LibCrypto+LibJS: Better bigint bitwise_and binop

Bitwise and is defined in terms of two's complement, so some converting
needs to happen for SignedBigInteger's sign/magnitude representation to
work out.

UnsignedBigInteger::bitwise_not() is repurposed to convert all
high-order zero bits to ones up to a limit, for the two's complement
conversion to work.

Fixes test262/test/language/expressions/bitwise-and/bigint.js.

1 files changed, 4 insertions, 2 deletions

diff --git a/Tests/LibCrypto/TestBigInteger.cpp b/Tests/LibCrypto/TestBigInteger.cpp
index 16cf58ae8c..8a58102cb9 100644
--- a/Tests/LibCrypto/TestBigInteger.cpp
+++ b/Tests/LibCrypto/TestBigInteger.cpp
@@ -478,9 +478,11 @@ TEST_CASE(test_signed_bigint_bitwise_and)
     auto num1 = "-1234567"_sbigint;
     auto num2 = "1234567"_sbigint;
     EXPECT_EQ(num1.bitwise_and(num1), num1);
-    EXPECT_EQ(num1.bitwise_and(num2), num2);
-    EXPECT_EQ(num2.bitwise_and(num1), num2);
+    EXPECT_EQ(num1.bitwise_and(num2), "1"_sbigint);
+    EXPECT_EQ(num2.bitwise_and(num1), "1"_sbigint);
     EXPECT_EQ(num2.bitwise_and(num2), num2);
+
+    EXPECT_EQ("-3"_sbigint.bitwise_and("-2"_sbigint), "-4"_sbigint);
 }
 
 TEST_CASE(test_bigint_bitwise_xor)