From fdf67dae2092e0d6fe460e16a939080493e00a3b Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 9 Jan 2020 14:48:49 -0800
Subject: gc: consolidate top-of-stack and context handling.

* gc.c (mark): Eliminate mach_context_t * argument; just
gc_stack_top is passed.
(gc): Specify the base address of the machine context as the
top of the stack. Still, on aarch64, STACK_TOP_EXTRA_WORDS
is required, otherwise we get prematurely freed objects.
---
 gc.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/gc.c b/gc.c
index 84fd5b3a..3029158c 100644
--- a/gc.c
+++ b/gc.c
@@ -494,7 +494,7 @@ static void mark_mem_region(val *low, val *high)
     mark_obj_maybe(*low);
 }
 
-static void mark(mach_context_t *pmc, val *gc_stack_top)
+static void mark(val *gc_stack_top)
 {
   val **rootloc;
 
@@ -518,11 +518,6 @@ static void mark(mach_context_t *pmc, val *gc_stack_top)
   }
 #endif
 
-  /*
-   * Then the machine context
-   */
-  mark_mem_region(coerce(val *, pmc), coerce(val *, (pmc + 1)));
-
   /*
    * Finally, the stack.
    */
@@ -794,7 +789,6 @@ static void call_finals(void)
 
 void gc(void)
 {
-  val gc_stack_top = nil;
 #if CONFIG_GEN_GC
   int exhausted = (free_list == 0);
   int full_gc_next_time = 0;
@@ -817,7 +811,7 @@ void gc(void)
   gc_enabled = 0;
   rcyc_empty();
   iobuf_list_empty();
-  mark(&mc, &gc_stack_top);
+  mark(coerce(val *, &mc));
   hash_process_weak();
   prepare_finals();
   swept = sweep();
-- 
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