On 06/11/24 13:39 +0100, Michal Jires wrote:
Commited with suggested changes.
---------------------------------------------------------------------
This patch disables propagation of ipcp information into partitions
where all instances of the node are marked to be inlined.
Motivation:
Incremental LTO needs stable values between compilations to be
effective. This requirement fails with following example:
void heavily_used_function(int);
...
heavily_used_function(__LINE__);
Ipcp creates long list of all __LINE__ arguments, and then
propagates it with every function clone, even though for inlined
functions this information is not useful.
gcc/ChangeLog:
* ipa-prop.cc (write_ipcp_transformation_info): Disable
uneeded value propagation.
* lto-cgraph.cc (lto_symtab_encoder_encode): Default values.
(lto_symtab_encoder_always_inlined_p): New.
(lto_set_symtab_encoder_not_always_inlined): New.
(add_node_to): Set always inlined.
* lto-streamer.h (struct lto_encoder_entry): New field.
(lto_symtab_encoder_always_inlined_p): New.
---
gcc/ipa-prop.cc | 12 +++++++++---
gcc/lto-cgraph.cc | 47 +++++++++++++++++++++++++++++-----------------
gcc/lto-streamer.h | 11 +++++++++++
3 files changed, 50 insertions(+), 20 deletions(-)
diff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc
index 032358fde22..c5633796721 100644
--- a/gcc/ipa-prop.cc
+++ b/gcc/ipa-prop.cc
@@ -5404,9 +5404,15 @@ write_ipcp_transformation_info (output_block *ob,
cgraph_node *node,
streamer_write_bitpack (&bp);
}
- streamer_write_uhwi (ob, vec_safe_length (ts->m_vr));
- for (const ipa_vr &parm_vr : ts->m_vr)
- parm_vr.streamer_write (ob);
+ /* If all instances of this node are inlined, ipcp info is not useful. */
+ if (!lto_symtab_encoder_only_for_inlining_p (encoder, node))
+ {
+ streamer_write_uhwi (ob, vec_safe_length (ts->m_vr));
+ for (const ipa_vr &parm_vr : ts->m_vr)
+ parm_vr.streamer_write (ob);
+ }
+ else
+ streamer_write_uhwi (ob, 0);
}
/* Stream in the aggregate value replacement chain for NODE from IB. */
diff --git a/gcc/lto-cgraph.cc b/gcc/lto-cgraph.cc
index 53cc965bdfd..c66f32852a7 100644
--- a/gcc/lto-cgraph.cc
+++ b/gcc/lto-cgraph.cc
@@ -114,7 +114,7 @@ lto_symtab_encoder_encode (lto_symtab_encoder_t encoder,
if (!encoder->map)
{
- lto_encoder_entry entry = {node, false, false, false};
+ lto_encoder_entry entry (node);
ref = encoder->nodes.length ();
encoder->nodes.safe_push (entry);
@@ -124,7 +124,7 @@ lto_symtab_encoder_encode (lto_symtab_encoder_t encoder,
size_t *slot = encoder->map->get (node);
if (!slot || !*slot)
{
- lto_encoder_entry entry = {node, false, false, false};
+ lto_encoder_entry entry (node);
ref = encoder->nodes.length ();
if (!slot)
encoder->map->put (node, ref + 1);
@@ -168,6 +168,15 @@ lto_symtab_encoder_delete_node (lto_symtab_encoder_t
encoder,
return true;
}
+/* Return TRUE if the NODE and its clones are always inlined. */
+
+bool
+lto_symtab_encoder_only_for_inlining_p (lto_symtab_encoder_t encoder,
+ struct cgraph_node *node)
+{
+ int index = lto_symtab_encoder_lookup (encoder, node);
+ return encoder->nodes[index].only_for_inlining;
+}
/* Return TRUE if we should encode the body of NODE (if any). */
@@ -179,17 +188,6 @@ lto_symtab_encoder_encode_body_p (lto_symtab_encoder_t
encoder,
return encoder->nodes[index].body;
}
-/* Specify that we encode the body of NODE in this partition. */
-
-static void
-lto_set_symtab_encoder_encode_body (lto_symtab_encoder_t encoder,
- struct cgraph_node *node)
-{
- int index = lto_symtab_encoder_encode (encoder, node);
- gcc_checking_assert (encoder->nodes[index].node == node);
- encoder->nodes[index].body = true;
-}
-
/* Return TRUE if we should encode initializer of NODE (if any). */
bool
@@ -799,13 +797,28 @@ output_refs (lto_symtab_encoder_t encoder)
static void
add_node_to (lto_symtab_encoder_t encoder, struct cgraph_node *node,
- bool include_body)
+ bool include_body, bool not_inlined)
{
if (node->clone_of)
- add_node_to (encoder, node->clone_of, include_body);
+ add_node_to (encoder, node->clone_of, include_body, not_inlined);
+
+ int index = lto_symtab_encoder_encode (encoder, node);
+ gcc_checking_assert (encoder->nodes[index].node == node);
+
if (include_body)
- lto_set_symtab_encoder_encode_body (encoder, node);
- lto_symtab_encoder_encode (encoder, node);
+ encoder->nodes[index].body = true;
+ if (not_inlined)
+ encoder->nodes[index].only_for_inlining = false;
+}
+
+/* Add NODE into encoder as well as nodes it is cloned from.
+ Do it in a way so clones appear first. */
+
+static void
+add_node_to (lto_symtab_encoder_t encoder, struct cgraph_node *node,
+ bool include_body)
+{
+ add_node_to (encoder, node, include_body, include_body && !node->inlined_to);
}
/* Add all references in NODE to encoders. */
diff --git a/gcc/lto-streamer.h b/gcc/lto-streamer.h
index 397f5fc8d68..2f8b842f081 100644
--- a/gcc/lto-streamer.h
+++ b/gcc/lto-streamer.h
@@ -443,12 +443,21 @@ struct lto_stats_d
/* Entry of LTO symtab encoder. */
struct lto_encoder_entry
{
+ /* Constructors. */
+ lto_encoder_entry () {}
If there's going to be a constructor then it should initialize the members.
Otherwise, your original patch was better, because you could write
this to get an all-zeros object:
lto_encoder_entry e{};
Now you can't safely initialize it, because the default constructor
leaves everything indeterminate. That's just a bug waiting to happen.
If you want to avoid repetition, just initialize everything in the
default constructor then delegate to that for the other one:
lto_encoder_entry ()
: node (nullptr), in_partition (false), body (false), only_for_inlining
(true),
initializer (false)
{}
lto_encoder_entry (symtab_node* n)
: lto_encoder_entry()
{
node = n;
}
+ lto_encoder_entry (symtab_node* n)
+ : node (n), in_partition (false), body (false), only_for_inlining (true),
+ initializer (false)
+ {}
+
symtab_node *node;
/* Is the node in this partition (i.e. ltrans of this partition will
be responsible for outputting it)? */
unsigned int in_partition:1;
/* Do we encode body in this partition? */
unsigned int body:1;
+ /* Do we stream this node only for inlining? */
+ unsigned int only_for_inlining:1;
/* Do we encode initializer in this partition?
For example the readonly variable initializers are encoded to aid
constant folding even if they are not in the partition. */
@@ -914,6 +923,8 @@ void lto_symtab_encoder_delete (lto_symtab_encoder_t);
bool lto_symtab_encoder_delete_node (lto_symtab_encoder_t, symtab_node *);
bool lto_symtab_encoder_encode_body_p (lto_symtab_encoder_t,
struct cgraph_node *);
+bool lto_symtab_encoder_only_for_inlining_p (lto_symtab_encoder_t,
+ struct cgraph_node *);
bool lto_symtab_encoder_in_partition_p (lto_symtab_encoder_t,
symtab_node *);
void lto_set_symtab_encoder_in_partition (lto_symtab_encoder_t,
--
2.47.0
