[NFC][KnownBits] Add getMinValue() / getMaxValue() methods

As it can be seen from accompanying cleanup, it is not unheard of
to write `~Known.Zero` meaning "what maximal value can this KnownBits
produce". But i think `~Known.Zero` isn't *that* self-explanatory,
as compared to a method with a name.

Note that not all `~Known.Zero` places were cleaned up,
only those where this arguably improves things.

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index 68c3c7ad90d..2a8ea0657db 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -64,11 +64,11 @@ ConstantRange ConstantRange::fromKnownBits(const KnownBits &Known,
   // For unsigned ranges, or signed ranges with known sign bit, create a simple
   // range between the smallest and largest possible value.
   if (!IsSigned || Known.isNegative() || Known.isNonNegative())
-    return ConstantRange(Known.One, ~Known.Zero + 1);
+    return ConstantRange(Known.getMinValue(), Known.getMaxValue() + 1);
 
   // If we don't know the sign bit, pick the lower bound as a negative number
   // and the upper bound as a non-negative one.
-  APInt Lower = Known.One, Upper = ~Known.Zero;
+  APInt Lower = Known.getMinValue(), Upper = Known.getMaxValue();
   Lower.setSignBit();
   Upper.clearSignBit();
   return ConstantRange(Lower, Upper + 1);