| Age | Commit message (Collapse) | Author |
|---|
|
v3_codegen is replaced by three new passes:
* beam_kernel_to_ssa which translates the Kernel Erlang format
to a new SSA-based intermediate format.
* beam_ssa_pre_codegen which prepares the SSA-based format
for code generation, including register allocation. Registers
are allocated using the linear scan algorithm.
* beam_ssa_codegen which generates BEAM assembly code from the
SSA-based format.
It easier and more effective to optimize the SSA-based format before X
and Y registers have been assigned. The current optimization passes
constantly have to make sure no "holes" in the X register assignments
are created (that is, that no X register becomes undefined that an
allocation instruction depends on).
This commit also introduces the following optimizations:
* Replacing of tuple matching of records with the is_tagged_tuple
instruction. (Replacing beam_record.)
* Sinking of get_tuple_element instructions to just before the first
use of the extracted values. As well as potentially avoiding
extracting tuple elements when they are not actually used on all
executions paths, this optimization could also reduce the number
values that will need to be stored in Y registers. (Similar to
beam_reorder, but more effective.)
* Live optimizations, removing the definition of a variable that is
not subsequently used (provided that the operation has no side
effects), as well strength reduction of binary matching by replacing
the extraction of value from a binary with a skip instruction. (Used
to be done by beam_block, beam_utils, and v3_codegen.)
* Removal of redundant bs_restore2 instructions. (Formerly done
by beam_bs.)
* Type-based optimizations across branches. More effective than
the old beam_type pass that only did type-based optimizations in
basic blocks.
* Optimization of floating point instructions. (Formerly done
by beam_type.)
* Optimization of receive statements to introduce recv_mark and
recv_set instructions. More effective with far fewer restrictions
on what instructions are allowed between creating the reference
and entering the receive statement.
* Common subexpression elimination. (Formerly done by beam_block.)
|
|
This optimization can be better done in the SSA format before
code generation.
|
|
The removal of redundant bs_restore2 instructions is done easier
on the SSA format. Keep the rest of the optimizations, because
they are easier to do on the BEAM instructions.
|
|
As a preparation for replacing v3_codegen with a new code generator,
remove unsafe optimization passes. Especially the older compiler
passes have implicit assumptions about how the code is generated.
Remove the optimizations in beam_block (keep the code that creates
blocks) because they are unsafe. beam_block also calls
beam_utils:live_opt/1, which is unsafe.
Remove beam_type because it calls beam_utils:live_opt/1, and also
because it recalculates the number of heaps words and number of live
registers in allocation instructions, thus potentially hiding bugs in
other passes.
Remove beam_receive because it is unsafe.
Remove beam_record because it is the only remaining user
of beam_utils:anno_defs/1.
Remove beam_reorder because it makes much more sense to run it
as an early SSA-based optimization pass.
Remove the now unused functions in beam_utils:
anno_def/1
delete_annos/1
is_killed_block/2
live_opt/1
usage/3
Note that the following test cases will fail because of the
removed optimizations:
compile_SUITE:optimized_guards/1
compile_SUITE:bc_options/1
receive_SUITE:ref_opt/1
|
|
|
|
This will enable more optimizations.
|
|
Don't match exact BEAM instructions when trying to recognize
function_clause exceptions that should be replaced with a jump to the
func_info instruction. Instead, do a symbolic evaluation of the list
building code and see if the result is a list of the argument
registers.
While at it, also teach fix_block_1/2 to completely remove a test_heap
instruction before an exception generation instruction.
|
|
Smarter code generation means that beam_validator must
be smarter too. In the following example, beam_validator
must be able to infer that y0 refers to a map:
move x0 y0
test is_map L1 x0
%% Here the type for y0 must be 'map'.
|
|
|
|
The func_info instruction does not expect a stack frame. There will
be an assertion failure in the debug-compiled runtime system.
|
|
|
|
If we transfer state appropriately to labels that can't be reached,
the state could taint other labels.
|
|
Since the compiler will start optimizing more aggressively, beam_validator
must keep up and improve the recognization of tuples and maps.
|
|
The new code generator will more aggressively reuse registers,
so we must be more careful about updating the state for try/catch.
In particular, an "empty" try/catch that can't throw an
exception must not update the try/catch state.
|
|
|
|
Nicer to read and less confusion.
|
|
* maint:
Fix compiler crash when compiling double receives
erts: Delete fd from poll-set when closing fd_driver port
|
|
remove_message just remove messages without writing to any register.
Compiler is already generating code like:
{get_tuple_element,{x,0},1,{x,0}}.
remove_message.
{jump,{f,6}}
That clearly uses x0 for other purposes.
|
|
The compiler would crash when compiling a function with two
receive statements.
https://bugs.erlang.org/browse/ERL-703
|
|
* maint:
Correct error behavior of is_map_key/2 in guards
|
|
Consider the following functions:
foo() -> bar(not_a_map).
bar(M) when not is_map_key(a, M) -> ok;
bar(_) -> error.
What will `foo/0` return? It depends. If the module is compiled
with the default compiler options, the return value will be
`ok`. If the module is compiled with the `inline` option,
the return value will be `error`.
The correct value is `error`, because the call to `is_map_key/2`
when the second argument is not a map should fail the entire
guard. That is the way other failing guards BIFs are handled.
For example:
foo() -> bar(not_a_tuple).
bar(T) when not element(1, T) -> ok;
bar(_) -> error.
`foo/0` always returns `error` (whether the code is inlined
or not).
This bug can be fixed by changing the classification of `is_map_key/2`
in the `erl_internal` module. It is now classified as a type test,
which is incorrect because type tests should not fail. Reclassifying
it as a plain guard BIF corrects the bug.
This correction also fixes the internal consistency check
failure which was reported in:
https://bugs.erlang.org/browse/ERL-699
|
|
* maint:
Fix bug in binary matching
|
|
bjorng/bjorn/compiler/binary-syntax/ERL-689/OTP-15219
Fix bug in binary matching
|
|
* maint:
Omit include path debug info for +deterministic builds
|
|
'john/compiler/fix-deterministic-include-paths/OTP-15204/ERL-679' into maint
* john/compiler/fix-deterministic-include-paths/OTP-15204/ERL-679:
Omit include path debug info for +deterministic builds
|
|
Compiling the same file with different include paths resulted in
different files with the `+deterministic` flag even if everything
but the paths were identical. This was caused by the absolute path
of each include directory being unconditionally included in a
debug information chunk.
This commit fixes this by only including this information in
non-deterministic builds.
|
|
* maint:
Fix side-effect optimization when compiling from Core Erlang
Conflicts:
lib/compiler/src/sys_core_fold.erl
|
|
bjorng/bjorn/compiler/letrec-side-effect-fix/ERL-658/OTP-15188
Fix side-effect optimization when compiling from Core Erlang
|
|
The compiler generates incorrect code for the following example:
decode_binary(_, <<Length, Data/binary>>) ->
case {Length, Data} of
{0, _} ->
%% When converting the match context back to a binary,
%% Data will be set to the entire original binary,
%% that is, to <<0>> instead of <<>>.
{{0, 0, 0}, Data};
{4, <<Y:16/little, M, D, Rest/binary>>} ->
{{Y, M, D}, Rest}
end.
The problem is the delayed sub binary creation optimization, which
is not safe to do in this case.
This commit introduces a heuristic that will disable the delayed
sub binary creation optimization for this example. Unfortunately, the
heuristic may turn off the optimization when it would actually be
safe. In the OTP codebase, the optimization is turned off in two
instances, once in string.erl and once in dets_v9.erl.
https://bugs.erlang.org/browse/ERL-689
|
|
Rewrite erlang:get_stacktrace calls to primop when safe
|
|
* maint:
Eliminate double computation of next var
beam_validator: Fix false diagnostic for a receive nested in a try
|
|
Eliminate double computation of next var
|
|
When an expression is only used for its side effects, we try to
remove everything that doesn't tie into a side-effect, but we
went a bit too far when we applied the optimization to funs
defined in such a context. Consider the following:
do letrec 'f'/0 = fun () -> ... whatever ...
in call 'side':'effect'(apply 'f'/0())
'ok'
When f/0 is optimized under the assumption that its return value
is unused, side:effect/1 will be fed the result of the last
side-effecting expression in f/0 instead of its actual result.
https://bugs.erlang.org/browse/ERL-658
Co-authored-by: Björn Gustavsson <[email protected]>
|
|
My compiler benchmarks on modules with huge functions, show the
next_free_variable_name call to be expensive. It turns out one
of the 3 calls to the function was completely ignored.
|
|
When nesting a receive in a try/catch, there could be a false
diagnostic that a fragile term is used.
https://bugs.erlang.org/browse/ERL-684
|
|
This allows taking advantage of further optimisations, like the
raw_raise instruction for code that can't upgrade (yet) to the
new stacktrace syntax for compatibility reasons.
The rewrite is only done when it is safe - when the get_stacktrace
call is the very first thing the handler does.
|
|
I did not find any legitimate use of "can not", however skipped
changing e.g RFCs archived in the source tree.
|
|
* maint:
Abort size calculation when a matched-out variable is used
|
|
Referencing a matched-out variable in a size expression makes it
impossible to calculate the size of the result based on the size of
the matched binary. The compiler would still generate code to do
this however, which would crash since the variable isn't defined
at the size calculation.
|
|
* maint:
Updated OTP version
Update release notes
Update version numbers
Eliminate a crash in the beam_jump pass
stdlib: Fix a 'chars_limit' bug
Fix a race condition when generating async operation ids
Fix internal compiler error for map_get/2
beam_type: Fix unsafe optimization
public_key: Remove moduli 5121 and 7167 Thoose were added by 598629aeba9de98e8cdf5637043eb34e5d407751 but are not universaly supported.
|
|
maint-21
* bjorn/compiler/fix-beam_jump-crash/ERL-660/OTP-15166:
Eliminate a crash in the beam_jump pass
|
|
* bjorn/compiler/fix-map_get/OTP-15157:
Fix internal compiler error for map_get/2
|
|
maint-21
* bjorn/compiler/fix-skipped-matching/ERL-655/OTP-15156:
beam_type: Fix unsafe optimization
|
|
https://bugs.erlang.org/browse/ERL-660
|
|
Code such as that the following:
Val = map_get(a, Map),
Map#{a:=z} %Could be any map update
would incorrectly cause an internal consistency check failure:
Internal consistency check failed - please report this bug.
Instruction: {put_map_exact,{f,0},{x,0},{x,0},1,{list,[{atom,a},{atom,z}]}}
Error: {bad_type,{needed,map},{actual,term}}:
Update beam_validator so that it understands that the second
argument for map_get/2 is a map.
|
|
beam_type assumed that the operand for the bs_context_to_binary
instruction must be a binary. That is not correct;
bs_context_to_binary accepts anything. Based on the incorrect
assumption, beam_type would remove other test instructions.
The bug was introduced in eee8655788d2, which was supposed
to be just a refactoring commit.
https://bugs.erlang.org/browse/ERL-655
|
|
Fold is_function/1,2 during compilation
|
|
Optimise beam_jump
|
|
The compiler would crash when compiling code such as:
serialize(#{tag := value, id := Id, domain := Domain}) ->
[case Id of
nil ->
error(id({required, id}));
_ ->
<<10, 1:16/signed, Id:16/signed>>
end,
case Domain of
nil ->
error(id({required, domain}));
_ ->
<<8, 2:16/signed, Domain:32/signed>>
end].
The crash would look like this:
Function: serialize/1
t.erl: internal error in block2;
crash reason: {badmatch,false}
in function beam_utils:live_opt/4 (beam_utils.erl, line 861)
in call from beam_utils:live_opt/1 (beam_utils.erl, line 285)
in call from beam_block:function/2 (beam_block.erl, line 47)
in call from beam_block:'-module/2-lc$^0/1-0-'/2 (beam_block.erl, line 33)
in call from beam_block:'-module/2-lc$^0/1-0-'/2 (beam_block.erl, line 33)
in call from beam_block:module/2 (beam_block.erl, line 33)
in call from compile:block2/2 (compile.erl, line 1358)
in call from compile:'-internal_comp/5-anonymous-1-'/3 (compile.erl, line 349)
The reason for the crash is an assertion failure caused by a previous
unsafe optimization. Here is the code before the unsafe optimization:
.
.
.
{bs_init2,{f,0},7,0,0,{field_flags,[]},{x,1}}.
{bs_put_string,3,{string,[8,0,2]}}.
{bs_put_integer,{f,0},{integer,32},1,{field_flags,[signed,big]},{y,1}}.
{move,{x,1},{x,0}}.
{test_heap,4,1}.
.
.
.
beam_block:move_allocate/1 moved up the test_heap/2 instruction past the
move/2 instruction, adjusting the number of live registers at the same
time:
.
.
.
{bs_init2,{f,0},7,0,0,{field_flags,[]},{x,1}}.
%% Only x1 is live now.
{bs_put_string,3,{string,[8,0,2]}}.
{bs_put_integer,{f,0},{integer,32},1,{field_flags,[signed,big]},{y,1}}.
{test_heap,4,2}. %Unsafe. x0 is dead.
{move,{x,1},{x,0}}.
.
.
.
This optimization is unsafe because the bs_init2 instruction killed
x0.
The bug is in beam_utils:anno_defs/1, which adds annotations indicating
the registers that are defined at the beginning of each block. The
annotation before the move/2 instruction incorrectly indicated that
x0 was live.
https://bugs.erlang.org/browse/ERL-650
https://github.com/elixir-lang/elixir/issues/7782
|
|
|
