtr = LocalDeclMap[CD->getContextParam()];
>
> Modified: cfe/trunk/lib/CodeGen/CGVTables.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGVTables.cpp?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGVTables.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGVTables.cpp Thu Apr 10 18:21:53 2014
> @@ -217,7 +217,7 @@ void CodeGenFunction::StartThunk(llvm::F
>
>    // Start defining the function.
>    StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs,
> -                SourceLocation());
> +                MD->getLocation(), SourceLocation());
>
>    // Since we didn't pass a GlobalDecl to StartFunction, do this ourselves.
>    CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
>
> Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.cpp?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CodeGenFunction.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CodeGenFunction.cpp Thu Apr 10 18:21:53 2014
> @@ -503,6 +503,7 @@ void CodeGenFunction::StartFunction(Glob
>                                      llvm::Function *Fn,
>                                      const CGFunctionInfo &FnInfo,
>                                      const FunctionArgList &Args,
> +                                    SourceLocation Loc,
>                                      SourceLocation StartLoc) {
>    const Decl *D = GD.getDecl();
>
> @@ -580,9 +581,7 @@ void CodeGenFunction::StartFunction(Glob
>      QualType FnType =
>        getContext().getFunctionType(RetTy, ArgTypes,
>                                     FunctionProtoType::ExtProtoInfo());
> -
> -    DI->setLocation(StartLoc);
> -    DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
> +    DI->EmitFunctionStart(GD, Loc, StartLoc, FnType, CurFn, Builder);
>    }
>
>    if (ShouldInstrumentFunction())
> @@ -759,8 +758,24 @@ void CodeGenFunction::GenerateCode(Globa
>    if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
>    CurEHLocation = BodyRange.getEnd();
>
> +  // Use the location of the start of the function to determine where
> +  // the function definition is located. By default use the location
> +  // of the declaration as the location for the subprogram. A function
> +  // may lack a declaration in the source code if it is created by code
> +  // gen. (examples: _GLOBAL__I_a, __cxx_global_array_dtor, thunk).
> +  SourceLocation Loc;
> +  if (FD) {
> +    Loc = FD->getLocation();
> +
> +    // If this is a function specialization then use the pattern body
> +    // as the location for the function.
> +    if (const FunctionDecl *SpecDecl = FD->getTemplateInstantiationPattern())
> +      if (SpecDecl->hasBody(SpecDecl))
> +        Loc = SpecDecl->getLocation();
> +  }
> +
>    // Emit the standard function prologue.
> -  StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin());
> +  StartFunction(GD, ResTy, Fn, FnInfo, Args, Loc, BodyRange.getBegin());
>
>    // Generate the body of the function.
>    PGO.assignRegionCounters(GD.getDecl(), CurFn);
>
> Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=205999&r1=205998&r2=205999&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
> +++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Thu Apr 10 18:21:53 2014
> @@ -1140,11 +1140,15 @@ public:
>
>    void GenerateCode(GlobalDecl GD, llvm::Function *Fn,
>                      const CGFunctionInfo &FnInfo);
> +  /// \brief Emit code for the start of a function.
> +  /// \param Loc       The location to be associated with the function.
> +  /// \param StartLoc  The location of the function body.
>    void StartFunction(GlobalDecl GD,
>                       QualType RetTy,
>                       llvm::Function *Fn,
>                       const CGFunctionInfo &FnInfo,
>                       const FunctionArgList &Args,
> +                     SourceLocation Loc,
>                       SourceLocation StartLoc);
>
>    void EmitConstructorBody(FunctionArgList &Args);
>
> Added: cfe/trunk/test/CodeGenCXX/globalinit-loc.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/globalinit-loc.cpp?rev=205999&view=auto
> ==============================================================================
> --- cfe/trunk/test/CodeGenCXX/globalinit-loc.cpp (added)
> +++ cfe/trunk/test/CodeGenCXX/globalinit-loc.cpp Thu Apr 10 18:21:53 2014
> @@ -0,0 +1,22 @@
> +// RUN: %clang_cc1 -emit-llvm -g %s -o - | FileCheck %s
> +// rdar://problem/14985269.
> +//
> +// Verify that the global init helper function does not get associated
> +// with any source location.
> +//
> +// CHECK: define internal void @_GLOBAL__I_a
> +// CHECK-NOT: !dbg
> +// CHECK: "_GLOBAL__I_a", i32 0, {{.*}}, i32 0} ; [ DW_TAG_subprogram ] [line 0] [local] [def]
> +# 99 "someheader.h"
> +class A {
> +public:
> +  A();
> +  int foo() { return 0; }
> +};
> +# 5 "main.cpp"
> +A a;
> +
> +int f() {
> +  return a.foo();
> +}
> +
>
>
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