[llvm] r274986 - [COFF, Dwarf] Don't emit DW_AT_location for dllimported entities
Anton Korobeynikov via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 13 16:50:41 PDT 2016
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}
>
>
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--
With best regards, Anton Korobeynikov
Department of Statistical Modelling, Saint Petersburg State University
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