[lld] r205391 - [ELF] Add -z muldefs option.

[Rui Ueyama]

On Tue, Apr 1, 2014 at 9:40 PM, Shankar Easwaran <shankare at codeaurora.org>wrote:

> On 4/1/2014 11:30 PM, Rui Ueyama wrote:
>
>> On Tue, Apr 1, 2014 at 9:17 PM, Shankar Easwaran <shankare at codeaurora.org
>> >wrote:
>>
>>  On 4/1/2014 11:12 PM, Rui Ueyama wrote:
>>>
>>>  On Tue, Apr 1, 2014 at 8:57 PM, Shankar Easwaran <shankarke at gmail.com
>>>>
>>>>> wrote:
>>>>>
>>>>   Author: shankare
>>>>
>>>>> Date: Tue Apr  1 22:57:37 2014
>>>>> New Revision: 205391
>>>>>
>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=205391&view=rev
>>>>> Log:
>>>>> [ELF] Add -z muldefs option.
>>>>>
>>>>> This adds -z muldefs option which is widely used over
>>>>> --allow-multiple-definition.
>>>>>
>>>>> This option is supported by the GNU linker.
>>>>>
>>>>> Modified:
>>>>>       lld/trunk/lib/Driver/GnuLdDriver.cpp
>>>>>       lld/trunk/test/elf/allowduplicates.objtxt
>>>>>
>>>>> Modified: lld/trunk/lib/Driver/GnuLdDriver.cpp
>>>>> URL:
>>>>> http://llvm.org/viewvc/llvm-project/lld/trunk/lib/Driver/
>>>>> GnuLdDriver.cpp?rev=205391&r1=205390&r2=205391&view=diff
>>>>>
>>>>> ============================================================
>>>>> ==================
>>>>> --- lld/trunk/lib/Driver/GnuLdDriver.cpp (original)
>>>>> +++ lld/trunk/lib/Driver/GnuLdDriver.cpp Tue Apr  1 22:57:37 2014
>>>>> @@ -440,6 +440,16 @@ bool GnuLdDriver::parse(int argc, const
>>>>>          groupStack.pop();
>>>>>          break;
>>>>>
>>>>> +    case OPT_z: {
>>>>> +      StringRef extOpt = inputArg->getValue();
>>>>> +      if (extOpt == "muldefs")
>>>>> +        ctx->setAllowDuplicates(true);
>>>>> +      else
>>>>> +        diagnostics << "warning: ignoring unknown argument for -z: "
>>>>> <<
>>>>> extOpt
>>>>> +                    << "\n";
>>>>> +      break;
>>>>> +    }
>>>>> +
>>>>>        case OPT_INPUT:
>>>>>        case OPT_l: {
>>>>>          bool isDashlPrefix = (inputArg->getOption().getID() == OPT_l);
>>>>>
>>>>> Modified: lld/trunk/test/elf/allowduplicates.objtxt
>>>>> URL:
>>>>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf/
>>>>> allowduplicates.objtxt?rev=205391&r1=205390&r2=205391&view=diff
>>>>>
>>>>> ============================================================
>>>>> ==================
>>>>> --- lld/trunk/test/elf/allowduplicates.objtxt (original)
>>>>> +++ lld/trunk/test/elf/allowduplicates.objtxt Tue Apr  1 22:57:37 2014
>>>>> @@ -1,8 +1,11 @@
>>>>> -# RUN: lld -flavor gnu -target x86_64 --allow-multiple-definition -r
>>>>> %s
>>>>> \
>>>>> -# RUN:     --output-filetype=yaml | FileCheck %s
>>>>> +# RUN: lld -flavor gnu -target x86_64 --allow-multiple-definition %s \
>>>>> +# RUN:     --output-filetype=yaml --noinhibit-exec | FileCheck %s
>>>>>    #
>>>>> -# RUN: not lld -flavor gnu -target x86_64 -r %s --output-filetype=yaml
>>>>> 2>&1 \
>>>>> -# RUN:   | FileCheck -check-prefix=ERROR %s
>>>>> +# RUN: not lld -flavor gnu -target x86_64 %s --output-filetype=yaml \
>>>>> +# RUN: --noinhibit-exec 2>&1 | FileCheck -check-prefix=ERROR %s
>>>>> +#
>>>>> +# RUN: lld -flavor gnu -target x86_64 -z muldefs %s \
>>>>> +# RUN: --noinhibit-exec --output-filetype=yaml | FileCheck %s
>>>>>
>>>>>   Why do you now need --noinhibit-exec?
>>>>>
>>>> The testcase previously used -r, which is not supported (or) not
>>> implemented at this time.
>>>
>>> --noinhibit-exec tries to keep the executable even if there is an
>>> undefined symbol, which in this case corresponds to _start undefined.
>>>
>>
>> -r was intentional -- although ELF writer does not support writing it,
>> YAML
>> writer does. It was slightly better than --noinhibit-exec because it did
>> not warn on unresolved symbols unlike --noinhibit-exec.
>>
>>
> You might already know, The -r option is not handled by YAML writer.
>
> The GnuLdDriver handles this and sets appropriate flags when -r option is
> seen in the LinkingContext, and nothing else is done with it, since you
> bypass the writer to the output yaml writer.
>
> With gnu, we consistently use --noinhibit-exec for all tests, and I would
> prefer to stay consistent with all tests.


Well, that's not true because I learned the use of -r from other test files
having .objtxt extension in the same directory.

Thanks
>
> Shankar Easwaran
> -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by the Linux Foundation
>
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