[lld] r189776 - Partially revert r189718 to add entry symbol to dead strip root.

[Shankar Easwaran]

First, I dont think setEntrySymbolName should add to the list of 
undefined symbols as soon as you see it.

If you still want to do that, make the setEntrySymbolName overridden in 
PECOFFLinkingContext and add your code there.

Default the behavior on how it was originally, that it just sets the 
internal protected variable, as ELF/MachO has the same usecase.

Thanks

Shankar Easwaran

On 9/2/2013 9:51 PM, Rui Ueyama wrote:
> Just rolling back this patch will again regress COFF handling, so I don't
> want to simply revert. Instead, I think I can add code to Driver.cpp to
> copy entry symbol name to deadStripRoot. In this way the two symbols won't
> be added in your example. What do you think?
>
>
> On Mon, Sep 2, 2013 at 6:50 PM, Shankar Easwaran <shankare at codeaurora.org>wrote:
>
>> Hi Ruiu,
>>
>> This cannot be done, there is a genuine case that if you set the entry
>> symbol twice like this
>>
>> lld -flavor gnu -target x86_64 -e _start -e main
>>
>> I want to take only the last entry symbol, now this will trigger an
>> undefine symbol twice.
>>
>> Can you please revert this change as it breaks ELF ?
>>
>> Thanks
>>
>> Shankar Easwaran
>>
>>
>>
>> On 9/2/2013 8:00 PM, Rui Ueyama wrote:
>>
>>> Author: ruiu
>>> Date: Mon Sep  2 20:00:01 2013
>>> New Revision: 189776
>>>
>>> URL: http://llvm.org/viewvc/llvm-**project?rev=189776&view=rev<http://llvm.org/viewvc/llvm-project?rev=189776&view=rev>
>>> Log:
>>> Partially revert r189718 to add entry symbol to dead strip root.
>>>
>>> Also added a test to verify that entry symbol is not stripped even if
>>> dead stripping is enabled.
>>>
>>> Added:
>>>       lld/trunk/test/pecoff/entry.**test
>>> Modified:
>>>       lld/trunk/include/lld/Core/**LinkingContext.h
>>>
>>> Modified: lld/trunk/include/lld/Core/**LinkingContext.h
>>> URL: http://llvm.org/viewvc/llvm-**project/lld/trunk/include/lld/**
>>> Core/LinkingContext.h?rev=**189776&r1=189775&r2=189776&**view=diff<http://llvm.org/viewvc/llvm-project/lld/trunk/include/lld/Core/LinkingContext.h?rev=189776&r1=189775&r2=189776&view=diff>
>>> ==============================**==============================**
>>> ==================
>>> --- lld/trunk/include/lld/Core/**LinkingContext.h (original)
>>> +++ lld/trunk/include/lld/Core/**LinkingContext.h Mon Sep  2 20:00:01
>>> 2013
>>> @@ -184,7 +184,9 @@ public:
>>>      // Set the entry symbol name. You may also need to call
>>> addDeadStripRoot() for
>>>      // the symbol if your platform supports dead-stripping, so that the
>>> symbol
>>>      // will not be removed from the output.
>>> -  virtual void setEntrySymbolName(StringRef name) {
>>> +  void setEntrySymbolName(StringRef name) {
>>> +    // Entry function have to be resolved as an undefined symbol.
>>> +    addInitialUndefinedSymbol(**name);
>>>        _entrySymbolName = name;
>>>      }
>>>
>>> Added: lld/trunk/test/pecoff/entry.**test
>>> URL: http://llvm.org/viewvc/llvm-**project/lld/trunk/test/pecoff/**
>>> entry.test?rev=189776&view=**auto<http://llvm.org/viewvc/llvm-project/lld/trunk/test/pecoff/entry.test?rev=189776&view=auto>
>>> ==============================**==============================**
>>> ==================
>>> --- lld/trunk/test/pecoff/entry.**test (added)
>>> +++ lld/trunk/test/pecoff/entry.**test Mon Sep  2 20:00:01 2013
>>> @@ -0,0 +1,9 @@
>>> +# REQUIRES: debug
>>> +# Verify that entry atom will not be dead-stripped.
>>> +
>>> +# RUN: yaml2obj %p/Inputs/main.obj.yaml > %t.obj
>>> +# RUN: lld -flavor link /mllvm -debug-only=WriterPECOFF /out:%t.exe \
>>> +# RUN:   /subsystem:console /entry:_main /force -- %t.obj >& %t.log
>>> +# RUN: FileCheck %s < %t.log
>>> +
>>> +CHECK: : _main
>>>
>>>
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>>>
>>>
>>>
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>>


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