llvm dev - Aug 2017 - [RFC] Enhance Partial Inliner by using a general outlining scheme for cold blocks

Hello Graham,

We are also starting some work in the general direction of
outlining/function splitting using profiling information.  In our case, we
are focusing on splitting functions into smaller parts to allow for a
better code layout and thus better Icache/ITLB utilization.

It wasn't clear to me from your description what type of subgraphs those
cold regions would generate, and whether you would need to extend the code
in CodeExtractor.h/FunctionCloner  to support those.

Abdoul-kader keita,
Compiler Engineering @ Facebook, Inc

Thanks,
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Hey Kader,

So I'm not sure what you mean by what type of subgraphs.  The cold regions
would be outlined into its own function (assuming single entry, single
exit), and there could be multiple regions we outline from a single
function.  I currently have a prototype that can do this type of outlining
without modifying the CodeExtractor, but the FunctionCloner needed some
changes to track multiple outline functions and its corresponding in the
parent function.

Graham Yiu
LLVM Compiler Development
IBM Toronto Software Lab
Office: (905) 413-4077      C2-707/8200/Markham
Email: gyiu at ca.ibm.com



From:	keita abdoul-kader via llvm-dev <llvm-dev at lists.llvm.org>
To:	llvm-dev at lists.llvm.org
Date:	08/25/2017 12:48 PM
Subject:	[llvm-dev] [RFC] Enhance Partial Inliner by using a general
            outlining scheme for cold blocks
Sent by:	"llvm-dev" <llvm-dev-bounces at lists.llvm.org>



Hello Graham,

We are also starting some work in the general direction of
outlining/function splitting using profiling information.  In our case, we
are focusing on splitting functions into smaller parts to allow for a
better code layout and thus better Icache/ITLB utilization.

It wasn't clear to me from your description what type of subgraphs those
cold regions would generate, and whether you would need to extend the code
in CodeExtractor.h/FunctionCloner  to support those.

Abdoul-kader keita,
Compiler Engineering @ Facebook, Inc

Thanks,

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