From 05100e597e4296a2e79e6c2d9cd75b7e1cc595c9 Mon Sep 17 00:00:00 2001
From: Mark Shinwell <mshinwell@janestreet.com>
Date: May 01 2014 13:07:48 +0000
Subject: initialize blocks with Val_unit, not zero


git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14720 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

---

diff --git a/Changes b/Changes
index e5646d4..effbe73 100644
--- a/Changes
+++ b/Changes
@@ -65,6 +65,8 @@ Toplevel interactive system:
 - PR#5377: New "#show_*" directives
 
 Runtime system:
+- Blocks initialized by [CAMLlocal*] and [caml_alloc] are now filled with
+  [Val_unit] rather than zero.
 - Fixed a major performance problem on large heaps (~1GB) by making heap
   increments proportional to heap size
 - PR#4765: Structural equality should treat exception specifically
diff --git a/byterun/alloc.c b/byterun/alloc.c
index a1fd2f0..1fc33b5 100644
--- a/byterun/alloc.c
+++ b/byterun/alloc.c
@@ -39,11 +39,13 @@ CAMLexport value caml_alloc (mlsize_t wosize, tag_t tag)
   }else if (wosize <= Max_young_wosize){
     Alloc_small (result, wosize, tag);
     if (tag < No_scan_tag){
-      for (i = 0; i < wosize; i++) Field (result, i) = 0;
+      for (i = 0; i < wosize; i++) Field (result, i) = Val_unit;
     }
   }else{
     result = caml_alloc_shr (wosize, tag);
-    if (tag < No_scan_tag) memset (Bp_val (result), 0, Bsize_wsize (wosize));
+    if (tag < No_scan_tag){
+      for (i = 0; i < wosize; i++) Field (result, i) = Val_unit;
+    }
     result = caml_check_urgent_gc (result);
   }
   return result;
diff --git a/byterun/memory.h b/byterun/memory.h
index 0761070..2d14796 100644
--- a/byterun/memory.h
+++ b/byterun/memory.h
@@ -266,27 +266,27 @@ CAMLextern struct caml__roots_block *caml_local_roots;  /* defined in roots.c */
     0)
 
 #define CAMLlocal1(x) \
-  value x = 0; \
+  value x = Val_unit; \
   CAMLxparam1 (x)
 
 #define CAMLlocal2(x, y) \
-  value x = 0, y = 0; \
+  value x = Val_unit, y = Val_unit; \
   CAMLxparam2 (x, y)
 
 #define CAMLlocal3(x, y, z) \
-  value x = 0, y = 0, z = 0; \
+  value x = Val_unit, y = Val_unit, z = Val_unit; \
   CAMLxparam3 (x, y, z)
 
 #define CAMLlocal4(x, y, z, t) \
-  value x = 0, y = 0, z = 0, t = 0; \
+  value x = Val_unit, y = Val_unit, z = Val_unit, t = Val_unit; \
   CAMLxparam4 (x, y, z, t)
 
 #define CAMLlocal5(x, y, z, t, u) \
-  value x = 0, y = 0, z = 0, t = 0, u = 0; \
+  value x = Val_unit, y = Val_unit, z = Val_unit, t = Val_unit, u = Val_unit; \
   CAMLxparam5 (x, y, z, t, u)
 
 #define CAMLlocalN(x, size) \
-  value x [(size)] = { 0, /* 0, 0, ... */ }; \
+  value x [(size)] = { Val_unit, /* Val_unit, Val_unit, ... */ }; \
   CAMLxparamN (x, (size))