[llvm-dev] LLVM Virtual registers after RA pass?

Joan Lluch via llvm-dev llvm-dev at lists.llvm.org
Fri May 3 13:31:50 PDT 2019

Hi Matt,

Overriding both “requiresFrameIndexScavenging” and “requiresRegisterScavenging” to return true did the trick. 

Thanks !!

Joan Lluch

Tel: 620 28 45 13

> On 3 May 2019, at 19:55, Arsenault, Matthew <Matthew.Arsenault at amd.com> wrote:
> There are a number of hooks to control this in PrologEpilogInserter spread between TargetFrameLowering and TargetRegisterInfo. The one you most want to look at is probably TargetRegisterInfo::requiresFrameIndexScavenging.
> -Matt
> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of llvm-dev <llvm-dev at lists.llvm.org>
> Reply-To: Joan Lluch <joan.lluch at icloud.com>
> Date: Friday, May 3, 2019 at 7:50 PM
> To: llvm-dev <llvm-dev at lists.llvm.org>
> Subject: [llvm-dev] LLVM Virtual registers after RA pass?
> I need to use ‘createVirtualRegister’ for a specific case in my ‘eliminateFrameIndex’ function implementation.
> However, whenever that code is executed, I get the assertion "MachineCopyPropagation should be run after register allocation!” at a later stage.
> I have seen that at least a couple of backend implementations (including ARM Thumb) create virtual registers in ‘eliminatedFrameIndex’.
> What am I missing?, is there something that I need to set for virtual registers to be allowed after the RA pass, and specifically in the ‘eliminateFrameIndex’ function?
> Thanks,
> Joan Lluch

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