[PATCH] Minor cleanup for GNU TLS support

[Eric Christopher]

On Sat, Oct 5, 2013 at 6:07 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> On Sat, Oct 5, 2013 at 5:45 PM, Richard Mitton <richard at codersnotes.com>
> wrote:
>>
>> It's better without the *user in the switch, as the code that calls it
>> will then just print 'invalid opcode %x' or whatever, as opposed to right
>> now, where it knows about DW_OP_lo_user+0, but not any other user OPs
>> (DW_OP_lo_user+N), which is silly.
>>
>> I don't think there's anything that really uses this much already, but
>> I'll see if I can figure something out to test it with and the update the
>> patch
>
>
> When we print assembly (rather than the usual debug info of emitting an
> object file and then using llvm-dwarfdump) we annotate the assembly with
> comments - but thinking about it, I don't think we annotate DWARF
> expressions/operators/etc, so this probably isn't visible. I wonder if we
> call the OperationEncodingString at all.
>

We may not, but it'll be nice to do so. It's handy to use when debugging anyhow.

-eric

>>
>> .
>>
>>
>> Eric Christopher wrote:
>>>
>>> Should dump differently I'd have thought. Also don't want to delete
>>> the DW_OP_*_user text I'd think.
>>>
>>> -eric
>>>
>>> On Sat, Oct 5, 2013 at 2:33 PM, Richard Mitton<richard at codersnotes.com>
>>> wrote:
>>>
>>>>>
>>>>> No functionality change.
>>>>>
>>>>
>>>> Nothing to test! :)
>>>>
>>>>
>>>>
>>>> Eric Christopher wrote:
>>>>
>>>>>
>>>>> Testcase? :)
>>>>>
>>>>> -eric
>>>>>
>>>>> On Sat, Oct 5, 2013 at 11:19 AM, Richard
>>>>> Mitton<richard at codersnotes.com>
>>>>> wrote:
>>>>>
>>>>>
>>>>>>
>>>>>> Formally added an explicit enum for DWARF TLS support. No
>>>>>> functionality
>>>>>> change.
>>>>>>
>>>>>>
>>>>>> http://llvm-reviews.chandlerc.com/D1845
>>>>>>
>>>>>> Files:
>>>>>>     include/llvm/Support/Dwarf.h
>>>>>>     lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>>>>     lib/Support/Dwarf.cpp
>>>>>>
>>>>>> Index: include/llvm/Support/Dwarf.h
>>>>>> ===================================================================
>>>>>> --- include/llvm/Support/Dwarf.h
>>>>>> +++ include/llvm/Support/Dwarf.h
>>>>>> @@ -486,6 +486,9 @@
>>>>>>      DW_OP_lo_user = 0xe0,
>>>>>>      DW_OP_hi_user = 0xff,
>>>>>>
>>>>>> +  // Extensions for GNU-style thread-local storage.
>>>>>> +  DW_OP_GNU_push_tls_address = 0xe0,
>>>>>> +
>>>>>>      // Extensions for Fission proposal.
>>>>>>      DW_OP_GNU_addr_index = 0xfb,
>>>>>>      DW_OP_GNU_const_index = 0xfc,
>>>>>> Index: lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>>>> ===================================================================
>>>>>> --- lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>>>> +++ lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>>>>>> @@ -1513,14 +1513,15 @@
>>>>>>            // 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
>>>>>> +        // 2) containing the (relocated) offset of the TLS variable
>>>>>> +        //    within the module's TLS block.
>>>>>>            addExpr(Block, 0, dwarf::DW_FORM_udata, Expr);
>>>>>>          } else {
>>>>>>            addUInt(Block, 0, dwarf::DW_FORM_data1,
>>>>>> dwarf::DW_OP_GNU_const_index);
>>>>>>            addUInt(Block, 0, dwarf::DW_FORM_udata,
>>>>>> DU->getAddrPoolIndex(Expr));
>>>>>>          }
>>>>>> -      // 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);
>>>>>> +      // 3) followed by a custom OP to make the debugger do a TLS
>>>>>> lookup.
>>>>>> +      addUInt(Block, 0, dwarf::DW_FORM_data1,
>>>>>> dwarf::DW_OP_GNU_push_tls_address);
>>>>>>        } else
>>>>>>          addOpAddress(Block, Sym);
>>>>>>        // Do not create specification DIE if context is either compile
>>>>>> unit
>>>>>> Index: lib/Support/Dwarf.cpp
>>>>>> ===================================================================
>>>>>> --- lib/Support/Dwarf.cpp
>>>>>> +++ lib/Support/Dwarf.cpp
>>>>>> @@ -456,10 +456,11 @@
>>>>>>      case DW_OP_bit_piece:                  return "DW_OP_bit_piece";
>>>>>>      case DW_OP_implicit_value:             return
>>>>>> "DW_OP_implicit_value";
>>>>>>      case DW_OP_stack_value:                return
>>>>>> "DW_OP_stack_value";
>>>>>> -  case DW_OP_lo_user:                    return "DW_OP_lo_user";
>>>>>> -  case DW_OP_hi_user:                    return "DW_OP_hi_user";
>>>>>>
>>>>>> -    // DWARF5 Fission Proposal Op Extensions
>>>>>> +  // GNU thread-local storage
>>>>>> +  case DW_OP_GNU_push_tls_address:       return
>>>>>> "DW_OP_GNU_push_tls_address";
>>>>>> +
>>>>>> +  // DWARF5 Fission Proposal Op Extensions
>>>>>>      case DW_OP_GNU_addr_index:             return
>>>>>> "DW_OP_GNU_addr_index";
>>>>>>      case DW_OP_GNU_const_index:            return
>>>>>> "DW_OP_GNU_const_index";
>>>>>>      }
>>>>>>
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