By the way, here is one case I tested where I was surprised GCC was not
more aggressive:
extern void bar();
int foo(int *i) {
if(*i) bar();
return *i;
}
With GCC 4.4.1 -O3 (Ubuntu, x86-64) this reloads *i if bar is called. I
suppose you have to allow that either "i" or "*i" is accessible as a
global. But this is a pretty big bummer, because it means that any
function call forces reloads of any data that was read from a pointer.
"restrict" doesn't help here, nor does "const". The only way to prevent
these reloads is to manually read the data into stack variable(s):
extern void bar();
int foo(int *i) {
int i_val = *i;
if(i_val) bar();
return i_val;
}
Josh
