On 7/17/23 15:14, Aldy Hernandez wrote:
> Instead of reading the known zero bits in IPA, read the value/mask
> pair which is available.
> 
> There is a slight change of behavior here.  I have removed the check
> for SSA_NAME, as the ranger can calculate the range and value/mask for
> INTEGER_CST.  This simplifies the code a bit, since there's no special
> casing when setting the jfunc bits.  The default range for VR is
> undefined, so I think it's safe just to check for undefined_p().

Final round of tests revealed a regression for which I've adjusted the 
testcase.

It turns out g++.dg/ipa/pure-const-3.C fails because IPA can now pick up 
value/mask from any pass that has an integrated ranger.  The test was 
previously disabling evrp and CCP, but now VRP[12], jump threading, and 
DOM can make value/mask adjustments visible to IPA so they must be 
disabled as well.

We've run into these scenarios multiple times in the past-- any 
improvements to the ranger pipeline causes everyone to get smarter, 
making changes visible earlier in the pipeline.

Aldy