Hi Andrew, Thanks so much for your explanation. I got it. I will address the issue.
Thanks Gui Haochen 在 2024/5/15 2:45, Andrew MacLeod 写道: > > On 5/9/24 04:47, HAO CHEN GUI wrote: >> Hi Mikael, >> >> Thanks for your comments. >> >> 在 2024/5/9 16:03, Mikael Morin 写道: >>> I think the canonical API behaviour sets R to varying and returns true >>> instead of just returning false if nothing is known about the range. >>> >>> I'm not sure whether it makes any difference; Aldy can probably tell. But >>> if the type is bool, varying is [0,1] which is better than unknown range. >> Should the varying be set by caller when fold_range returns false? >> Just like following codes in value-query.cc. >> >> if (!op.fold_range (r, type, r0, r1)) >> r.set_varying (type); >> > This would be dangerous in the general case. fold_range may have returned > false because 'type' is an unsupported range type. Generally this is why we > prefer range-ops to return TRUE and VARYING rather than FALSE for unknown > values. When FALSE is returned, we should stop working with ranges because > something is amok. > > Andrew >
