From 203211090f9e67750a0f953d6dbefe5045271921 Mon Sep 17 00:00:00 2001
From: Guillaume Melquiond
Date: Sun, 30 Aug 2020 10:31:02 +0200
Subject: Restore discard_dead_code and use it to simplify match-with
 constructs.

Otherwise, these constructs would be followed by a spurious Kreturn
opcode, when in tail position.
---
 kernel/vmbytegen.ml | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

(limited to 'kernel')

diff --git a/kernel/vmbytegen.ml b/kernel/vmbytegen.ml
index 6899ebe1a6..489929d2be 100644
--- a/kernel/vmbytegen.ml
+++ b/kernel/vmbytegen.ml
@@ -315,12 +315,10 @@ let pos_evar evk r =
 (* non-terminating instruction (branch, raise, return, appterm)          *)
 (* in front of it.                                                       *)
 
-let discard_dead_code cont = cont
-(*function
-    [] -> []
+let rec discard_dead_code = function
+  | [] -> []
   | (Klabel _ | Krestart ) :: _ as cont -> cont
   | _ :: cont -> discard_dead_code cont
-*)
 
 (* Return a label to the beginning of the given continuation.            *)
 (*   If the sequence starts with a branch, use the target of that branch *)
@@ -700,6 +698,7 @@ let rec compile_lam env cenv lam sz cont =
         | _ -> assert false
       in
 
+      let cont = discard_dead_code cont in
       let c = ref cont in
       (* Perform the extra match if needed (too many block constructors) *)
       if neblock <> 0 then begin
-- 
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