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authorNick Alcock <nick.alcock@oracle.com>2024-06-11 19:51:33 +0100
committerNick Alcock <nick.alcock@oracle.com>2024-06-18 13:20:31 +0100
commitf8da1a05db64d8c5c700e07a008a1938858a7adf (patch)
tree3418ffefbfa35c3683d5279d5be87fedc0d78d17 /libctf
parent0c5f03a9d5ed35731742df2c98cc5ec6aa738828 (diff)
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libctf: dedup: enums with overlapping enumerators are conflicting
The CTF deduplicator was not considering enumerators inside enum types to be things that caused type conflicts, so if the following two TUs were linked together, you would end up with the following in the resulting dict: 1.c: enum foo { A, B }; 2.c: enum bar { A, B }; linked: enum foo { A, B }; enum bar { A, B }; This does work -- but it's not something that's valid C, and the general point of the shared dict is that it is something that you could potentially get from any valid C TU. So consider such types to be conflicting, but obviously don't consider actually identical enums to be conflicting, even though they too have (all) their identifiers in common. This involves surprisingly little code. The deduplicator detects conflicting types by counting types in a hash table of hash tables: decorated identifier -> (type hash -> count) where the COUNT is the number of times a given hash has been observed: any name with more than one hash associated with it is considered conflicting (the count is used to identify the most common such name for promotion to the shared dict). Before now, those identifiers were all the identifiers of types (possibly decorated with their namespace on the front for enumerator identifiers), but we can equally well put *enumeration constant names* in there, undecorated like the identifiers of types in the global namespace, with the type hash being the hash of each enum containing that enumerator. The existing conflicting-type-detection code will then accurately identify distinct enums with enumeration constants in common. The enum that contains the most commonly-appearing enumerators will be promoted to the shared dict. libctf/ * ctf-impl.h (ctf_dedup_t) <cd_name_counts>: Extend comment. * ctf-dedup.c (ctf_dedup_count_name): New, split out of... (ctf_dedup_populate_mappings): ... here. Call it for all * enumeration constants in an enum as well as types. ld/ * testsuite/ld-ctf/enum-3.c: New test CTF. * testsuite/ld-ctf/enum-4.c: Likewise. * testsuite/ld-ctf/overlapping-enums.d: New test. * testsuite/ld-ctf/overlapping-enums-2.d: Likewise.
Diffstat (limited to 'libctf')
-rw-r--r--libctf/ctf-dedup.c42
-rw-r--r--libctf/ctf-impl.h3
2 files changed, 38 insertions, 7 deletions
diff --git a/libctf/ctf-dedup.c b/libctf/ctf-dedup.c
index c7db6ab..dd23494 100644
--- a/libctf/ctf-dedup.c
+++ b/libctf/ctf-dedup.c
@@ -1149,6 +1149,9 @@ ctf_dedup_hash_type (ctf_dict_t *fp, ctf_dict_t *input,
return NULL;
}
+static int
+ctf_dedup_count_name (ctf_dict_t *fp, const char *name, void *id);
+
/* Populate a number of useful mappings not directly used by the hashing
machinery: the output mapping, the cd_name_counts mapping from name -> hash
-> count of hashval deduplication state for a given hashed type, and the
@@ -1164,8 +1167,6 @@ ctf_dedup_populate_mappings (ctf_dict_t *fp, ctf_dict_t *input _libctf_unused_,
{
ctf_dedup_t *d = &fp->ctf_dedup;
ctf_dynset_t *type_ids;
- ctf_dynhash_t *name_counts;
- long int count;
#ifdef ENABLE_LIBCTF_HASH_DEBUGGING
ctf_dprintf ("Hash %s, %s, into output mapping for %i/%lx @ %s\n",
@@ -1258,24 +1259,53 @@ ctf_dedup_populate_mappings (ctf_dict_t *fp, ctf_dict_t *input _libctf_unused_,
&& ctf_dynset_insert (type_ids, id) < 0)
return ctf_set_errno (fp, errno);
+ if (ctf_type_kind_unsliced (input, type) == CTF_K_ENUM)
+ {
+ ctf_next_t *i = NULL;
+ const char *enumerator;
+
+ while ((enumerator = ctf_enum_next (input, type, &i, NULL)) != NULL)
+ {
+ if (ctf_dedup_count_name (fp, enumerator, id) < 0)
+ {
+ ctf_next_destroy (i);
+ return -1;
+ }
+ }
+ if (ctf_errno (input) != ECTF_NEXT_END)
+ return ctf_set_errno (fp, ctf_errno (input));
+ }
+
/* The rest only needs to happen for types with names. */
if (!decorated_name)
return 0;
+ if (ctf_dedup_count_name (fp, decorated_name, id) < 0)
+ return -1; /* errno is set for us. */
+
+ return 0;
+}
+
+static int
+ctf_dedup_count_name (ctf_dict_t *fp, const char *name, void *id)
+{
+ ctf_dedup_t *d = &fp->ctf_dedup;
+ ctf_dynhash_t *name_counts;
+ long int count;
+ const char *hval;
+
/* Count the number of occurrences of the hash value for this GID. */
hval = ctf_dynhash_lookup (d->cd_type_hashes, id);
/* Mapping from name -> hash(hashval, count) not already present? */
- if ((name_counts = ctf_dynhash_lookup (d->cd_name_counts,
- decorated_name)) == NULL)
+ if ((name_counts = ctf_dynhash_lookup (d->cd_name_counts, name)) == NULL)
{
if ((name_counts = ctf_dynhash_create (ctf_hash_string,
ctf_hash_eq_string,
NULL, NULL)) == NULL)
return ctf_set_errno (fp, errno);
- if (ctf_dynhash_cinsert (d->cd_name_counts, decorated_name,
- name_counts) < 0)
+ if (ctf_dynhash_cinsert (d->cd_name_counts, name, name_counts) < 0)
{
ctf_dynhash_destroy (name_counts);
return ctf_set_errno (fp, errno);
diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index 03e1a66..eb89f8b 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -294,7 +294,8 @@ typedef struct ctf_dedup
ctf_dynhash_t *cd_decorated_names[4];
/* Map type names to a hash from type hash value -> number of times each value
- has appeared. */
+ has appeared. Enumeration constants are tracked via the enum they appear
+ in. */
ctf_dynhash_t *cd_name_counts;
/* Map global type IDs to type hash values. Used to determine if types are