[llvm] r210814 - CodeGen: enable mov.w/mov.t pairs with minsize for WoA

Saleem Abdulrasool abdulras at fb.com
Thu Jun 12 17:11:06 PDT 2014

On Jun 12, 2014, at 1:46 PM, Tim Northover <t.p.northover at gmail.com> wrote:

>> +    // NOTE Windows on ARM needs to use mov.w/mov.t pairs to materialise 32-bit
>> +    // immediates as it is inherently position independent, and may be out of
>> +    // range otherwise.
> What does "inherently position independent" mean here? Because I can
> see no way in which the fragment you're testing could be loaded at an
> arbitrary address without runtime fixup.
> And if you are relying on runtime fixup, "inherently
> position-dependent" would probably be a better description.

Yes, these are accompanied by a IMAGE_REL_ARM_MOV32T relocation which will be adjusted if loaded an address other than the preferred base address.  I suppose that its a perspective thing: Windows requires that everything can be rebased, which makes it position independent.  The load itself is position dependent though.  I can adjust the comment if you like.

> Cheers.
> Tim.
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Saleem Abdulrasool
abdulras (at) fb (dot) com

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