commit 0fc4989f34bdaf1bc443d05ece886ea91e7bc9cc (HEAD, refs/remotes/origin/master)
Author: Paul Eggert <eggert@cs.ucla.edu>
Date:   Tue May 26 15:47:59 2020 -0700

    Tweak GC performance if !USE_LSB_TAG
    
    Performance issue reported by Eli Zaretskii (Bug#41321#149).
    * src/alloc.c (GC_OBJECT_ALIGNMENT_MINIMUM): New constant.
    (maybe_lisp_pointer): Use it instead of GCALIGNMENT.

diff --git a/src/alloc.c b/src/alloc.c
index f8609398a3..e241b9933a 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -4687,16 +4687,33 @@ mark_maybe_objects (Lisp_Object const *array, ptrdiff_t nelts)
     mark_maybe_object (*array);
 }
 
+/* A lower bound on the alignment of Lisp objects that need marking.
+   Although 1 is safe, higher values speed up mark_maybe_pointer.
+   If USE_LSB_TAG, this value is typically GCALIGNMENT; otherwise,
+   it's determined by the natural alignment of Lisp structs.
+   All vectorlike objects have alignment at least that of union
+   vectorlike_header and it's unlikely they all have alignment greater,
+   so use the union as a safe and likely-accurate standin for
+   vectorlike objects.  */
+
+enum { GC_OBJECT_ALIGNMENT_MINIMUM
+         = max (GCALIGNMENT,
+		min (alignof (union vectorlike_header),
+		     min (min (alignof (struct Lisp_Cons),
+			       alignof (struct Lisp_Float)),
+			  min (alignof (struct Lisp_String),
+			       alignof (struct Lisp_Symbol))))) };
+
 /* Return true if P might point to Lisp data that can be garbage
    collected, and false otherwise (i.e., false if it is easy to see
    that P cannot point to Lisp data that can be garbage collected).
    Symbols are implemented via offsets not pointers, but the offsets
-   are also multiples of GCALIGNMENT.  */
+   are also multiples of GC_OBJECT_ALIGNMENT_MINIMUM.  */
 
 static bool
 maybe_lisp_pointer (void *p)
 {
-  return (uintptr_t) p % GCALIGNMENT == 0;
+  return (uintptr_t) p % GC_OBJECT_ALIGNMENT_MINIMUM == 0;
 }
 
 /* If P points to Lisp data, mark that as live if it isn't already

commit 5467aac131fb49ff2af57ca21d7ec9cba7c19c82
Author: Alan Mackenzie <acm@muc.de>
Date:   Tue May 26 20:08:15 2020 +0000

    Introduce some Objective-C 2.0 keywords.  This fixes bug #5953
    
    * lisp/progmodes/cc-langs.el (c-other-decl-kwds): New keywords @property,
    @dynamic, @synthesize, @compatibility_alias.
    (c-protection-kwds): New keywords @package, @required, @optional.
    (c-block-stmt-1-kwds): New keyword @autoreleasepool.
    (c-constant-kwds): New keywords IBAction, IBOutlet.

diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index 2369cb0342..dcffc0d31b 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -2416,7 +2416,8 @@ If any of these also are on `c-type-list-kwds', `c-ref-list-kwds',
 `c-<>-type-kwds', or `c-<>-arglist-kwds' then the associated clauses
 will be handled."
   t       nil
-  objc    '("@class" "@end" "@defs")
+  objc    '("@class" "@defs" "@end" "@property" "@dynamic" "@synthesize"
+	    "@compatibility_alias")
   java    '("import" "package")
   pike    '("import" "inherit"))
 
@@ -2539,7 +2540,8 @@ one of `c-type-list-kwds', `c-ref-list-kwds',
   "Access protection label keywords in classes."
   t    nil
   c++  '("private" "protected" "public")
-  objc '("@private" "@protected" "@public"))
+  objc '("@private" "@protected" "@package" "@public"
+	 "@required" "@optional"))
 
 (c-lang-defconst c-protection-key
   ;; A regexp match an element of `c-protection-kwds' cleanly.
@@ -2754,7 +2756,7 @@ identifiers that follows the type in a normal declaration."
   "Statement keywords followed directly by a substatement."
   t    '("do" "else")
   c++  '("do" "else" "try")
-  objc '("do" "else" "@finally" "@try")
+  objc '("do" "else" "@finally" "@try" "@autoreleasepool")
   java '("do" "else" "finally" "try")
   idl  nil)
 
@@ -2897,7 +2899,8 @@ This construct is \"<keyword> <expression> :\"."
   c++     (append
            '("nullptr")
            (c-lang-const c-constant-kwds c))
-  objc    '("nil" "Nil" "YES" "NO" "NS_DURING" "NS_HANDLER" "NS_ENDHANDLER")
+  objc    '("nil" "Nil" "YES" "NO" "IBAction" "IBOutlet"
+	    "NS_DURING" "NS_HANDLER" "NS_ENDHANDLER")
   idl     '("TRUE" "FALSE")
   java    '("true" "false" "null") ; technically "literals", not keywords
   pike    '("UNDEFINED")) ;; Not a keyword, but practically works as one.