Age | Commit message (Collapse) | Author | |
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2018-08-08 | Fix side-effect optimization when compiling from Core Erlang | John Högberg | |
When an expression is only used for its side effects, we try to remove everything that doesn't tie into a side-effect, but we went a bit too far when we applied the optimization to funs defined in such a context. Consider the following: do letrec 'f'/0 = fun () -> ... whatever ... in call 'side':'effect'(apply 'f'/0()) 'ok' When f/0 is optimized under the assumption that its return value is unused, side:effect/1 will be fed the result of the last side-effecting expression in f/0 instead of its actual result. https://bugs.erlang.org/browse/ERL-658 Co-authored-by: Björn Gustavsson <[email protected]> | |||
2018-06-04 | sys_core_fold: Fix name capture problem | Björn Gustavsson | |
sys_core_fold could do unsafe transformations on the code from the old inliner (invoked using the compiler option `{inline,[{F/A}]}` to request inlining of specific functions). To explain the bug, let's first look at an example that sys_core_fold handles correctly. Consider this code: 'foo'/2 = fun (Arg1,Arg2) -> let <B> = Arg2 in let <A,B> = <B,Arg1> in {A,B} In this example, the lets can be completely eliminated, since the arguments for the lets are variables (as opposed to expressions). Since the variable B is rebound in the inner let, `sys_core_fold` must take special care when doing the substitutions. Here is the correct result: 'foo'/2 = fun (Arg1, Arg2) -> {Arg2,Arg1} Consider a slight modifictation of the example: 'bar'/2 = fun (Arg1,Arg2) -> let <B> = [Arg2] in let <A,B> = <B,[Arg1]> in {A,B} Here some of the arguments for the lets are expressions, so the lets must be kept. sys_core_fold does not handle this example correctly: 'bar'/2 = fun (Arg1,Arg2) -> let <B> = [Arg2] in let <B> = [Arg1] in {B,B} In the inner let, the variable A has been eliminated and replaced with the variable B in the body (the first B in the tuple). Since the B in the outer let is never used, the outer let will be eliminated, giving: 'bar'/2 = fun (Arg1,Arg2) -> let <B> = [Arg1] in {B,B} To handle this example correctly, sys_core_fold must rename the variable B in the inner let like this to avoid capturing B: 'bar'/2 = fun (Arg1,Arg2) -> let <B> = [Arg2] in let <NewName> = [Arg1] in {B,NewName} (Note: The `v3_kernel` pass alreday handles those examples correctly in case `sys_core_fold` has been disabled.) | |||
2017-08-07 | sys_core_fold: Fix unsafe optimization of non-variable apply | Björn Gustavsson | |
The sys_core_fold pass would do an unsafe "optimization" when an apply operation did not have a variable in the function position as in the following example: > cat test1.core module 'test1' ['test1'/2] attributes [] 'i'/1 = fun (_f) -> _f 'test1'/2 = fun (_f, _x) -> apply apply 'i'/1 (_f) (_x) end > erlc test1.core no_file: Warning: invalid function call Reported-by: Mikael Pettersson | |||
2016-11-18 | v3_kernel: Generate optimized code for guards | Björn Gustavsson | |
The compiler produces poor code for complex guard expressions with andalso/orelse. Here is an example from the filename module: -define(IS_DRIVELETTER(Letter),(((Letter >= $A) andalso (Letter =< $Z)) orelse ((Letter >= $a) andalso (Letter =< $z)))). skip_prefix(Name, false) -> Name; skip_prefix([L, DrvSep|Name], DrvSep) when ?IS_DRIVELETTER(L) -> Name; skip_prefix(Name, _) -> Name. beam_bool fails to simplify the code for the guard, leaving several 'bif' instructions: {function, skip_prefix, 2, 49}. {label,48}. {line,[{location,"filename.erl",187}]}. {func_info,{atom,filename},{atom,skip_prefix},2}. {label,49}. {test,is_ne_exact,{f,52},[{x,1},{atom,false}]}. {test,is_nonempty_list,{f,52},[{x,0}]}. {get_list,{x,0},{x,2},{x,3}}. {test,is_nonempty_list,{f,52},[{x,3}]}. {get_list,{x,3},{x,4},{x,5}}. {bif,'=:=',{f,52},[{x,1},{x,4}],{x,6}}. {test,is_ge,{f,50},[{x,2},{integer,65}]}. {bif,'=<',{f,52},[{x,2},{integer,90}],{x,7}}. {test,is_eq_exact,{f,51},[{x,7},{atom,false}]}. {test,is_ge,{f,50},[{x,2},{integer,97}]}. {bif,'=<',{f,52},[{x,2},{integer,122}],{x,7}}. {jump,{f,51}}. {label,50}. {move,{atom,false},{x,7}}. {label,51}. {bif,'=:=',{f,52},[{x,7},{atom,true}],{x,7}}. {test,is_eq_exact,{f,52},[{x,6},{atom,true}]}. {test,is_eq_exact,{f,52},[{x,7},{atom,true}]}. {move,{x,5},{x,0}}. return. {label,52}. return. We can add optimizations of guard tests to v3_kernel to achive a better result: {function, skip_prefix, 2, 49}. {label,48}. {line,[{location,"filename.erl",187}]}. {func_info,{atom,filename},{atom,skip_prefix},2}. {label,49}. {test,is_ne_exact,{f,51},[{x,1},{atom,false}]}. {test,is_nonempty_list,{f,51},[{x,0}]}. {get_list,{x,0},{x,2},{x,3}}. {test,is_nonempty_list,{f,51},[{x,3}]}. {get_list,{x,3},{x,4},{x,5}}. {test,is_eq_exact,{f,51},[{x,1},{x,4}]}. {test,is_ge,{f,51},[{x,2},{integer,65}]}. {test,is_lt,{f,50},[{integer,90},{x,2}]}. {test,is_ge,{f,51},[{x,2},{integer,97}]}. {test,is_ge,{f,51},[{integer,122},{x,2}]}. {label,50}. {move,{x,5},{x,0}}. return. {label,51}. return. Looking at the STDLIB application, there were 112 lines of BIF calls in guards that beam_bool failed to convert to test instructions. This commit eliminates all those BIF calls. Here is how I counted the instructions: $ PATH=$ERL_TOP/bin:$PATH erlc -I ../include -I ../../kernel/include -S *.erl $ grep "bif,'[=<>]" *.S | grep -v f,0 dets.S: {bif,'=:=',{f,547},[{x,4},{atom,read_write}],{x,4}}. dets.S: {bif,'=:=',{f,547},[{x,5},{atom,saved}],{x,5}}. dets.S: {bif,'=:=',{f,589},[{x,5},{atom,read}],{x,5}}. . . . $ grep "bif,'[=<>]" *.S | grep -v f,0 | wc 112 224 6765 $ | |||
2015-04-22 | test suite: Always place .core files in data directories | Björn Gustavsson | |
For tidiness, always place .core files in data directories. | |||
2015-01-30 | Make the syntax for map pairs readable | Björn Gustavsson | |
Use the same syntax for map pairs in Core Erlang code as in the Erlang Code. This Erlang code: M#{x:=42,y=>1} will look like this in Core Erlang: ~{'x':=42,'y'=>1|M}~ | |||
2014-03-17 | compiler: Change Maps Core Format | Björn-Egil Dahlberg | |
Ex. Instead of: M~{~<K,V>}~ The format is now: ~{~<K,V>|M}~ This also removes a shift/reduce warning. The changes in core_pp now requires compiler-5.0 to compile because of is_map/1 guard, i.e. a need for a compiler with Maps know-how. | |||
2014-03-05 | Do not try to optimize non-boolean guards | Anthony Ramine | |
Expressions such as erlang:'or'(bar, true) can make beam_bool crash if it tries to optimize them, as this code is not quite really written by users, no attempt to rewrite them more efficiently should be done, for simplicity's sake. Reported-by: Ulf Norell | |||
2014-02-11 | Teach sys_core_fold:eval_case/2 to cope with handwritten Core Erlang | Björn Gustavsson | |
Starting in e12b7d5331c58b41db06cadfa4af75b78b62a2b1, sys_core_fold:eval_case/2 will crash on handwritten but legal Core Erlang programs such as: case let <Var> = Arg in {'x',Var} of {x,X} -> X end The problem is that the only clause *is* guaranteed to match, but cerl_clauses:match_list/2 does not understand that; all it can say is that the clause *may* match. In those circumstances, we will need to keep the case. Also make sure that we keep the case if the guard is something else than 'true'. That is not strictly necessary, because in a legal Core Erlang program the guard in the last clause in a case must always evaluate to 'true', so removing the guard test would still leave the program correct. Keeping the guard, however, will make it somewhat easier to debug an incorrect Core Erlang program. (The unsafe_case test case has guard test in the only clause in a case, so we don't need to write a new test case to test that.) Reported-by: Anthony Ramine | |||
2014-01-29 | compiler: Add core compile test for maps | Björn-Egil Dahlberg | |
2012-01-11 | v3_kernel: Handle sequences in guards | Björn Gustavsson | |
A guard with a sequence will cause a crash in v3_codegen. Currently, it seems that a sequence in a guard will never happen when compiling from Erlang code, but there are several reasons to fix this problem anyway: * There are other compilers that generate Core Erlang code. * Changes to sys_core_fold (perhaps additional optimizations) may cause sequences to be generated in guards. * A previously uncovered line in sys_core_fold:opt_guard_try/1 will now be covered. | |||
2012-01-04 | Cover v3_kernel:get_line/1 | Björn Gustavsson | |
2012-01-04 | core_SUITE: Cover the nomatch_shadow warning in v3_kernel | Björn Gustavsson | |
2012-01-04 | core_SUITE: Cover v3_kernel:build_match/2 | Björn Gustavsson | |
2012-01-04 | core_SUITE: Cover sys_core_fold:eval_is_boolean/2 | Björn Gustavsson | |
2012-01-04 | core_SUITE: Cover sys_core_fold:make_effect_seq/2 | Björn Gustavsson | |
We need to write a test case in Core Erlang in order to cover make_effect_seq/2, since v3_core does not generate "deep" Core Erlang code. | |||
2010-05-20 | core_SUITE_data: Don't ignore *.core files in this directory | Björn Gustavsson | |
2009-11-20 | The R13B03 release.OTP_R13B03 | Erlang/OTP | |