derek@UUNET.UU.NET (Derek Clegg) (03/10/89)
/* Version:
* gcc version 1.34
* File:
* <this file>
* Problem:
* `gcc' fails to optimize fully in the case of dereference +
* autoincrement + pointer cast.
* Repeat by:
* % gcc -O -S <this file>
* Notes:
* `gcc' doesn't always take into account the size of the object pointed
* to by a pointer when dereferencing & autoincrementing. If the size is
* 1, 2, or 4 bytes, a simpler set of instructions could often be generated.
*
* The generated assembler isn't affected by any of the `-f' flags.
*
* gcc was compiled with `config.gcc sun3'.
* I am using a Sun 3/60 with UNIX 4.2 (Sun release 3.5).
*
* Derek B Clegg ({uunet,ucbcad,sun}!island!derek)
*/
void
xyzzy(int n, int *i1, int *i2, int k, char *s1, char *s2)
{
while (--n >= 0)
*i1++ = *i2++;
/*
* The above generates something similar to
* L4:
* movel a0@+,a1@+
* L2:
* subql #1,d0
* jpl L4
*/
while (--k >= 0)
*((int *)s1)++ = *((int *)s2)++;
/*
* This generates, however, something similar to
* L7:
* movel d2,a0
* addql #4,d2
* movel d1,a1
* addql #4,d1
* movel a1@,a0@
* L5:
* subql #1,d3
* jpl L7
*
* when, of course, the first sequence would be perfectly appropriate.
*/
}