[llvm] r274986 - [COFF, Dwarf] Don't emit DW_AT_location for dllimported entities
Robinson, Paul via llvm-commits
llvm-commits at lists.llvm.org
Sun Jul 10 15:55:07 PDT 2016
This leaves the DWARF in a disconcerting state: the entity
appears to be a definition, but has no location, which normally
means the entity has been optimized away. That's obviously not
the case.
Better to mark the entity as a declaration in this case, so that
the consumer isn't expecting to be able to locate it.
--paulr
> -----Original Message-----
> From: llvm-commits [mailto:llvm-commits-bounces at lists.llvm.org] On Behalf
> Of David Majnemer via llvm-commits
> Sent: Saturday, July 09, 2016 1:48 PM
> To: llvm-commits at lists.llvm.org
> Subject: [llvm] r274986 - [COFF, Dwarf] Don't emit DW_AT_location for
> dllimported entities
>
> 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=2749
> 85&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}
>
>
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