[llvm] r274986 - [COFF, Dwarf] Don't emit DW_AT_location for dllimported entities
David Blaikie via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 13 16:53:58 PDT 2016
I think that's a bit different - I Think it might be reasonable to emit
that as a definiton without a location, since we have no way to describe
the location but there really is a definition there.
Whereas a dllimport isn't really a definition at all - there's a definition
on the dllexport side, which we should be describing.
On Wed, Jul 13, 2016 at 4:51 PM Anton Korobeynikov via llvm-commits <
llvm-commits at lists.llvm.org> wrote:
> It seems we have to deal with TLS symbols in pretty similar way.
>
> Sometimes there is no relocation which could describe the location.
> The recent example is AArch64, see
> https://llvm.org/bugs/show_bug.cgi?id=21077 for more information.
>
> Good thing is that we're having TLOF::getDebugThreadLocalSymbol()
> hook, which can be made to return nullptr in default case and we would
> handle it here the same way as dllimport stuff.
>
> On Sat, Jul 9, 2016 at 11:47 PM, David Majnemer via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
> > Author: majnemer
> > Date: Sat Jul 9 15:47:48 2016
> > New Revision: 274986
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=274986&view=rev
> > Log:
> > [COFF, Dwarf] Don't emit DW_AT_location for dllimported entities
> >
> > There exists no relocation which can describe the address of a
> > dllimported variable: do not try to describe their location.
> >
> > Added:
> > llvm/trunk/test/DebugInfo/X86/dllimport.ll
> > Modified:
> > llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
> > llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
> >
> > Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp?rev=274986&r1=274985&r2=274986&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp (original)
> > +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp Sat Jul 9
> 15:47:48 2016
> > @@ -148,62 +148,69 @@ DIE *DwarfCompileUnit::getOrCreateGlobal
> > // Add location.
> > bool addToAccelTable = false;
> > if (auto *Global =
> dyn_cast_or_null<GlobalVariable>(GV->getVariable())) {
> > - addToAccelTable = true;
> > - DIELoc *Loc = new (DIEValueAllocator) DIELoc;
> > - const MCSymbol *Sym = Asm->getSymbol(Global);
> > - if (Global->isThreadLocal()) {
> > - if (Asm->TM.Options.EmulatedTLS) {
> > - // TODO: add debug info for emulated thread local mode.
> > - } else {
> > - // FIXME: Make this work with -gsplit-dwarf.
> > - unsigned PointerSize = Asm->getDataLayout().getPointerSize();
> > - assert((PointerSize == 4 || PointerSize == 8) &&
> > - "Add support for other sizes if necessary");
> > - // Based on GCC's support for TLS:
> > - if (!DD->useSplitDwarf()) {
> > - // 1) Start with a constNu of the appropriate pointer size
> > - addUInt(*Loc, dwarf::DW_FORM_data1, PointerSize == 4
> > - ? dwarf::DW_OP_const4u
> > - :
> dwarf::DW_OP_const8u);
> > - // 2) containing the (relocated) offset of the TLS variable
> > - // within the module's TLS block.
> > - addExpr(*Loc, dwarf::DW_FORM_udata,
> > -
> Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
> > + // We cannot describe the location of dllimport'd variables: the
> computation
> > + // of their address requires loads from the IAT.
> > + if (!Global->hasDLLImportStorageClass()) {
> > + addToAccelTable = true;
> > + DIELoc *Loc = new (DIEValueAllocator) DIELoc;
> > + const MCSymbol *Sym = Asm->getSymbol(Global);
> > + if (Global->isThreadLocal()) {
> > + if (Asm->TM.Options.EmulatedTLS) {
> > + // TODO: add debug info for emulated thread local mode.
> > } else {
> > - addUInt(*Loc, dwarf::DW_FORM_data1,
> dwarf::DW_OP_GNU_const_index);
> > - addUInt(*Loc, dwarf::DW_FORM_udata,
> > - DD->getAddressPool().getIndex(Sym, /* TLS */ true));
> > + // FIXME: Make this work with -gsplit-dwarf.
> > + unsigned PointerSize = Asm->getDataLayout().getPointerSize();
> > + assert((PointerSize == 4 || PointerSize == 8) &&
> > + "Add support for other sizes if necessary");
> > + // Based on GCC's support for TLS:
> > + if (!DD->useSplitDwarf()) {
> > + // 1) Start with a constNu of the appropriate pointer size
> > + addUInt(*Loc, dwarf::DW_FORM_data1, PointerSize == 4
> > + ?
> dwarf::DW_OP_const4u
> > + :
> dwarf::DW_OP_const8u);
> > + // 2) containing the (relocated) offset of the TLS variable
> > + // within the module's TLS block.
> > + addExpr(*Loc, dwarf::DW_FORM_udata,
> > +
> Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
> > + } else {
> > + addUInt(*Loc, dwarf::DW_FORM_data1,
> dwarf::DW_OP_GNU_const_index);
> > + addUInt(*Loc, dwarf::DW_FORM_udata,
> > + DD->getAddressPool().getIndex(Sym, /* TLS */ true));
> > + }
> > + // 3) followed by an OP to make the debugger do a TLS lookup.
> > + addUInt(*Loc, dwarf::DW_FORM_data1,
> > + DD->useGNUTLSOpcode() ?
> dwarf::DW_OP_GNU_push_tls_address
> > + :
> dwarf::DW_OP_form_tls_address);
> > }
> > - // 3) followed by an OP to make the debugger do a TLS lookup.
> > - addUInt(*Loc, dwarf::DW_FORM_data1,
> > - DD->useGNUTLSOpcode() ?
> dwarf::DW_OP_GNU_push_tls_address
> > - : dwarf::DW_OP_form_tls_address);
> > + } else {
> > + DD->addArangeLabel(SymbolCU(this, Sym));
> > + addOpAddress(*Loc, Sym);
> > }
> > - } else {
> > - DD->addArangeLabel(SymbolCU(this, Sym));
> > - addOpAddress(*Loc, Sym);
> > - }
> >
> > - addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
> > - if (DD->useAllLinkageNames())
> > - addLinkageName(*VariableDIE, GV->getLinkageName());
> > + addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
> > + if (DD->useAllLinkageNames())
> > + addLinkageName(*VariableDIE, GV->getLinkageName());
> > + }
> > } else if (const ConstantInt *CI =
> > dyn_cast_or_null<ConstantInt>(GV->getVariable())) {
> > addConstantValue(*VariableDIE, CI, GTy);
> > } else if (const ConstantExpr *CE =
> getMergedGlobalExpr(GV->getVariable())) {
> > - addToAccelTable = true;
> > - // GV is a merged global.
> > - DIELoc *Loc = new (DIEValueAllocator) DIELoc;
> > auto *Ptr = cast<GlobalValue>(CE->getOperand(0));
> > - MCSymbol *Sym = Asm->getSymbol(Ptr);
> > - DD->addArangeLabel(SymbolCU(this, Sym));
> > - addOpAddress(*Loc, Sym);
> > - addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
> > - SmallVector<Value *, 3> Idx(CE->op_begin() + 1, CE->op_end());
> > - addUInt(*Loc, dwarf::DW_FORM_udata,
> > -
> Asm->getDataLayout().getIndexedOffsetInType(Ptr->getValueType(), Idx));
> > - addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
> > - addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
> > + if (!Ptr->hasDLLImportStorageClass()) {
> > + addToAccelTable = true;
> > + // GV is a merged global.
> > + DIELoc *Loc = new (DIEValueAllocator) DIELoc;
> > + MCSymbol *Sym = Asm->getSymbol(Ptr);
> > + DD->addArangeLabel(SymbolCU(this, Sym));
> > + addOpAddress(*Loc, Sym);
> > + addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
> > + SmallVector<Value *, 3> Idx(CE->op_begin() + 1, CE->op_end());
> > + addUInt(*Loc, dwarf::DW_FORM_udata,
> > +
> Asm->getDataLayout().getIndexedOffsetInType(Ptr->getValueType(),
> > + Idx));
> > + addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
> > + addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
> > + }
> > }
> >
> > if (addToAccelTable) {
> >
> > Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=274986&r1=274985&r2=274986&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
> > +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Sat Jul 9 15:47:48
> 2016
> > @@ -1053,14 +1053,18 @@ void DwarfUnit::constructTemplateValuePa
> > if (ConstantInt *CI = mdconst::dyn_extract<ConstantInt>(Val))
> > addConstantValue(ParamDIE, CI, resolve(VP->getType()));
> > else if (GlobalValue *GV = mdconst::dyn_extract<GlobalValue>(Val)) {
> > - // For declaration non-type template parameters (such as global
> values and
> > - // functions)
> > - DIELoc *Loc = new (DIEValueAllocator) DIELoc;
> > - addOpAddress(*Loc, Asm->getSymbol(GV));
> > - // Emit DW_OP_stack_value to use the address as the immediate
> value of the
> > - // parameter, rather than a pointer to it.
> > - addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_stack_value);
> > - addBlock(ParamDIE, dwarf::DW_AT_location, Loc);
> > + // We cannot describe the location of dllimport'd entities: the
> > + // computation of their address requires loads from the IAT.
> > + if (!GV->hasDLLImportStorageClass()) {
> > + // For declaration non-type template parameters (such as global
> values
> > + // and functions)
> > + DIELoc *Loc = new (DIEValueAllocator) DIELoc;
> > + addOpAddress(*Loc, Asm->getSymbol(GV));
> > + // Emit DW_OP_stack_value to use the address as the immediate
> value of
> > + // the parameter, rather than a pointer to it.
> > + addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_stack_value);
> > + addBlock(ParamDIE, dwarf::DW_AT_location, Loc);
> > + }
> > } else if (VP->getTag() ==
> dwarf::DW_TAG_GNU_template_template_param) {
> > assert(isa<MDString>(Val));
> > addString(ParamDIE, dwarf::DW_AT_GNU_template_name,
> >
> > Added: llvm/trunk/test/DebugInfo/X86/dllimport.ll
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dllimport.ll?rev=274986&view=auto
> >
> ==============================================================================
> > --- llvm/trunk/test/DebugInfo/X86/dllimport.ll (added)
> > +++ llvm/trunk/test/DebugInfo/X86/dllimport.ll Sat Jul 9 15:47:48 2016
> > @@ -0,0 +1,27 @@
> > +; RUN: llc -mtriple=i686-pc-windows-msvc -O0 -filetype=obj < %s |
> llvm-dwarfdump -debug-dump=info - | FileCheck %s
> > +
> > +; CHECK-NOT: DW_AT_location
> > +
> > +target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
> > +target triple = "i686-pc-windows-msvc"
> > +
> > +@"\01?id@?$numpunct at D@@0HA" = available_externally dllimport global
> i32 0, align 4
> > +
> > +!llvm.dbg.cu = !{!0}
> > +!llvm.module.flags = !{!13, !14}
> > +
> > +!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1,
> producer: "clang version 3.9.0 (trunk 272628) (llvm/trunk 272566)",
> isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2,
> globals: !3)
> > +!1 = !DIFile(filename:
> "/usr/local/google/home/majnemer/Downloads/<stdin>", directory:
> "/usr/local/google/home/majnemer/llvm/src")
> > +!2 = !{}
> > +!3 = !{!4}
> > +!4 = distinct !DIGlobalVariable(name: "id", linkageName: "\01?id@
> ?$numpunct at D@@0HA", scope: !0, file: !5, line: 4, type: !6, isLocal:
> false, isDefinition: true, variable: i32* @"\01?id@?$numpunct at D@@0HA",
> declaration: !7)
> > +!5 = !DIFile(filename:
> "/usr/local/google/home/majnemer/Downloads/t.ii", directory:
> "/usr/local/google/home/majnemer/llvm/src")
> > +!6 = !DIBasicType(name: "int", size: 32, align: 32, encoding:
> DW_ATE_signed)
> > +!7 = !DIDerivedType(tag: DW_TAG_member, name: "id", scope: !8, file:
> !5, line: 2, baseType: !6, flags: DIFlagStaticMember)
> > +!8 = distinct !DICompositeType(tag: DW_TAG_class_type, name:
> "numpunct<char>", file: !5, line: 2, size: 8, align: 8, elements: !9,
> templateParams: !10)
> > +!9 = !{!7}
> > +!10 = !{!11}
> > +!11 = !DITemplateTypeParameter(type: !12)
> > +!12 = !DIBasicType(name: "char", size: 8, align: 8, encoding:
> DW_ATE_signed_char)
> > +!13 = !{i32 2, !"Dwarf Version", i32 3}
> > +!14 = !{i32 2, !"Debug Info Version", i32 3}
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
>
>
> --
> With best regards, Anton Korobeynikov
> Department of Statistical Modelling, Saint Petersburg State University
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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