llvm dev - Jan 2015 - [LLVMdev] [Mips][TargetOptions] How to properly instantiate TargetOptions in MC layer?

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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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
>  _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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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().

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().

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<mailto: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
_______________________________________________
LLVM Developers mailing list
LLVMdev at cs.uiuc.edu<mailto:LLVMdev at cs.uiuc.edu>        
http://llvm.cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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