On Mon, Jun 19, 2017 at 4:20 PM, Richard Biener
<richard.guent...@gmail.com> wrote:
> On Mon, Jun 19, 2017 at 3:40 PM, Bin.Cheng <amker.ch...@gmail.com> wrote:
>> On Wed, Jun 14, 2017 at 2:54 PM, Richard Biener
>> <richard.guent...@gmail.com> wrote:
>>> On Mon, Jun 12, 2017 at 7:03 PM, Bin Cheng <bin.ch...@arm.com> wrote:
>>>> Hi,
>>>> Current primitive cost model merges partitions with data references
>>>> sharing the same
>>>> base address. I believe it's designed to maximize data reuse in
>>>> distribution, but
>>>> that should be done by dedicated data reusing algorithm. At this stage of
>>>> merging,
>>>> we should be conservative and only merge partitions with the same
>>>> references.
>>>> Bootstrap and test on x86_64 and AArch64. Is it OK?
>>>
>>> Well, I'd say "conservative" is merging more, not less. For example
>>> splitting a[i+1] from a[i]
>>> would be bad(?), so I'd see to allow unequal DR_INIT as "equal" for
>>> merging. Maybe
>>> DR_INIT within a cacheline or so.
>>>
>>> How many extra distributions in say SPEC do you get from this change alone?
>> Hi,
>> I collected data for spec2006 only with/without this patch. I am a
>> bit surprised that it doesn't change the number of distributed loops.
>>>
>>> It shows also that having partition->reads_and_writes would be nice
>>> ... the code duplication
>> Yeah, I merged read/write data references in previous patch, now this
>> duplication is gone. Update patch attached. Is it OK?
>
> + gcc_assert (i < datarefs_vec.length ());
> + dr1 = datarefs_vec[i];
>
> these asserts are superfluous -- vec::operator[] does them as well.
>
> Ok if you remove them.
Done.
I realized I made mistakes when measuring the impact of this patch.
This patch only apparently causes failure of
gcc.dg/tree-ssa/ldist-6.c, so here is the updated patch. I also
collected the number of distributed loops in spec2k6 as below:
trunk: 5882
only this patch: 7130
whole patch series: 5237
So the conclusion is, this patch does aggressive distribution like
ldist-6.c, which means worse data-locality. The following patch does
more fusion which mitigates impact of this patch and results in
conservative distribution overall. But as we lack of data locality
cost model, ldist-6.c remains failed even after applying whole patch
series. Hmm, a cache-sensitive cost model is need for several passes
now, distribution, prefetch and (possible) interchange.
Richard, do you have second comment based on the new data?
Thanks,
bin
2017-06-20 Bin Cheng <bin.ch...@arm.com>
* tree-loop-distribution.c (ref_base_address): Delete.
(similar_memory_accesses): Rename ...
(share_memory_accesses): ... to this. Check if partitions access
the same memory reference.
(distribute_loop): Call share_memory_accesses.
gcc/testsuite/ChangeLog
2017-06-20 Bin Cheng <bin.ch...@arm.com>
* gcc.dg/tree-ssa/ldist-6.c: XFAIL.
From a002d0a88ab9e981d9c57bd8f1203072290623ad Mon Sep 17 00:00:00 2001
From: Bin Cheng <binch...@e108451-lin.cambridge.arm.com>
Date: Fri, 9 Jun 2017 12:41:36 +0100
Subject: [PATCH 08/13] share-memory-access-20170608.txt
---
gcc/testsuite/gcc.dg/tree-ssa/ldist-6.c | 2 +-
gcc/tree-loop-distribution.c | 69 +++++++++++++++------------------
2 files changed, 32 insertions(+), 39 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ldist-6.c b/gcc/testsuite/gcc.dg/tree-ssa/ldist-6.c
index 8eb1c62..e0a68d8 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ldist-6.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ldist-6.c
@@ -34,4 +34,4 @@ int loop1 (int k)
return a[1000-2] + b[1000-1] + c[1000-2] + d[1000-2];
}
-/* { dg-final { scan-tree-dump-times "distributed: split to 2 loops" 0 "ldist" } } */
+/* { dg-final { scan-tree-dump-times "distributed: split to 2 loops" 0 "ldist" { xfail *-*-* } } } */
diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index eafd119..119863f 100644
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -1268,30 +1268,16 @@ classify_partition (loop_p loop, struct graph *rdg, partition *partition)
}
}
-/* For a data reference REF, return the declaration of its base
- address or NULL_TREE if the base is not determined. */
-
-static tree
-ref_base_address (data_reference_p dr)
-{
- tree base_address = DR_BASE_ADDRESS (dr);
- if (base_address
- && TREE_CODE (base_address) == ADDR_EXPR)
- return TREE_OPERAND (base_address, 0);
-
- return base_address;
-}
-
-/* Returns true when PARTITION1 and PARTITION2 have similar memory
- accesses in RDG. */
+/* Returns true when PARTITION1 and PARTITION2 access the same memory
+ object in RDG. */
static bool
-similar_memory_accesses (struct graph *rdg, partition *partition1,
- partition *partition2)
+share_memory_accesses (struct graph *rdg,
+ partition *partition1, partition *partition2)
{
- unsigned i, j, k, l;
+ unsigned i, j;
bitmap_iterator bi, bj;
- data_reference_p ref1, ref2;
+ data_reference_p dr1, dr2;
/* First check whether in the intersection of the two partitions are
any loads or stores. Common loads are the situation that happens
@@ -1301,23 +1287,30 @@ similar_memory_accesses (struct graph *rdg, partition *partition1,
|| RDG_MEM_READS_STMT (rdg, i))
return true;
- /* Then check all data-references against each other. */
- EXECUTE_IF_SET_IN_BITMAP (partition1->stmts, 0, i, bi)
- if (RDG_MEM_WRITE_STMT (rdg, i)
- || RDG_MEM_READS_STMT (rdg, i))
- EXECUTE_IF_SET_IN_BITMAP (partition2->stmts, 0, j, bj)
- if (RDG_MEM_WRITE_STMT (rdg, j)
- || RDG_MEM_READS_STMT (rdg, j))
- {
- FOR_EACH_VEC_ELT (RDG_DATAREFS (rdg, i), k, ref1)
- {
- tree base1 = ref_base_address (ref1);
- if (base1)
- FOR_EACH_VEC_ELT (RDG_DATAREFS (rdg, j), l, ref2)
- if (base1 == ref_base_address (ref2))
- return true;
- }
- }
+ /* Then check whether the two partitions access the same memory object. */
+ EXECUTE_IF_SET_IN_BITMAP (partition1->datarefs, 0, i, bi)
+ {
+ dr1 = datarefs_vec[i];
+
+ if (!DR_BASE_ADDRESS (dr1)
+ || !DR_OFFSET (dr1) || !DR_INIT (dr1) || !DR_STEP (dr1))
+ continue;
+
+ EXECUTE_IF_SET_IN_BITMAP (partition2->datarefs, 0, j, bj)
+ {
+ dr2 = datarefs_vec[j];
+
+ if (!DR_BASE_ADDRESS (dr2)
+ || !DR_OFFSET (dr2) || !DR_INIT (dr2) || !DR_STEP (dr2))
+ continue;
+
+ if (operand_equal_p (DR_BASE_ADDRESS (dr1), DR_BASE_ADDRESS (dr2), 0)
+ && operand_equal_p (DR_OFFSET (dr1), DR_OFFSET (dr2), 0)
+ && operand_equal_p (DR_INIT (dr1), DR_INIT (dr2), 0)
+ && operand_equal_p (DR_STEP (dr1), DR_STEP (dr2), 0))
+ return true;
+ }
+ }
return false;
}
@@ -1654,7 +1647,7 @@ distribute_loop (struct loop *loop, vec<gimple *> stmts,
for (int j = i + 1;
partitions.iterate (j, &partition); ++j)
{
- if (similar_memory_accesses (rdg, into, partition))
+ if (share_memory_accesses (rdg, into, partition))
{
partition_merge_into (into, partition, FUSE_SHARE_REF);
partitions.unordered_remove (j);
--
1.9.1
