From 6c5c39827cc06a9e9b3e3fa4fa856f4610eb40b6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Valim?= <jose.valim@plataformatec.com.br>
Date: Fri, 8 Nov 2013 23:50:43 +0100
Subject: Support non top level letrecs in dialyzer

Dialyzer so far only supported letrecs at the top-level
and comprehension-like letrecs (i.e. that were directly applied)
in their body.

This commit address this issue by storing in the callgraph
bound letrec labels pointing to their functions. This information
is then used by the dataflow to properly lookup recursive
definitions.
---
 lib/dialyzer/src/dialyzer_dep.erl | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

(limited to 'lib/dialyzer/src/dialyzer_dep.erl')

diff --git a/lib/dialyzer/src/dialyzer_dep.erl b/lib/dialyzer/src/dialyzer_dep.erl
index febb65b766..1a477f4388 100644
--- a/lib/dialyzer/src/dialyzer_dep.erl
+++ b/lib/dialyzer/src/dialyzer_dep.erl
@@ -39,7 +39,7 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%
-%% analyze(CoreTree) -> {Deps, Esc, Calls}.
+%% analyze(CoreTree) -> {Deps, Esc, Calls, Letrecs}.
 %%
 %% Deps =  a dict mapping labels of functions to an ordset of functions
 %%         it calls.
@@ -53,6 +53,10 @@
 %%         which the operation can refer to. If 'external' is part of
 %%         the set the operation can be externally defined.
 %%
+%% Letrecs = a dict mapping var labels to their recursive definition.
+%%           top-level letrecs are not included as they are handled
+%%           separatedly.
+%%
 
 -spec analyze(cerl:c_module()) -> {dict(), ordset('external' | label()), dict()}.
 
@@ -64,7 +68,8 @@ analyze(Tree) ->
   State1 = state__add_deps(external, output(Esc), State),
   Deps = state__deps(State1),
   Calls = state__calls(State1),
-  {map__finalize(Deps), set__to_ordsets(Esc), map__finalize(Calls)}.
+  Letrecs = state__letrecs(State1),
+  {map__finalize(Deps), set__to_ordsets(Esc), map__finalize(Calls), Letrecs}.
 
 traverse(Tree, Out, State, CurrentFun) ->
   %% io:format("Type: ~w\n", [cerl:type(Tree)]),
@@ -131,9 +136,12 @@ traverse(Tree, Out, State, CurrentFun) ->
     letrec ->
       Defs = cerl:letrec_defs(Tree),
       Body = cerl:letrec_body(Tree),
+      State1 = lists:foldl(fun({ Var, Fun }, Acc) ->
+	state__add_letrecs(cerl_trees:get_label(Var), cerl_trees:get_label(Fun), Acc)
+      end, State, Defs),
       Out1 = bind_defs(Defs, Out),
-      State1 = traverse_defs(Defs, Out1, State, CurrentFun),
-      traverse(Body, Out1, State1, CurrentFun);
+      State2 = traverse_defs(Defs, Out1, State1, CurrentFun),
+      traverse(Body, Out1, State2, CurrentFun);
     literal ->
       {output(none), State};
     module ->
@@ -463,7 +471,8 @@ all_vars(Tree, AccIn) ->
 -record(state, {deps    :: dict(), 
 		esc     :: local_set(), 
 		call    :: dict(), 
-		arities :: dict()}).
+		arities :: dict(),
+		letrecs :: dict()}).
 
 state__new(Tree) ->
   Exports = set__from_list([X || X <- cerl:module_exports(Tree)]),
@@ -471,7 +480,7 @@ state__new(Tree) ->
 			    || {Var, Fun} <- cerl:module_defs(Tree),
 			       set__is_element(Var, Exports)]),
   Arities = cerl_trees:fold(fun find_arities/2, dict:new(), Tree),
-  #state{deps = map__new(), esc = InitEsc, call = map__new(), arities = Arities}.
+  #state{deps = map__new(), esc = InitEsc, call = map__new(), arities = Arities, letrecs = map__new()}.
 
 find_arities(Tree, AccMap) ->
   case cerl:is_c_fun(Tree) of
@@ -490,9 +499,15 @@ state__add_deps(From, #output{type = single, content=To},
   %% io:format("Adding deps from ~w to ~w\n", [From, set__to_ordsets(To)]),
   State#state{deps = map__add(From, To, Map)}.
 
+state__add_letrecs(Var, Fun, #state{letrecs = Map} = State) ->
+  State#state{letrecs = map__store(Var, Fun, Map)}.
+
 state__deps(#state{deps = Deps}) ->
   Deps.
 
+state__letrecs(#state{letrecs = Letrecs}) ->
+  Letrecs.
+
 state__add_esc(#output{content = none}, State) ->
   State;
 state__add_esc(#output{type = single, content = Set},
-- 
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