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authorBjörn Gustavsson <[email protected]>2014-02-12 14:52:44 +0100
committerBjörn Gustavsson <[email protected]>2014-02-12 14:52:44 +0100
commit152f1a4ba2f4e2f0dfbcde2efe5b5fd5edbdb986 (patch)
treebbd2547b06badbf7537ca966707f1367fb7d0b3f /lib
parentce1e2d3e865c42b01c8088ee07470a6f25be55cb (diff)
parentc89ada7517420ce9065840ea857a0009418ce2af (diff)
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Merge branch 'bjorn/compiler/optimizations/OTP-11584'
* bjorn/compiler/optimizations/OTP-11584: Teach sys_core_fold:eval_case/2 to cope with handwritten Core Erlang sys_core_fold: Remove a redundant word in a comment
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/sys_core_fold.erl24
-rw-r--r--lib/compiler/test/core_SUITE.erl5
-rw-r--r--lib/compiler/test/core_SUITE_data/eval_case.core34
3 files changed, 54 insertions, 9 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index e302e2324d..500d431afe 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -1940,7 +1940,9 @@ opt_bool_case_guard(Arg, [#c_clause{pats=[#c_literal{val=false}]}=Fc,Tc]) ->
%% last clause is guaranteed to match so if there is only one clause
%% with a pattern containing only variables then rewrite to a let.
-eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,body=B}]}, Sub) ->
+eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,
+ guard=#c_literal{val=true},
+ body=B}]}=Case, Sub) ->
Es = case cerl:is_c_values(E) of
true -> cerl:values_es(E);
false -> [E]
@@ -1955,7 +1957,7 @@ eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,body=B}]}, Sub) ->
%%
%% let <X,Y> = <SomeSideEffect(),SomeSideEffect()> in ...
%%
- %% because SomeSideEffect() would be called evaluated twice.
+ %% because SomeSideEffect() would be evaluated twice.
%%
%% Instead we must evaluate the case expression in an outer let
%% like this:
@@ -1964,11 +1966,19 @@ eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,body=B}]}, Sub) ->
%% let <X,Y> = <NewVar,NewVar> in ...
%%
Vs = make_vars([], length(Es)),
- {true,Bs} = cerl_clauses:match_list(Ps0, Vs),
- {Ps,As} = unzip(Bs),
- InnerLet = cerl:c_let(Ps, core_lib:make_values(As), B),
- Let = cerl:c_let(Vs, E, InnerLet),
- expr(Let, sub_new(Sub));
+ case cerl_clauses:match_list(Ps0, Vs) of
+ {false,_} ->
+ %% This can only happen if the Core Erlang code is
+ %% handwritten or generated by another code generator
+ %% than v3_core. Assuming that the Core Erlang program
+ %% is correct, the clause will always match at run-time.
+ Case;
+ {true,Bs} ->
+ {Ps,As} = unzip(Bs),
+ InnerLet = cerl:c_let(Ps, core_lib:make_values(As), B),
+ Let = cerl:c_let(Vs, E, InnerLet),
+ expr(Let, sub_new(Sub))
+ end;
eval_case(Case, _) -> Case.
%% case_opt(CaseArg, [Clause]) -> {CaseArg,[Clause]}.
diff --git a/lib/compiler/test/core_SUITE.erl b/lib/compiler/test/core_SUITE.erl
index 1a521c3591..aa222c48de 100644
--- a/lib/compiler/test/core_SUITE.erl
+++ b/lib/compiler/test/core_SUITE.erl
@@ -24,7 +24,7 @@
dehydrated_itracer/1,nested_tries/1,
seq_in_guard/1,make_effect_seq/1,eval_is_boolean/1,
unsafe_case/1,nomatch_shadow/1,reversed_annos/1,
- map_core_test/1]).
+ map_core_test/1,eval_case/1]).
-include_lib("test_server/include/test_server.hrl").
@@ -50,7 +50,7 @@ groups() ->
[{p,test_lib:parallel(),
[dehydrated_itracer,nested_tries,seq_in_guard,make_effect_seq,
eval_is_boolean,unsafe_case,nomatch_shadow,reversed_annos,
- map_core_test
+ map_core_test,eval_case
]}].
@@ -76,6 +76,7 @@ end_per_group(_GroupName, Config) ->
?comp(nomatch_shadow).
?comp(reversed_annos).
?comp(map_core_test).
+?comp(eval_case).
try_it(Mod, Conf) ->
Src = filename:join(?config(data_dir, Conf), atom_to_list(Mod)),
diff --git a/lib/compiler/test/core_SUITE_data/eval_case.core b/lib/compiler/test/core_SUITE_data/eval_case.core
new file mode 100644
index 0000000000..f2776e2b1f
--- /dev/null
+++ b/lib/compiler/test/core_SUITE_data/eval_case.core
@@ -0,0 +1,34 @@
+module 'eval_case' ['eval_case'/0]
+ attributes []
+'eval_case'/0 =
+ fun () ->
+ case <> of
+ <> when 'true' ->
+ case apply 'do_case'/0() of
+ <'ok'> when 'true' ->
+ 'ok'
+ ( <_cor0> when 'true' ->
+ primop 'match_fail'
+ ({'badmatch',_cor0})
+ -| ['compiler_generated'] )
+ end
+ ( <> when 'true' ->
+ ( primop 'match_fail'
+ ({'function_clause'})
+ -| [{'function_name',{'eval_case',0}}] )
+ -| ['compiler_generated'] )
+ end
+'do_case'/0 =
+ fun () ->
+ case let <_cor0> =
+ apply 'id'/1(42)
+ in let <_cor1> =
+ call 'erlang':'+'
+ (_cor0, 7)
+ in {'x',_cor1} of
+ <{'x',49}> when 'true' ->
+ 'ok'
+ end
+'id'/1 =
+ fun (_cor0) -> _cor0
+end