[lld] r229762 - PECOFF: Fix symbol aliases

[Shankar Easwaran]

Hi Rui,

This is only in the Context of modeling Alias symbols. I agree we dont 
want to bring the complete LayoutPass for simple usecases.

Do you have a different solution/design that works with ordinals to 
layout multiple alias atoms ?

Are you considering / need to support more than one alias to the *first 
*atom created for a file ?

Shankar Easwaran

On 2/18/2015 8:28 PM, Rui Ueyama wrote:
> I know you wanted to bring LayoutPass back, and I think I described about
> why that's not a good idea many times. The most recent discussion is this.
> Could you read this and then elaborate why you think we should use the
> LayoutPass based on that discussion?
>
> http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-February/082130.html
>
> On Wed, Feb 18, 2015 at 6:06 PM, Shankar Easwaran <shankare at codeaurora.org>
> wrote:
>
>> I feel using kindLayoutBefore references would be a preferred way for this
>> solution.
>>
>> We could enable the LayoutPass only if Alias symbols exist. Does COFF need
>> alias symbols for default operation ?
>>
>> Shankar Easwaran
>>
>>
>> On 2/18/2015 5:50 PM, Rui Ueyama wrote:
>>
>>> On Wed, Feb 18, 2015 at 3:47 PM, Shankar Easwaran <
>>> shankare at codeaurora.org>
>>> wrote:
>>>
>>>   On 2/18/2015 5:11 PM, Rui Ueyama wrote:
>>>>   +  alias->setOrdinal(target->ordinal() - 1);
>>>>>   Wouldn't this cause a wrap around when the ordinal of the first atom
>>>> is 0 ?
>>>>
>>>>      +// getNextOrdinal returns a monotonically increasaing uint64_t
>>>>> number
>>>>> +// starting from 1. There's a large gap between two numbers returned
>>>>> +// from this function, so that you can put other atoms between them.
>>>>> +uint64_t FileCOFF::getNextOrdinal() {
>>>>> +  return _ordinal++ << 32;
>>>>> +}
>>>>> +
>>>>>
>>>>>   Do you need it this to be shifted by 32 ? Wouldnt incrementing by 2 be
>>>> enough ?
>>>>
>>> You could define two or more aliases to a symbol so we need more room than
>>> for one alias. That doesn't work now, though.
>>>
>>>
>>>
>>>> Shankar Easwaran
>>>>
>>>> --
>>>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted
>>>> by the Linux Foundation
>>>>
>>>>
>>>>
>> --
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted
>> by the Linux Foundation
>>
>>


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

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