[PATCH] [AArch64] FPLoadBalancing: move ownership of the chain to its current accumulator register

[Arnaud A. de Grandmaison]

Committed @ r216721. Thanks James !

 

Cheers,

Arnaud A. de Grandmaison

 

From: mankeyrabbit at gmail.com [mailto:mankeyrabbit at gmail.com] On Behalf Of James Molloy
Sent: 29 August 2014 11:59
To: Arnaud De Grandmaison
Cc: LLVM Commits
Subject: Re: [PATCH] [AArch64] FPLoadBalancing: move ownership of the chain to its current accumulator register

 

Hi Arnaud,

 

LGTM, please commit.

 

Cheers,

 

James

 

On 29 August 2014 10:48, Arnaud A. de Grandmaison <arnaud.degrandmaison at arm.com> wrote:

While experimenting with the PBQP allocator on aarch64, it triggered a bug

in AArch64A57FPLoadBalancing.cpp, where an accumulator chain could be

reference from different accumulator registers at the same time.

 

The attached patch fixes it.

 

Coming up with a simple testcase is not easy, as this highly depends on

what the register allocator is doing: this issue showed up while working

with the PBQP allocator, which produced a different allocation scheme.

A testcase would need to come up with chain starting in D[0-7], then

Moving it to D[8-15], followed by a call to a function whose regmask

clobbers the starting accumulator in D[0-7], then another use of the chain.

 

I also fixed some formatting and added some invariant checks while there.

 

Cheers,

--

Arnaud A. de Grandmaison

 


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