From 6adc5f20bba1b32dd0c43c0b9b819099f3df396f Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Thu, 24 Oct 2019 21:56:49 +0200
Subject: [PATCH] core: Prepaere for M2-Planet.

* src/gc.c (M2_CELL_SIZE): Hack for missing pointer arithmetic in
M2-Planet.
(gc_init, alloc, make_cell, gc_up_arena, gc_copy, gc_loop, gc_): Use it.
---
 src/gc.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/src/gc.c b/src/gc.c
index cb121496..602b18de 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -36,6 +36,9 @@
 
 void init_symbols_ ();
 
+// CONSTANT M2_CELL_SIZE 12
+#define M2_CELL_SIZE 1
+
 #if POINTER_CELLS
 long g_stack;
 #else
@@ -119,7 +122,7 @@ gc_init ()                      /*:((internal)) */
   TYPE (cell_arena) = TVECTOR;
   LENGTH (cell_arena) = 1000;
   VECTOR (cell_arena) = 0;
-  g_cells = g_cells + 1;
+  g_cells = g_cells + M2_CELL_SIZE;
   TYPE (cell_arena) = TCHAR;
   VALUE (cell_arena) = 'c';
 
@@ -157,7 +160,7 @@ SCM
 alloc (long n)
 {
   SCM x = g_free;
-  g_free = g_free + n;
+  g_free = g_free + n * M2_CELL_SIZE;
 #if POINTER_CELLS
   long i = g_free - g_cells;
 #else
@@ -172,7 +175,7 @@ SCM
 make_cell (long type, SCM car, SCM cdr)
 {
   SCM x = g_free;
-  g_free = g_free + 1;
+  g_free = g_free + M2_CELL_SIZE;
 #if POINTER_CELLS
   long i = g_free - g_cells;
 #else
@@ -211,7 +214,7 @@ copy_stack (long index, SCM from)
 SCM
 cell_ref (SCM cell, long index)
 {
-  return cell + index;
+  return cell + index * M2_CELL_SIZE;
 }
 
 SCM
@@ -330,7 +333,7 @@ gc_up_arena ()                  /*:((internal)) */
   else
     ARENA_SIZE = MAX_ARENA_SIZE - JAM_SIZE;
   long arena_bytes = (ARENA_SIZE + JAM_SIZE) * sizeof (struct scm);
-  void *p = realloc (g_cells - 1, arena_bytes + STACK_SIZE * sizeof (SCM));
+  void *p = realloc (g_cells - M2_CELL_SIZE, arena_bytes + STACK_SIZE * sizeof (SCM));
   if (p == 0)
     {
       eputs ("realloc failed, g_free=");
@@ -348,7 +351,7 @@ gc_up_arena ()                  /*:((internal)) */
     }
   g_cells = p;
   memcpy (p + arena_bytes, p + old_arena_bytes, STACK_SIZE * sizeof (SCM));
-  g_cells = g_cells + 1;
+  g_cells = g_cells + M2_CELL_SIZE;
 
   return 0;
 }
@@ -378,7 +381,7 @@ gc_copy (SCM old)               /*:((internal)) */
   if (TYPE (old) == TBROKEN_HEART)
     return CAR (old);
   SCM new = g_free;
-  g_free = g_free + 1;
+  g_free = g_free + M2_CELL_SIZE;
   copy_news (new, old);
   if (NTYPE (new) == TSTRUCT || NTYPE (new) == TVECTOR)
     {
@@ -387,7 +390,7 @@ gc_copy (SCM old)               /*:((internal)) */
       for (i = 0; i < LENGTH (old); i = i + 1)
         {
           copy_news (g_free, cell_ref (VECTOR (old), i));
-          g_free = g_free + 1;
+          g_free = g_free + M2_CELL_SIZE;
         }
     }
   else if (NTYPE (new) == TBYTES)
@@ -400,7 +403,7 @@ gc_copy (SCM old)               /*:((internal)) */
       size_t length = NLENGTH (new);
 #endif
       memcpy (dest, src, length + 1);
-      g_free = g_free + bytes_cells (length) - 1;
+      g_free = g_free + (bytes_cells (length) - 1) * M2_CELL_SIZE;
 
       if (g_debug > 4)
         {
@@ -460,8 +463,8 @@ gc_loop (SCM scan)              /*:((internal)) */
           gc_relocate_cdr (scan, cdr);
         }
       if (NTYPE (scan) == TBYTES)
-        scan = scan + bytes_cells (NLENGTH (scan)) - 1;
-      scan = scan + 1;
+        scan = scan + (bytes_cells (NLENGTH (scan)) - 1) * M2_CELL_SIZE;
+      scan = scan + M2_CELL_SIZE;
     }
   gc_flip ();
 }
@@ -521,14 +524,14 @@ gc_ ()                          /*:((internal)) */
     }
 
   SCM s;
-  for (s = cell_nil; s < g_symbol_max; s = s + 1)
+  for (s = cell_nil; s < g_symbol_max; s = s + M2_CELL_SIZE)
     gc_copy (s);
   g_symbols = gc_copy (g_symbols);
   g_macros = gc_copy (g_macros);
   g_ports = gc_copy (g_ports);
   M0 = gc_copy (M0);
   long i;
-  for (i = g_stack; i < STACK_SIZE; i = i + 1)
+  for (i = g_stack; i < STACK_SIZE; i = i + M2_CELL_SIZE)
     copy_stack (i, gc_copy (g_stack_array[i]));
 #if POINTER_CELLS
   long save_gfree = g_free;