[lld] r227711 - [test] Add test for section groups and deadstrip

[Shankar Easwaran]

The test case here tests using YAML and lld core( which uses --dead-strip).

On 2/5/2015 5:15 PM, Rui Ueyama wrote:
> I added --gc-sections and used it in your testcase. And... it crashed. :(
>
> I guess the garbage collector reclaims live atoms. I wouldn't be surprised
> because ELF reader has never been tested with garbage collection enabled.
>
> On Thu, Feb 5, 2015 at 3:05 PM, Rui Ueyama <ruiu at google.com> wrote:
>
>> Looks like the GNU driver doesn't support --gc-sections, and the
>> gc-sections feature is turned off by default. So no section is removed as
>> long as you are using the GNU driver.
>>
>> I think we first have to add that command line option to the driver to
>> turn on the flag in the linking context. Whether turning on the flag is
>> enough or not is that I don't know. We should just try.
>>
>> On Thu, Feb 5, 2015 at 2:53 PM, Rafael Espíndola <
>> rafael.espindola at gmail.com> wrote:
>>
>>> I think this is testing for a gnu ld bug/limitation:
>>>
>>> With the attached testcase, gnu ld keeps zed and bar. Gold keeps only bar.
>>>
>>> lld keeps _start, bad, zed and produces wrong bindings :-(
>>>
>>>
>>> On 1 February 2015 at 00:47, Shankar Easwaran <shankare at codeaurora.org>
>>> wrote:
>>>> Author: shankare
>>>> Date: Sat Jan 31 23:47:02 2015
>>>> New Revision: 227711
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=227711&view=rev
>>>> Log:
>>>> [test] Add test for section groups and deadstrip
>>>>
>>>> This adds a test that deadstrip should preserve the section group even
>>> if there
>>>> is only one reference to a function in the group.
>>>>
>>>> Added:
>>>>      lld/trunk/test/core/sectiongroup-deadstrip.objtxt
>>>>
>>>> Added: lld/trunk/test/core/sectiongroup-deadstrip.objtxt
>>>> URL:
>>> http://llvm.org/viewvc/llvm-project/lld/trunk/test/core/sectiongroup-deadstrip.objtxt?rev=227711&view=auto
>>> ==============================================================================
>>>> --- lld/trunk/test/core/sectiongroup-deadstrip.objtxt (added)
>>>> +++ lld/trunk/test/core/sectiongroup-deadstrip.objtxt Sat Jan 31
>>> 23:47:02 2015
>>>> @@ -0,0 +1,92 @@
>>>> +# Test for section group members be preserved even if there is a
>>>> +# reference to only one functions in the group.
>>>> +# RUN: lld -core --dead-strip %s | FileCheck %s
>>>> +
>>>> +#
>>>> +# Test that section groups are parsed properly when there is a
>>> reference to a
>>>> +# group atom from outside a group.
>>>> +#
>>>> +
>>>> +---
>>>> +defined-atoms:
>>>> +  - name:         entry
>>>> +    dead-strip:   never
>>>> +    references:
>>>> +    - offset:          1
>>>> +      kind:            pcrel32
>>>> +      target:          d1
>>>> +  - name:            f1
>>>> +    scope:           global
>>>> +    type:            code
>>>> +  - name:            f2
>>>> +    scope:           global
>>>> +    type:            code
>>>> +  - name:            g1
>>>> +    scope:           global
>>>> +    type:            code
>>>> +  - name:            d1
>>>> +    scope:           global
>>>> +    type:            data
>>>> +  - name:            g1
>>>> +    scope:           global
>>>> +    type:            group-comdat
>>>> +    references:
>>>> +      - kind:            group-child
>>>> +        target:          f1
>>>> +      - kind:            group-child
>>>> +        target:          f2
>>>> +      - kind:            group-child
>>>> +        target:          d1
>>>> +      - kind:            group-child
>>>> +        target:          g1
>>>> +  - name:            anotherfunction
>>>> +    scope:           global
>>>> +    type:            data
>>>> +    references:
>>>> +      - kind:            layout-before
>>>> +        target:          f1
>>>> +---
>>>> +undefined-atoms:
>>>> +    - name:              f1
>>>> +      can-be-null:       never
>>>> +...
>>>> +
>>>> +#CHECK: defined-atoms:
>>>> +#CHECK:   - name:            g1
>>>> +#CHECK:     ref-name:        [[PARENT:[a-zA-Z\.0-9_]+]]
>>>> +#CHECK:     scope:           global
>>>> +#CHECK:     type:            group-comdat
>>>> +#CHECK:     references:
>>>> +#CHECK:       - kind:            group-child
>>>> +#CHECK:         offset:          0
>>>> +#CHECK:         target:          [[GCHILDONE:[a-zA-Z\.0-9_]+]]
>>>> +#CHECK:       - kind:            group-child
>>>> +#CHECK:         offset:          0
>>>> +#CHECK:         target:          [[GCHILDTWO:[a-zA-Z\.0-9_]+]]
>>>> +#CHECK:       - kind:            group-child
>>>> +#CHECK:         offset:          0
>>>> +#CHECK:         target:          [[GCHILDTHREE:[a-zA-Z\.0-9_]+]]
>>>> +#CHECK:       - kind:            group-child
>>>> +#CHECK:         offset:          0
>>>> +#CHECK:         target:          [[GCHILDFOUR:[a-zA-Z\.0-9_]+]]
>>>> +#CHECK:   - name:            f1
>>>> +#CHECK:     ref-name:        [[GCHILDONE]]
>>>> +#CHECK:     scope:           global
>>>> +#CHECK:   - name:            f2
>>>> +#CHECK:     ref-name:        [[GCHILDTWO]]
>>>> +#CHECK:     scope:           global
>>>> +#CHECK:   - name:            d1
>>>> +#CHECK:     ref-name:        [[GCHILDTHREE]]
>>>> +#CHECK:     scope:           global
>>>> +#CHECK:     type:            data
>>>> +#CHECK:   - name:            g1
>>>> +#CHECK:     ref-name:        [[GCHILDFOUR]]
>>>> +#CHECK:     scope:           global
>>>> +#CHECK:   - name:            anotherfunction
>>>> +#CHECK:     scope:           global
>>>> +#CHECK:     type:            data
>>>> +#CHECK:     references:
>>>> +#CHECK:       - kind:            layout-before
>>>> +#CHECK:         offset:          0
>>>> +#CHECK:         target:          [[GCHILDONE]]
>>>> +#CHECK: ...
>>>>
>>>>
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>>


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