Hi,
thanks for looking at this.
On Fri, Jun 02 2023, Richard Biener wrote:
> On Mon, 29 May 2023, Martin Jambor wrote:
>
[...]
>> diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
>> index 27c84e78fcf..33215b5fc82 100644
>> --- a/gcc/tree-ssa-sccvn.cc
>> +++ b/gcc/tree-ssa-sccvn.cc
>> @@ -74,6 +74,9 @@ along with GCC; see the file COPYING3. If not see
>> #include "ipa-modref-tree.h"
>> #include "ipa-modref.h"
>> #include "tree-ssa-sccvn.h"
>> +#include "alloc-pool.h"
>> +#include "symbol-summary.h"
>> +#include "ipa-prop.h"
>>
>> /* This algorithm is based on the SCC algorithm presented by Keith
>> Cooper and L. Taylor Simpson in "SCC-Based Value numbering"
>> @@ -2327,7 +2330,7 @@ vn_walk_cb_data::push_partial_def (pd_data pd,
>> with the current VUSE and performs the expression lookup. */
>>
>> static void *
>> -vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *data_)
>> +vn_reference_lookup_2 (ao_ref *op, tree vuse, void *data_)
>> {
>> vn_walk_cb_data *data = (vn_walk_cb_data *)data_;
>> vn_reference_t vr = data->vr;
>> @@ -2361,6 +2364,37 @@ vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED,
>> tree vuse, void *data_)
>> return *slot;
>> }
>>
>> + if (SSA_NAME_IS_DEFAULT_DEF (vuse))
>> + {
>> + HOST_WIDE_INT offset, size;
>> + tree v = NULL_TREE;
>> + if (op->base && TREE_CODE (op->base) == PARM_DECL
>> + && op->offset.is_constant (&offset)
>> + && op->size.is_constant (&size)
>> + && op->max_size_known_p ()
>> + && known_eq (op->size, op->max_size))
>> + v = ipcp_get_aggregate_const (cfun, op->base, false, offset, size);
>
> We've talked about partial definition support, this does not
> have this implemented AFAICS. But that means you cannot simply
> do ->finish () without verifying data->partial_defs.is_empty ().
>
You are right, partial definitions are not implemented. I have added
the is_empty check to the patch. I'll continue looking into adding the
support as a follow-up.
>> + else if (op->ref)
>> + {
>
> does this ever happen to imrpove things?
Yes, this branch is necessary for propagation of all known constants
passed in memory pointed to by a POINTER_TYPE_P parameter. It handles
the second testcase added by the patch.
> There's the remote
> possibility op->base isn't initialized yet, for this reason
> above you should use ao_ref_base (op) instead of accessing
> op->base directly.
OK
>
>> + HOST_WIDE_INT offset, size;
>> + bool reverse;
>> + tree base = get_ref_base_and_extent_hwi (op->ref, &offset,
>> + &size, &reverse);
>> + if (base
>> + && TREE_CODE (base) == MEM_REF
>> + && integer_zerop (TREE_OPERAND (base, 1))
>> + && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
>
> And this then should be done within the above branch as well,
> just keyed off base == MEM_REF.
I am sorry but I don't understand this comment, can you please try to
re-phrase it? The previous branch handles direct accesses to
PARM_DECLs, MEM_REFs don't need to be there at all.
Updated (bootstrap and testing passing) patch is below for reference,
but I obviously expect to incorporate the above comment as well before
proposing to push it.
Thanks,
Martin
Subject: [PATCH 2/2] ipa-cp: Feed results of IPA-CP into value numbering
PRs 68930 and 92497 show that when IPA-CP figures out constants in
aggregate parameters or when passed by reference but the loads happen
in an inlined function the information is lost. This happens even
when the inlined function itself was known to have - or even cloned to
have - such constants in incoming parameters because the transform
phase of IPA passes is not run on them. See discussion in the bugs
for reasons why.
Honza suggested that we can plug the results of IPA-CP analysis into
value numbering, so that FRE can figure out that some loads fetch
known constants. This is what this patch attempts to do.
This version of the patch uses the new way we represent aggregate
constants discovered IPA-CP and so avoids linear scan to find them.
Similarly, it depends on the previous patch which avoids potentially
slow linear look ups of indices of PARM_DECLs when there are many of
them.
gcc/ChangeLog:
2023-06-07 Martin Jambor <mjam...@suse.cz>
PR ipa/68930
PR ipa/92497
* ipa-prop.h (ipcp_get_aggregate_const): Declare.
* ipa-prop.cc (ipcp_get_aggregate_const): New function.
(ipcp_transform_function): Do not deallocate transformation info.
* tree-ssa-sccvn.cc: Include alloc-pool.h, symbol-summary.h and
ipa-prop.h.
(vn_reference_lookup_2): When hitting default-def vuse, query
IPA-CP transformation info for any known constants.
gcc/testsuite/ChangeLog:
2023-06-07 Martin Jambor <mjam...@suse.cz>
PR ipa/68930
PR ipa/92497
* gcc.dg/ipa/pr92497-1.c: New test.
* gcc.dg/ipa/pr92497-2.c: Likewise.
---
gcc/ipa-prop.cc | 33 +++++++++++++++++++++----
gcc/ipa-prop.h | 3 +++
gcc/testsuite/gcc.dg/ipa/pr92497-1.c | 26 +++++++++++++++++++
gcc/testsuite/gcc.dg/ipa/pr92497-2.c | 26 +++++++++++++++++++
gcc/tree-ssa-sccvn.cc | 37 +++++++++++++++++++++++++++-
5 files changed, 119 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/ipa/pr92497-1.c
create mode 100644 gcc/testsuite/gcc.dg/ipa/pr92497-2.c
diff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc
index f0976e363f7..fb2c0c0466b 100644
--- a/gcc/ipa-prop.cc
+++ b/gcc/ipa-prop.cc
@@ -5765,6 +5765,34 @@ ipcp_modif_dom_walker::before_dom_children (basic_block
bb)
return NULL;
}
+/* If IPA-CP discovered a constant in parameter PARM at OFFSET of a given SIZE
+ - whether passed by reference or not is given by BY_REF - return that
+ constant. Otherwise return NULL_TREE. */
+
+tree
+ipcp_get_aggregate_const (struct function *func, tree parm, bool by_ref,
+ HOST_WIDE_INT bit_offset, HOST_WIDE_INT bit_size)
+{
+ cgraph_node *node = cgraph_node::get (func->decl);
+ ipcp_transformation *ts = ipcp_get_transformation_summary (node);
+
+ if (!ts || !ts->m_agg_values)
+ return NULL_TREE;
+
+ int index = ts->get_param_index (func->decl, parm);
+ if (index < 0)
+ return NULL_TREE;
+
+ ipa_argagg_value_list avl (ts);
+ unsigned unit_offset = bit_offset / BITS_PER_UNIT;
+ tree v = avl.get_value (index, unit_offset, by_ref);
+ if (!v
+ || maybe_ne (tree_to_poly_int64 (TYPE_SIZE (TREE_TYPE (v))), bit_size))
+ return NULL_TREE;
+
+ return v;
+}
+
/* Return true if we have recorded VALUE and MASK about PARM.
Set VALUE and MASk accordingly. */
@@ -6037,11 +6065,6 @@ ipcp_transform_function (struct cgraph_node *node)
free_ipa_bb_info (bi);
fbi.bb_infos.release ();
- ipcp_transformation *s = ipcp_transformation_sum->get (node);
- s->m_agg_values = NULL;
- s->bits = NULL;
- s->m_vr = NULL;
-
vec_free (descriptors);
if (cfg_changed)
delete_unreachable_blocks_update_callgraph (node, false);
diff --git a/gcc/ipa-prop.h b/gcc/ipa-prop.h
index c570e8ec25a..9f25b44c71b 100644
--- a/gcc/ipa-prop.h
+++ b/gcc/ipa-prop.h
@@ -1232,6 +1232,9 @@ void ipa_dump_param (FILE *, class ipa_node_params *info,
int i);
void ipa_release_body_info (struct ipa_func_body_info *);
tree ipa_get_callee_param_type (struct cgraph_edge *e, int i);
bool ipcp_get_parm_bits (tree, tree *, widest_int *);
+tree ipcp_get_aggregate_const (struct function *func, tree parm, bool by_ref,
+ HOST_WIDE_INT bit_offset,
+ HOST_WIDE_INT bit_size);
bool unadjusted_ptr_and_unit_offset (tree op, tree *ret,
poly_int64 *offset_ret);
diff --git a/gcc/testsuite/gcc.dg/ipa/pr92497-1.c
b/gcc/testsuite/gcc.dg/ipa/pr92497-1.c
new file mode 100644
index 00000000000..dcece15963c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/pr92497-1.c
@@ -0,0 +1,26 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-early-inlining" } */
+
+struct a {int a;};
+static int
+foo (struct a a)
+{
+ if (!__builtin_constant_p (a.a))
+ __builtin_abort ();
+ return a.a;
+}
+
+static int __attribute__ ((noinline))
+bar (struct a a)
+{
+ return foo(a);
+}
+
+volatile int r;
+
+int main()
+{
+ struct a a={1};
+ r = bar (a);
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/ipa/pr92497-2.c
b/gcc/testsuite/gcc.dg/ipa/pr92497-2.c
new file mode 100644
index 00000000000..c64090d1a7a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/pr92497-2.c
@@ -0,0 +1,26 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-early-inlining -fno-ipa-sra" } */
+
+struct a {int a;};
+static int
+foo (struct a *a)
+{
+ if (!__builtin_constant_p (a->a))
+ __builtin_abort ();
+ return a->a;
+}
+
+static int __attribute__ ((noinline))
+bar (struct a *a)
+{
+ return foo(a);
+}
+
+volatile int r;
+
+int main()
+{
+ struct a a={1};
+ r = bar (&a);
+ return 0;
+}
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 27c84e78fcf..ce88b9bc95f 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -74,6 +74,9 @@ along with GCC; see the file COPYING3. If not see
#include "ipa-modref-tree.h"
#include "ipa-modref.h"
#include "tree-ssa-sccvn.h"
+#include "alloc-pool.h"
+#include "symbol-summary.h"
+#include "ipa-prop.h"
/* This algorithm is based on the SCC algorithm presented by Keith
Cooper and L. Taylor Simpson in "SCC-Based Value numbering"
@@ -2327,7 +2330,7 @@ vn_walk_cb_data::push_partial_def (pd_data pd,
with the current VUSE and performs the expression lookup. */
static void *
-vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *data_)
+vn_reference_lookup_2 (ao_ref *op, tree vuse, void *data_)
{
vn_walk_cb_data *data = (vn_walk_cb_data *)data_;
vn_reference_t vr = data->vr;
@@ -2361,6 +2364,38 @@ vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree
vuse, void *data_)
return *slot;
}
+ if (SSA_NAME_IS_DEFAULT_DEF (vuse))
+ {
+ HOST_WIDE_INT offset, size;
+ tree v = NULL_TREE;
+ if (ao_ref_base (op) && TREE_CODE (ao_ref_base (op)) == PARM_DECL
+ && op->offset.is_constant (&offset)
+ && op->size.is_constant (&size)
+ && op->max_size_known_p ()
+ && known_eq (op->size, op->max_size))
+ v = ipcp_get_aggregate_const (cfun, ao_ref_base (op), false, offset,
+ size);
+ else if (op->ref)
+ {
+ HOST_WIDE_INT offset, size;
+ bool reverse;
+ tree base = get_ref_base_and_extent_hwi (op->ref, &offset,
+ &size, &reverse);
+ if (base
+ && TREE_CODE (base) == MEM_REF
+ && integer_zerop (TREE_OPERAND (base, 1))
+ && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
+ && SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (base, 0))
+ && (TREE_CODE (SSA_NAME_VAR (TREE_OPERAND (base, 0)))
+ == PARM_DECL))
+ v = ipcp_get_aggregate_const (cfun,
+ SSA_NAME_VAR (TREE_OPERAND (base, 0)),
+ true, offset, size);
+ }
+ if (v && data->partial_defs.is_empty ())
+ return data->finish (vr->set, vr->base_set, v);
+ }
+
return NULL;
}
--
2.40.1
