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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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The compiler stopped using sys_pre_expand in ae3e177c514c354831.
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* maint:
beam_validator: Handle unreachable instructions
Turn off parallel make for start scripts Makefile
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ab03678e introduced an optimization in the beam_z pass that could
introduce unreachable code in BEAM files (a 'jump' instruction is
removed after a 'raise' instruction, but the code following the
target of the 'jump' is not removed).
Since this situation happens very rarely, there is no point in adding
another pass that can remove unreachable code after beam_z. Instead we
will make sure that beam_validator can skip the unreachable code.
Skipping unreachable code is already done in valfun_1/2 (for
historical reasons), but we will also need to do it in val_dsetel/2.
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* maint:
[snmp] Correct bug when path to mib contains UTF-8 characters
[ic] Fix but when UTF-8 character in path to idl spec
sys_core_fold: Don't move a fun into a guard
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Moving a fun into a guard may cause code that is not accepted
by beam_validator.
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* bjorn/floor-ceiling/OTP-13692:
Add math:floor/1 and math:ceil/1
Implement the new ceil/1 and floor/1 guard BIFs
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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).
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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.
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The filters in a list comprehension can be guard expressions or
an ordinary expressions.
If a guard expression is used as a filter, an exception will basically
mean the same as 'false':
t() ->
L = [{some_tag,42},an_atom],
[X || X <- L, element(1, X) =:= some_tag]
%% Returns [{some_tag,42}]
On the other hand, if an ordinary expression is used as a filter, there
will be an exception:
my_element(N, T) -> element(N, T).
t() ->
L = [{some_tag,42},an_atom],
[X || X <- L, my_element(1, X) =:= some_tag]
%% Causes a 'badarg' exception when element(1, an_atom) is evaluated
It has been allowed for several releases to override a BIF with
a local function. Thus, if we define a function called element/2,
it will be called instead of the BIF element/2 within the module.
We must use the "erlang:" prefix to call the BIF.
Therefore, the following code is expected to work the same way as in
our second example above:
-compile({no_auto_import,[element/2]}).
element(N, T) ->
erlang:element(N, T).
t() ->
L = [{some_tag,42},an_atom],
[X || X <- L, element(1, X) =:= some_tag].
%% Causes a 'badarg' exception when element(1, an_atom) is evaluated
But the compiler refuses to compile the code with the following
diagnostic:
call to local/imported function element/2 is illegal in guard
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The previous commits have made sys_pre_expand superfluous. Since
sys_pre_expand is undocumented and unsupported it can be removed in
a major release without prior deprecation.
Also remove code in erl_parse that handles abstract code that has
passed through sys_pre_expand.
We considered deprecating sys_pre_expand just in case, but decided
against it for the following reasons:
- Anyone brave and knowledgeable enough to use sys_pre_expand should
be able to cope with sys_pre_expand being removed.
- If we kept it, but didn't test it anywhere in OTP, it could
potentially stop working. So we would probably have to add some test
cases.
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sys_pre_expand previously did a lot more work, for example,
translating records and funs, but now is merely a grab bag
of small transformations. Move those transformations to
v3_core.
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105c5b0071 was reverted in dd1162846e because clauses that were
supposed to match would not match. (See 8b83bc0b.)
Reintroduce the optimization, but make sure that we only shortcut
bs_context_to_binary instructions and not bs_start_match2 instructions.
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* maint:
asn1_test_lib: Compile ASN.1 modules in parallel
Support 'make -j' when compiling ASN.1 modules
[ERL-209] Fix ambiguous_catch_try_state inconsistency error
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It is not safe to share code between 'catch' blocks.
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* josevalim/large-binary-strings/PR-1131/OTP-13794:
Move expansion of strings in binaries to v3_core
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beam_block has an optimization that only is safe when it is applied
immediately after code generation. That is pointed out in a comment:
NOTE: Moving allocation instructions is only safe because it is done
immediately after code generation so that we KNOW that if {x,X} is
initialized, all x registers with lower numbers are also initialized.
That assumption may not be true after other optimizations, such as
the beam_utils:live_opt/1 optimization.
The new beam_reorder pass added in OTP 19 runs before beam_block.
Therefore, the optimization is potentially unsafe. The optimization
is also unsafe if compilation is started from assembly code in a
.S file.
Rewrite the optimization to make it safe. See the newly added comment
for details.
ERL-202
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This speeds up the compilation of binary literals
with string values in them. For example, compiling
a file with a ~340kB binary would yield the following
times by the compiler:
Compiling "foo"
parse_module : 0.130 s 5327.6 kB
transform_module : 0.000 s 5327.6 kB
lint_module : 0.011 s 5327.8 kB
expand_module : 0.508 s 71881.2 kB
v3_core : 0.463 s 11.5 kB
Notice the increase in memory and processing time
in expand_module and v3_core. This happened because
expand_module would expand the string in binaries
into chars. For example, the binary <<"foo">>, which
is represented as
{bin, 1, [
{bin_element, 1, {string, 1, "foo"}, default, default}
]}
would be converted to
{bin, 1, [
{bin_element, 1, {char, 1, $f}, default, default},
{bin_element, 1, {char, 1, $o}, default, default},
{bin_element, 1, {char, 1, $o}, default, default}
]}
However, v3_core would then traverse all of those
characters and convert it into an actual binary, as it
is a literal value.
This patch addresses this issue by moving the expansion
of string into chars to v3_core and only if a literal
value cannot not be built. This reduces the compilation
time of the file mentioned above to the values below:
Compiling "bar"
parse_module : 0.134 s 5327.6 kB
transform_module : 0.000 s 5327.6 kB
lint_module : 0.005 s 5327.8 kB
expand_module : 0.000 s 5328.7 kB
v3_core : 0.013 s 11.2 kB
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This reverts commit 105c5b0071056dc062797e58772e098d2a3a4627.
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* aronisstav/compiler/fix-compile-forms-spec/PR-1109:
Fix spec of compile:(noenv_)forms/2
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Any exceptions at this point would be of class error, not exit.
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When the compiler fails to write an output file, it used to just print
"error writing file". With this change, it also prints the error
reason:
$ echo "-module(foo)." > foo.erl
$ chmod -w .
$ erlc foo.erl
/tmp/bar/foo.bea#: error writing file: permission denied
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The input for a call to compile:(noenv_)forms/2 can also be a cerl
module (useful e.g. to resume with 'from_core' after a 'to_core'
compilation).
Internal representations used for 'from_asm' and 'from_beam'
compilation can also be valid, but have no relevant types defined.
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retrieve the value of the environment variable ERL_COMPILER_OPTIONS
in the same manner as used by file/2, forms/2 and output_generated/2
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* bjorn/compiler/misc:
misc_SUITE: Cover the remaining lines in beam_peep
Avoid the dreaded "no_file" in warnings
Eliminate crash for map updates in guards
beam_block: Eliminate crash in beam_utils
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* jv/compiler/mapsify-rec_env/PR-1082/OTP-13646:
Convert dict() to map() in rec_env.erl
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Add more filename/line number annotations while translating to
Core Erlang in v3_core, and ensure that sys_core_fold retains
existing annotations. The goal is to avoid that sys_core_fold
generate warnings with "no_file" instead of a filename.
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beam_validator would complain that x(1) is uninitialized
in a test_heap instruction when attempting to compile
the following code with sys_core_fold turned off:
foo(M) when not (M#{true := 0}); [M] ->
ok.
Simplified, the generated BEAM assembly code looked like
this:
test is_map BadMap x(0)
put_map_exact Fail x(0) => x(1) ...
jump BooleanStuff
BadMap:
move ok => x(1)
jump Fail
BooleanStuff:
...
move Boolean => x(2)
jump Build
Fail:
move false => x(2)
Build:
test_heap 2 3 %% x(0), x(1), x(2) must be live.
...
That is, if put_map_exact failed, control would transfer
to the label Fail without initializing x(1).
Fix that by making sure that x(1) is initilized even if
put_map_exact fails:
test is_map BadMap x(0)
put_map_exact BadLbl x(0) => x(1) ...
jump OkLbl
BadLbl:
move ok => x(1)
jump Fail
OkLbl:
jump BooleanStuff
BadMap:
move ok => x(1)
jump Fail
BooleanStuff:
...
move Boolean => x(2)
jump Build
Fail:
move false => x(2)
Build:
test_heap 2 3 %% x(0), x(1), x(2) must be live.
...
Note that this situation is rare, and that other optimization passes
(beam_dead and beam_jump in particular) will clean up this mess.
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Somewhat simplified, beam_block would rewrite the target for
the first instruction in this code sequence:
move x(0) => y(1)
gc_bif '+' 1 x(0) => y(0)
move y(1) => x(1)
move nil => x(0)
call 2 local_function/2
The resulting code would be:
move x(0) => x(1) %% Changed target.
gc_bif '+' 1 x(0) => y(0)
move x(1) => y(1) %% Operands swapped (see 02d6135813).
move nil => x(0)
call 2 local_function/2
The resulting code is not safe because the x(1) will be killed
by the gc_bif instruction.
7a47b20c3a cleaned up move optimizations and would reject the
optimization if the target was an X register and an allocating
instruction was found. To avoid this bug, the optimization must be
rejected even if the target is a Y register.
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We want to find bugs in the compiler during compilation. Validation of
match contexts was weak, which could allow serious bugs in the
generated code to slip through.
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Using a record will make it much easier to add additional information.
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* bjorn/compiler/misc:
Eliminate unsafe use of Y registers
beam_validator: Add is_bitstring/1 as a safe BIF
beam_validator: Remove uncovered line
Teach beam_utils:is_pure_test/1 to handle is_bitstr and is_function2
beam_utils: Simplify handling of 'return' to eliminate uncovered line
beam_jump: Clean up handling of labels before func_info
beam_expect: Correctly handle blocks with multiple allocs
v3_codegen: Don't confuse beam_validator
v3_codegen: Correct code generation for an error/1 call in a guard
beam_receive: Don't crash when encountering nonsensical code
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If the Core Erlang optimization were turned off (using no_copt),
the optimization passes for Beam assembly could generate unsafe
code that did not initialize all Y registers before (for example)
a call instruction.
To fix this, beam_dead should not attempt to remove stores to Y
registers. That is not safe if there is an exception-generating
instruction inside a try...catch block.
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beam_validator wrongly complained that the following was
not safe because it didn't know that is_bitstring/1 is safe:
food(Curriculum) ->
[try
is_bitstring(functions)
catch _ ->
0
end, Curriculum].
While we are it, also add a new bif_SUITE test suite to cover some
more code in beam_validator.
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The raise/3 instruction is specially handled, thus there is no need
for bif_type/3 to handle raise/3 (also, the number of arguments was
incorrect, so it could never have matched).
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