Re: [RFC][PATCH] PR tree-optimization/109071 - -Warray-bounds false positive warnings due to code duplication from jump threading

[Qing Zhao <qing.zhao@oracle.com>]

> On May 14, 2024, at 13:14, Richard Biener <rguenther@suse.de> wrote:
> 
> On Tue, 14 May 2024, Qing Zhao wrote:
> 
>> 
>> 
>>> On May 14, 2024, at 10:29, Richard Biener <rguenther@suse.de> wrote:
>>> 
> [...]
>>> It would of course
>>> need experimenting since we can end up moving stmts and merging blocks
>>> though the linear traces created by jump threading should be quite
>>> stable (as opposed to say the unrolling case where multiple instances
>>> of the loop body likely will end up in the exact same basic block).
>> 
>> Do you mean, for loop unrolling the approach with one extra stmt for one 
>> basic block might be even harder and unreliable?
> 
> The question is whether the stmt marks the whole block or whether we
> for example add both a START and END stmt covering a copied path.
> I would guess for unrolling we need definitely need to do the latter
> (so we can diagnose "on the 3rd iteration of an unrolled loop" or
> similar).

Okay. I see. 

Is it possible that the START and END stmts might be moved around and out-of-place by the different optimizations?

Qing
> 
> Richard.
>