[PATCH] VirtRegRewriter compile time reduction.

[Puyan Lotfi]

Added feedback changes.

PL

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> On May 21, 2015, at 11:46 AM, Matthias Braun <mbraun at apple.com> wrote:
> 
> Hi Puyan,
> 
> LGTM with the following nitpicks fixed:
> 
> +  /// addLiveIn - Add the specified register as a live in. Note that it is
> 
> +  /// sortUniqueLiveIns - Sorts and uniques the LiveIns vector. It can be
> 
> Don't repeat the method name in the documentation comment.
> 
> +  for (auto MBBI = MF->begin(), MBBE = MF->end(); MBBI != MBBE; ++MBBI)
> A range based for loop and the actual type instead of "auto" is better for readers of the code.
> 
> - Matthias
> 
> 
>> On May 21, 2015, at 9:59 AM, Mehdi Amini <mehdi.amini at apple.com> wrote:
>> 
>> Hi,
>> 
>> Your patch does not pass clang-format (80 columns limit for example).
>> It also seems to me that the loop you are adding could be a C++11 for-range loop.
>> 
>> — 
>> Mehdi
>> 
>>> On May 21, 2015, at 12:54 AM, Puyan Lotfi <plotfi at apple.com> wrote:
>>> 
>>> Hi
>>> 
>>> I have a patch (attached) for reducing compile time in VirtRegRewriter
>>> (especially for targets with a very high number of registers).
>>> 
>>> The patch changes how VirtRegRewriter::addMBBLiveIns adds registers to
>>> each MachineBasicBlock's LiveIns vector by adding registers to
>>> MachineBasicBlock::LiveIns without a isLiveIn check (the vector should
>>> be sorted and not have duplicates), and after all registers are added
>>> the LiveIns vector for each MachineBasicBlock for the current
>>> MachineFunction is sorted and uniqued (a call to sortUniqueLiveIns).
>>> This improves compile time by avoiding the O(LiveIns.size()) checks at
>>> every addLiveIn attempt which can get expensive if MRI->getNumVirtRegs()
>>> is high as this is number of iterations of the outer loop.
>>> 
>>> I'd like any feedback.
>>> 
>>> Thanks
>>> 
>>> PL
>>> 
>>> <VirtRegRewriterCompileTime.patch>_______________________________________________
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>> 
>> 
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