[llvm] r185398 - PR14728: DebugInfo: TLS variables with -gsplit-dwarf

David Blaikie dblaikie at gmail.com
Mon Jul 1 17:02:00 PDT 2013


On Mon, Jul 1, 2013 at 4:59 PM, Eric Christopher <echristo at gmail.com> wrote:
> Looks good. Thanks!

Oh, meant to mention - this does pass the relevant GDB 7.5 tests with
-gsplit-dwarf enabled:

$ make check RUNTESTFLAGS="CC_FOR_TARGET='clang-tot'
CXX_FOR_TARGET='clang++-tot' CFLAGS_FOR_TARGET='-w
-fno-limit-debug-info -gsplit-dwarf' gdb.threads/tls.exp
gdb.threads/tls-var.exp gdb.threads/tls-main.exp"
...
                === gdb Summary ===

# of expected passes            68

(there were two unexpected failures here without this patch)

>
> -eric
>
> On Mon, Jul 1, 2013 at 4:55 PM, David Blaikie <dblaikie at gmail.com> wrote:
>> Author: dblaikie
>> Date: Mon Jul  1 18:55:52 2013
>> New Revision: 185398
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=185398&view=rev
>> Log:
>> PR14728: DebugInfo: TLS variables with -gsplit-dwarf
>>
>> Added:
>>     llvm/trunk/test/DebugInfo/X86/tls-fission.ll
>> Modified:
>>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
>>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp?rev=185398&r1=185397&r2=185398&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp Mon Jul  1 18:55:52 2013
>> @@ -201,15 +201,12 @@ void CompileUnit::addLabelAddress(DIE *D
>>  /// form given and an op of either DW_FORM_addr or DW_FORM_GNU_addr_index.
>>  ///
>>  void CompileUnit::addOpAddress(DIE *Die, const MCSymbol *Sym) {
>> -
>>    if (!DD->useSplitDwarf()) {
>>      addUInt(Die, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_addr);
>>      addLabel(Die, 0, dwarf::DW_FORM_udata, Sym);
>>    } else {
>> -    unsigned idx = DU->getAddrPoolIndex(Sym);
>> -    DIEValue *Value = new (DIEValueAllocator) DIEInteger(idx);
>>      addUInt(Die, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_addr_index);
>> -    Die->addValue(0, dwarf::DW_FORM_GNU_addr_index, Value);
>> +    addUInt(Die, 0, dwarf::DW_FORM_GNU_addr_index, DU->getAddrPoolIndex(Sym));
>>    }
>>  }
>>
>> @@ -1358,13 +1355,19 @@ void CompileUnit::createGlobalVariableDI
>>        unsigned PointerSize = Asm->getDataLayout().getPointerSize();
>>        assert((PointerSize == 4 || PointerSize == 8) &&
>>               "Add support for other sizes if necessary");
>> +      const MCSymbolRefExpr *Ref =
>> +          Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym);
>>        // Based on GCC's support for TLS:
>> -      // 1) Start with a constNu of the appropriate pointer size
>> -      addUInt(Block, 0, dwarf::DW_FORM_data1,
>> -              PointerSize == 4 ? dwarf::DW_OP_const4u : dwarf::DW_OP_const8u);
>> -      // 2) containing the (relocated) address of the TLS variable
>> -      addLabel(Block, 0, dwarf::DW_FORM_udata,
>> -               Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
>> +      if (!DD->useSplitDwarf()) {
>> +        // 1) Start with a constNu of the appropriate pointer size
>> +        addUInt(Block, 0, dwarf::DW_FORM_data1,
>> +                PointerSize == 4 ? dwarf::DW_OP_const4u : dwarf::DW_OP_const8u);
>> +        // 2) containing the (relocated) address of the TLS variable
>> +        addLabel(Block, 0, dwarf::DW_FORM_udata, Ref);
>> +      } else {
>> +        addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
>> +        addUInt(Block, 0, dwarf::DW_FORM_udata, DU->getAddrPoolIndex(Ref));
>> +      }
>>        // 3) followed by a custom OP to tell the debugger about TLS (presumably)
>>        addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_lo_user);
>>      } else
>>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=185398&r1=185397&r2=185398&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Mon Jul  1 18:55:52 2013
>> @@ -248,7 +248,11 @@ unsigned DwarfUnits::getStringPoolIndex(
>>  }
>>
>>  unsigned DwarfUnits::getAddrPoolIndex(const MCSymbol *Sym) {
>> -  std::pair<DenseMap<const MCSymbol *, unsigned>::iterator, bool> P =
>> +  return getAddrPoolIndex(MCSymbolRefExpr::Create(Sym, Asm->OutContext));
>> +}
>> +
>> +unsigned DwarfUnits::getAddrPoolIndex(const MCSymbolRefExpr *Sym) {
>> +  std::pair<DenseMap<const MCSymbolRefExpr *, unsigned>::iterator, bool> P =
>>        AddressPool.insert(std::make_pair(Sym, NextAddrPoolNumber));
>>    if (P.second)
>>      ++NextAddrPoolNumber;
>> @@ -2357,10 +2361,11 @@ void DwarfUnits::emitAddresses(const MCS
>>
>>    // Get all of the address pool entries and put them in an array by their ID so
>>    // we can sort them.
>> -  SmallVector<std::pair<unsigned, const MCSymbol *>, 64> Entries;
>> +  SmallVector<std::pair<unsigned, const MCSymbolRefExpr *>, 64> Entries;
>>
>> -  for (DenseMap<const MCSymbol *, unsigned>::iterator I = AddressPool.begin(),
>> -                                                      E = AddressPool.end();
>> +  for (DenseMap<const MCSymbolRefExpr *, unsigned>::iterator
>> +           I = AddressPool.begin(),
>> +           E = AddressPool.end();
>>         I != E; ++I)
>>      Entries.push_back(std::make_pair(I->second, I->first));
>>
>> @@ -2368,8 +2373,8 @@ void DwarfUnits::emitAddresses(const MCS
>>
>>    for (unsigned i = 0, e = Entries.size(); i != e; ++i) {
>>      // Emit a label for reference from debug information entries.
>> -    if (const MCSymbol *Sym = Entries[i].second)
>> -      Asm->EmitLabelReference(Sym, Asm->getDataLayout().getPointerSize());
>> +    if (const MCSymbolRefExpr *Sym = Entries[i].second)
>> +      Asm->OutStreamer.EmitValue(Sym, Asm->getDataLayout().getPointerSize());
>>      else
>>        Asm->OutStreamer.EmitIntValue(0, Asm->getDataLayout().getPointerSize());
>>    }
>>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h?rev=185398&r1=185397&r2=185398&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h (original)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h Mon Jul  1 18:55:52 2013
>> @@ -197,7 +197,7 @@ typedef StringMap<std::pair<MCSymbol*, u
>>
>>  // A Symbol->unsigned mapping of addresses used by indirect
>>  // references.
>> -typedef DenseMap<const MCSymbol *, unsigned> AddrPool;
>> +typedef DenseMap<const MCSymbolRefExpr *, unsigned> AddrPool;
>>
>>  /// \brief Collects and handles information specific to a particular
>>  /// collection of units.
>> @@ -270,6 +270,7 @@ public:
>>
>>    /// \brief Returns the index into the address pool with the given
>>    /// label/symbol.
>> +  unsigned getAddrPoolIndex(const MCSymbolRefExpr *);
>>    unsigned getAddrPoolIndex(const MCSymbol *);
>>
>>    /// \brief Returns the address pool.
>>
>> Added: llvm/trunk/test/DebugInfo/X86/tls-fission.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/tls-fission.ll?rev=185398&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/DebugInfo/X86/tls-fission.ll (added)
>> +++ llvm/trunk/test/DebugInfo/X86/tls-fission.ll Mon Jul  1 18:55:52 2013
>> @@ -0,0 +1,31 @@
>> +; RUN: llc -split-dwarf=Enable -mtriple=x86_64-linux -O0 -filetype=asm < %s | FileCheck %s
>> +
>> +; FIXME: add relocation and DWARF expression support to llvm-dwarfdump & use
>> +; that here instead of raw assembly printing
>> +
>> +; CHECK: debug_info.dwo
>> +; 3 bytes of data in this DW_FORM_block1 representation of the location of 'tls'
>> +; CHECK: .byte 3{{ *}}# DW_AT_location
>> +; DW_OP_const_index (0xfx == 252) to refer to the debug_addr table
>> +; CHECK-NEXT: .byte 252
>> +; an index of zero into the debug_addr table
>> +; CHECK-NEXT: .byte 0
>> +; DW_OP_lo_user based on GCC/GDB extension presumably (by experiment) to support TLS
>> +; CHECK-NEXT: .byte 224
>> +; check that the expected TLS address description is the first thing in the debug_addr section
>> +; CHECK: debug_addr
>> +; CHECK-NEXT: .quad    tls at DTPOFF
>> +
>> + at tls = thread_local global i32 0, align 4
>> +
>> +!llvm.dbg.cu = !{!0}
>> +!llvm.module.flags = !{!7}
>> +
>> +!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.4 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !2, metadata !3, metadata !2, metadata !"tls.dwo"} ; [ DW_TAG_compile_unit ] [/tmp/tls.cpp] [DW_LANG_C_plus_plus]
>> +!1 = metadata !{metadata !"tls.cpp", metadata !"/tmp"}
>> +!2 = metadata !{i32 0}
>> +!3 = metadata !{metadata !4}
>> +!4 = metadata !{i32 786484, i32 0, null, metadata !"tls", metadata !"tls", metadata !"", metadata !5, i32 1, metadata !6, i32 0, i32 1, i32* @tls, null} ; [ DW_TAG_variable ] [tls] [line 1] [def]
>> +!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/tmp/tls.cpp]
>> +!6 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
>> +!7 = metadata !{i32 2, metadata !"Dwarf Version", i32 3}
>>
>>
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