diff options
| -rw-r--r-- | bytecomp/simplif.ml | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/bytecomp/simplif.ml b/bytecomp/simplif.ml index e17c1d0b1..fc2559f66 100644 --- a/bytecomp/simplif.ml +++ b/bytecomp/simplif.ml @@ -363,6 +363,14 @@ let simplify_lets lam = let subst = Hashtbl.create 83 in let optimize = !Clflags.native_code || not !Clflags.debug in +(* This (small) optimisation is always legal, it may uncover some + tail call later on. *) + + let mklet (kind,v,e1,e2) = match e2 with + | Lvar w when optimize && Ident.same v w -> e1 + | _ -> Llet (kind,v,e1,e2) in + + let rec simplif = function Lvar v as l -> begin try @@ -381,9 +389,9 @@ let simplify_lets lam = let slinit = simplif linit in let slbody = simplif lbody in begin try - Llet(Variable, v, slinit, eliminate_ref v slbody) + mklet (Variable, v, slinit, eliminate_ref v slbody) with Real_reference -> - Llet(Strict, v, Lprim(Pmakeblock(0, Mutable), [slinit]), slbody) + mklet(Strict, v, Lprim(Pmakeblock(0, Mutable), [slinit]), slbody) end | Llet(Alias, v, l1, l2) -> begin match count_var v with @@ -394,9 +402,9 @@ let simplify_lets lam = | Llet(StrictOpt, v, l1, l2) -> begin match count_var v with 0 -> simplif l2 - | n -> Llet(Alias, v, simplif l1, simplif l2) + | n -> mklet(Alias, v, simplif l1, simplif l2) end - | Llet(kind, v, l1, l2) -> Llet(kind, v, simplif l1, simplif l2) + | Llet(kind, v, l1, l2) -> mklet(kind, v, simplif l1, simplif l2) | Lletrec(bindings, body) -> Lletrec(List.map (fun (v, l) -> (v, simplif l)) bindings, simplif body) | Lprim(p, ll) -> Lprim(p, List.map simplif ll) |