llvm dev - May 2019 - 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
Puigsacalm, 7 
17458 - Fornells de la Selva
Girona

Tel: 620 28 45 13

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20190503/bfb0c6e9/attachment.html>

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
Puigsacalm, 7
17458 - Fornells de la Selva
Girona

Tel: 620 28 45 13

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20190503/36fd01bb/attachment.html>

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20190503/dcfbde1e/attachment.html>