[libc][Obvious] Some clean work with memmove.

libc/src/string/memmove.cpp

@@ -28,30 +28,30 @@ static inline void move_byte_backward(char *dest_m, const char *src_m,
 }
 
 LLVM_LIBC_FUNCTION(void *, memmove,
-                   (void *dest, const void *src, size_t count)) {
-  char *dest_c = reinterpret_cast<char *>(dest);
+                   (void *dst, const void *src, size_t count)) {
+  char *dest_c = reinterpret_cast<char *>(dst);
   const char *src_c = reinterpret_cast<const char *>(src);
 
-  // If the distance between src_c and dest_c is equal to or greater
-  // than count (integerAbs(src_c - dest_c) >= count), they would not overlap.
+  // If the distance between `src_c` and `dest_c` is equal to or greater
+  // than `count` (integerAbs(src_c - dest_c) >= count), they would not overlap.
   // e.g.   greater     equal       overlapping
   //        [12345678]  [12345678]  [12345678]
   // src_c: [_ab_____]  [_ab_____]  [_ab_____]
   // dest_c:[_____yz_]  [___yz___]  [__yz____]
 
-  // Use memcpy if src_c and dest_c do not overlap.
+  // Call `memcpy` if `src_c` and `dest_c` do not overlap.
   if (__llvm_libc::integerAbs(src_c - dest_c) >= static_cast<ptrdiff_t>(count))
     return __llvm_libc::memcpy(dest_c, src_c, count);
 
-  // Overlap cases.
-  // If dest_c starts before src_c (dest_c < src_c), copy forward(pointer add 1)
-  // from beginning to end.
-  // If dest_c starts after src_c (dest_c > src_c), copy backward(pointer add
-  // -1) from end to beginning.
-  // If dest_c and src_c start at the same address (dest_c == src_c),
+  // Overlapping cases.
+  // If `dest_c` starts before `src_c` (dest_c < src_c), copy
+  // forward(pointer add 1) from beginning to end.
+  // If `dest_c` starts after `src_c` (dest_c > src_c), copy
+  // backward(pointer add -1) from end to beginning.
+  // If `dest_c` and `src_c` start at the same address (dest_c == src_c),
   // just return dest.
   // e.g.    forward      backward
-  //             *-->        <--*
+  //                *->    <-*
   // src_c : [___abcde_]  [_abcde___]
   // dest_c: [_abc--___]  [___--cde_]
 
@@ -60,7 +60,7 @@ LLVM_LIBC_FUNCTION(void *, memmove,
     move_byte_forward(dest_c, src_c, count);
   if (dest_c > src_c)
     move_byte_backward(dest_c, src_c, count);
-  return dest;
+  return dst;
 }
 
 } // namespace __llvm_libc

libc/src/string/memmove.h

@@ -13,7 +13,7 @@
 
 namespace __llvm_libc {
 
-void *memmove(void *dest, const void *src, size_t count);
+void *memmove(void *dst, const void *src, size_t count);
 
 } // namespace __llvm_libc
 

libc/test/src/string/memmove_test.cpp

@@ -6,64 +6,65 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/string/memcmp.h"
 #include "src/string/memmove.h"
 #include "utils/CPP/ArrayRef.h"
 #include "utils/UnitTest/Test.h"
 
 class LlvmLibcMemmoveTest : public __llvm_libc::testing::Test {
 public:
-  void check_memmove(void *dest, const void *src, size_t count, const void *str,
+  void check_memmove(void *dst, const void *src, size_t count,
+                     const unsigned char *str,
                      const __llvm_libc::cpp::ArrayRef<unsigned char> expected) {
-    void *result = __llvm_libc::memmove(dest, src, count);
-    // Making sure the pointer returned is same with dest.
-    EXPECT_EQ(result, dest);
-    // expected is designed according to str.
-    // dest and src might be part of str.
-    // Making sure the str is same with expected.
-    EXPECT_EQ(__llvm_libc::memcmp(str, expected.data(), expected.size()), 0);
+    void *result = __llvm_libc::memmove(dst, src, count);
+    // Making sure the pointer returned is same with `dst`.
+    EXPECT_EQ(result, dst);
+    // `expected` is designed according to `str`.
+    // `dst` and `src` might be part of `str`.
+    // Making sure `str` is same with `expected`.
+    for (size_t i = 0; i < expected.size(); ++i)
+      EXPECT_EQ(str[i], expected[i]);
   }
 };
 
 TEST_F(LlvmLibcMemmoveTest, MoveZeroByte) {
-  unsigned char dest[] = {'a', 'b'};
+  unsigned char dst[] = {'a', 'b'};
   const unsigned char src[] = {'y', 'z'};
   const unsigned char expected[] = {'a', 'b'};
-  check_memmove(dest, src, 0, dest, expected);
+  check_memmove(dst, src, 0, dst, expected);
 }
 
-TEST_F(LlvmLibcMemmoveTest, OverlapThatDestAndSrcPointToSameAddress) {
+TEST_F(LlvmLibcMemmoveTest, OverlapThatDstAndSrcPointToSameAddress) {
   unsigned char str[] = {'a', 'b'};
   const unsigned char expected[] = {'a', 'b'};
   check_memmove(str, str, 1, str, expected);
 }
 
-TEST_F(LlvmLibcMemmoveTest, OverlapThatDestStartsBeforeSrc) {
+TEST_F(LlvmLibcMemmoveTest, OverlapThatDstStartsBeforeSrc) {
   // Set boundary at beginning and end for not overstepping when
   // copy forward or backward.
   unsigned char str[] = {'z', 'a', 'b', 'c', 'z'};
   const unsigned char expected[] = {'z', 'b', 'c', 'c', 'z'};
-  // dest is &str[1].
+  // `dst` is `&str[1]`.
   check_memmove(&str[1], &str[2], 2, str, expected);
 }
 
-TEST_F(LlvmLibcMemmoveTest, OverlapThatDestStartsAfterSrc) {
+TEST_F(LlvmLibcMemmoveTest, OverlapThatDstStartsAfterSrc) {
   unsigned char str[] = {'z', 'a', 'b', 'c', 'z'};
   const unsigned char expected[] = {'z', 'a', 'a', 'b', 'z'};
   check_memmove(&str[2], &str[1], 2, str, expected);
 }
 
-// e.g. dest follow src.
+// e.g. `dst` follow `src`.
 // str: [abcdefghij]
 //      [__src_____]
-//      [_____dest_]
-TEST_F(LlvmLibcMemmoveTest, SrcFollowDest) {
+//      [_____dst__]
+TEST_F(LlvmLibcMemmoveTest, SrcFollowDst) {
   unsigned char str[] = {'z', 'a', 'b', 'z'};
   const unsigned char expected[] = {'z', 'b', 'b', 'z'};
   check_memmove(&str[1], &str[2], 1, str, expected);
 }
 
-TEST_F(LlvmLibcMemmoveTest, DestFollowSrc) {
+TEST_F(LlvmLibcMemmoveTest, DstFollowSrc) {
   unsigned char str[] = {'z', 'a', 'b', 'z'};
   const unsigned char expected[] = {'z', 'a', 'a', 'z'};
   check_memmove(&str[2], &str[1], 1, str, expected);