Index: asmcomp/cmmgen.ml
===================================================================
--- asmcomp/cmmgen.ml	(revision 13092)
+++ asmcomp/cmmgen.ml	(working copy)
@@ -411,6 +411,13 @@
 
 (* To compile "let rec" over values *)
 
+let rec is_seq_ending_with x id =
+  match x with
+  | Uvar id2 -> Ident.same id id2
+  | Usequence (_, y) -> is_seq_ending_with y id
+  | _ -> false
+;;
+
 let fundecls_size fundecls =
   let sz = ref (-1) in
   List.iter
@@ -426,6 +433,10 @@
 let rec expr_size = function
   | Uclosure(fundecls, clos_vars) ->
       RHS_block (fundecls_size fundecls + List.length clos_vars)
+  | Ulet (id, Uprim (Pduprecord (Record_regular, sz), _, _), body)
+    when is_seq_ending_with body id -> RHS_block sz
+  | Ulet (id, Uprim (Pduprecord (Record_float, sz), _, _), body)
+    when is_seq_ending_with body id -> RHS_floatblock sz
   | Ulet(id, exp, body) ->
       expr_size body
   | Uletrec(bindings, body) ->

Index: asmcomp/cmmgen.ml
===================================================================
--- asmcomp/cmmgen.ml	(revision 13092)
+++ asmcomp/cmmgen.ml	(working copy)
@@ -423,21 +423,27 @@
   | RHS_floatblock of int
   | RHS_nonrec
 ;;
-let rec expr_size = function
+let rec expr_size env = function
+  | Uvar id ->
+      begin try Ident.find_same id env with Not_found -> RHS_nonrec end
   | Uclosure(fundecls, clos_vars) ->
       RHS_block (fundecls_size fundecls + List.length clos_vars)
   | Ulet(id, exp, body) ->
-      expr_size body
+      expr_size (Ident.add id (expr_size env exp) env) body
   | Uletrec(bindings, body) ->
-      expr_size body
+      expr_size env body
   | Uprim(Pmakeblock(tag, mut), args, _) ->
       RHS_block (List.length args)
   | Uprim(Pmakearray(Paddrarray | Pintarray), args, _) ->
       RHS_block (List.length args)
   | Uprim(Pmakearray(Pfloatarray), args, _) ->
       RHS_floatblock (List.length args)
+  | Uprim (Pduprecord (Record_regular, sz), _, _) ->
+      RHS_block sz
+  | Uprim (Pduprecord (Record_float, sz), _, _) ->
+      RHS_floatblock sz
   | Usequence(exp, exp') ->
-      expr_size exp'
+      expr_size env exp'
   | _ -> RHS_nonrec
 
 (* Record application and currying functions *)
@@ -1557,7 +1563,8 @@
           (Array.of_list !inters) actions)
 
 and transl_letrec bindings cont =
-  let bsz = List.map (fun (id, exp) -> (id, exp, expr_size exp)) bindings in
+  let bsz =
+    List.map (fun (id, exp) -> (id, exp, expr_size Ident.empty exp)) bindings in
   let op_alloc prim sz =
     Cop(Cextcall(prim, typ_addr, true, Debuginfo.none), [int_const sz]) in
   let rec init_blocks = function
Index: boot/ocamldep
===================================================================
Cannot display: file marked as a binary type.
svn:mime-type = application/octet-stream
Index: boot/ocamllex
===================================================================
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svn:mime-type = application/octet-stream
Index: boot/ocamlc
===================================================================
Cannot display: file marked as a binary type.
svn:mime-type = application/octet-stream
Index: Changes
===================================================================
--- Changes	(revision 13092)
+++ Changes	(working copy)
@@ -10,8 +10,8 @@
 - PR#5785: misbehaviour with abstracted structural type used as GADT index
 - PR#5806: ensure that backtrace tests are always run (testsuite)
 - PR#5810: error in switch printing when using -dclambda
+- PR#5819: segfault when using [with] on large recursive record (ocamlopt)
 
-
 OCaml 4.00.1:
 -------------