[m-rev.] diff: java mutables don't require synchronisation

[Julien Fischer]

On Fri, 7 May 2010, Peter Wang wrote:

> Branches: main, 10.04
>
> Reads/writes of 32-bit variables in Java are are atomic and do not require
> further synchronisation.  Don't generate `synchronized' statements in Java
> mutable accessors.
>
> compiler/make_hlds_passes.m:
> compiler/prog_mutable.m:
>        As above.

This change broke the nightly builds -- I've committed the patch below
that fixes this.

Julien.

--------

Branches: main, 10.04

Fix a problem that broke the nightly builds.

compiler/make_hlds_passes.m:
 	Avoid singleton variables.

Index: make_hlds_passes.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/compiler/make_hlds_passes.m,v
retrieving revision 1.98
diff -u -r1.98 make_hlds_passes.m
--- make_hlds_passes.m	7 May 2010 03:46:24 -0000	1.98
+++ make_hlds_passes.m	7 May 2010 11:42:58 -0000
@@ -1678,8 +1678,8 @@
              % Add foreign_code item that defines the global variable used to
              % implement the mutable.
              IsThreadLocal = mutable_var_thread_local(MutAttrs),
-            add_java_mutable_defn(TargetMutableName, Type, IsConstant,
-                IsThreadLocal, Context, !ModuleInfo, !QualInfo, !Specs),
+            add_java_mutable_defn(TargetMutableName, Type, IsThreadLocal,
+                Context, !ModuleInfo, !QualInfo, !Specs),

              % Add all the predicates related to mutables.
              add_java_mutable_preds(ItemMutable, TargetMutableName,
@@ -2309,24 +2309,23 @@
      % Add foreign_code item that defines the global variable used to hold the
      % mutable.
      %
-:- pred add_java_mutable_defn(string::in, mer_type::in, bool::in,
+:- pred add_java_mutable_defn(string::in, mer_type::in,
      mutable_thread_local::in, prog_context::in,
      module_info::in, module_info::out, qual_info::in, qual_info::out,
      list(error_spec)::in, list(error_spec)::out) is det.

-add_java_mutable_defn(TargetMutableName, Type, IsConstant, IsThreadLocal,
-        Context, !ModuleInfo, !QualInfo, !Specs) :-
+add_java_mutable_defn(TargetMutableName, Type, IsThreadLocal, Context,
+        !ModuleInfo, !QualInfo, !Specs) :-
      get_java_mutable_global_foreign_defn(!.ModuleInfo, Type,
-        TargetMutableName, IsConstant, IsThreadLocal, Context, ForeignDefn),
+        TargetMutableName, IsThreadLocal, Context, ForeignDefn),
      ItemStatus0 = item_status(status_local, may_be_unqualified),
      add_item_decl_pass_2(ForeignDefn, ItemStatus0, _, !ModuleInfo, !Specs).

  :- pred get_java_mutable_global_foreign_defn(module_info::in, mer_type::in,
-    string::in, bool::in, mutable_thread_local::in, prog_context::in,
-    item::out) is det.
+    string::in, mutable_thread_local::in, prog_context::in, item::out) is det.

  get_java_mutable_global_foreign_defn(_ModuleInfo, _Type, TargetMutableName,
-        IsConstant, IsThreadLocal, Context, DefnItem) :-
+        IsThreadLocal, Context, DefnItem) :-
      (
          IsThreadLocal = mutable_not_thread_local,
          % Synchronization is only required for double and long values, which
@@ -2415,7 +2414,6 @@
      set_purity(purity_semipure, Attrs, GetAttrs0),
      set_thread_safe(proc_thread_safe, GetAttrs0, GetAttrs),
      varset.new_named_var(varset.init, "X", X, ProgVarSet),
-    MutableMutexVarName = mutable_mutex_var_name(TargetMutableName),
      (
          IsThreadLocal = mutable_not_thread_local,
          GetCode = "\tX = " ++ TargetMutableName ++ ";\n"
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