[PATCH] D12799: [ValueTracking] Teach isKnownNonZero a new trick

[hfinkel@anl.gov via llvm-commits]

hfinkel added inline comments.

================
Comment at: lib/Analysis/ValueTracking.cpp:1832
@@ +1831,3 @@
+    if (ConstantInt *Shift = dyn_cast<ConstantInt>(Y))
+      if (Shift->getLimitedValue() < BitWidth) {
+        APInt KnownZero(BitWidth, 0);
----------------
I don't think this check is necessary, and you can just use Shift->getLimitedValue(BitWidth-1) below, because it is undefined behavior for the number to be larger than that regardless.



Repository:
  rL LLVM

http://reviews.llvm.org/D12799