[AArch64] Re: [PATCH] Relax check against commuting XOR and ASHIFTRT in combine.c

Jeff Law law@redhat.com
Mon Sep 22 17:02:00 GMT 2014


On 09/22/14 05:16, Alan Lawrence wrote:
> Ok thanks Jeff. In that case I think I should draw this to the attention
> of the AArch64 maintainers to check the testsuite updates are OK before
> I commit...?
Can't hurt.

>
> Methinks it may be possible to get further, or at least increase our
> confidence, if I "mock" out try_widen_shift_mode, and/or try injecting
> some dubious RTL from a builtin, although this'll only give a momentary
> snapshot of behaviour. I may or may not have time to look into this
> though ;)...
Yea, it's something I'd pondered as well, though I tend to inject the 
RTL I want directly in the debugger.  The downside is doing so doesn't 
ensure various tables are updated properly, and I vaguely recall a 
per-pseudo table for the combiner's nonzero_bits, signbit_copies and 
friends.


jeff



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