[APInt] Make operator<<= shift in place. Improve the implementation of tcShiftLeft and use it to implement operator<<=.

llvm-svn: 300526

1 files changed, 33 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/APIntTest.cpp b/llvm/unittests/ADT/APIntTest.cpp
index 0bd309dd087..0f1d2d6d8f9 100644
--- a/llvm/unittests/ADT/APIntTest.cpp
+++ b/llvm/unittests/ADT/APIntTest.cpp
@@ -2024,4 +2024,37 @@ TEST(APIntTest, LogicalRightShift) {
   EXPECT_EQ(0, neg_one.lshr(257));
 }
 
+TEST(APIntTest, LeftShift) {
+  APInt i256(APInt::getLowBitsSet(256, 2));
+
+  i256 <<= 1;
+  EXPECT_EQ(253U, i256.countLeadingZeros());
+  EXPECT_EQ(1U, i256.countTrailingZeros());
+  EXPECT_EQ(2U, i256.countPopulation());
+
+  i256 <<= 62;
+  EXPECT_EQ(191U, i256.countLeadingZeros());
+  EXPECT_EQ(63U, i256.countTrailingZeros());
+  EXPECT_EQ(2U, i256.countPopulation());
+
+  i256 <<= 65;
+  EXPECT_EQ(126U, i256.countLeadingZeros());
+  EXPECT_EQ(128U, i256.countTrailingZeros());
+  EXPECT_EQ(2U, i256.countPopulation());
+
+  i256 <<= 64;
+  EXPECT_EQ(62U, i256.countLeadingZeros());
+  EXPECT_EQ(192U, i256.countTrailingZeros());
+  EXPECT_EQ(2U, i256.countPopulation());
+
+  i256 <<= 63;
+  EXPECT_EQ(0U, i256.countLeadingZeros());
+  EXPECT_EQ(255U, i256.countTrailingZeros());
+  EXPECT_EQ(1U, i256.countPopulation());
+
+  // Ensure we handle large shifts of multi-word.
+  const APInt neg_one(128, static_cast<uint64_t>(-1), true);
+  EXPECT_EQ(0, neg_one.shl(257));
+}
+
 } // end anonymous namespace