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2018-06-06Fold is_function/1,2 during compilationMichał Muskała
This can often appear in code after inlining some higher-order functions. * mark is_function/2 as pure * track function types in sys_core_fold * use those types to eval is_function/1,2 at compile-time when possible
2018-04-29Introduce is_map_key/2 guard BIFMichał Muskała
This complements the `map_get/2` guard BIF introduced in #1784. Rationale. `map_get/2` allows accessing map fields in guards, but it might be problematic in more complex guard expressions, for example: foo(X) when map_get(a, X) =:= 1 or is_list(X) -> ... The `is_list/1` part of the guard could never succeed since the `map_get/2` guard would fail the whole guard expression. In this situation, this could be solved by using `;` instead of `or` to separate the guards, but it is not possible in every case. To solve this situation, this PR proposes a `is_map_key/2` guard that allows to check if a map has key inside a guard before trying to access that key. When combined with `is_map/1` this allows to construct a purely boolean guard expression testing a value of a key in a map. Implementation. Given the use case motivating the introduction of this function, the PR contains compiler optimisations that produce optimial code for the following guard expression: foo(X) when is_map(X) and is_map_key(a, X) and map_get(a, X) =:= 1 -> ok; foo(_) -> error. Given all three tests share the failure label, the `is_map_key/2` and `is_map/2` tests are optimised away. As with `map_get/2` the `is_map_key/2` BIF is allowed in match specs.
2018-04-24Introduce map_get guard-safe functionMichał Muskała
Rationale Today all compound data types except for maps can be deconstructed in guards. For tuples we have `element/2` and for lists `hd/1` and `tl/1`. Maps are completely opaque to guards. This means matching on maps can't be abstracted into macros, which is often done with repetitive guards. It also means that maps have to be always selected whole from ETS tables, even when only one field would be enough, which creates a potential efficiency issue. This PR introduces an `erlang:map_get/2` guard-safe function that allows extracting a map field in guard. An alternative to this function would be to introduce the syntax for extracting a value from a map that was planned in the original EEP: `Map#{Key}`. Even outside of guards, since this function is a guard-BIF it is more efficient than using `maps:get/2` (since it does not need to set up the stack), and more convenient from pattern matching on the map (compare: `#{key := Value} = Map, Value` to `map_get(key, Map)`). Performance considerations A common concern against adding this function is the notion that "guards have to be fast" and ideally execute in constant time. While there are some counterexamples (`length/1`), what is more important is the fact that adding those functions does not change in any way the time complexity of pattern matching - it's already possible to match on map fields today directly in patterns - adding this ability to guards will niether slow down or speed up the execution, it will only make certain programs more convenient to write. This first version is very naive and does not perform any optimizations.
2018-03-26Compile external fun expressions to literalsMichał Muskała
The expressions fun M:F/A, when all elements are literals are also treated as a literal. Since they have consistent representation and don't depend on the code currently loaded in the VM, this is safe. This can provide significant performance improvements in code using such functions extensively - a full function call to erlang:make_fun/3 is replaced by a single move instruction and no register shuffling or saving registers to stack is necessary. Additionally, compound data types that contain such external functions as elements can be treated as literals too. The commit also changes the representation of external funs to be a valid Erlang syntax and adds support for literal external funs to core Erlang.
2017-05-10erl_bifs: Remove pure BIFs serving no useful purposeBjörn Gustavsson
Functions that can are known be pure can be evaluated at compile-time if the arguments are literals and if the result is expressible as a literal. list_to_ref/1 and list_to_port/1 returns terms that cannot be expressed as literals, so the optimization is not possible. The argument for port_to_list/1 is never a literal, so there is no way to evaluate it at compile-time. Therefore, marking those functions as pure serves no useful purpose. Note: list_to_pid/1 *is* marked as pure, but only so that we can test the code in sys_core_fold that rejects pure functions that evaluate to at term that is not possible to express as a literal. It is sufficient to have one pure function of that kind.
2017-05-10erl_bifs: Remove erlang:hash/2 from list of pure functionsBjörn Gustavsson
erlang:hash/2 was removed in c5d9b970fb5b3a71.
2017-05-04Update copyright yearRaimo Niskanen
2017-04-25erts: Add erlang:list_to_port/1 debug bifLukas Larsson
2017-04-25erts: Auto-import port_to_list for consistencyLukas Larsson
Follow the same pattern as pid_to_list
2017-04-21erts: Polish off erlang:list_to_ref/1Lukas Larsson
2016-11-02Support math:fmod/2 BIF on compilerGuilherme Andrade
2016-09-21erl_bifs: Remove error_logger:warning_map/0 as a safe BIFBjörn Gustavsson
There is no need to list every obscure safe BIF in erl_bifs:is_safe/3. The purpose of erl_bifs:is_safe/3 is merely to warn when the return value of one of the safe BIFs is ignored.
2016-09-05Add math:floor/1 and math:ceil/1Björn Gustavsson
Add math:floor/1 and math:ceil/1 to avoid unnecessary conversions in floating point expressions. That is, instead of having to write float(floor(X)) as part of a floating point expressions, we can write simply math:floor(X).
2016-09-05Implement the new ceil/1 and floor/1 guard BIFsBjörn Gustavsson
Implement as ceil/1 and floor/1 as new guard BIFs (essentially part of Erlang language). They are guard BIFs because trunc/1 is a guard BIF. It would be strange to have trunc/1 as a part of the language, but not ceil/1 and floor/1.
2016-03-15update copyright-yearHenrik Nord
2015-06-18Change license text to APLv2Bruce Yinhe
2015-01-14Add math:log2/1Olivier Girondel
2014-03-17compiler: Guard BIF is_map/1 is pureBjörn-Egil Dahlberg
2013-02-22Update copyright yearsBjörn-Egil Dahlberg
2013-02-14Add float_to_binary and binary_to_floatLukas Larsson
2013-02-14Add new binary conversion bifsLukas Larsson
Added: binary_to_integer/1,2, integer_to_binary/1,2
2011-12-09Update copyright yearsBjörn-Egil Dahlberg
2011-11-30compiler: Turn calls to math:pi/0 into constant valuesBjörn Gustavsson
Mark math:pi/0 as pure, informing the compiler that the value can be calculated at compile time.
2011-07-06Remove deprecated concat_binary/1Björn Gustavsson
concat_binary/1 was deprecated in R13B04, but already in the R10B-2 release, the documentation recommends using list_to_binary/1 instead.
2010-05-20Merge branch 'pan/otp_8217_binary' into devErlang/OTP
* pan/otp_8217_binary: Add documentation for binary module Add more tests and make some go easier on small systems Correct Boyer More and trapping for longest_common_suffix Add longer timetrap to testcases and add binary to app file Add guard BIFs binary_part/2,3 Add binary:{encode,decode}_unsigned({1,2} Add referenced_byte_size/1 Add binary:list_to_bin/1 and binary:copy/1,2 Add bin_to_list/{1,2,3} Add binary:longest_common_prefix/longest_common_suffix Add binary:part to erl_bif_binary.c Move binary module bif's to erl_bif_binary.c Count reductions for process even when not trapping Add random compare testcase Teach BIF's binary:match/matches interrupting/restarting Teach binary.c the semantics to take longest instead of shortest match Initial commit of the binary EEP OTP-8217 Implement EEP31 The module binary from EEP31 (and EEP9) is implemented.
2010-05-17Add guard BIFs binary_part/2,3Patrik Nyblom
Add the gc_bif's to the VM. Add infrastructure for gc_bif's (guard bifs that can gc) with two and. three arguments in VM (loader and VM). Add compiler support for gc_bif with three arguments. Add compiler (and interpreter) support for new guard BIFs. Add testcases for new guard BIFs in compiler and emulator.
2009-11-20The R13B03 release.OTP_R13B03Erlang/OTP