libctf: eliminate dtd_u, part 4: enums

This is the first tricky one, the first complex multi-entry vlen
containing strings.  To handle this in vlen form, we have to handle
pending refs moving around on realloc.

We grow vlen regions using a new ctf_grow_vlen function, and iterate
through the existing enums every time a grow happens, telling the string
machinery the distance between the old and new vlen region and letting
it adjust the pending refs accordingly.  (This avoids traversing all
outstanding refs to find the refs that need adjusting, at the cost of
having to traverse one enum: an obvious major performance win.)

Addition of enums themselves (and also structs/unions later) is a bit
trickier than earlier forms, because the type might be being promoted
from a forward, and forwards have no vlen: so we have to spot that and
create it if needed.

Serialization of enums simplifies down to just telling the string
machinery about the string refs; all the enum type-lookup code loses all
its dynamic member lookup complexity entirely.

A new test is added that iterates over (and gets values of) an enum with
enough members to force a round of vlen growth.

libctf/ChangeLog
2021-03-18  Nick Alcock  <nick.alcock@oracle.com>

	* ctf-impl.h (ctf_dtdef_t) <dtd_vlen_alloc>: New.
	(ctf_str_move_pending): Declare.
	* ctf-string.c (ctf_str_add_ref_internal): Fix error return.
	(ctf_str_move_pending): New.
	* ctf-create.c (ctf_grow_vlen): New.
	(ctf_dtd_delete): Zero out the vlen_alloc after free.  Free the
	vlen later: iterate over it and free enum name refs first.
	(ctf_add_generic): Populate dtd_vlen_alloc from vlen.
	(ctf_add_enum): populate the vlen; do it by hand if promoting
	forwards.
	(ctf_add_enumerator): Set up the vlen rather than the dmd.  Expand
	it as needed, repointing string refs via ctf_str_move_pending. Add
	the enumerand names as pending strings.
	* ctf-serialize.c (ctf_copy_emembers): Remove.
	(ctf_emit_type_sect): Copy the vlen into place and ref the
	strings.
	* ctf-types.c (ctf_enum_next): The dynamic portion now uses
	the same code as the non-dynamic.
	(ctf_enum_name): Likewise.
	(ctf_enum_value): Likewise.
	* testsuite/libctf-lookup/enum-many-ctf.c: New test.
	* testsuite/libctf-lookup/enum-many.lk: New test.

1 files changed, 17 insertions, 0 deletions

diff --git a/libctf/ctf-string.c b/libctf/ctf-string.c
index 9f0e540..2e98484 100644
--- a/libctf/ctf-string.c
+++ b/libctf/ctf-string.c
@@ -19,6 +19,7 @@
 
 #include <ctf-impl.h>
 #include <string.h>
+#include <assert.h>
 
 /* Convert an encoded CTF string name into a pointer to a C string, using an
   explicit internal strtab rather than the fp-based one.  */
@@ -228,6 +229,7 @@ ctf_str_add_ref_internal (ctf_dict_t *fp, const char *str,
   free (atom);
   free (aref);
   free (newstr);
+  ctf_set_errno (fp, ENOMEM);
   return NULL;
 }
 
@@ -288,6 +290,21 @@ ctf_str_add_pending (ctf_dict_t *fp, const char *str, uint32_t *ref)
   return atom->csa_offset;
 }
 
+/* Note that a pending ref now located at NEW_REF has moved by BYTES bytes.  */
+int
+ctf_str_move_pending (ctf_dict_t *fp, uint32_t *new_ref, ptrdiff_t bytes)
+{
+  if (bytes == 0)
+    return 0;
+
+  if (ctf_dynset_insert (fp->ctf_str_pending_ref, (void *) new_ref) < 0)
+    return (ctf_set_errno (fp, ENOMEM));
+
+  ctf_dynset_remove (fp->ctf_str_pending_ref,
+		     (void *) ((signed char *) new_ref - bytes));
+  return 0;
+}
+
 /* Add an external strtab reference at OFFSET.  Returns zero if the addition
    failed, nonzero otherwise.  */
 int