[erlang-patches] Optimize handling of local fun variables in v3_kernel

Fredrik <>
Tue Jan 15 10:42:24 CET 2013


After further research we can see that the patch is also failing these 
testcases in tools,
cover_SUITE, modules
cover_SUITE, on_load

Please fix this and give me notice,

BR Fredrik Gustafsson
Erlang OTP Team
On 01/10/2013 01:33 PM, Anthony Ramine wrote:
> Le 9 janv. 2013 à 17:32, Björn Gustavsson a écrit :
>
>> The code handles free variables. As far as I can understand, there
>> can be no free variables in this case, so you should simplify the code.
> You're right and wrong :) There can be no free variables if the Core Erlang
> code comes from a current Erlang module, but there can be if the Core Erlang
> was handwritten or generated by my EEP37 patch, for example:
>
> module 'foo' ['bar'/1,
> 	      'module_info'/0,
> 	      'module_info'/1]
>      attributes []
> 'bar'/1 =
>      %% Line 4
>      fun (_cor0) ->
> 	letrec
> 	    'Bar'/1 =
> 		%% Line 5
> 		( fun (_cor4) ->
> 		let<Bar>  = 'Bar'/1
> 		      in  case _cor4 of
> 			<1>  when 'true' ->
> 				1
> 			<N>  when 'true' ->
> 				let<_cor3>  =
> 				    call 'erlang':'*'
> 					(N, _cor0)
> 				in  let<_cor1>  =
> 					call 'erlang':'-'
> 					    (N, 1)
> 				    in  let<_cor2>  =
> 					    apply Bar
> 						(_cor1)
> 					in  call 'erlang':'*'
> 						(_cor3, _cor2)
> 			  end
> 		  -| [{'id',{0,0,'Bar'}}] )
> 	in  'Bar'/1
> 'module_info'/0 =
>      fun () ->
> 	call 'erlang':'get_module_info'
> 	    ('foo')
> 'module_info'/1 =
>      fun (_cor0) ->
> 	call 'erlang':'get_module_info'
> 	    ('foo', _cor0)
> end
>
> In 'bar'/1, _cor0 is a free variable inside 'Bar'/1; thus free variables need
> to be handled to remove the reverse eta conversion in a future-proof way.
>
> The differences between master and my patch when running erlc +to_kernel foo.core
> are:
>
> --- foo.kernel.orig	2013-01-10 13:27:28.000000000 +0100
> +++ foo.kernel	2013-01-10 13:27:36.000000000 +0100
> @@ -5,18 +5,16 @@
>   attributes []
>   fdef 'bar'/1(_Xcor0) =
>     do
> -    bif (internal 'make_fun'/4)('-bar/1-anonymous-2-', 2, 0, 0, _Xcor0)>>  <_ker2>
> +    bif (internal 'make_fun'/4)('-bar/1-Bar/1-0-', 2, 0, 0, _Xcor0)>>  <_ker1>
>     then
> -<<_ker2>>
> +<<_ker1>>
>   fdef 'module_info'/0() =
>     enter (remote 'erlang':'get_module_info'/1)('foo')
>   fdef 'module_info'/1(_Xcor0) =
>     enter (remote 'erlang':'get_module_info'/2)('foo', _Xcor0)
> -fdef '-bar/1-anonymous-2-'/2(_ker0, _Xcor0) =
> -  enter (local '-bar/1-Bar/1-0-'/2)(_ker0, _Xcor0)
>   fdef '-bar/1-Bar/1-0-'/2(_Xcor4, _Xcor0) =
>     do
> -    bif (internal 'make_fun'/4)('-bar/1-anonymous-1-', 2, 0, 0, _Xcor0)>>  <Bar>
> +    bif (internal 'make_fun'/4)('-bar/1-Bar/1-0-', 2, 0, 0, _Xcor0)>>  <Bar>
>     then
>     match _Xcor4
>       alt
> @@ -34,10 +32,8 @@
>   	call (Bar)(_Xcor1)>>  <_Xcor2>
>         then
>         do
> -	bif (remote 'erlang':'*'/2)(_Xcor3, _Xcor2)>>  <_ker1>
> +	bif (remote 'erlang':'*'/2)(_Xcor3, _Xcor2)>>  <_ker0>
>         then
> -<<_ker1>>
> +<<_ker0>>
>     end>>  <>
> -fdef '-bar/1-anonymous-1-'/2(V1, _Xcor0) =
> -  enter (local '-bar/1-Bar/1-0-'/2)(V1, _Xcor0)
>   end
> \ No newline at end of file
>
> Fredrik, I'll fix the failing test cases from trace_local_SUITE and come back to you
> when I'm done. Thanks for the feedback.
>
> Regards,
>



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