From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 26 May 2020 07:47:24 +0000 (-0700)
Subject: Port struct Lisp_FLoat to oddball platforms
X-Git-Tag: emacs-28.0.90~7273
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=9f7bfb6cb06f1480a0904184cabf187e03628e55;p=emacs.git

Port struct Lisp_FLoat to oddball platforms

* src/lisp.h (struct Lisp_Float): Declare via
GCALIGNED_UNION_MEMBER, not via GCALIGNED_STRUCT, since alloc.c
creates these in arrays and GCALIGNED_STRUCT does not necessarily
suffice to align struct Lisp_Float when it’s used in an array.
This avoids undefined behavior on oddball machines where
sizeof (struct Lisp_Float) is not a multiple of 8 and the compiler
does not support __attribute__ ((aligned 8)).
---

diff --git a/src/lisp.h b/src/lisp.h
index 8bd83a888ce..f5d581a2f1d 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2801,8 +2801,10 @@ struct Lisp_Float
     {
       double data;
       struct Lisp_Float *chain;
+      GCALIGNED_UNION_MEMBER
     } u;
-  } GCALIGNED_STRUCT;
+  };
+verify (GCALIGNED (struct Lisp_Float));
 
 INLINE bool
 (FLOATP) (Lisp_Object x)