[PATCH] D48283: [SCEV] Properly solve quadratic equations

[Eli Friedman via Phabricator via llvm-commits]

efriedma added subscribers: mkazantsev, mzolotukhin.
efriedma added inline comments.


================
Comment at: lib/Analysis/ScalarEvolution.cpp:8715
+    Optional<APInt> Min = MinOptional(SO, UO);
+    if (Min.hasValue() && LeavesRange(*Min))
+      return { Min, true };
----------------
Min.hasValue() is always true here.


================
Comment at: lib/Analysis/ScalarEvolution.cpp:8719
+    if (Max.hasValue() && LeavesRange(*Max))
+      return { Max, true };
+
----------------
How do you ensure the correct solution isn't some value between Min and Max?

Similarly, in the case where SolveForBoundary returns None, how can you be sure the correct solution isn't some value between the Max for this boundary and the Min of the other boundary?


Repository:
  rL LLVM

https://reviews.llvm.org/D48283