With frame-pointers entertrap restores base pointer

Changes

@@ -465,6 +465,10 @@ OCaml 4.14.0
 - #10907, #10959: Wrong type inferred from existential types
   (Jacques Garrigue and Gabriel Scherer, report by @dyzsr, review by Leo White)
 
+- #11031: Exception handlers restore the rbp register when using frame-pointers
+  on amd64.
+  (Fabrice Buoro, with help from Stephen Dolan, Tom Kelly and Mark Shinwell,
+  review by Xavier Leroy)
 
 OCaml 4.13 maintenance branch
 -----------------------------

asmcomp/amd64/emit.mlp

@@ -804,7 +804,10 @@ let emit_instr env fallthrough i =
       done;
       emit_named_text_section env.f.fun_name
   | Lentertrap ->
-      ()
+      if fp then begin
+        let delta = frame_size env - 16 (* retaddr + rbp *) in
+        I.lea (mem64 NONE delta RSP) rbp
+      end;
   | Ladjust_trap_depth { delta_traps; } ->
       (* each trap occupies 16 bytes on the stack *)
       let delta = 16 * delta_traps in