Revert "Merge pull request #378 from bobot/feature/reraise_raw_backtr…

…ace_primitive"

This reverts commit 5adf895, reversing
changes made to 38c3db4.

The reason for the revert is a continuous integration failure on 32bit
arm machines. I don't have the time (or capabilities) to investigate
it right now, and we need functional continuous testing for other
upcoming merges, so the safest choice is to revert -- and hopefully
merge back after the issue is fixed.

Changes

@@ -152,10 +152,6 @@ OCaml 4.04.0:
   array of floats
   (Thomas Braibant)
 
-- GPR#378: Add [Printexc.raise_with_backtrace] raise an exception using
-  an explicit backtrace
-  (François Bobot, review by Gabriel Scherer, Xavier Leroy, Damien Doligez,
-   Frédéric Bour)
 
 ### Manual and documentation:
 

asmrun/backtrace_prim.c

@@ -69,14 +69,6 @@ frame_descr * caml_next_frame_descriptor(uintnat * pc, char ** sp)
   }
 }
 
-int caml_alloc_backtrace_buffer(void){
-  Assert(caml_backtrace_pos == 0);
-  caml_backtrace_buffer = malloc(BACKTRACE_BUFFER_SIZE
-                                 * sizeof(backtrace_slot));
-  if (caml_backtrace_buffer == NULL) return -1;
-  return 0;
-}
-
 /* Stores the return addresses contained in the given stack fragment
    into the backtrace array ; this version is performance-sensitive as
    it is called at each [raise] in a program compiled with [-g], so we
@@ -89,9 +81,12 @@ void caml_stash_backtrace(value exn, uintnat pc, char * sp, char * trapsp)
     caml_backtrace_pos = 0;
     caml_backtrace_last_exn = exn;
   }
-
-  if (caml_backtrace_buffer == NULL && caml_alloc_backtrace_buffer() == -1)
-    return;
+  if (caml_backtrace_buffer == NULL) {
+    Assert(caml_backtrace_pos == 0);
+    caml_backtrace_buffer = malloc(BACKTRACE_BUFFER_SIZE
+                                   * sizeof(backtrace_slot));
+    if (caml_backtrace_buffer == NULL) return;
+  }
 
   /* iterate on each frame  */
   while (1) {

bytecomp/translcore.ml

@@ -338,9 +338,6 @@ let primitives_table = create_hashtable 57 [
 let find_primitive prim_name =
   Hashtbl.find primitives_table prim_name
 
-let prim_restore_raw_backtrace =
-  Primitive.simple ~name:"caml_restore_raw_backtrace" ~arity:2 ~alloc:false
-
 let specialize_comparison table env ty =
   let (gencomp, intcomp, floatcomp, stringcomp,
            nativeintcomp, int32comp, int64comp, _) = table in
@@ -774,26 +771,6 @@ and transl_exp0 e =
         match argl with [obj; meth; cache; pos] ->
           wrap (Lsend(Cached, meth, obj, [cache; pos], e.exp_loc))
         | _ -> assert false
-      else if p.prim_name = "%raise_with_backtrace" then begin
-        let texn1 = List.hd args (* Should not fail by typing *) in
-        let texn2,bt = match argl with
-          | [a;b] -> a,b
-          | _ -> assert false (* idem *)
-        in
-        let vexn = Ident.create "exn" in
-        Llet(Strict, Pgenval, vexn, texn2,
-             event_before e begin
-               Lsequence(
-                 wrap  (Lprim (Pccall prim_restore_raw_backtrace,
-                               [Lvar vexn;bt],
-                               e.exp_loc)),
-                 wrap0 (Lprim(Praise Raise_reraise,
-                              [event_after texn1 (Lvar vexn)],
-                              e.exp_loc))
-               )
-             end
-            )
-      end
       else begin
         let prim = transl_primitive_application
             e.exp_loc p e.exp_env prim_type (Some path) args in

byterun/backtrace.c

@@ -49,11 +49,9 @@ CAMLprim value caml_record_backtrace(value vflag)
     caml_backtrace_active = flag;
     caml_backtrace_pos = 0;
     caml_backtrace_last_exn = Val_unit;
-    /* Note: We do lazy initialization of caml_backtrace_buffer when
-       needed in order to simplify the interface with the thread
-       library (thread creation doesn't need to allocate
-       caml_backtrace_buffer). So we don't have to allocate it here.
-    */
+    /* Note: lazy initialization of caml_backtrace_buffer in
+       caml_stash_backtrace to simplify the interface with the thread
+       libraries */
   }
   return Val_unit;
 }
@@ -169,41 +167,6 @@ CAMLprim value caml_get_exception_raw_backtrace(value unit)
   CAMLreturn(res);
 }
 
-/* Copy back a backtrace and exception to the global state.
-   This function should be used only with Printexc.raw_backtrace */
-/* noalloc (caml value): so no CAMLparam* CAMLreturn* */
-CAMLprim value caml_restore_raw_backtrace(value exn, value backtrace)
-{
-  intnat i;
-  mlsize_t bt_size;
-
-  caml_backtrace_last_exn = exn;
-
-  bt_size = Wosize_val(backtrace);
-  if(bt_size > BACKTRACE_BUFFER_SIZE){
-    bt_size = BACKTRACE_BUFFER_SIZE;
-  }
-
-  /* We don't allocate if the backtrace is empty (no -g or backtrace
-     not activated) */
-  if(bt_size == 0){
-    caml_backtrace_pos = 0;
-    return Val_unit;
-  }
-
-  /* Allocate if needed and copy the backtrace buffer */
-  if (caml_backtrace_buffer == NULL && caml_alloc_backtrace_buffer() == -1){
-    return Val_unit;
-  }
-
-  caml_backtrace_pos = bt_size;
-  for(i=0; i < caml_backtrace_pos; i++){
-    caml_backtrace_buffer[i] = Backtrace_slot_val(Field(backtrace, i));
-  }
-
-  return Val_unit;
-}
-
 #define Val_debuginfo(bslot) (Val_long((uintnat)(bslot)>>1))
 #define Debuginfo_val(vslot) ((debuginfo)(Long_val(vslot) << 1))
 

byterun/backtrace_prim.c

@@ -217,13 +217,6 @@ CAMLprim value caml_remove_debug_info(code_t start)
   CAMLreturn(Val_unit);
 }
 
-int caml_alloc_backtrace_buffer(void){
-  Assert(caml_backtrace_pos == 0);
-  caml_backtrace_buffer = malloc(BACKTRACE_BUFFER_SIZE * sizeof(code_t));
-  if (caml_backtrace_buffer == NULL) return -1;
-  return 0;
-}
-
 /* Store the return addresses contained in the given stack fragment
    into the backtrace array */
 
@@ -235,8 +228,11 @@ void caml_stash_backtrace(value exn, code_t pc, value * sp, int reraise)
     caml_backtrace_last_exn = exn;
   }
 
-  if (caml_backtrace_buffer == NULL && caml_alloc_backtrace_buffer() == -1)
-    return;
+  if (caml_backtrace_buffer == NULL) {
+    Assert(caml_backtrace_pos == 0);
+    caml_backtrace_buffer = malloc(BACKTRACE_BUFFER_SIZE * sizeof(code_t));
+    if (caml_backtrace_buffer == NULL) return;
+  }
 
   if (caml_backtrace_pos >= BACKTRACE_BUFFER_SIZE) return;
   /* testing the code region is needed: PR#1554 */

byterun/caml/backtrace_prim.h

@@ -70,9 +70,6 @@ void caml_debuginfo_location(debuginfo dbg, /*out*/ struct caml_loc_info * li);
 #define Val_backtrace_slot(bslot) (Val_long(((uintnat)(bslot))>>1))
 #define Backtrace_slot_val(vslot) ((backtrace_slot)(Long_val(vslot) << 1))
 
-/* Allocate the caml_backtrace_buffer. Returns 0 on success, -1 otherwise */
-int caml_alloc_backtrace_buffer(void);
-
 #define BACKTRACE_BUFFER_SIZE 1024
 
 /* Besides decoding backtrace info, [backtrace_prim] has two other

stdlib/printexc.ml

@@ -89,9 +89,6 @@ type raw_backtrace
 external get_raw_backtrace:
   unit -> raw_backtrace = "caml_get_exception_raw_backtrace"
 
-external raise_with_backtrace: exn -> raw_backtrace -> 'a
-  = "%raise_with_backtrace"
-
 type backtrace_slot =
   | Known_location of {
       is_raise    : bool;
@@ -239,7 +236,8 @@ external get_raw_backtrace_next_slot :
 
 (* confusingly named:
    returns the *string* corresponding to the global current backtrace *)
-let get_backtrace () = raw_backtrace_to_string (get_raw_backtrace ())
+let get_backtrace () =
+  backtrace_to_string (convert_raw_backtrace (get_raw_backtrace ()))
 
 external record_backtrace: bool -> unit = "caml_record_backtrace"
 external backtrace_status: unit -> bool = "caml_backtrace_status"

stdlib/printexc.mli

@@ -42,20 +42,13 @@ val print_backtrace: out_channel -> unit
     on the output channel [oc].  The backtrace lists the program
     locations where the most-recently raised exception was raised
     and where it was propagated through function calls.
-
-    If the call is not inside an exception handler, the returned
-    backtrace is unspecified. If the call is after some
-    exception-catching code (before in the handler, or in a when-guard
-    during the matching of the exception handler), the backtrace may
-    correspond to a later exception than the handled one.
-
     @since 3.11.0
 *)
 
 val get_backtrace: unit -> string
 (** [Printexc.get_backtrace ()] returns a string containing the
     same exception backtrace that [Printexc.print_backtrace] would
-    print. Same restriction usage than {!print_backtrace}.
+    print.
     @since 3.11.0
 *)
 
@@ -113,7 +106,7 @@ type raw_backtrace
 val get_raw_backtrace: unit -> raw_backtrace
 (** [Printexc.get_raw_backtrace ()] returns the same exception
     backtrace that [Printexc.print_backtrace] would print, but in
-    a raw format. Same restriction usage than {!print_backtrace}.
+    a raw format.
 
     @since 4.01.0
 *)
@@ -132,14 +125,6 @@ val raw_backtrace_to_string: raw_backtrace -> string
     @since 4.01.0
 *)
 
-external raise_with_backtrace: exn -> raw_backtrace -> 'a
-  = "%raise_with_backtrace"
-(** Reraise the exception using the given raw_backtrace for the
-    origin of the exception
-
-    @since 4.03.0
-*)
-
 (** {6 Current call stack} *)
 
 val get_callstack: int -> raw_backtrace

testsuite/tests/backtrace/backtrace2.byte.reference

@@ -2,57 +2,26 @@ a
 No exception
 b
 Uncaught exception Backtrace2.Error("b")
-Raised at file "backtrace2.ml", line 8, characters 23-34
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 13, characters 4-11
-Re-raised at file "backtrace2.ml", line 15, characters 68-71
-Called from file "backtrace2.ml", line 58, characters 11-23
+Raised at file "backtrace2.ml", line 7, characters 21-32
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 11, characters 4-11
+Re-raised at file "backtrace2.ml", line 13, characters 68-71
+Called from file "backtrace2.ml", line 18, characters 11-23
 Uncaught exception Backtrace2.Error("c")
-Raised at file "backtrace2.ml", line 16, characters 26-37
-Called from file "backtrace2.ml", line 58, characters 11-23
+Raised at file "backtrace2.ml", line 14, characters 26-37
+Called from file "backtrace2.ml", line 18, characters 11-23
 Uncaught exception Backtrace2.Error("d")
-Raised at file "backtrace2.ml", line 8, characters 23-34
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 8, characters 44-55
-Called from file "backtrace2.ml", line 13, characters 4-11
-Called from file "backtrace2.ml", line 58, characters 11-23
-e
-Uncaught exception Backtrace2.Error("e")
-Raised at file "backtrace2.ml", line 22, characters 56-59
-Called from file "backtrace2.ml", line 58, characters 11-23
-f
-Uncaught exception Backtrace2.Error("f")
-Raised at file "backtrace2.ml", line 28, characters 68-71
-Called from file "backtrace2.ml", line 58, characters 11-23
+Raised at file "backtrace2.ml", line 7, characters 21-32
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 7, characters 42-53
+Called from file "backtrace2.ml", line 11, characters 4-11
+Called from file "backtrace2.ml", line 18, characters 11-23
 Uncaught exception Invalid_argument("index out of bounds")
-Raised by primitive operation at file "backtrace2.ml", line 58, characters 14-22
-test_Not_found
-Uncaught exception Not_found
-Raised at file "hashtbl.ml", line 192, characters 19-28
-Called from file "backtrace2.ml", line 39, characters 9-42
-Re-raised at file "backtrace2.ml", line 39, characters 67-70
-Called from file "backtrace2.ml", line 58, characters 11-23
-Uncaught exception Not_found
-Raised at file "backtrace2.ml", line 43, characters 24-33
-Called from file "backtrace2.ml", line 43, characters 43-52
-Called from file "backtrace2.ml", line 43, characters 43-52
-Called from file "backtrace2.ml", line 43, characters 43-52
-Called from file "backtrace2.ml", line 43, characters 43-52
-Called from file "backtrace2.ml", line 43, characters 43-52
-Called from file "camlinternalLazy.ml", line 27, characters 17-27
-Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
-Called from file "backtrace2.ml", line 58, characters 11-23
-Uncaught exception Not_found
-Raised at file "hashtbl.ml", line 192, characters 19-28
-Called from file "backtrace2.ml", line 46, characters 8-41
-Re-raised at file "camlinternalLazy.ml", line 33, characters 62-63
-Called from file "camlinternalLazy.ml", line 27, characters 17-27
-Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
-Called from file "backtrace2.ml", line 58, characters 11-23
+Raised by primitive operation at file "backtrace2.ml", line 18, characters 14-22