From 287f6608519a7a986ef17898a26daddb4b7d3e3a Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Thu, 5 Nov 2015 22:17:42 -0500
Subject: [PATCH] Moving stack limits away from global vars

---
 gc.c                           | 19 +++++++++++++++++--
 include/cyclone/runtime-main.h |  2 +-
 include/cyclone/types.h        | 16 +++++++---------
 runtime.c                      |  4 ++--
 4 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/gc.c b/gc.c
index 682b06c7..1f9ccebe 100644
--- a/gc.c
+++ b/gc.c
@@ -657,9 +657,24 @@ void gc_empty_collector_stack()
 /////////////////////////////////////////////
 
 
-// Initialize a thread from scratch
-void gc_thread_data_init(gc_thread_data *thd)
+// Initialize runtime data structures for a thread.
+// Must be called on the target thread itself during startup,
+// to verify stack limits are setup correctly.
+void gc_thread_data_init(gc_thread_data *thd, char *stack_base, long stack_size)
 {
+  char stack_ref;
+  thd->stack_start = stack_base;
+#if STACK_GROWS_DOWNWARD
+  thd->stack_limit = stack_base - stack_size;
+#else
+  thd->stack_limit = stack_base + stack_size;
+#endif
+  if (check_overflow(stack_base, &stack_ref)){
+    fprintf(stderr, 
+      "Error: recompile with STACK_GROWS_DOWNWARD set to %d\n",
+      (1 - STACK_GROWS_DOWNWARD));
+    exit(1);
+  }
   thd->moveBufLen = 0;
   gc_thr_grow_move_buffer(thd);
 // TODO: depends on collector state:  thd->gc_alloc_color = ATOMIC_GET(&gc_;
diff --git a/include/cyclone/runtime-main.h b/include/cyclone/runtime-main.h
index e189f067..da75c5b4 100644
--- a/include/cyclone/runtime-main.h
+++ b/include/cyclone/runtime-main.h
@@ -60,7 +60,7 @@ static void Cyc_main (stack_size,heap_size,stack_base)
   Cyc_heap = gc_heap_create(heap_size / 2, 0, 0);
   //Cyc_heap = gc_heap_create(1024, 0, 0);
   Cyc_thread = malloc(sizeof(gc_thread_data));
-  gc_thread_data_init(Cyc_thread);
+  gc_thread_data_init(Cyc_thread, stack_base, stack_size);
   
 
   // JAE TODO: clean up below (and all of this old code, really)
diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index 9a38d798..88556bdd 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -22,17 +22,15 @@
 typedef void *object;
 
 /* Thread data structures */
-typedef struct gc_thread_stack_t gc_thread_stack;
-struct gc_thread_stack {
-  char *begin;
-  // TODO: move moveBuf stuff over here?
-};
-
 typedef struct gc_thread_data_t gc_thread_data;
 struct gc_thread_data_t {
-  void **moveBuf; /* list of objects moved to heap during GC */
+  // Data needed for stack-based minor GC
+  char *stack_start;
+  char *stack_limit;
+  // List of objects moved to heap during minor GC
+  void **moveBuf;
   int moveBufLen;
-  // Data needed for tri-color marking 
+  // Data needed for heap GC
   int gc_alloc_color;
   int gc_mut_status;
   int last_write;
@@ -118,7 +116,7 @@ size_t gc_sweep(gc_heap *h, size_t *sum_freed_ptr);
 size_t gc_collect(gc_heap *h, size_t *sum_freed);
 void gc_thr_grow_move_buffer(gc_thread_data *d);
 void gc_thr_add_to_move_buffer(gc_thread_data *d, int *alloci, object obj);
-void gc_thread_data_init(gc_thread_data *thd);
+void gc_thread_data_init(gc_thread_data *thd, char *stack_base, long stack_size);
 void gc_thread_data_free(gc_thread_data *thd);
 // Prototypes for mutator/collector:
 void gc_mark_gray(gc_thread_data *thd, object obj);
diff --git a/runtime.c b/runtime.c
index 9c2fea1a..7b815a40 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2594,7 +2594,7 @@ char *gc_move(char *obj, gc_thread_data *thd, int *alloci, int *heap_grown) {
   temp = obj; \
   if (check_overflow(low_limit, temp) && \
       check_overflow(temp, high_limit)){ \
-    (obj) = (object) gc_move(temp, Cyc_thread, &alloci, &heap_grown); \
+    (obj) = (object) gc_move(temp, (gc_thread_data *)data, &alloci, &heap_grown); \
   } \
 }
 
@@ -2660,7 +2660,7 @@ void GC(void *data, closure cont, object *args, int num_args)
 
   // Check allocated objects, moving additional objects as needed
   while (scani < alloci) {
-    object obj = Cyc_thread->moveBuf[scani];
+    object obj = ((gc_thread_data *)data)->moveBuf[scani];
     switch(type_of(obj)) {
       case cons_tag: {
         gc_move2heap(car(obj));