flambda-backend: Make stack allocation the default (ocaml-flambda#1013)

Author: mshinwell

configure

@@ -2035,10 +2035,10 @@ AS_IF([test x"$DEFAULT_STRING" = "xunsafe"],
   [default_safe_string=false],
   [default_safe_string=true])
 
-AS_IF([test x"$enable_stack_allocation" = "xyes"],
+AS_IF([test x"$enable_stack_allocation" = "xno"],
+  [stack_allocation=false],
   [AC_DEFINE([STACK_ALLOCATION])
-   stack_allocation=true],
-  [stack_allocation=false])
+   stack_allocation=true])
 
 AS_IF([test x"$enable_poll_insertion" = "xyes"],
   [AC_DEFINE([POLL_INSERTION])

configure.ac

@@ -8,6 +8,7 @@
  *)
 
 external local_stack_offset : unit -> int = "caml_local_stack_offset"
+let local_stack_offset () = local_stack_offset () / (Sys.word_size / 8)
 external opaque_local : ('a[@local_opt]) -> ('a[@local_opt]) = "%opaque"
 
 let print_offsets (name,allocs) =

testsuite/tests/typing-local/loop_regions.ml

@@ -1,6 +1,6 @@
-                local for: [0; 16; 16]
-            non-local for: [0; 16; 0]
-         local while body: [0; 16; 16]
-      nonlocal while body: [0; 16; 0]
-         local while cond: [0; 16; 16]
-      nonlocal while cond: [0; 16; 0]
+                local for: [0; 2; 2]
+            non-local for: [0; 2; 0]
+         local while body: [0; 2; 2]
+      nonlocal while body: [0; 2; 0]
+         local while cond: [0; 2; 2]
+      nonlocal while cond: [0; 2; 0]

testsuite/tests/typing-local/loop_regions.stack.reference

@@ -28,5 +28,5 @@ let () =
   let p = to_be_overapplied () () () 42 () in
   let end_offset = local_stack_offset () in
   assert (is_local p);
-  let ok = end_offset - start_offset = 64 in
+  let ok = end_offset - start_offset = Sys.word_size (* eight words *) in
   Printf.printf "PR902: %s\n" (if ok then "ok" else "FAIL")