d0p1/ack
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Take hreg aliases into account when finding evicted registers and performing

Browse source 
the register shuffle dance.
This commit is contained in:
David Given 2018-09-22 11:19:50 +02:00
parent bbb708717a
commit 99fcde69dc
1 changed files with 60 additions and 31 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

91
mach/proto/mcg/pass_registerallocator.c
View file

@ -18,6 +18,8 @@ static int insert_moves(struct basicblock* bb, int index,
static bool type_match(struct hreg* hreg, struct vreg* vreg); static bool type_match(struct hreg* hreg, struct vreg* vreg);
static bool constraints_match(struct hreg* hreg, struct vreg* vreg);
static void populate_hregs(void) static void populate_hregs(void)
{ {
int i; int i;
@ -102,33 +104,47 @@ static struct hreg* evict(struct vreg* vreg)
* doing some calculation here to figure out the cheapest register to * doing some calculation here to figure out the cheapest register to
* evict, but for now we're picking the first one. FIXME. */ * evict, but for now we're picking the first one. FIXME. */
tracef('R', "R: considering evicting a register to rehome %%%d\n", vreg->id);
for (i=0; i<hregs.count; i++) for (i=0; i<hregs.count; i++)
{ {
struct hreg* hreg = hregs.item[i]; struct hreg* hreg = hregs.item[i];
struct vreg* candidatein = pmap_findleft(current_ins, hreg); if ((hreg->attrs & vreg->type) && constraints_match(hreg, vreg))
struct vreg* candidateout = pmap_findleft(current_outs, hreg);
if (hreg->attrs & vreg->type)
{ {
if (!candidatein && /* Our vreg can be stored in this hreg. But it's only safe to
!candidateout && * evict the hreg if we can also evict all the hreg's aliases. */
!register_used(current_ins, hreg) &&
!register_used(current_outs, hreg)) int j;
{ for (j=0; j<hreg->aliases.count; j++)
/* This hreg is unused, so we don't need to evict anything. {
* Shouldn't really happen in real life. */ struct hreg* alias = hreg->aliases.item[j];
return hreg; struct vreg* candidatein = pmap_findleft(current_ins, alias);
} struct vreg* candidateout = pmap_findleft(current_outs, alias);
if (candidatein && candidateout && (candidatein == candidateout)) /* Check this is a through. */
{ if (candidatein != candidateout)
/* This is a through register. */ goto next_hreg;
tracef('R', "R: evicting %%%d from %s\n", candidatein->id, hreg->id); }
pmap_put(&evicted, candidatein, hreg);
pmap_remove(current_ins, hreg, candidatein); /* We've now verified that this hreg is safe to evict. */
pmap_remove(current_outs, hreg, candidatein);
return hreg; for (j=0; j<hreg->aliases.count; j++)
} {
struct hreg* alias = hreg->aliases.item[j];
struct vreg* candidatein = pmap_findleft(current_ins, alias);
struct vreg* candidateout = pmap_findleft(current_outs, alias);
/* Check this is a through. */
if (candidatein && (candidatein == candidateout))
{
tracef('R', "R: evicting %%%d from %s so we can use %s\n", candidatein->id, alias->id, hreg->id);
pmap_put(&evicted, candidatein, alias);
pmap_remove(current_ins, alias, candidatein);
pmap_remove(current_outs, alias, candidatein);
}
}
return hreg;
} }
next_hreg:;
} }
/* Couldn't find anything to evict */ /* Couldn't find anything to evict */
@ -233,7 +249,12 @@ static void add_input_register(struct vreg* vreg, struct hreg* hreg)
if (hreg) if (hreg)
{ {
if (hreg->is_stacked) if (!constraints_match(hreg, vreg))
{
/* This hint isn't allowed for this instruction. */
hreg = NULL;
}
else if (hreg->is_stacked)
{ {
/* This vreg is stacked; we need to put it in a register. That's /* This vreg is stacked; we need to put it in a register. That's
* slightly exciting because the vreg might be a through, which * slightly exciting because the vreg might be a through, which
@ -559,7 +580,7 @@ static void assign_hregs_to_vregs(void)
select_registers(hop, old, in, out); select_registers(hop, old, in, out);
tracef('R', "R: %d from $%d: [", hop->id, hop->ir->id); tracef('R', "R: %d from $%d: ins: [", hop->id, hop->ir->id);
for (k=0; k<hop->regsin.count; k++) for (k=0; k<hop->regsin.count; k++)
{ {
struct hreg* hreg = hop->regsin.item[k].left; struct hreg* hreg = hop->regsin.item[k].left;
@ -568,7 +589,7 @@ static void assign_hregs_to_vregs(void)
tracef('R', " "); tracef('R', " ");
tracef('R', "%%%d=>%s", vreg->id, hreg->id); tracef('R', "%%%d=>%s", vreg->id, hreg->id);
} }
tracef('R', "] ["); tracef('R', "] outs: [");
for (k=0; k<hop->regsout.count; k++) for (k=0; k<hop->regsout.count; k++)
{ {
struct hreg* hreg = hop->regsout.item[k].left; struct hreg* hreg = hop->regsout.item[k].left;
@ -612,17 +633,25 @@ static int insert_moves(struct basicblock* bb, int index,
struct hreg* other; struct hreg* other;
struct hop* hop; struct hop* hop;
/* Try and find a destination which isn't a source. */ /* Try and find a destination which isn't a source (or an alias of a source). */
src = NULL; src = NULL;
for (i=0; i<copies.count; i++) for (i=0; i<copies.count; i++)
{ {
int j;
dest = copies.item[i].right; dest = copies.item[i].right;
if (!pmap_findleft(&copies, dest))
{ for (j=0; j<dest->aliases.count; j++)
src = copies.item[i].left; {
break; struct hreg* alias = dest->aliases.item[j];
} if (pmap_findleft(&copies, alias))
goto nextcopy;
}
src = copies.item[i].left;
break;
nextcopy:;
} }
if (src) if (src)