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authorBjörn Gustavsson <[email protected]>2019-03-22 07:42:24 +0100
committerBjörn Gustavsson <[email protected]>2019-03-25 09:58:58 +0100
commitf3293ecdb3c223ec10babbbf26569e00f89ae28d (patch)
treec997b65462962ce68f360d479a18dc3ed0ab5661 /lib
parentafe49ef2610b597f172e0fcc0c2b7b3f110bb7b4 (diff)
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sys_core_fold: Simplify case_expand_var/2
5239eb0c62a9 stopped storing patterns that a variable has matched. The only tuples that are stored in the type database are tuples that have been previously constructed. Therefore, the code in sys_core_fold:case_expand_var/2 and friends that converts a tuple pattern to a tuple construction can be simplified to used the stored tuple directly.
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/sys_core_fold.erl45
1 files changed, 7 insertions, 38 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 7e219da0af..4939a94a92 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -1997,53 +1997,22 @@ case_opt_compiler_generated(Core) ->
%% case_expand_var(Expr0, Sub) -> Expr
-%% If Expr0 is a variable that has been previously matched and
-%% is known to be a tuple, return the tuple instead. Otherwise
+%% If Expr0 is a variable that is known to be bound to a
+%% constructed tuple, return the tuple instead. Otherwise
%% return Expr0 unchanged.
-%%
+
case_expand_var(E, #sub{t=Tdb}) ->
Key = cerl:var_name(E),
case Tdb of
- #{Key:=T0} ->
- case cerl:is_c_tuple(T0) of
- false ->
- E;
- true ->
- %% The pattern was a tuple. Now we must make sure
- %% that the elements of the tuple are suitable. In
- %% particular, we don't want binary or map
- %% construction here, since that means that the
- %% binary or map will be constructed in the 'case'
- %% argument. That is wasteful for binaries. Even
- %% worse is that any map pattern that use the ':='
- %% operator will fail when used in map
- %% construction (only the '=>' operator is allowed
- %% when constructing a map from scratch).
- try
- cerl_trees:map(fun coerce_to_data/1, T0)
- catch
- throw:impossible ->
- %% Something unsuitable was found (map or
- %% or binary). Keep the variable.
- E
- end
+ #{Key:=T} ->
+ case cerl:is_c_tuple(T) of
+ false -> E;
+ true -> T
end;
_ ->
E
end.
-%% coerce_to_data(Core) -> Core'
-%% Coerce an element originally from a pattern to an data item or or
-%% variable. Throw an 'impossible' exception if non-data Core Erlang
-%% terms such as binary construction or map construction are
-%% encountered.
-
-coerce_to_data(C) ->
- case cerl:is_data(C) orelse cerl:is_c_var(C) of
- true -> C;
- false -> throw(impossible)
- end.
-
%% case_opt_nomatch(E, Clauses, LitExpr) -> Clauses'
%% Remove all clauses that cannot possibly match.