Add unit tests for BitVector, minor BV rewrite fix (#1622)

This commit adds unit tests for the BitVector class and adds some additional argument checks. Additionally, it fixes a minor issue in the ZeroExtendUltConst rule if the zero_extend was by 0 bits. In that case, the rule was calling BitVector::extract() with high < low.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/util/bitvector.cpp b/src/util/bitvector.cpp
index 2d94be875..549c94dc9 100644
--- a/src/util/bitvector.cpp
+++ b/src/util/bitvector.cpp
@@ -90,6 +90,8 @@ BitVector BitVector::concat(const BitVector& other) const
 
 BitVector BitVector::extract(unsigned high, unsigned low) const
 {
+  CheckArgument(high < d_size, high);
+  CheckArgument(low <= high, low);
   return BitVector(high - low + 1,
                    d_value.extractBitRange(high - low + 1, low));
 }