regalloc: fail when some reg bool variables remain unallocated

CHANGELOG.md

@@ -41,6 +41,10 @@
   ([PR #311](https://github.com/jasmin-lang/jasmin/pull/311);
   fixes [#309](https://github.com/jasmin-lang/jasmin/issues/309)).
 
+- Register allocation fails when some `reg bool` variables remain unallocated
+  ([PR #313](https://github.com/jasmin-lang/jasmin/pull/313);
+  fixes [#310](https://github.com/jasmin-lang/jasmin/issues/310)).
+
 ## Other changes
 
 - Explicit if-then-else in flag combinations is no longer supported

compiler/src/regalloc.ml

@@ -712,6 +712,15 @@ let two_phase_coloring
         A.set i y a
     ) schedule
 
+let check_allocated
+      (vars: (int, var list) Hashtbl.t)
+      (a: A.allocation) : unit =
+  match Hashtbl.fold (fun i x m -> if A.mem i a then m else x @ m) vars [] with
+  | [] -> ()
+  | m ->
+     hierror_reg ~loc:Lnone "variables { %a } remain unallocated"
+       (pp_list "; " (Printer.pp_var ~debug:true)) m
+
 let greedy_allocation
     (vars: int Hv.t)
     (nv: int) (cnf: conflicts)
@@ -720,6 +729,7 @@ let greedy_allocation
   let scalars : (int, var list) Hashtbl.t = Hashtbl.create nv in
   let extra_scalars : (int, var list) Hashtbl.t = Hashtbl.create nv in
   let vectors : (int, var list) Hashtbl.t = Hashtbl.create nv in
+  let flags : (int, var list) Hashtbl.t = Hashtbl.create nv in
   let push_var tbl i v =
     match Hashtbl.find tbl i with
     | old -> Hashtbl.replace tbl i (v :: old)
@@ -731,12 +741,13 @@ let greedy_allocation
           if reg_kind v.v_kind = Normal then push_var scalars i v
           else push_var extra_scalars i v
       | Vector -> push_var vectors i v
-      | Flag
+      | Flag -> push_var flags i v
       | Unknown _ -> ()
       ) vars;
   two_phase_coloring Arch.allocatable_vars scalars cnf fr a;
   two_phase_coloring Arch.extra_allocatable_vars extra_scalars cnf fr a;
   two_phase_coloring Arch.xmm_allocatable_vars vectors cnf fr a;
+  check_allocated flags a;
   ()
 
 let var_subst_of_allocation (vars: int Hv.t)

compiler/tests/fail/register_allocation/bug_310.jazz

@@ -0,0 +1,15 @@
+export
+fn test(reg u64 x y) -> reg u64 {
+  reg u64 r;
+  r = y;
+  reg bool valid;
+  if x > 56 {
+    valid = true;
+  } else {
+    valid = false;
+  }
+  if valid {
+    r = x;
+  }
+  return r;
+}