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Code such as:
bar(X) ->
case {X+1} of
1 -> ok
end.
would crash the beam_except pass of the compiler.
The reason for the crash is that the '+' operator would add a line/1
instruction that the beam_except pass was not prepared to handle.
Reported-by: Erik Søe Sørensen
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re needs unicode option
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* bjorn/compiler/optimizations/OTP-11584:
Generalize optimizations of case statements
Ignore warnings when running sys_core_fold after inlining
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Case expressions such as:
case {Expr1,Expr} of
{V1,V2} -> ...
end
are already optimized to not actually build the tuple. Generalize
the optimization to avoid building any kind of composite term,
such as:
case {ok,[A,B]} of
{ok,[X,Y]} -> ...
end
We don't expect programmers to write such code directly, but
inlining can produce such code.
We need to be careful about the warnings we produce. If the case
expression is a literal, it is expected that no warnings should be
produced for clauses that don't match. We must make sure that we
continue to suppress those warnings.
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* nox/fix-dbg_ieval-exporting-rules/OTP-11553:
compiler tests: Test exporting rules for andalso/orelse
Fix evaluation of andalso and orelse in the debugger
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erlc is wired to treat *.S files as assembler and build them as
compile:file(File, [from_asm]), but this is not documented. There's also
a documented compile:file/2 option called 'asm' (mapping to 'from_asm'),
but the wording discourages its use. All of this has been in place and
in use for a long time. Therefore, it should be supported officially.
To fix that, make the following changes:
* document erlc handling of *.core files
* un-document 'asm' and document 'from_asm' instead
* deprecate 'asm'
While at it, fix a minor typo in the test suite.
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* maint:
Rename otp_8949_a/0 which common_test interprets as an info function
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Before running a test case named testcase/1, common_test will call
testcase/0 (the info function). Exceptions and illegal return values
would be silently ignored. In a planned update to common_test, errors
will instead cause the test case to fail.
The test case otp_8949_a/1 has a helper function called otp_8949_a/0.
Rename it to do_otp_8949_a/0.
While at it, also fix a copy and paste bug in the list of test cases.
otp_8949_a was run twice; otp_8949_b was never run.
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* maint:
compiler: Conform returned errors to the documented format
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ErrorInfo is documented to be:
{ErrorLine,Module,ErrorDescriptor}
but for some errors with line numbers it would look like:
{Module,ErrorDescriptor}
Ensure that all ErrorInfo tuples have three elements. Use 'none'
instead of a line number:
{none,Module,ErrorDescriptor}
There already are errors that return 'none' when no line number is
available, but that convention was not documented. Mention it in the
documentation.
Also make sure that the compiler will not print 'none' as a line
number in error messages (if the 'report_errors' option is given) as
that looks stupid. That is, when attempting to compile a non-existing
module, the error message should be:
non-existing.erl: no such file or directory
and not:
non-existing.erl:none: no such file or directory
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* nox/match-context-return/OTP-11247:
Added primary bootstrap
Forbid returning a match context in beam_validator
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* maint:
Fix compiler crash for 'B and B' guard
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If a match context is returned from a function without being converted
back to a plain old binary, the whole VM will crash.
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Conflicts:
bootstrap/lib/compiler/ebin/v3_core.beam
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* nox/fix-comp-warnings/OTP-11212:
Bootstrap
Silence a misleading warning with some comprehensions
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Conflicts:
bootstrap/lib/compiler/ebin/cerl_inline.beam
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* nox/fix-fname-inlining/OTP-11211:
Added primary bootstrap
Restrict inlining of local fun references
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* jw/fix-float-middle-endian/OTP-11201:
Fix binary construction on floating point middle-endian machines
Fix binary matching on floating point middle-endian machines
Fix erlang:phash2() on floating point middle-endian machines
Fix external term format BIFs on floating point middle-endian machines
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Local fun references look like plain old variables in the Core Erlang
AST but should not be treated as such. Inlining of such expressions is
now restricted to application contexts as a local fun reference should
never occur in a guard.
This is not perfect as it forbids inlining in some safe situations, but
that is still better than a compiler crash.
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* nox/illegal-bitstring-gen-pattern/OTP-11186:
Bootstrap added
Simplify v3_core's translation of bit string generators
Forbid unsized fields in patterns of binary generators
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This complements 933e701 (OTP-10209). Without this patch the test cases
"in_guard/1" and "coerce_to_float/1" in bs_construct_SUITE fail.
The added lines in bs_construct_SUITE cover all branches that were not
covered before (small and big numbers if BIT_OFFSET(erts_bin_offset) != 0).
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When compiling comprehensions with generators which are foldable to
'true', a misleading warning is emitted by sys_core_fold because a
clause resulting from the compilation of the comprehension to Core
Erlang is not marked as generated by the compiler.
An example of such a comprehension is [ true || true ].
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It makes no sense to be able to do `<<...,Rest/binary>> <= ...` in a
comprehension. The related Dialyzer test is removed.
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* maint:
compiler: Correct liveness optimization for wait/1
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The live optimization in beam_utils:live_opt/4 did not take into
account that the wait/1 instruction *never* falls through to
the next instruction (it has the same effect on the control flow
as the jump/1 instruction).
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Conflicts:
bootstrap/lib/stdlib/ebin/beam_lib.beam
lib/public_key/test/erl_make_certs.erl
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Since both the STDLIB and compiler applications turn warnings
into errors, we must stop using the old deprecated crypto functions.
While we are at it, generalize the format of the key tuple returned
by beam_lib:make_crypto_key/2 to facilitate introducing new crypto
methods in the future. Change the format to:
{Type,Key,IV,BlockSize}
where Type, Key, and IV are the first three arguments for either
crypto:block_encrypt4/ or crypto:block_decrypt/4, and BlockSize
is the block size for the crypto algorithm (it is needed to properly
pad the plaintext blocks before encryption).
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In some circumstances, as when inlining code, when some optimization
passes are disabled or with hand-written but semantically correct Core
Erlang or BEAM assembly, a fresh reference may be live in more than one
register:
...
{allocate_zero,2,2}.
...
{call_ext,0,{extfunc,erlang,make_ref,0}}. % Ref in [x0]
...
{move,{x,0},{y,0}}. % Ref in [x0,y0]
{move,{y,1},{x,0}}. % Ref in [y0]
...
{move,{y,0},{x,0}}. % Ref in [x0,y0]
{move,{x,0},{y,1}}. % Ref in [x0,y0,y1]
{label,5}.
{loop_rec,{f,6},{x,0}}. % Ref in [y0,y1]
...
{loop_rec_end,{f,5}}.
{label,6}.
{wait,{f,5}}.
...
Pass beam_receive expects a single live register for the ref when it
encounters the loop_rec instruction and crashes with the following
reason:
$ erlc t.S
...
crash reason: {{case_clause,
{'EXIT',
{{case_clause,[{y,1},{y,0}]},
[{beam_receive,opt_recv,5,
[{file,"beam_receive.erl"},{line,154}]},
...]}}},
...}
This commit teaches beam_receive how to use a set of registers instead
of a single one when tracking fresh references, thus avoiding the crash.
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* nox/fix-bc-optim/OTP-11005:
Add a new option +clint0 to the compiler
Fix optimization of some binary comprehensions
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If a variable bound in a generator is used as the size of a segment
in the comprehension body, v3_core uses this variable in the code
generated to compute the initial size given to the `bs_init_writable`
primop before the variable is actually bound, as in:
<< <<0:S>> || S <- Slist >>
Reported-By: Peer Stritzinger
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beam_utils:is_not_used_at/3 could be very slow for complex guards,
because the cached result for previously encountered labels were
neither used nor updated within blocks.
Reported-by: Magnus Müller
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Commits 53bd4974a101 and 726f6e4c7afe simplified the handling of
match_fail (used to generated exceptions such as 'function_clause')
by first rewriting them to a call to erlang/error{1,2} and later
rewriting them to specialized BEAM instructions (to reduce the
code size).
There was one flaw, though, which only was exposed when more
aggressive optimizations were added in c3b60f86c622. Here is an
example to explain it:
t(V) ->
fun(get) -> V end.
The following BEAM code will be initially generated for the fun:
{function, '-t/1-fun-0-', 2, 5}.
{label,1}.
{line,[{location,"t.erl",5}]}.
{func_info,{atom,t},{atom,'-t/1-fun-0-'},2}.
{label,2}.
{test,is_eq_exact,{f,2},[{x,0},{atom,get}]}.
{move,{x,1},{x,0}}.
return.
{label,2}.
{test_heap,2,1}.
{put_list,{x,0},nil,{x,1}}.
{move,{atom,function_clause},{x,0}}.
{line,[{location,"t.erl",5}]}.
{call_ext_only,2,{extfunc,erlang,error,2}}.
Translating back to Erlang code, that would be roughly:
'-t/1-fun-0-'(get, V) -> V;
'-t/1-fun-0-'(Arg1, _) -> erlang:error(function_clause, [Arg1]).
Note that the second argument (the free variable V) is not included
in the call to erlang:error/2.
The beam_except pass will simplify the code to:
{function, '-t/1-fun-0-', 2, 8}.
{label,1}.
{line,[{location,"t.erl",5}]}.
{func_info,{atom,t},{atom,'-t/1-fun-0-'},2}.
{label,2}.
{test,is_eq_exact,{f,1},[{x,0},{atom,get}]}.
{move,{x,1},{x,0}}.
return.
The code has been shortened by jumping to the func_info/3 instruction.
Translating back to Erlang:
'-t/1-fun-0-'(get, V) -> V;
'-t/1-fun-0-'(Arg1, Arg2) -> erlang:error(function_clause, [Arg1,Arg2]).
it is clear that both arguments are now included in the
'function_clause' exception, even though the initially generated
code only included the first argument.
That is no problem in this particular case, but for some more complex
funs, optimizing the first version based on variable usage could make
the second version unsafe.
I rejected the following potential solutions:
- Including the free arguments in the call to erlang:error/2:
'-t/1-fun-0-'(get, V) -> V;
'-t/1-fun-0-'(Arg1, Arg2) -> erlang:error(function_clause, [Arg1,Arg2]).
Unfortunately, that is tricky. The free variables are only known
after the second pass in v3_kernel when variable usage has been
calculated. We would need to add a third pass (only for funs) that
would the free arguments to the second argument for erlang:error/2
*and* update the variable usage information.
- Calling beam_except earlier, from within beam_block before any
optimizations based on variable usages are done. But means that the
problem could reappear in some other form in the future when other
updates are done to the code generator and/or optimization passes.
The solution I have chosen is to modify beam_except to only replace
a call to erlang:error(function_class, Args) if the length of Args
is the same as the arity in the func_info/3 instruction. The code
will be slightly larger. Also, the free variables for funs and list
comprehensions will no longer be included in the function_clause
exception (that could be less confusing, but it also means less
information during debugging).
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* nox/fix-seq-opt/OTP-10818:
Add two tests for unused multiple values in effect context
Forbid multiple values in Core Erlang sequence arguments
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The following code:
check(<<"string">>, a1) ->
one;
check(_, a2) ->
two;
check(undefined, a3) ->
three.
produces an internal consistency failure:
check: function check/2+17:
Internal consistency check failed - please report this bug.
Instruction: {test,is_eq_exact,{f,7},[{x,0},{atom,undefined}]}
Error: {match_context,{x,0}}:
Actually, in the current implementation of the run-time system,
comparing a match context to an atom is safe, so I briefly considered
updating the beam_validator to let this code pass through. I
abandoned that approach because not all terms would be safe to
compare to a match context, and the implementation might change
in the future.
Therefore, fix this problem by not allowing any matching of non-variables
(in the argument position for binary being matched) following binary
matching. That solution is simple and safe, and since this kind of
code seems to be rare in practice, there is no need to pursue any
more compilicated solution.
Reported-by: Viktor Sovietov
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