Re: Which pass optimizes if (x != x + 10) to if (1)?

[Andrew Haley <aph@xxxxxxxxxx>]

On 03/21/2012 07:00 AM, Zhenqiang Chen wrote:
> Thank you for the comment. I found the root cause. In function
> tree_swap_operands_p (fold-const.c), there is a check
> 
> if (optimize_function_for_size_p (cfun))
>     return 0;
> 
> which blocks to swap (x != x + 10) to (x + 10 != x). And the following
> optimization can only handle (x + 10 != x).
> 
> In most cases, constant-folding will benefit for code size. Any reason
> to add this check?

If you search the history you'll probably find a bug that was
fixed by this (admittedly rather odd) test.

Andrew.