[m-rev.] for post-commit review: additions to region points-to analysis

[Julien Fischer]

For post-commit review by Quan.

Estimated hours taken: 1
Branches: main

Minor additions to the intraprocedural region points-to analysis.

compiler/rbmm.points_to_analysis.m:
 	Handle generic and foreign calls like normal calls rather than
 	aborting when they are encountered.

 	Abort if we encounter a complicated unification since they should
 	have been transformed away by the time this runs.

 	Reorder some code, and rename some procedures and variables within
 	that code.

 	Use state variables in more places.

Julien.

Index: rbmm.points_to_analysis.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/compiler/rbmm.points_to_analysis.m,v
retrieving revision 1.2
diff -u -r1.2 rbmm.points_to_analysis.m
--- rbmm.points_to_analysis.m	23 May 2007 09:41:45 -0000	1.2
+++ rbmm.points_to_analysis.m	24 May 2007 04:33:26 -0000
@@ -132,34 +132,21 @@
  intra_analyse_goal_expr(conj(_ConjType, Goals), !RptaInfo) :-
      list.foldl(intra_analyse_goal, Goals, !RptaInfo).

-    % Procedure calls are ignored in the intraprocedural analysis.
+    % Calls (of all types) are not considered during the intraprocedural
+    % analysis.
      %
  intra_analyse_goal_expr(plain_call(_, _, _, _, _, _), !RptaInfo).
-
-intra_analyse_goal_expr(generic_call(_,_,_,_), !RptaInfo) :-
-    sorry(this_file,
-        "intra_analyse_goal_expr: generic_call not handled").
+intra_analyse_goal_expr(generic_call(_, _, _, _), !RptaInfo).
+intra_analyse_goal_expr(call_foreign_proc(_, _, _, _, _, _, _), !RptaInfo).

  intra_analyse_goal_expr(switch(_, _, Cases), !RptaInfo) :-
      list.foldl(intra_analyse_case, Cases, !RptaInfo).
-
-:- pred intra_analyse_case(case::in, rpta_info::in, rpta_info::out) is det.
-
-intra_analyse_case(Case, !RptaInfo) :-
-    Case = case(_, Goal),
-    intra_analyse_goal(Goal, !RptaInfo).
-
-    % Most of the processing in intraprocedural analysis happens to
-    % unifications.
-    %
-intra_analyse_goal_expr(unify(_, _, _, Unification, _), !RptaInfo) :- 
-    process_unification(Unification, !RptaInfo).
-
  intra_analyse_goal_expr(disj(Goals), !RptaInfo) :-
      list.foldl(intra_analyse_goal, Goals, !RptaInfo). 
-
  intra_analyse_goal_expr(negation(Goal), !RptaInfo) :-
      intra_analyse_goal(Goal, !RptaInfo). 
+intra_analyse_goal_expr(unify(_, _, _, Unification, _), !RptaInfo) :- 
+    intra_analyse_unification(Unification, !RptaInfo).

      % scope
      % XXX: only analyse the goal. May need to take into account the Reason. 
@@ -186,35 +173,63 @@
      intra_analyse_goal(Then, !RptaInfo),
      intra_analyse_goal(Else, !RptaInfo).

-intra_analyse_goal_expr(GoalExpr, !RptaInfo) :-
-    GoalExpr = call_foreign_proc(_, _, _, _, _, _, _),
-    unexpected(this_file,
-        "intra_analyse_goal_expr: call_foreign_proc not handled").
-
-intra_analyse_goal_expr(shorthand(_), !RptaInfo) :- 
+intra_analyse_goal_expr(shorthand(_), _, _) :-
      unexpected(this_file, "intra_analyse_goal_expr: shorthand not handled").
+
+:- pred intra_analyse_case(case::in, rpta_info::in, rpta_info::out) is det.
+
+intra_analyse_case(Case, !RptaInfo) :-
+    Case = case(_, Goal),
+    intra_analyse_goal(Goal, !RptaInfo).

-:- pred process_unification(unification::in,
+%-----------------------------------------------------------------------------%
+
+    % For construction and deconstruction unifications, add an edge from the
+    % variable on the LHS to each variable on the RHS.
+    %
+    % For assignment unifications we merge the nodes corresponding to 
+    % the variables on either side.
+    %
+    % For simple test unifications we do nothing.
+    %
+:- pred intra_analyse_unification(unification::in,
      rpta_info::in, rpta_info::out) is det.

      % For construction and deconstruction, add edges from LVar to
      % each of RVars.
-process_unification(construct(LVar, ConsId, RVars, _, _, _, _), !RptaInfo) :-
-    list.foldl2(process_cons_and_decons(LVar, ConsId), RVars, 
-        1, _, !RptaInfo).
- 
-process_unification(deconstruct(LVar, ConsId, RVars, _, _, _), !RptaInfo) :-
-    list.foldl2(process_cons_and_decons(LVar, ConsId), RVars, 
-        1, _, !RptaInfo).
+intra_analyse_unification(Unification, !RptaInfo) :-
+    ( Unification = construct(LVar, ConsId, RVars, _, _, _, _)
+    ; Unification = deconstruct(LVar, ConsId, RVars, _, _, _)
+    ),
+    list.foldl2(process_cons_and_decons(LVar, ConsId), RVars, 1, _,
+        !RptaInfo).
+intra_analyse_unification(assign(ToVar, FromVar), !RptaInfo) :-
+    !.RptaInfo = rpta_info(Graph0, AlphaMapping),
+    get_node_by_variable(Graph0, ToVar, ToNode),
+    get_node_by_variable(Graph0, FromVar, FromNode),
+    ( if    ToNode = FromNode
+      then  true
+      else
+            unify_operator(ToNode, FromNode, Graph0, Graph),
+            !:RptaInfo = rpta_info(Graph, AlphaMapping),
+            % After merging the two nodes, apply rule P1 to restore the
+            % RPTG's invariants.
+            apply_rule_1(ToNode, !RptaInfo)
+    ).
+intra_analyse_unification(simple_test(_, _), !RptaInfo).
+intra_analyse_unification(complicated_unify(_, _, _), _, _) :-
+    unexpected(this_file,
+        "complicated_unify in region points-to analysis.").

  :- pred process_cons_and_decons(prog_var::in, cons_id::in, prog_var::in,
      int::in, int::out, rpta_info::in, rpta_info::out) is det.
+
  process_cons_and_decons(LVar, ConsId, RVar, !Component, !RptaInfo) :-
      !.RptaInfo = rpta_info(Graph0, AlphaMapping),
-    get_node_by_variable(Graph0, LVar, Node1),
-    get_node_by_variable(Graph0, RVar, Node2),
+    get_node_by_variable(Graph0, LVar, L_Node),
+    get_node_by_variable(Graph0, RVar, R_Node),
      Sel = [termsel(ConsId, !.Component)],
-    ArcContent = rptg_arc_content(Sel),
+    EdgeLabel = rptg_arc_content(Sel),

      % Only add the edge if it is not in the graph
      % It is more suitable to the edge_operator's semantics if we check 
@@ -222,49 +237,20 @@
      % is actually added or not so it is convenient to check the edge's
      % existence outside edge_operator. Otherwise we can extend edge_operator
      % with one more argument to indicate that.
-    ( if
-        edge_in_graph(Node1, ArcContent, Node2, Graph0)
-      then
-        true
+    ( if    edge_in_graph(L_Node, EdgeLabel, R_Node, Graph0)
+      then  true
        else
-        edge_operator(Node1, Node2, ArcContent, Graph0, Graph1),
-        RptaInfo1 = rpta_info(Graph1, AlphaMapping), 
+            edge_operator(L_Node, R_Node, EdgeLabel, Graph0, Graph1),
+            !:RptaInfo = rpta_info(Graph1, AlphaMapping),

-        % After an edge is added, rules P2 and P3 are applied to ensure 
-        % the invariants of the graph.
-        apply_rule_2(Node1, Node2, ConsId, !.Component, RptaInfo1, RptaInfo2),
-        RptaInfo2 = rpta_info(Graph2, _), 
-        get_node_by_variable(Graph2, RVar, RVarNode),
-        apply_rule_3(RVarNode, RptaInfo2, !:RptaInfo)
+            % After an edge is added, rules P2 and P3 are applied to ensure 
+            % the invariants of the graph.
+            apply_rule_2(L_Node, R_Node, ConsId, !.Component, !RptaInfo),
+            !.RptaInfo = rpta_info(Graph2, _), 
+            get_node_by_variable(Graph2, RVar, RVarNode),
+            apply_rule_3(RVarNode, !RptaInfo)
      ),
      !:Component = !.Component + 1.
-
-    % Unification is an assignment: merge the corresponding nodes of ToVar 
-    % and FromVar.
-    % 
-process_unification(assign(ToVar, FromVar), !RptaInfo) :-
-    !.RptaInfo = rpta_info(Graph0, AlphaMapping),
-    get_node_by_variable(Graph0, ToVar, ToNode),
-    get_node_by_variable(Graph0, FromVar, FromNode),
-    ( if
-        ToNode = FromNode
-      then
-        true
-      else
-        unify_operator(ToNode, FromNode, Graph0, Graph1),
-        RptaInfo1 = rpta_info(Graph1, AlphaMapping),
-        % After the merge of two nodes, apply rule P1 to ensure rptg's 
-        % invariants.
-        apply_rule_1(ToNode, RptaInfo1, !:RptaInfo)
-    ).
-
-    % Do nothing with the simple test.
-    %
-process_unification(simple_test(_, _), !RptaInfo).
-
-    % XXX: do not consider this for the time being.
-    %
-process_unification(complicated_unify(_, _, _), !RptaInfo).

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

--------------------------------------------------------------------------
mercury-reviews mailing list
Post messages to:       mercury-reviews at csse.unimelb.edu.au
Administrative Queries: owner-mercury-reviews at csse.unimelb.edu.au
Subscriptions:          mercury-reviews-request at csse.unimelb.edu.au
--------------------------------------------------------------------------