[llvm-dev] [AArch64] Address computation folding

[Tim Northover via llvm-dev]

On 11 November 2015 at 11:57, Meador Inge <meadori at gmail.com> wrote:
> Why wouldn't it consider the number of uses in any operation?  The
> "expected" code is easy to get by checking the number of uses.  This
> may be desirable on some micro-architectures depending on the cost of
> the various loads and stores.

As you say, very microarchitecture-dependent. The code produced is
probably optimal for Cyclone ("[x0, x8]" is no more expensive than
"[x8]" and the "lsl" is slightly cheaper than the complicated "add").
If I'm reading the Cortex-A57 optimisation guide correctly, the same
reasoning applies there too.

Cheers.

Tim.