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

[Krzysztof Parzyszek via Phabricator via llvm-commits]

kparzysz added inline comments.


================
Comment at: lib/Analysis/ScalarEvolution.cpp:10710
+      return UpperValid ? SE.getConstant(SU.getValue())
+                        : SE.getConstant(SL.getValue());
+
----------------
kparzysz wrote:
> efriedma wrote:
> > I'm not convinced this is correct: why is the "valid" solution guaranteed to be smaller?
> Are you referring to line 10720?  Because it's the number of iterations. Both solutions are positive and both are validated as leaving the range, so the smaller one will happen first.
In this line, either UpperValid or LowerValid are true, but not both.  If UpperValid is false, then the lower solution is.


Repository:
  rL LLVM

https://reviews.llvm.org/D48283