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While at it, do some other minor clean-ups.
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* bg/compiler-suppress-result-ignored:
compiler tests: Eliminate "result of expression is ignored" warnings
Silence warnings for expressions that are assigned to "_"
OTP-8602 bg/compiler-suppress-result-ignored
It is now possible to suppress the warning in code such as
"list_to_integer(S), ok" by assigning the ignored value "_" like this: "_ =
list_to_integer(S), ok".
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The following instruction sequence:
fmove {fr,Fr} {x,TempXreg}
move {x,TempXreg} {y,Dest}
is rewritten to:
fmove {fr,Fr} {y,Dest}
(Provided that {x,TempXreg} is killed by the instructions following
the sequence.)
Generalize the optimization to also handle:
fmove {fr,Fr} {x,TempXreg}
move {x,TempXreg} {_,Dest}
That is, the destination register can be either an X or Y register.
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There is currently no zero-cost way to silence the warning
"the result of the expression is ignored", which is issued
for code such as:
list_to_integer(S),
ok
Such code can be useful for assertions or input validation.
Teach the compiler to silence the warning for expressions
that are explicitly assigned to to the "_" variable,
such as:
_ = list_to_integer(S),
ok
Implement it by having the v3_core pass annotate calls in
Core Erlang like this:
let <_> = ( call 'erlang':'list_to_integer'(S) -| ['result_not_wanted'] )
in 'ok'
and modifiy sys_core_fold to suppress the warning for any call
having the annotation.
We deliberately do not make it possible to silence the warnings
for expressions like:
{build,an,unnecessary,term}, ok
or
is_list(L), ok
because we don't know of any real-world scenarios in which that would
be useful.
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* bg/compiler-inliner:
pmod_SUITE: Again test inlining parameterized modules
compiler tests: Cope with missing args in function_clause for native code
compiler tests: Compile a few more modules with 'inline'
Consistently rewrite an inlined function_clause exception to case_clause
compiler tests: Test the 'inline' option better
compiler: Suppress bs_context_to_binary/1 for a literal operand
compiler: Fix binary matching bug in the inliner
sys_core_inline: Don't generated multiple compiler_generated annos
OTP-8552 bg/compiler-inliner
Several problems in the inliner have been fixed.
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A function_clause exception is generated by jumping to a func_info/3
instruction at the beginning of the function. The x registers are
assumed to contain the arguments for the function. That means
that a func_info/3 instruction copied from another function
(or even from the same function if not at the top level) will
not work, so it must be replaced with an instruction that
generates a case_clause exception.
In Core Erlang, a func_info/3 instruction is represented as
a the primop match_fail({function_clause,Arg1,...ArgN}).
The current mechanism that is supposed to replace the
primop match_fail(function_clause) with match_fail(case_clause)
will fail to do that in the following circumstances:
1. If the inliner has inlined a function into itself.
Fix that by having the inliner clear the function_name annotations
on all match_fail primops in functions that are inlined. (To simplify
doing that, the annotation is now on the primop node itself and not on
the 'function_clause' atom inside it.)
2. If the inliner has rewritten the tuple node in the primop node
to a literal (when inlining a function call with literal arguments),
v3_kernel would not recognize the match_fail(function_clause) primop
and would not rewrite it. Fix it by making v3_kernel smarter.
Also simplify the "old" inliner (sys_core_inline) to only clear
the function_name annotations instead of rewriting function_clause
execptions to case_clause execptions itself.
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The inliner can cause illegal uses of the bs_context_to_binary/1
instruction, such as:
bs_context_to_binary {literal,"string"}
or
bs_context_to_binary {integer,1}
Remove the bs_context_to_binary/1 instruction if the operand
is not a register (it is clearly not needed).
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The inliner incorrectly assumes that a literal cannot
match a binary in code such as:
t() ->
bc(<<"string">>).
bc(<<A:1,T/bits>>) -> [A|bc(T)];
bc(<<>>) -> [].
The bug was introduced when binary literals were introduced.
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Multiple compiler_generated annotations are harmless, but makes
listing files harder to read during debugging.
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* bg/compiler-remove-r11-support:
compiler: Don't support the no_binaries option
erts: Don't support the put_string/3 instruction
compiler: Don't support the no_constant_pool option
compiler: Don't support the r11 option
test_server: Don't support communication with R11 nodes
binary_SUITE: Don't test bit-level binary roundtrips with R11 nodes
erts: Test compatibility of funs with R12 instead of R11
OTP-8531 bg/compiler-remove-r11-support
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The no_binaries option terminates the compiler with an error
if any bit syntax is used in the module being compiled.
(It used to be implied by the removed r11 option.)
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Since R14 does not need to load code that can also be loaded
in an R11 run-time system, support for the put_string/3
instruction can be removed.
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The no_constant_pool option was implied by the r11 option. It turns
off the usage of the constant (literal) pool, so that BEAM
instructions that use constants can be loaded in an R11 system.
Since the r11 option has been removed, there is no need to
retain the no_constant_pool option.
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The r11 option was used to generate BEAM modules that could
loaded both on both R11 and R12/R13 to facilitate testing
that R11 and R13 nodes could communicate with each other.
Since R14 is only required to be compatible with R12 and
R13 nodes, the r11 option is no longer needed.
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Print the name and arity of the function being compiled
if the v3_life compiler pass crashes to facilitate finding
out which part of the source code that triggered the problem.
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modules. (Thanks to Jebu Ittiachen.)
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* ks/compiler:
compiler: keep line numbers for attributes
compiler Makefile: alphabetize module names
compile.erl: eliminate compiler warning
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In the future, we might want to generate warnings
for attributes, referring to them with line numbers.
sys_pre_expand used to replace line number for attributes
with 0. Change sys_pre_expand to retain the real line
number.
v3_core used to throw away the line numbers. Change
v3_core so that it retains the line numbers in annotations.
While at it, do some tidying as suggested by tidier.
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We must also catch exits, not only errors, since the hipe
compilers does an exit/1 if an internal error is found.
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Implement the 'no_native' option to disable native-code
compilation. If given in a module like this:
-compile(no_native).
it will override a 'native' option given on the command
line.
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* cf/compile_warning_as_error:
Add option -Werror in erlc(1)
compile: add flag warnings_as_errors to treat warnings as errors
compile.erl: remove trailing whitespace
OTP-8382 The -Werror option for erlc and the compiler option
warnings_as_errors will cause warnings to be treated as errors.
(Thanks to Christopher Faulet.)
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With this flag, warnings are treated as errors, like gcc flag '-Werror'.
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* bg/compiler-beam_validator:
beam_validator: fix incorrect assumptions about GC guard BIFs
OTP-8378 In rare circumstances when using garbaging collecting guard BIFs,
the validation pass (beam_validator) would signal that the code
was unsafe, when it in fact was correct. (Thanks to Kiran
Khaladkar.)
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The beam_validator pass incorrectly assumes that a GC guard
BIF (such as length/1) may first do a garbage collection
and then fail. That assumption is not correct (guards BIF
only do garbage collection when it is known that the BIF
call will succeed), and will cause the compiler to reject
valid programs.
Modify the beam_validator to assume that if the branch is
taken for a gc_bif instruction, all registers are unchanged
and no garbage collection has occurred. Also add a comment
in the emulator about that assumption.
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* bg/compiler-bopt-bug:
beam_bool: Fix generation of code that does not validate
Fix crash in beam_bool
OTP-8338 Using complex boolean expressions in ifs could cause the compiler
to either crash or teminate with an internal error. (Thanks to
Simon Cornish.)
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The following code (by Simon Cornish)
bad(XDo1, XDo2, Do3) ->
Do1 = (XDo1 =/= []),
Do2 = (XDo2 =/= []),
CH1 = if Do1 == true;
Do1 == false,Do2==false,Do3 == blah ->
ch1;
true ->
no
end,
CH2 = if Do1 == true;
Do1 == false,Do2==false,Do3 == xx ->
ch2;
true ->
no
end,
{CH1,CH2}.
is optimized by beam_bool even though the optimization is not
safe. The trouble is that an assignment to {y,0} no longer
occurs on all paths leading to its use.
The bug is in dst_regs/2 which is supposed to return a set
of all registers assigned in a code block, but it ignores
registers assigned in 'move' instructions.
Fix the bug by taking 'move' instructions into account. This change
is safe since it can only cause more registers to be added
to the MustBeKilled and MustBeUnused sets in ensure_opt_safe/6,
which means that it can only cause the optimization to be turned
off for code that used to be optimized.
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The following code crashes beam_bool:
bad(XDo1, XDo2, Do3) ->
Do1 = (XDo1 =/= []),
Do2 = (XDo2 =/= []),
if Do1 =:= true;
Do1 =:= false, Do2 =:= false, Do3 =:= delete ->
no
end.
(Reported by Simon Cornish; minimized by Kostis Sagonas.)
For the moment fix the bug in the simplest and safest way possible
(basically, instead of crashing just don't do the optimization).
In a future major release (e.g. R14), the following improvements
could be considered:
* In beam_bool, it should be possible to move the Do1 and Do2
expressions to the pre-block and still optimize the expression
in the 'if' statement.
* In sys_core_fold, it should be possible to eliminate the
try/catch around the guard expression in the 'if', because
none of the guard tests can actually fail.
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The original intention for the undocumented 'slim' option was
to omit non-essential parts of *.beam files to reduce the
size of the primary bootstrap. Therefore, debug information and
local function information (only used by xref, not by the loader)
are omitted, but information about the compilation time and
compiler version are still included.
Including compilation information is troublesome, however, when
committing the bootstrap into a revision control system, because
every beam file is guaranteed to be changed every time the bootstrap
is updated.
Therefore, change the 'slim' option to also omit compilation
information.
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