Hello.
On 31-05-2013 10:53, Clemens Ladisch wrote:
+ const unsigned long timing[] = { 5, 100, 500};
You'll save space and time if you also make this array "static",
otherwise the compiler will build the array every time this function is
called.
No, *const* specifier is enough to not build this array every time. It will be put into the .const section.
gcc disagrees:
$ cat const_static.c
int f(int x) {
const unsigned long timing[] = { 5, 100, 500};
static const unsigned long timing2[] = { 5, 100, 500};
return timing[x] + timing2[x];
}
$ gcc -Os -S const_static.c
$ cat const_static.s
...
timing2.0:
.long 5
.long 100
.long 500
...
movl 8(%ebp), %edx
movl $5, -16(%ebp)
movl $100, -12(%ebp)
movl $500, -8(%ebp)
movl timing2.0(,%edx,4), %eax
addl -16(%ebp,%edx,4), %eax
Hm, I remember I was convinced by somebody just *const* was enough
for the data to be put to .const section. Don't remember if he gave an
object code example... Well, it means that person was wrong. Mark, we
then need *static* as well...
Regards,
Clemens
WBR, Sergei
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