[Cryptography] Compiler optimization side channel

[Dave Horsfall]

On Fri, 23 Aug 2024, Phillip Hallam-Baker wrote:

[...]

> Which looked all well and good. But then I thought to myself, what if 
> the compiler gets hold of that data and decides to optimize the 
> arithmetic creating temporary variables that it leaves hanging about?

This raises something that I've been thinking about for a while; having 
written your carefully-crafted code, why would anyone want an "optimiser" 
to get its paws on it?

I've been bitten before by the optimiser (C, not C#) which decided that a 
floating point instruction was redundant; I had to buy a book on Intel 
assembly (ick!), and study the code before and after "-O".

-- Dave