[lld] r230219 - [ELF][Writer] Use llvm::StringMap instead

David Blaikie dblaikie at gmail.com
Mon Feb 23 09:43:50 PST 2015


On Mon, Feb 23, 2015 at 9:32 AM, Shankar Easwaran <shankare at codeaurora.org>
wrote:

> On 2/23/2015 10:56 AM, David Blaikie wrote:
>
>> On Mon, Feb 23, 2015 at 5:50 AM, Shankar Easwaran <
>> shankare at codeaurora.org>
>> wrote:
>>
>>  Author: shankare
>>> Date: Mon Feb 23 07:50:23 2015
>>> New Revision: 230219
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=230219&view=rev
>>> Log:
>>> [ELF][Writer] Use llvm::StringMap instead
>>>
>>>  This does change the semantics somewhat - StringMaps own their strings.
>> do
>> you need that? (if so, is there a test case for where the map<StringRef
>> was
>> insufficient?) Or does this use case neither require nor forbid copying
>> the
>> strings, and just benefit from the StringMap optimizations in memory, etc?
>>
>>  Thanks for the review!.
>
> Oh, I dont want StringMaps to start copying the strings and own it. Is the
> alternative to use llvm::DenseMap then ?
>
> The reason I dont want to use std::map was for performance.


If it's performance, it's possible that copying the strings is still better
than not - your perf experiments/numbers should show if it's the wrong
tradeoff.

But yeah, if you're running some experiments, it might be worth trying a
DenseMap to see if non-owning StringRefs are the better tradeoff.


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