On Wed, Sep 30, 2015 at 11:33 AM, Bin.Cheng <[email protected]> wrote:
> On Tue, Sep 29, 2015 at 1:21 AM, Jeff Law <[email protected]> wrote:
>> On 09/28/2015 05:28 AM, Bernd Schmidt wrote:
>>>
>>> On 09/28/2015 11:43 AM, Bin Cheng wrote:
>>>>
>>>> Bootstrap and test on x86_64 and x86_32. Will test it on aarch64. So
>>>> any
>>>> comments?
>>>>
>>>> Thanks,
>>>> bin
>>>>
>>>> 2015-09-28 Bin Cheng <[email protected]>
>>>>
>>>> * loop-invariant.c (struct def): New field cant_fwprop_to_addr_uses.
>>>> (inv_cant_fwprop_to_addr_use): New function.
>>>> (record_use): Call inv_cant_fwprop_to_addr_use, set the new field.
>>>> (get_inv_cost): Count cost if inv can't be propagated into its
>>>> address uses.
>>>
>>>
>>> It looks at least plausible.
>>
>> Definitely plausible. Many targets have restrictions on the immediate
>> offsets, so this potentially affects many targets (in a good way).
> Here is some more information.
> For spec2k6 on x86, no regression or obvious improvement.
> For spec2k6 on aarch64, several cases are improved.
> Given the results and your positive feedback, I will continue to work
> on this patch when I get back from holiday.
I further bootstrap and test attached patch on aarch64. Also three
cases in spec2k6/fp are improved by 3~6%, two cases in spec2k6/fp are
regressed by ~2%. Overall score is improved by ~0.8% for spec2k6/fp
on aarch64 of my run. I may later analyze the regression.
So is this patch OK?
Thanks,
bin
2015-10-09 Bin Cheng <[email protected]>
* loop-invariant.c (struct def): New field cant_prop_to_addr_uses.
(inv_cant_prop_to_addr_use): New function.
(record_use): Call inv_cant_prop_to_addr_use, set the new field.
(get_inv_cost): Count cost if inv can't be propagated into its
address uses.
>
>>
>>
>> Another option which I think has had some
>>>
>>> discussion recently would be to just move everything, and leave it to
>>> cprop to put things back together if the costs allow it.
>>
>> I go back and forth on this kind of approach.
> Hmm, either way we need to model rtx/register pressure costs, in loop
> invariant or cprop.
>
> Thanks,
> bin
>
>>
>> jeff
diff --git a/gcc/loop-invariant.c b/gcc/loop-invariant.c
index 52c8ae8..3c2395c 100644
--- a/gcc/loop-invariant.c
+++ b/gcc/loop-invariant.c
@@ -99,6 +99,8 @@ struct def
unsigned n_uses; /* Number of such uses. */
unsigned n_addr_uses; /* Number of uses in addresses. */
unsigned invno; /* The corresponding invariant. */
+ bool cant_prop_to_addr_uses; /* True if the corresponding inv can't be
+ propagated into its address uses. */
};
/* The data stored for each invariant. */
@@ -762,6 +764,34 @@ create_new_invariant (struct def *def, rtx_insn *insn,
bitmap depends_on,
return inv;
}
+/* Given invariant DEF and its address USE, check if the corresponding
+ invariant expr can be propagated into the use or not. */
+
+static bool
+inv_cant_prop_to_addr_use (struct def *def, df_ref use)
+{
+ struct invariant *inv;
+ rtx *pos = DF_REF_REAL_LOC (use), def_set;
+ rtx_insn *use_insn = DF_REF_INSN (use);
+ rtx_insn *def_insn;
+ bool ok;
+
+ inv = invariants[def->invno];
+ /* No need to check if address expression is expensive. */
+ if (!inv->cheap_address)
+ return true;
+
+ def_insn = inv->insn;
+ def_set = single_set (def_insn);
+ if (!def_set)
+ return true;
+
+ validate_unshare_change (use_insn, pos, SET_SRC (def_set), true);
+ ok = verify_changes (0);
+ cancel_changes (0);
+ return !ok;
+}
+
/* Record USE at DEF. */
static void
@@ -777,7 +807,11 @@ record_use (struct def *def, df_ref use)
def->uses = u;
def->n_uses++;
if (u->addr_use_p)
- def->n_addr_uses++;
+ {
+ def->n_addr_uses++;
+ if (!def->cant_prop_to_addr_uses && inv_cant_prop_to_addr_use (def, use))
+ def->cant_prop_to_addr_uses = true;
+ }
}
/* Finds the invariants USE depends on and store them to the DEPENDS_ON
@@ -1158,7 +1192,9 @@ get_inv_cost (struct invariant *inv, int *comp_cost,
unsigned *regs_needed,
if (!inv->cheap_address
|| inv->def->n_uses == 0
- || inv->def->n_addr_uses < inv->def->n_uses)
+ || inv->def->n_addr_uses < inv->def->n_uses
+ /* Count cost if the inv can't be propagated into address uses. */
+ || inv->def->cant_prop_to_addr_uses)
(*comp_cost) += inv->cost * inv->eqno;
#ifdef STACK_REGS
