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Since Index =:= OldIndex and OldUniq =:= 0, there is no need to
store OldIndex and OldUniq in the internal data structure for the
lambda table.
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* maint:
dialyzer: Compact 'file' annotations in Core code
dialyzer: Try to reduce memory usage
dialyzer: Use less memory when translating contracts
dialyzer: Use maps instaed of dict
dialyzer: Use maps instead of dict for module contracts map
dialyzer: Compress a few more ETS tables
dialyzer: Optimize memory consumption
dialyzer: Reduce memory consumption during 'remote' phase
dialyzer: Update code for finding parallelism
compiler: Do not spawn process when dialyzing
dialyzer: Reduce ETS usage during the typesig phase
dialyzer: Optimize graph condensation
dialyzer: Do not send full PLTs as messages
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Memory consumption is reduced during the compilation phase by keeping
the Core parse tree shared. In particular the file annotation takes a
lot of memory when not shared.
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Code with huge literal case expressions such as the following would
compile very slowly:
case "Very long literal string (thousands of characters)..." of
.
.
.
end.
The reason is that in the case optimization each character in the
string would be handled individually. Fix this bug by handling
literals all at once.
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The compiler would keep the data structures for two compiler
passes in memory. That could increase the maximum amount of
memory that the compiler uses, and could also have a negative
impact on performance (terms that would not be used again would be
copied by a garbage collection).
Here is an example that shows how the previous version of the code
could get captured:
a_compiler_pass(Mod, St) ->
case Mod:module(St#compile.code, St#compile.options) of
{ok,Code} ->
{ok,St#compile{code=Code}};
...
The reference to the code from the previous pass will only be released
when St is updated. We can avoid the problem by passing the
current version of the code as a function argument:
a_compiler_pass(Mod, Code0, St) ->
case Mod:module(Code0, St#compile.options) of
{ok,Code} ->
{ok,Code,St};
...
In practice, this change does not seem to significantly speed up
the compiler, but it does not do any harm either. It should help
dialyzer in situations when dialyzer compiles several large modules
at the same time.
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The beam_type may pass move and recalculates test_heap instructions.
The number of live registers are not always the lowest. Minimize the
number of registers by running beam_utils:live_opt/1 one more time.
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Add the option 'deterministic' to make it easier to
achieve reproducible builds.
This option omits the {options,...} and {source,...} tuples in
M:module_info(compile), because those options may contain absolute
paths.
The author of ERL-310 suggested that only compiler options that
may contain absolute paths (such as {i,...}) should be excluded. But I
find it confusing to keep only some options.
Alternatives considered: Always omitting this information. Since this
information has been available for a long time, that would probably
break some workflows. As an example that some people care about
{source,...}, 2d785c07fbf9 made it possible to give a compiler option
to set {source,...}.
ERL-310
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* maint:
Update copyright-year
Conflicts:
lib/dialyzer/src/dialyzer.hrl
lib/dialyzer/src/dialyzer_options.erl
lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer.hrl
lib/dialyzer/test/opaque_SUITE_data/src/recrec/dialyzer_races.erl
lib/hipe/icode/hipe_icode.erl
lib/hipe/main/hipe.erl
lib/hipe/main/hipe.hrl.src
lib/hipe/main/hipe_main.erl
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* egil/compiler/opt-maps-pattern-matching/OTP-14072:
compiler: Add regression tests
compiler: Optimize maps pattern matching
compiler: Allow for unaligned match argument in value groups
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* egil/compiler/maps-warn-repeated-keys/OTP-14058:
compiler: Test repeated map key warnings
compiler: Warn for repeated identical map keys
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A map expression such as,
#{'a' => 1, 'b' => 2, 'a' => 3}
will produce a warning for the repeated key 'a'.
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* maint:
Update primary bootstrap
document {yield/nb_yield}() limitation
Suppress warnings from v3_kernel when inlining is turned on
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In practice, this optimization will only apply to contrived guards
that are almost never used in real applications. The only reason we
add this optimization is to help approach the goal of zero tolerance
for 'bif' instructions instead of 'test' instructions in guards.
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A 'bif' or 'gc_bif' instruction is redundant if it has the same
failure label as a 'jump' instruction immediately following it.
There is no need to test for liveness of the destination register,
because the code at the failure label cannot safely assume that
the destination register is initialized. See the comments in the
code for further details.
In practice, this optimization will only apply to contrived guards
that are almost never used in real applications. The only reason we
add this optimization is to help approach the goal of zero tolerance
for 'bif' instructions instead of 'test' instructions in guards.
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The guard optimizations in v3_kernel has removed the need for
beam_bool.
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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
$
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v3_kernel may produce unwanted and confusing warnings for code that
has been inlined with the new inliner (cerl_inline). Consider this
code:
-compile(inline).
compute1(X) ->
add(X, 0).
compute2(X, Y) ->
add(X, Y).
add(1, 0) ->
1;
add(1, Y) -> %% "this clause cannot match..."
1 + Y;
add(X, Y) ->
X + Y.
v3_kernel warns because add/2 has been inlined into compute1/1 and only
the first clause in add/2 will match. But the other clauses are needed
when add/2 is inlined into compute2/2, so the user cannot do anything
to eliminate the warning (short of manually inlining add/2, defeating the
purpose of the 'inline' option).
The warning would be reasonable if compute2/2 didn't exist, but it would
be too complicated for the compiler to figure whether a warning make
sense or not.
Therefore, suppress all warnings generated by v3_kernel if cerl_inline
has been run.
ERL-301
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The fixpoint iteration added in 05130e48 makes those calls
superfluous.
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* gandrade/fmod/PR-1216/OTP-14000:
Add test cases for math:fmod/2 BIF
Support math:fmod/2 BIF on compiler
Add math:fmod/2 BIF
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There are two calls opt_not_in_let(). Since 05130e4855
introduced iteration to a fixpoint, only the first call
is needed. Removing the redundant call will slightly speed
up compilation.
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* maint:
Don't copy funs into guards
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Funs must not be created in guards. The instruction for creating
a fun clobbers all X registers, which is a bad thing to do in
a guard.
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* maint:
Don't let inline_list_funcs degrade optimizations
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83199af0263 refactored sys_core_fold to break out the code for the
inline_lists_funcs option to its own module. Unfortunately, it also
accidentally turned off compile-time evaluation of calls to BIFs with
wholly or partial constant arguments.
For example, the code for the following funtion gets much worse
when inline_list_funcs is used:
b() ->
R0 = #r{},
R1 = setelement(1+2, R0, "deux"),
R2 = setelement(1+3, R1, "trois"),
R3 = setelement(1+5, R2, "cinq"),
R4 = setelement(1+2, R3, "DEUX"),
R4.
ERL-285
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* maint:
beam_bsm: Eliminate unsafe optimization
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The following code causes a compiler failure:
first_after(Data, Offset) ->
case byte_size(Data) > Offset of
false ->
{First, Rest} = {ok, ok},
ok;
true ->
<<_:Offset/binary, Rest/binary>> = Data,
%% 'Rest' saved in y(0) before the call.
{First, _} = match_first(Data, Rest),
%% When beam_bsm sees the code, the following line
%% which uses y(0) has been optimized away.
{First, Rest} = {First, Rest},
First
end.
match_first(_, <<First:1/binary, Rest/binary>>) ->
{First, Rest}.
Here is the error message from beam_validator:
t: function first_after/2+15:
Internal consistency check failed - please report this bug.
Instruction: {call,2,{f,7}}
Error: {multiple_match_contexts,[{x,1},0]}:
Basically, what happens is that at time of code generation,
the variable 'Rest' is needed after the call to match_first/2
and is therefore saved in y(0). When beam_bsm (a late optimization
pass) sees the code, the use of y(0) following the call
to match_first/2 has been optimized away. beam_bsm therefore
assumes that the delayed sub-binary creation is safe. (Actually,
it is safe, but beam_validator does not realize it.)
The bug was caused by two separate commits:
e199e2471a reduced the number of special cases to handle in BEAM
optimization passed by breaking apart the tail-recursive call
instructions (call_only and call_last) into separate instructions.
Unfortunately, the special handling for tail calls was lost, which
resulted in worse code (i.e. the delayed sub-binary creation
optimization could not be applied).
e1aa422290 tried to compensate, but did so in a way that was not
always safe.
Teaching beam_validator that this kind of code is safe would be
expensive.
Instead, we will undo the damage caused by the two
commits. Re-introduce the special handling of tail-recursive calls in
beam_bsm that was lost in the first commit. (Effectively) revert the
change in the second commit.
ERL-268
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* maint:
Update primary bootstrap
beam_block: Avoid unsafe inclusion of get_map_elements in blocks
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c2035ebb8b restricted the get_map_elements instruction so that it
could only occur at the beginning of a block. It turns out that
including it anywhere in a block is unsafe.
Therefore, never put get_map_elements instruction in blocks.
(Also remove the beam_utils:join_even/2 function since it is no
longer used.)
ERL-266
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* rickard/time-unit/OTP-13831:
Replace usage of deprecated time units
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At this stage in match compilation we are allowed to change the
alignment of arguments and constructors as long as they are the
same aligned in the same group.
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* josevalim/compiler/at-var/PR-1081/OTP-13924:
Use @ in variable names generated by core and kernel
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Run the optimizations until a fixpoint is reached, or until
the maximum iteration count is reached.
The hope is that in the future we can many small optimizations
instead of optimizations that try to do everything in one pass.
This change allows us to remove the ad-hoc calls to expr/2
to run more optimizations on a piece of code.
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The optimization that avoids building a tuple in a case
expression would not work if any clause matched a tuple
as in the following example:
f(A, B) ->
case {A,B} of
{<<X>>,Y} ->
{X,Y}
end.
The generated Core Erlang code would look like this (note
the tuples in the case expression and the pattern):
'f'/2 =
fun (_cor1,_cor0) ->
case {_cor1,_cor0} of
<{#{#<X>(8,1,'integer',['unsigned'|['big']])}#,Y}>
when 'true' ->
{X,Y}
.
.
.
end
It is expected that the code should look like this (note
that tuples have been replaced with "values"):
'f'/2 =
fun (_cor1,_cor0) ->
%% Line 5
case <_cor1,_cor0> of
<#{#<X>(8,1,'integer',['unsigned'|['big']])}#,Y> ->
{X,Y}
.
.
.
end
While at it, also fix bugs in the handling of pattern with
aliases. The bindings were produced in the wrong order (creating
'let's with referring to free variables), but in most cases
the incorrect bindings were discarded later without causing any
harm.
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703e8f4490bf broke the scope verification code (by calling
ordsets:is_subset/2 with an unsorted second argument).
While we are it, also optimize the verification function
by avoiding converting the map to a sorted list.
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The previous variable names can be generated by
projects like LFE and Elixir, leading to possible
conflicts. Our first to choice to solve such conflicts
was to use $ but that's not a valid variable name in core.
Therefore we picked @ which is currently supported and
still reduces the chance of conflicts.
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Do a simpler translation of internal BIFs.
While we are it, also remove the dummy values of Index and Uniq
from the make_fun internal operation.
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Remove the special handling #k_try{} in guards in v3_life. If we
introduce a new #k_protected{} record in v3_kernel, v3_life no longer
needs to know whether it is processing guards or bodies.
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When beam_utils was first written, it did not have the functions
for testing whether a register was not used. Those were added
later, in sort of a hacky way.
Also, is_killed*() and is_not_used*() for Y registers would
return the same answer. Fix that to make the API more consistent
(an Y register can only be killed by a deallocate/1 instruction).
We will need to change beam_trim to call beam_utils:is_not_used/3
instead of beam_utils:is_killed/3.
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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.
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The error would be:
{multiple_match_contexts,[{x,0},2]}
instead of:
{multiple_match_contexts,[{x,0},{y,2}]}
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Since the beam_a pass has always been run and have removed any
unused label, there can never be a label as the very last
instruction in a function.
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eliminate_fallthroughs/2 has special code to handle two labels next to
each other, but that does not seem to ever happen and there was one
line uncovered in is_label/1. Since inserting an extra jump between
two labels would not cause any real problems, remove the extra
handling of two consecutive labels.
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