[Guile-commits] 07/12: Replace dynamic link on stack with previous frame size

[Andy Wingo]

wingo pushed a commit to branch master
in repository guile.

commit 72353de77d0a06f158d8af66a2540015658e2574
Author: Andy Wingo <address@hidden>
Date:   Sun Oct 18 22:59:23 2015 +0200

    Replace dynamic link on stack with previous frame size
    
    * libguile/frames.h (SCM_FRAME_DYNAMIC_LINK)
      (SCM_FRAME_SET_DYNAMIC_LINK): Instead of storing the absolute value of
      the previous FP, store its offset from the current FP.  This allows us
      to avoid relinking when composing continuations or when relocating the
      stack.
    
    * libguile/frames.c (scm_frame_dynamic_link, scm_c_frame_previous): No
      need to relocate the dynamic link.
    
    * libguile/vm.c (vm_return_to_continuation_inner):
      (vm_reinstate_partial_continuation_inner, vm_expand_stack_inner):
      Don't relocate the frame pointer chain.
      (scm_i_vm_mark_stack): Terminate when FP is above stack_top, not when
      0.
      (make_vm): Init FP to stack_top.
---
 libguile/frames.c |   12 ++----------
 libguile/frames.h |    6 +++---
 libguile/vm.c     |   49 +++++++------------------------------------------
 3 files changed, 12 insertions(+), 55 deletions(-)

diff --git a/libguile/frames.c b/libguile/frames.c
index f89b0fd..a1c7f3e 100644
--- a/libguile/frames.c
+++ b/libguile/frames.c
@@ -309,8 +309,6 @@ SCM_DEFINE (scm_frame_return_address, 
"frame-return-address", 1, 0, 0,
 }
 #undef FUNC_NAME
 
-#define RELOC(kind, frame, val) ((val) + frame_offset (kind, frame))
-
 SCM_DEFINE (scm_frame_dynamic_link, "frame-dynamic-link", 1, 0, 0,
            (SCM frame),
            "")
@@ -320,8 +318,7 @@ SCM_DEFINE (scm_frame_dynamic_link, "frame-dynamic-link", 
1, 0, 0,
   /* fixme: munge fp if holder is a continuation */
   return scm_from_uintptr_t
     ((scm_t_uintptr)
-     RELOC (SCM_VM_FRAME_KIND (frame), SCM_VM_FRAME_DATA (frame),
-            SCM_FRAME_DYNAMIC_LINK (SCM_VM_FRAME_FP (frame))));
+     SCM_FRAME_DYNAMIC_LINK (SCM_VM_FRAME_FP (frame)));
 }
 #undef FUNC_NAME
 
@@ -339,12 +336,7 @@ scm_c_frame_previous (enum scm_vm_frame_kind kind, struct 
scm_frame *frame)
 
   new_fp = SCM_FRAME_DYNAMIC_LINK (this_fp);
 
-  if (!new_fp)
-    return 0;
-
-  new_fp = RELOC (kind, frame, new_fp);
-
-  if (new_fp > stack_top)
+  if (new_fp >= stack_top)
     return 0;
 
   new_sp = SCM_FRAME_PREVIOUS_SP (this_fp);
diff --git a/libguile/frames.h b/libguile/frames.h
index 870477d..e1130e9 100644
--- a/libguile/frames.h
+++ b/libguile/frames.h
@@ -88,7 +88,7 @@
 /* Each element on the stack occupies the same amount of space.  */
 union scm_vm_stack_element
 {
-  union scm_vm_stack_element *as_fp;
+  scm_t_uintptr as_uint;
   scm_t_uint32 *as_ip;
   SCM as_scm;
 
@@ -100,8 +100,8 @@ union scm_vm_stack_element
 #define SCM_FRAME_PREVIOUS_SP(fp)      ((fp) + 2)
 #define SCM_FRAME_RETURN_ADDRESS(fp)    ((fp)[0].as_ip)
 #define SCM_FRAME_SET_RETURN_ADDRESS(fp, ra) ((fp)[0].as_ip = (ra))
-#define SCM_FRAME_DYNAMIC_LINK(fp)      ((fp)[1].as_fp)
-#define SCM_FRAME_SET_DYNAMIC_LINK(fp, dl) ((fp)[1].as_fp = (dl))
+#define SCM_FRAME_DYNAMIC_LINK(fp)      ((fp) + (fp)[1].as_uint)
+#define SCM_FRAME_SET_DYNAMIC_LINK(fp, dl) ((fp)[1].as_uint = ((dl) - (fp)))
 #define SCM_FRAME_SLOT(fp,i)            ((fp) - (i) - 1)
 #define SCM_FRAME_LOCAL(fp,i)           (SCM_FRAME_SLOT (fp, i)->as_scm)
 #define SCM_FRAME_NUM_LOCALS(fp, sp)    ((fp) - (sp))
diff --git a/libguile/vm.c b/libguile/vm.c
index bc9f290..2db0795 100644
--- a/libguile/vm.c
+++ b/libguile/vm.c
@@ -179,21 +179,6 @@ vm_return_to_continuation_inner (void *data_ptr)
           cp->stack_size * sizeof (*cp->stack_bottom));
   vm_restore_sp (vp, vp->stack_top - cp->stack_size);
 
-  if (reloc)
-    {
-      union scm_vm_stack_element *fp = vp->fp;
-      while (fp)
-        {
-          union scm_vm_stack_element *next_fp = SCM_FRAME_DYNAMIC_LINK (fp);
-          if (next_fp)
-            {
-              next_fp += reloc;
-              SCM_FRAME_SET_DYNAMIC_LINK (fp, next_fp);
-            }
-          fp = next_fp;
-        }
-    }
-
   return NULL;
 }
 
@@ -385,13 +370,6 @@ vm_reinstate_partial_continuation_inner (void *data_ptr)
   vp->fp = cp->fp + reloc;
   vp->ip = cp->ra;
 
-  /* now relocate frame pointers */
-  {
-    union scm_vm_stack_element *fp;
-    for (fp = vp->fp; fp < base_fp; fp = SCM_FRAME_DYNAMIC_LINK (fp))
-      SCM_FRAME_SET_DYNAMIC_LINK (fp, SCM_FRAME_DYNAMIC_LINK (fp) + reloc);
-  }
-
   data->reloc = reloc;
 
   return NULL;
@@ -876,7 +854,7 @@ make_vm (void)
   vp->ip = NULL;
   vp->sp = vp->stack_top;
   vp->sp_min_since_gc = vp->sp;
-  vp->fp = NULL;
+  vp->fp = vp->stack_top;
   vp->engine = vm_default_engine;
   vp->trace_level = 0;
   for (i = 0; i < SCM_VM_NUM_HOOKS; i++)
@@ -967,7 +945,9 @@ scm_i_vm_mark_stack (struct scm_vm *vp, struct GC_ms_entry 
*mark_stack_ptr,
 
   memset (&cache, 0, sizeof (cache));
 
-  for (fp = vp->fp, sp = vp->sp; fp; fp = SCM_FRAME_DYNAMIC_LINK (fp))
+  for (fp = vp->fp, sp = vp->sp;
+       fp < vp->stack_top;
+       fp = SCM_FRAME_DYNAMIC_LINK (fp))
     {
       scm_t_ptrdiff nlocals = SCM_FRAME_NUM_LOCALS (fp, sp);
       size_t slot = nlocals - 1;
@@ -1047,24 +1027,9 @@ vm_expand_stack_inner (void *data_ptr)
   vp->stack_limit = vp->stack_bottom;
   reloc = vp->stack_top - old_top;
 
-  if (reloc)
-    {
-      union scm_vm_stack_element *fp;
-      if (vp->fp)
-        vp->fp += reloc;
-      data->new_sp += reloc;
-      fp = vp->fp;
-      while (fp)
-        {
-          union scm_vm_stack_element *next_fp = SCM_FRAME_DYNAMIC_LINK (fp);
-          if (next_fp)
-            {
-              next_fp += reloc;
-              SCM_FRAME_SET_DYNAMIC_LINK (fp, next_fp);
-            }
-          fp = next_fp;
-        }
-    }
+  if (vp->fp)
+    vp->fp += reloc;
+  data->new_sp += reloc;
 
   return new_bottom;
 }