Use wrappers of PG_DETOAST_DATUM_PACKED() more.

This makes almost all core code follow the policy introduced in the
previous commit.  Specific decisions:

- Text search support functions with char* and length arguments, such as
  prsstart and lexize, may receive unaligned strings.  I doubt
  maintainers of non-core text search code will notice.

- Use plain VARDATA() on values detoasted or synthesized earlier in the
  same function.  Use VARDATA_ANY() on varlenas sourced outside the
  function, even if they happen to always have four-byte headers.  As an
  exception, retain the universal practice of using VARDATA() on return
  values of SendFunctionCall().

- Retain PG_GETARG_BYTEA_P() in pageinspect.  (Page images are too large
  for a one-byte header, so this misses no optimization.)  Sites that do
  not call get_page_from_raw() typically need the four-byte alignment.

- For now, do not change btree_gist.  Its use of four-byte headers in
  memory is partly entangled with storage of 4-byte headers inside
  GBT_VARKEY, on disk.

- For now, do not change gtrgm_consistent() or gtrgm_distance().  They
  incorporate the varlena header into a cache, and there are multiple
  credible implementation strategies to consider.

1 files changed, 3 insertions, 3 deletions

diff --git a/contrib/pageinspect/btreefuncs.c b/contrib/pageinspect/btreefuncs.c
index d50ec3a68d9..6f35e288fd1 100644
--- a/contrib/pageinspect/btreefuncs.c
+++ b/contrib/pageinspect/btreefuncs.c
@@ -159,7 +159,7 @@ GetBTPageStatistics(BlockNumber blkno, Buffer buffer, BTPageStat *stat)
 Datum
 bt_page_stats(PG_FUNCTION_ARGS)
 {
-	text	   *relname = PG_GETARG_TEXT_P(0);
+	text	   *relname = PG_GETARG_TEXT_PP(0);
 	uint32		blkno = PG_GETARG_UINT32(1);
 	Buffer		buffer;
 	Relation	rel;
@@ -256,7 +256,7 @@ struct user_args
 Datum
 bt_page_items(PG_FUNCTION_ARGS)
 {
-	text	   *relname = PG_GETARG_TEXT_P(0);
+	text	   *relname = PG_GETARG_TEXT_PP(0);
 	uint32		blkno = PG_GETARG_UINT32(1);
 	Datum		result;
 	char	   *values[6];
@@ -408,7 +408,7 @@ bt_page_items(PG_FUNCTION_ARGS)
 Datum
 bt_metap(PG_FUNCTION_ARGS)
 {
-	text	   *relname = PG_GETARG_TEXT_P(0);
+	text	   *relname = PG_GETARG_TEXT_PP(0);
 	Datum		result;
 	Relation	rel;
 	RangeVar   *relrv;