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authorBjörn Gustavsson <[email protected]>2018-03-23 11:51:28 +0100
committerBjörn Gustavsson <[email protected]>2018-03-23 15:13:58 +0100
commit9d2f5cde19cffca9a00b8fad8075bf160cc872d3 (patch)
tree0333cab6eb4452f1a0f533a7fa390cf6a8e7ef98
parent43a91c5e461e3fbec924e332f42fd69b81be34b2 (diff)
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Add cerl_trees:next_free_variable_name/1
-rw-r--r--lib/compiler/src/cerl_trees.erl109
-rw-r--r--lib/compiler/src/sys_core_fold.erl8
2 files changed, 116 insertions, 1 deletions
diff --git a/lib/compiler/src/cerl_trees.erl b/lib/compiler/src/cerl_trees.erl
index f30a0b33ac..c7a129b42c 100644
--- a/lib/compiler/src/cerl_trees.erl
+++ b/lib/compiler/src/cerl_trees.erl
@@ -22,7 +22,8 @@
-module(cerl_trees).
-export([depth/1, fold/3, free_variables/1, get_label/1, label/1, label/2,
- map/2, mapfold/3, mapfold/4, size/1, variables/1]).
+ map/2, mapfold/3, mapfold/4, next_free_variable_name/1,
+ size/1, variables/1]).
-import(cerl, [alias_pat/1, alias_var/1, ann_c_alias/3, ann_c_apply/3,
ann_c_binary/2, ann_c_bitstr/6, ann_c_call/4,
@@ -507,6 +508,7 @@ mapfold_pairs(_, _, S, []) ->
%% well-formed Core Erlang syntax tree.
%%
%% @see free_variables/1
+%% @see next_free_variable_name/1
-spec variables(cerl:cerl()) -> [cerl:var_name()].
@@ -519,6 +521,7 @@ variables(T) ->
%% @doc Like <code>variables/1</code>, but only includes variables
%% that are free in the tree.
%%
+%% @see next_free_variable_name/1
%% @see variables/1
-spec free_variables(cerl:cerl()) -> [cerl:var_name()].
@@ -678,6 +681,110 @@ var_list_names([V | Vs], A) ->
var_list_names([], A) ->
A.
+%% ---------------------------------------------------------------------
+
+%% @spec next_free_variable_name(Tree::cerl()) -> var_name()
+%%
+%% var_name() = integer()
+%%
+%% @doc Returns a integer variable name higher than any other integer
+%% variable name in the syntax tree. An exception is thrown if
+%% <code>Tree</code> does not represent a well-formed Core Erlang
+%% syntax tree.
+%%
+%% @see variables/1
+%% @see free_variables/1
+
+-spec next_free_variable_name(cerl:cerl()) -> integer().
+
+next_free_variable_name(T) ->
+ 1 + next_free(T, -1).
+
+next_free(T, Max) ->
+ case type(T) of
+ literal ->
+ Max;
+ var ->
+ case var_name(T) of
+ Int when is_integer(Int) ->
+ max(Int, Max);
+ _ ->
+ Max
+ end;
+ values ->
+ next_free_in_list(values_es(T), Max);
+ cons ->
+ next_free(cons_hd(T), next_free(cons_tl(T), Max));
+ tuple ->
+ next_free_in_list(tuple_es(T), Max);
+ map ->
+ next_free_in_list([map_arg(T)|map_es(T)], Max);
+ map_pair ->
+ next_free_in_list([map_pair_op(T),map_pair_key(T),
+ map_pair_val(T)], Max);
+ 'let' ->
+ Max1 = next_free(let_body(T), Max),
+ Max2 = next_free_in_list(let_vars(T), Max1),
+ next_free(let_arg(T), Max2);
+ seq ->
+ next_free(seq_arg(T),
+ next_free(seq_body(T), Max));
+ apply ->
+ next_free(apply_op(T),
+ next_free_in_list(apply_args(T), Max));
+ call ->
+ next_free(call_module(T),
+ next_free(call_name(T),
+ next_free_in_list(
+ call_args(T), Max)));
+ primop ->
+ next_free_in_list(primop_args(T), Max);
+ 'case' ->
+ next_free(case_arg(T),
+ next_free_in_list(case_clauses(T), Max));
+ clause ->
+ Max1 = next_free(clause_guard(T),
+ next_free(clause_body(T), Max)),
+ next_free_in_list(clause_pats(T), Max1);
+ alias ->
+ next_free(alias_var(T),
+ next_free(alias_pat(T), Max));
+ 'fun' ->
+ next_free(fun_body(T),
+ next_free_in_list(fun_vars(T), Max));
+ 'receive' ->
+ Max1 = next_free_in_list(receive_clauses(T),
+ next_free(receive_timeout(T), Max)),
+ next_free(receive_action(T), Max1);
+ 'try' ->
+ Max1 = next_free(try_body(T), Max),
+ Max2 = next_free_in_list(try_vars(T), Max1),
+ Max3 = next_free(try_handler(T), Max2),
+ Max4 = next_free_in_list(try_evars(T), Max3),
+ next_free(try_arg(T), Max4);
+ 'catch' ->
+ next_free(catch_body(T), Max);
+ binary ->
+ next_free_in_list(binary_segments(T), Max);
+ bitstr ->
+ next_free(bitstr_val(T), next_free(bitstr_size(T), Max));
+ letrec ->
+ Max1 = next_free_in_defs(letrec_defs(T), Max),
+ Max2 = next_free(letrec_body(T), Max1),
+ next_free_in_list(letrec_vars(T), Max2);
+ module ->
+ next_free_in_defs(module_defs(T), Max)
+ end.
+
+next_free_in_list([H | T], Max) ->
+ next_free_in_list(T, next_free(H, Max));
+next_free_in_list([], Max) ->
+ Max.
+
+next_free_in_defs([{_, Post} | Ds], Max) ->
+ next_free_in_defs(Ds, next_free(Post, Max));
+next_free_in_defs([], Max) ->
+ Max.
%% ---------------------------------------------------------------------
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index a9bd363ee1..0354981562 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -119,6 +119,14 @@ module(#c_module{defs=Ds0}=Mod, Opts) ->
function_1({#c_var{name={F,Arity}}=Name,B0}) ->
try
+ %% Find a suitable starting value for the variable
+ %% counter. Note that this pass assumes that new_var_name/1
+ %% returns a variable name distinct from any variable used in
+ %% the entire body of the function. We use integers as
+ %% variable names to avoid filling up the atom table when
+ %% compiling huge functions.
+ Count = cerl_trees:next_free_variable_name(B0),
+ put(new_var_num, Count),
B = find_fixpoint(fun(Core) ->
%% This must be a fun!
expr(Core, value, sub_new())