From: Nick Alcock <nick.alcock@oracle.com>
Date: Thu, 3 Apr 2025 14:21:47 +0000 (+0100)
Subject: libctf: simplify ctf_txlate
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a80b903b45313cb6b17b79395d6bdb5bf016bc02;p=thirdparty%2Fbinutils-gdb.git

libctf: simplify ctf_txlate

Before now, this critical internal structure was an array mapping from a
type ID to the type index of the type with that ID.  This was critical for
the old world in which ctf_update() reserialized the entire dict, so things
moved around in memory all the time: but these days, a ctf_type_t * never
moves after creation, so we can just make ctf_txlate an array of ctf_type_t *
and be done with it.

This lets us point type indexes anywhere in memory, not just to entries
in the ctf_buf, which means we can have synthetic ones for various purposes.
And we will.
---

diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index db2ad1d8e53..9833f6c3377 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -402,7 +402,7 @@ struct ctf_dict
   uint32_t *ctf_sxlate;		  /* Translation table for unindexed symtypetab
 				     entries.  */
   unsigned long ctf_nsyms;	  /* Number of entries in symtab xlate table.  */
-  uint32_t *ctf_txlate;		  /* Translation table for type IDs.  */
+  ctf_type_t **ctf_txlate;	  /* Translation table for type IDs.  */
   uint32_t *ctf_ptrtab;		  /* Translation table for pointer-to lookups.  */
   size_t ctf_ptrtab_len;	  /* Num types storable in ptrtab currently.  */
   uint32_t *ctf_pptrtab;	  /* Parent types pointed to by child dicts.  */
@@ -592,8 +592,8 @@ extern ctf_id_t ctf_index_to_type (const ctf_dict_t *, uint32_t);
 
 #define LCTF_INDEX_TO_TYPEPTR(fp, i)					\
   ((i > fp->ctf_stypes) ?						\
-   &(ctf_dtd_lookup (fp, ctf_index_to_type (fp, i))->dtd_data) :	\
-   (ctf_type_t *)((uintptr_t)(fp)->ctf_buf + (fp)->ctf_txlate[(i)]))
+   ctf_dtd_lookup (fp, ctf_index_to_type (fp, i))->dtd_data :		\
+   (fp)->ctf_txlate[(i)])
 
 /* The non *INFO variants of these macros acquire the relevant info from the
    suffixed type, if the type is prefixed.  (Internally to libctf, all types
diff --git a/libctf/ctf-open.c b/libctf/ctf-open.c
index b17dae6bdbd..61dbdd55d03 100644
--- a/libctf/ctf-open.c
+++ b/libctf/ctf-open.c
@@ -696,7 +696,7 @@ init_static_types (ctf_dict_t *fp, ctf_header_t *cth)
      because later-added types will call grow_ptrtab() automatically, as
      needed.  */
 
-  fp->ctf_txlate = calloc (typemax + 1, sizeof (uint32_t));
+  fp->ctf_txlate = calloc (typemax + 1, sizeof (ctf_type_t *));
   fp->ctf_ptrtab = calloc (typemax + 1, sizeof (uint32_t));
   fp->ctf_ptrtab_len = typemax + 1;
   fp->ctf_stypes = typemax;
@@ -773,8 +773,7 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 
   assert (!(fp->ctf_flags & LCTF_NO_STR));
 
-  xp = fp->ctf_txlate;
-  *xp++ = 0;			/* Type id 0 is used as a sentinel value.  */
+  xp = &fp->ctf_txlate[1];
 
   /* In this second pass through the types, we fill in each entry of the type
      and pointer tables and add names to the appropriate hashes.