[m-rev.] for review: new required_feature_set feature

[Julien Fischer]

Estimated hours taken: 1
Branches: main

Support a new feature in required_feature_set pragmas that specifies that a
module should be compiled with conservative garbage collection enabled.
This feature is only checked when using the C backends, the other backends
ignore it.

compiler/prog_data.m:
 	Add the new feature.

compiler/prog_io_pragma.m:
 	Parse the new feature.

compiler/add_pragma.m:
 	If a conservative_gc feature is present check that
 	conservative GC is implied by the current options
 	and emit an error message if it is not.  Do nothing
 	in the case where `--garbage-collection automatic'
 	because that implies the use of one of the non-C
 	backends.

compiler/mercury_to_mercury.m:
 	Conform to the above change.

doc/reference_manual.texi:
 	Document the new feature.

Julien.

Index: compiler/add_pragma.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/compiler/add_pragma.m,v
retrieving revision 1.77
diff -u -r1.77 add_pragma.m
--- compiler/add_pragma.m	22 Jan 2008 15:06:08 -0000	1.77
+++ compiler/add_pragma.m	24 Jan 2008 11:39:02 -0000
@@ -3893,6 +3893,32 @@
              Spec = error_spec(severity_error, phase_parse_tree_to_hlds, [Msg]),
              !:Specs = [Spec | !.Specs]
          )
+    ;
+        Feature = reqf_conservative_gc,
+        globals.get_gc_method(Globals, GC_Method),
+        (
+            % We consider gc_automatic to be conservative even it may not be.
+            % This is okay because this feature is only of interest with the
+            % C or asm backends.  We ignore it if the target language is
+            % something else.
+            %
+            ( GC_Method = gc_automatic
+            ; GC_Method = gc_boehm
+            ; GC_Method = gc_boehm_debug
+            ; GC_Method = gc_mps
+            )
+        ;
+            ( GC_Method = gc_accurate
+            ; GC_Method = gc_none
+            ),
+            Pieces = [
+                words("Error: this module must be compiled in a grade that"),
+                words("uses conservative garbage collection.")
+            ],
+            Msg = simple_msg(Context, [always(Pieces)]),
+            Spec = error_spec(severity_error, phase_parse_tree_to_hlds, [Msg]),
+            !:Specs = [Spec | !.Specs] 
+        )
      ).

  %----------------------------------------------------------------------------%
Index: compiler/mercury_to_mercury.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/compiler/mercury_to_mercury.m,v
retrieving revision 1.324
diff -u -r1.324 mercury_to_mercury.m
--- compiler/mercury_to_mercury.m	22 Jan 2008 15:06:12 -0000	1.324
+++ compiler/mercury_to_mercury.m	24 Jan 2008 11:39:02 -0000
@@ -3816,6 +3816,8 @@
      add_string("trailing", !U).
  mercury_format_required_feature(reqf_strict_sequential, !U) :-
      add_string("strict_sequential", !U).
+mercury_format_required_feature(reqf_conservative_gc, !U) :-
+    add_string("conservative_gc", !U).

  %-----------------------------------------------------------------------------%

Index: compiler/prog_data.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/compiler/prog_data.m,v
retrieving revision 1.202
diff -u -r1.202 prog_data.m
--- compiler/prog_data.m	22 Jan 2008 15:06:14 -0000	1.202
+++ compiler/prog_data.m	24 Jan 2008 11:39:02 -0000
@@ -637,7 +637,8 @@
      ;       reqf_memo
      ;       reqf_parallel_conj
      ;       reqf_trailing
-    ;       reqf_strict_sequential.
+    ;       reqf_strict_sequential
+    ;       reqf_conservative_gc.

  %-----------------------------------------------------------------------------%
  %
Index: compiler/prog_io_pragma.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/compiler/prog_io_pragma.m,v
retrieving revision 1.131
diff -u -r1.131 prog_io_pragma.m
--- compiler/prog_io_pragma.m	10 Jan 2008 04:29:53 -0000	1.131
+++ compiler/prog_io_pragma.m	24 Jan 2008 11:39:04 -0000
@@ -2747,6 +2747,7 @@
  string_to_required_feature("parallel_conj",     reqf_parallel_conj).
  string_to_required_feature("trailing",          reqf_trailing).
  string_to_required_feature("strict_sequential", reqf_strict_sequential).
+string_to_required_feature("conservative_gc",   reqf_conservative_gc).

  %-----------------------------------------------------------------------------%

Index: doc/reference_manual.texi
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/doc/reference_manual.texi,v
retrieving revision 1.418
diff -u -r1.418 reference_manual.texi
--- doc/reference_manual.texi	24 Jan 2008 04:29:36 -0000	1.418
+++ doc/reference_manual.texi	24 Jan 2008 11:39:04 -0000
@@ -10540,9 +10540,15 @@
  feature.

  @item @samp{strict_sequential}
-This feature specifes that a semantics that is equivalent to the strict
+This feature specifies that a semantics that is equivalent to the strict
  sequential operational semantics must be used.

+ at item @samp{conservative_gc}
+This feature specifies that a module requires conservative garbage
+collection.
+This feature is only check when using the C backends, it is ignored
+by the non-C backends. 
+
  @end table

  When a module containing a @samp{pragma require_feature_set} declaration

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