Hi Richard,
On 18/07/16 13:22, Richard Biener wrote:
<snip>
+ /* Record the original statements so that we can keep track of
+ statements emitted in this pass and not re-process new
+ statements. */
+ for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple *stmt = gsi_stmt (gsi);
+ if (!is_gimple_debug (stmt))
+ orig_stmts.add (stmt);
+ num_statements++;
+ }
please use gimple_set_visited () instead, that should be cheaper.
+ do
+ {
+ changes_made = false;
+ for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
...
+ }
+ while (changes_made);
looks pretty quadratic to me. Instead of tracking things with m_curr_base_expr
why not use a hash-map to track stores related to a base?
I've implemented this scheme but I'm having trouble making it work.
In particular I have a hash_map keyed on a 'tree' that is the base
object (as extracted by get_inner_reference) but I can't get the hash_map
to properly extract the already recorded stores to the same base.
For example for the simple code:
struct bar {
int a;
char b;
char c;
char d;
char e;
char f;
char g;
};
void
foo1 (struct bar *p)
{
p->b = 0;
p->a = 0;
p->c = 0;
p->d = 0;
p->e = 0;
}
As we can see, the stores are all to the same object and should
be recognised as such.
The base of the first store is recorded as:
<mem_ref 0x7f527a482820 ...>
and for the second store as <mem_ref 0x7f527a482848 ...>
where the dumps of the two mem_refs are identical except for that first
hex number (their address in memory?)
In my first version of the patch I compare these with operand_equal_p and that
detects that they are the same, but in the hash_map they are not detected
as equal. Is there some special hashing function I must specify?
Thanks,
Kyrill
