[PATCH] D105942: [SCEV] Fix unsound reasoning in howManyLessThans

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

As I mostly expected, my concerning validation result turned out to be a bug in my brute force checker program instead.  (C++ promotion rules bite again!)  I have checked the logic for this transform on both signed and unsigned comparisons for all 8 bit values of start, end, and stride.  The optimized form produces the same answer as both the generic n-bit ceiling logic (used in getUDivCeilSCEV) and an implementation of the N + (D - 1) /D formula using wide types.

Eli, it sounds like you're on board with me landing this.  Can I get a LGTM for the record?


Repository:
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https://reviews.llvm.org/D105942