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

[Arnaud A. de Grandmaison]

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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