add an evil macro expansion perf test from Neil.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@40138 91177308-0d34-0410-b5e6-96231b3b80d8

INPUTS/stpcpy-test.c

+#define __extension__
+
+#define __stpcpy(dest, src) (__extension__ (__builtin_constant_p (src) ? (__string2_1bptr_p (src) && strlen (src) + 1 <= 8 ? __stpcpy_small (dest, __stpcpy_args (src), strlen (src) + 1) : ((char *) __mempcpy (dest, src, strlen (src) + 1) - 1)) : __stpcpy (dest, src)))
+#define stpcpy(dest, src) __stpcpy (dest, src)
+#define __stpcpy_args(src) __extension__ __STRING2_SMALL_GET16 (src, 0), __extension__ __STRING2_SMALL_GET16 (src, 4), __extension__ __STRING2_SMALL_GET32 (src, 0), __extension__ __STRING2_SMALL_GET32 (src, 4)
+
+#define __mempcpy(dest, src, n) (__extension__ (__builtin_constant_p (src) && __builtin_constant_p (n) && __string2_1bptr_p (src) && n <= 8 ? __mempcpy_small (dest, __mempcpy_args (src), n) : __mempcpy (dest, src, n)))
+#define mempcpy(dest, src, n) __mempcpy (dest, src, n)
+#define __mempcpy_args(src) ((char *) (src))[0], ((char *) (src))[2], ((char *) (src))[4], ((char *) (src))[6], __extension__ __STRING2_SMALL_GET16 (src, 0), __extension__ __STRING2_SMALL_GET16 (src, 4), __extension__ __STRING2_SMALL_GET32 (src, 0), __extension__ __STRING2_SMALL_GET32 (src, 4)
+
+#define __STRING2_SMALL_GET16(src, idx) (((__const unsigned char *) (__const char *) (src))[idx + 1] << 8 | ((__const unsigned char *) (__const char *) (src))[idx])
+
+#define __STRING2_SMALL_GET32(src, idx) (((((__const unsigned char *) (__const char *) (src))[idx + 3] << 8 | ((__const unsigned char *) (__const char *) (src))[idx + 2]) << 8 | ((__const unsigned char *) (__const char *) (src))[idx + 1]) << 8 | ((__const unsigned char *) (__const char *) (src))[idx])
+
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)
+stpcpy (stpcpy (stpcpy (stpcpy (a, b), c), d), e)