[LLVMdev] [Mips][TargetOptions] How to properly instantiate TargetOptions in MC layer?

[Eric Christopher]

On Wed Jan 28 2015 at 11:59:18 AM Daniel Sanders <Daniel.Sanders at imgtec.com>
wrote:

>   Hi Eric,
>
>
>  The main thing we need to fix is that the selection between ELF32/ELF64
> needs to depend on the ABI being N64 and not on whether we used a mips-
> linux-gnu triple versus a mips64-linux-gnu triple. So 'clang -target
> mips-linux-gnu' -mips64r2 -mabi=64' should produce an ELF64 and 'clang
> -target mips64-linux-gnu -mips32r2 -mabi=32' should produce an ELF32. In
> terms of code, we need to get the ABI name to createMipsELFObjectWriter().
>
>
>
*nod* Frustrating, but not your fault for sure ;)


>  One of your commits on Monday (r227102) seems to make this a lot easier
> than it was looking last week when Vladimir and I were discussing this
> internally (I've been off sick so I only saw your commit last night). I
> haven't had chance to try this but I'm currently thinking that
> createMCAsmBackend() should have an LLVMTargetMachine* argument. The
> Mips-specific versions of this function can then get the ABI name from
> there and pass it down to createMipsELFObjectWriter().
>

Nope, can't do this. Unfortunately this will break the layering in that MC
isn't allowed to depend in this way. At best you can pass MCOptions down to
that level.

-eric

>
>
> *From:* llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] *On
> Behalf Of *Eric Christopher
> *Sent:* 28 January 2015 00:00
> *To:* Vladimir Medic; llvmdev at cs.uiuc.edu
> *Subject:* Re: [LLVMdev] [Mips][TargetOptions] How to properly
> instantiate TargetOptions in MC layer?
>
>
>
> You can't really get there from here is the short answer. You can possible
> get MCTargetOptions, but then you need to change all of the constructors
> and calls across all of the backends to do this.
>
> I fixed all of the things that are currently in tree - what are you seeing
> or what do you need migrated around?
>
>
>
> -eric
>
>
>
> ps. Also, cc'ing me on it would have likely gotten you a faster answer, I
> just noticed this while going through email.
>
>
>
> On Tue Jan 27 2015 at 5:49:58 AM Vladimir Medic <Vladimir.Medic at imgtec.com>
> wrote:
>
> Hi all,
> we have several features in Mips that are dependent on target abi. A
> recent commit(r224492) introduced a new -target-abi option to TargetOptions
> struct that provides access to abi string. This info is stored in
> MCSubtarget class(ARMSubratget in this case) and distributed to other
> libraries. Unfortunately, for Mips we need this info in other classes that
> don't have access to MCSubtarget class, like MCAsmBackend and
> MCTargetStreamer and instantiating a new copy od TargetOption causes  link
> errors as it is already instantiated in some drivers(llc.cpp for example).
> What would be the proper way to get the TargetOptions struct available in
> other classes?
>
> Kind regards,
>
> Vladimir
>
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