Fix implementation of bit count functions.

test/base-unittests/bits-unittest.cc

Index: test/base-unittests/bits-unittest.cc
diff --git a/test/base-unittests/bits-unittest.cc b/test/base-unittests/bits-unittest.cc
index 689fb41daece31dffb2a3298dee66f3f903b3bf4..56d3d9261beb9aaab847de70f31e03d7b71b751f 100644
--- a/test/base-unittests/bits-unittest.cc
+++ b/test/base-unittests/bits-unittest.cc
@@ -10,6 +10,36 @@ namespace v8 {
 namespace base {
 namespace bits {
 
+TEST(BitsTest, CountSetBits32) {
+  EXPECT_EQ(0u, CountSetBits32(0));
+  EXPECT_EQ(1u, CountSetBits32(1));
+  EXPECT_EQ(8u, CountSetBits32(0x11111111));
+  EXPECT_EQ(16u, CountSetBits32(0xf0f0f0f0));
+  EXPECT_EQ(24u, CountSetBits32(0xfff0f0ff));
+  EXPECT_EQ(32u, CountSetBits32(0xffffffff));
+}
+
+
+TEST(BitsTest, CountLeadingZeros32) {
+  EXPECT_EQ(32u, CountLeadingZeros32(0));
+  EXPECT_EQ(31u, CountLeadingZeros32(1));
+  TRACED_FORRANGE(uint32_t, shift, 0, 31) {
+    EXPECT_EQ(31u - shift, CountLeadingZeros32(1u << shift));
+  }
+  EXPECT_EQ(4u, CountLeadingZeros32(0x0f0f0f0f));
+}
+
+
+TEST(BitsTest, CountTrailingZeros32) {
+  EXPECT_EQ(32u, CountTrailingZeros32(0));
+  EXPECT_EQ(31u, CountTrailingZeros32(0x80000000));
+  TRACED_FORRANGE(uint32_t, shift, 0, 31) {
+    EXPECT_EQ(shift, CountTrailingZeros32(1u << shift));
+  }
+  EXPECT_EQ(4u, CountTrailingZeros32(0xf0f0f0f0));
+}
+
+
 TEST(BitsTest, RotateRight32) {
   TRACED_FORRANGE(uint32_t, shift, 0, 31) {
     EXPECT_EQ(0u, RotateRight32(0u, shift));