[Valgrind-developers] Iop_Leftxx semantics

[Florian K. <fl...@ei...>]

What is the semantics of Iop_Left32 and friends?

In libvex_ir.h it says:  \x -> x | -x
which is not descriptive at all.
I could simply copy that formula over and use in the constant folding checker.
But by doing so it is impossible to find any bugs - be it in VEX's fold_expr or 
in the checker program. So I want to write my own implementation of that IROp.
Can't do without a spec...

I took a guess and thought that "left" perhaps meant to left-propagate the 
left-most "1" bit. E.g. 00000101 --> 11111101
But that's not it.. In fact for every odd integer the result has all bits set.

Before I pester Julian .... Anybody knows anything?

Thanks,
    Florian