1 files changed, 8 insertions, 17 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 43b3ec618f0..bf9db591bd5 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -228,14 +228,12 @@ extern bool suppress_checking EXTERNALLY_VISIBLE;
 
    USE_LSB_TAG not only requires the least 3 bits of pointers returned by
    malloc to be 0 but also needs to be able to impose a mult-of-8 alignment
-   on the few static Lisp_Objects used: lispsym, all the defsubr, and
-   the two special buffers buffer_defaults and buffer_local_symbols.  */
+   on the few static Lisp_Objects used, all of which are aligned via
+   the GCALIGN macro defined below.  */
 
 enum Lisp_Bits
   {
-    /* 2**GCTYPEBITS.  This must be a macro that expands to a literal
-       integer constant, for MSVC.  */
-#define GCALIGNMENT 8
+    GCALIGNMENT = 1 << GCTYPEBITS,
 
     /* Number of bits in a Lisp_Object value, not counting the tag.  */
     VALBITS = EMACS_INT_WIDTH - GCTYPEBITS,
@@ -247,10 +245,6 @@ enum Lisp_Bits
     FIXNUM_BITS = VALBITS + 1
   };
 
-#if GCALIGNMENT != 1 << GCTYPEBITS
-# error "GCALIGNMENT and GCTYPEBITS are inconsistent"
-#endif
-
 /* The maximum value that can be stored in a EMACS_INT, assuming all
    bits other than the type bits contribute to a nonnegative signed value.
    This can be used in #if, e.g., '#if USE_LSB_TAG' below expands to an
@@ -277,18 +271,15 @@ DEFINE_GDB_SYMBOL_END (VALMASK)
 error !;
 #endif
 
+/* Declare an object to have an address that is a multiple of
+   GCALIGNMENT.  alignas is not suitable here, as it fails if the
+   object's natural alignment exceeds GCALIGNMENT.  */
 #ifdef HAVE_STRUCT_ATTRIBUTE_ALIGNED
 # define GCALIGNED __attribute__ ((aligned (GCALIGNMENT)))
 #else
 # define GCALIGNED /* empty */
 #endif
 
-/* A common multiple of the positive integers A and B.  Ideally this
-   would be the least common multiple, but there's no way to do that
-   as a constant expression in C, so do the best that we can easily do.  */
-#define COMMON_MULTIPLE(a, b) \
-  ((a) % (b) == 0 ? (a) : (b) % (a) == 0 ? (b) : (a) * (b))
-
 /* Some operations are so commonly executed that they are implemented
    as macros, not functions, because otherwise runtime performance would
    suffer too much when compiling with GCC without optimization.
@@ -2946,7 +2937,7 @@ CHECK_NUMBER_CDR (Lisp_Object x)
 #ifdef _MSC_VER
 #define DEFUN(lname, fnname, sname, minargs, maxargs, intspec, doc)     \
    Lisp_Object fnname DEFUN_ARGS_ ## maxargs ;                          \
-   static struct Lisp_Subr alignas (GCALIGNMENT) sname =                \
+   static struct Lisp_Subr GCALIGNED sname =                            \
    { { (PVEC_SUBR << PSEUDOVECTOR_AREA_BITS)                            \
        | (sizeof (struct Lisp_Subr) / sizeof (EMACS_INT)) },            \
       { (Lisp_Object (__cdecl *)(void))fnname },                        \
@@ -2954,7 +2945,7 @@ CHECK_NUMBER_CDR (Lisp_Object x)
    Lisp_Object fnname
 #else  /* not _MSC_VER */
 #define DEFUN(lname, fnname, sname, minargs, maxargs, intspec, doc)     \
-   static struct Lisp_Subr alignas (GCALIGNMENT) sname =                \
+   static struct Lisp_Subr GCALIGNED sname =                            \
      { { PVEC_SUBR << PSEUDOVECTOR_AREA_BITS },                         \
        { .a ## maxargs = fnname },                                      \
        minargs, maxargs, lname, intspec, 0};                            \