llvm dev - Oct 2020 - How to determine the most-immediate dominator from a set?

Hi llvm-dev,

Given an instruction, is there a standard way in llvm, such as a function or
methodology, to determine its most-immediate dominator from a set?

Many thanks,
Orlando
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Hi Orlando,

If I understand correctly, you should be able to use
`DT::findNearestCommonDominator` [1]. Because this function takes 2 blocks
at a time, you'd need to call it in a loop. Basically NCD(B1, B2, B3, ...)
= NCD(NCD(B1, B2), B3, ...).

Sincerely,
Jakub

[1]
https://llvm.org/doxygen/classllvm_1_1DominatorTreeBase.html#af555c3593d46d5f057fbebc8d292eac8

On Wed, Oct 21, 2020 at 11:03 AM Cazalet-Hyams, Orlando via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi llvm-dev,
>
>
>
> Given an instruction, is there a standard way in llvm, such as a function
> or
>
> methodology, to determine its most-immediate dominator from a set?
>
> Many thanks,
>
> Orlando
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>

-- 
Jakub Kuderski
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That looks useful, thanks for the help.

Orlando

From: Jakub (Kuba) Kuderski <kubakuderski at gmail.com>
Sent: 21 October 2020 20:09
To: Cazalet-Hyams, Orlando <orlando.hyams at sony.com>
Cc: llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] How to determine the most-immediate dominator from a
set?

Hi Orlando,

If I understand correctly, you should be able to use
`DT::findNearestCommonDominator` [1]. Because this function takes 2 blocks at a
time, you'd need to call it in a loop. Basically NCD(B1, B2, B3, ...) =
NCD(NCD(B1, B2), B3, ...).

Sincerely,
Jakub

[1]
https://llvm.org/doxygen/classllvm_1_1DominatorTreeBase.html#af555c3593d46d5f057fbebc8d292eac8

On Wed, Oct 21, 2020 at 11:03 AM Cazalet-Hyams, Orlando via llvm-dev
<llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>>
wrote:
Hi llvm-dev,

Given an instruction, is there a standard way in llvm, such as a function or
methodology, to determine its most-immediate dominator from a set?
Many thanks,
Orlando
_______________________________________________
LLVM Developers mailing list
llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev


--
Jakub Kuderski
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