[LLVMdev] [Mips][TargetOptions] How to properly instantiate TargetOptions in MC layer? (original) (raw)

Eric Christopher echristo at gmail.com
Thu Jan 29 12:00:30 PST 2015

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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