[PATCH 08/16] libctf: eliminate dtd_u, part 3: functions

[Nick Alcock]

One more member vanishes from the dtd_u, leaving only the member for
struct/union/enum members.

There's not much to do here, since as of commit afd78bd6f0a30ba5 we use
the same representation (type sizes, etc) in the dtu_argv as we will
use in the final vlen, with one exception: the vlen has alignment
padding, and the dtu_argv did not.  Simplify things by adding suitable
padding in both cases.

libctf/ChangeLog
2021-03-02  Nick Alcock  <nick.alcock@oracle.com>

	* ctf-impl.h (ctf_dtdef_t) <dtd_u.dtu_argv>: Remove.
	* ctf-create.c (ctf_dtd_delete): No longer free it.
	(ctf_add_function): Use the dtd_vlen, not dtu_argv.  Properly align.
	* ctf-serialize.c (ctf_emit_type_sect): Just copy the dtd_vlen.
	* ctf-types.c (ctf_func_type_info): Just use the vlen.
	(ctf_func_type_args): Likewise.
---
 libctf/ctf-create.c    | 33 ++++++++++++++-------------------
 libctf/ctf-impl.h      |  1 -
 libctf/ctf-serialize.c | 16 +++-------------
 libctf/ctf-types.c     |  4 ++--
 4 files changed, 19 insertions(+), 35 deletions(-)

diff --git a/libctf/ctf-create.c b/libctf/ctf-create.c
index bc46cfa6ca8..6acc2428cd7 100644
--- a/libctf/ctf-create.c
+++ b/libctf/ctf-create.c
@@ -242,9 +242,6 @@ ctf_dtd_delete (ctf_dict_t *fp, ctf_dtdef_t *dtd)
 	  free (dmd);
 	}
       break;
-    case CTF_K_FUNCTION:
-      free (dtd->dtd_u.dtu_argv);
-      break;
     case CTF_K_FORWARD:
       name_kind = dtd->dtd_data.ctt_type;
       break;
@@ -703,8 +700,9 @@ ctf_add_function (ctf_dict_t *fp, uint32_t flag,
   ctf_dtdef_t *dtd;
   ctf_id_t type;
   uint32_t vlen;
-  uint32_t *vdat = NULL;
+  uint32_t *vdat;
   ctf_dict_t *tmp = fp;
+  size_t initial_vlen;
   size_t i;
 
   if (!(fp->ctf_flags & LCTF_RDWR))
@@ -720,38 +718,35 @@ ctf_add_function (ctf_dict_t *fp, uint32_t flag,
 
   if (ctc->ctc_return != 0
       && ctf_lookup_by_id (&tmp, ctc->ctc_return) == NULL)
-    return CTF_ERR;		/* errno is set for us.  */
+    return CTF_ERR;				/* errno is set for us.  */
 
   if (vlen > CTF_MAX_VLEN)
     return (ctf_set_errno (fp, EOVERFLOW));
 
-  if (vlen != 0 && (vdat = malloc (sizeof (ctf_id_t) * vlen)) == NULL)
-    return (ctf_set_errno (fp, EAGAIN));
+  /* One word extra allocated for padding for 4-byte alignment if need be.
+     Not reflected in vlen: we don't want to copy anything into it, and
+     it's in addition to (e.g.) the trailing 0 indicating varargs.  */
+
+  initial_vlen = (sizeof (uint32_t) * (vlen + (vlen & 1)));
+  if ((type = ctf_add_generic (fp, flag, NULL, CTF_K_FUNCTION,
+			       initial_vlen, &dtd)) == CTF_ERR)
+    return CTF_ERR;				/* errno is set for us.  */
+
+  vdat = (uint32_t *) dtd->dtd_vlen;
 
   for (i = 0; i < ctc->ctc_argc; i++)
     {
       tmp = fp;
       if (argv[i] != 0 && ctf_lookup_by_id (&tmp, argv[i]) == NULL)
-	{
-	  free (vdat);
-	  return CTF_ERR;	   /* errno is set for us.  */
-	}
+	return CTF_ERR;				/* errno is set for us.  */
       vdat[i] = (uint32_t) argv[i];
     }
 
-  if ((type = ctf_add_generic (fp, flag, NULL, CTF_K_FUNCTION,
-			       0, &dtd)) == CTF_ERR)
-    {
-      free (vdat);
-      return CTF_ERR;		   /* errno is set for us.  */
-    }
-
   dtd->dtd_data.ctt_info = CTF_TYPE_INFO (CTF_K_FUNCTION, flag, vlen);
   dtd->dtd_data.ctt_type = (uint32_t) ctc->ctc_return;
 
   if (ctc->ctc_flags & CTF_FUNC_VARARG)
     vdat[vlen - 1] = 0;		   /* Add trailing zero to indicate varargs.  */
-  dtd->dtd_u.dtu_argv = vdat;
 
   return type;
 }
diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index c1ce50bc3b9..7a4e418ce2d 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -196,7 +196,6 @@ typedef struct ctf_dtdef
   union
   {
     ctf_list_t dtu_members;	/* struct, union, or enum */
-    uint32_t *dtu_argv;		/* function */
   } dtd_u;
 } ctf_dtdef_t;
 
diff --git a/libctf/ctf-serialize.c b/libctf/ctf-serialize.c
index d8e78f361f4..460ae1a510e 100644
--- a/libctf/ctf-serialize.c
+++ b/libctf/ctf-serialize.c
@@ -892,19 +892,9 @@ ctf_emit_type_sect (ctf_dict_t *fp, unsigned char **tptr)
 	  break;
 
 	case CTF_K_FUNCTION:
-	  {
-	    uint32_t *argv = (uint32_t *) (uintptr_t) t;
-	    uint32_t argc;
-
-	    for (argc = 0; argc < vlen; argc++)
-	      *argv++ = dtd->dtd_u.dtu_argv[argc];
-
-	    if (vlen & 1)
-	      *argv++ = 0;	/* Pad to 4-byte boundary.  */
-
-	    t = (unsigned char *) argv;
-	    break;
-	  }
+	  memcpy (t, dtd->dtd_vlen, sizeof (uint32_t) * (vlen + (vlen & 1)));
+	  t += sizeof (uint32_t) * (vlen + (vlen & 1));
+	  break;
 
 	case CTF_K_STRUCT:
 	case CTF_K_UNION:
diff --git a/libctf/ctf-types.c b/libctf/ctf-types.c
index 8c983d5542f..1e1ce8ee529 100644
--- a/libctf/ctf-types.c
+++ b/libctf/ctf-types.c
@@ -1678,7 +1678,7 @@ ctf_func_type_info (ctf_dict_t *fp, ctf_id_t type, ctf_funcinfo_t *fip)
   if ((dtd = ctf_dynamic_type (fp, type)) == NULL)
     args = (uint32_t *) ((uintptr_t) tp + increment);
   else
-    args = dtd->dtd_u.dtu_argv;
+    args = (uint32_t *) dtd->dtd_vlen;
 
   if (fip->ctc_argc != 0 && args[fip->ctc_argc - 1] == 0)
     {
@@ -1715,7 +1715,7 @@ ctf_func_type_args (ctf_dict_t *fp, ctf_id_t type, uint32_t argc, ctf_id_t *argv
   if ((dtd = ctf_dynamic_type (fp, type)) == NULL)
     args = (uint32_t *) ((uintptr_t) tp + increment);
   else
-    args = dtd->dtd_u.dtu_argv;
+    args = (uint32_t *) dtd->dtd_vlen;
 
   for (argc = MIN (argc, f.ctc_argc); argc != 0; argc--)
     *argv++ = *args++;
-- 
2.30.0.252.gc27e85e57d