| Age | Commit message (Collapse) | Author |
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All other instructions that increment the stack pointer takes a 'Q'
operand.
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Add the CHECK_ALIGNED() macro that can be used for testing that
the storage destination is word-aligned.
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In the 'P' operator, don't assume that a packed target label ('f'
or 'j') is always the leftmost argument. Instead, transfer the
patch position from the accumulator to the stack.
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process_main() is already too big.
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Introduce the IsOpCode() macro that can be used to compare
instructions.
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Consider the types in the code below:
BeamInstr* I;
.
.
.
BeamInstr* next;
next = (BeamInstr *) *I;
Goto(next);
This is illogical. If 'I' points to a BeamInstr, then 'next' should
be a BeamInstr, not a pointer to a BeamInstr. The Goto() macros does
not require a pointer, because it will cast its argument to a void*
anyway.
Therefore, this code example can be simplified to:
BeamInstr* I;
.
.
.
BeamInstr next;
next = *I;
Goto(next);
Similarly, we can remove the casts in the macros when NO_JUMP_TABLE
is defined.
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The BeamOp() macro in erl_vm.h is clumsy to use. All users
cast the return value to BeamInstr.
Define new macros that are easier to use. In the future,
we might want to pack an operand into the same word as
the pointer to the instruction, so we will define two macros.
BeamIsOpCode() is used to rewrite code like this:
if (Instr == (BeamInstr) BeamOp(op_i_func_info_IaaI) {
...
}
to:
if (BeamIsOpCode(Instr, op_i_func_info_IaaI)) {
...
}
BeamOpCodeAddr(op_apply_bif) is used when we need the address
for an instruction.
Also elimiminate the global variables em_* in beam_emu.c.
They are not really needed. Use the BeamOpCodeAddr() macro
instead.
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The inconsistent order has annoyed me for a long time.
While at it, also remove the unecessary definition of LabelAddr() if
NO_JUMP_TABLE is defined.
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Test more instructions and use register numbers >= 512.
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For a long time, there has been the two macros IS_SSMALL() and
MY_IS_SSMALL() that do exactly the same thing.
There should only be one, and it should be called IS_SSMALL().
However, we must decide which implementation to use. When
MY_IS_SSMALL() was introduced a long time ago, it was the most
efficient. In a modern C compiler, there might not be any
difference.
To find out, I used the following small C program to examine
the code generation:
#include <stdio.h>
typedef unsigned int Uint32;
typedef unsigned long Uint64;
typedef long Sint;
#define SWORD_CONSTANT(Const) Const##L
#define SMALL_BITS (64-4)
#define MAX_SMALL ((SWORD_CONSTANT(1) << (SMALL_BITS-1))-1)
#define MIN_SMALL (-(SWORD_CONSTANT(1) << (SMALL_BITS-1)))
#define MY_IS_SSMALL32(x) (((Uint32) ((((x)) >> (SMALL_BITS-1)) + 1)) < 2)
#define MY_IS_SSMALL64(x) (((Uint64) ((((x)) >> (SMALL_BITS-1)) + 1)) < 2)
#define MY_IS_SSMALL(x) (sizeof(x) == sizeof(Uint32) ? MY_IS_SSMALL32(x) : MY_IS_SSMALL64(x))
#define IS_SSMALL(x) (((x) >= MIN_SMALL) && ((x) <= MAX_SMALL))
void original(Sint n)
{
if (IS_SSMALL(n)) {
printf("yes\n");
}
}
void enhanced(Sint n)
{
if (MY_IS_SSMALL(n)) {
printf("yes\n");
}
}
gcc 7.2 produced the following code for the original() function:
.LC0:
.string "yes"
original(long):
movabs rax, 576460752303423488
add rdi, rax
movabs rax, 1152921504606846975
cmp rdi, rax
jbe .L4
rep ret
.L4:
mov edi, OFFSET FLAT:.LC0
jmp puts
clang 5.0.0 produced the following code which is slightly better:
original(long):
movabs rax, 576460752303423488
add rax, rdi
shr rax, 60
jne .LBB0_1
mov edi, .Lstr
jmp puts # TAILCALL
.LBB0_1:
ret
.Lstr:
.asciz "yes"
However, in the context of beam_emu.c, clang could produce
similar to what gcc produced.
gcc 7.2 produced the following code when MY_IS_SSMALL() was used:
.LC0:
.string "yes"
enhanced(long):
sar rdi, 59
add rdi, 1
cmp rdi, 1
jbe .L4
rep ret
.L4:
mov edi, OFFSET FLAT:.LC0
jmp puts
clang produced similar code.
This code seems to be the cheapest. There are four instructions, and
there is no loading of huge integer constants.
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* lukas/erts/fix_threads_error_printout:
erts: Print the error reason when threads fail to start
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* kvakvs/zero-size-read_file/ERL-327/PR-1524/OTP-14637:
erts: On zero-size files attempt to read until EOF
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fix off by one error in docs
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* bjorn/speed-up-disassembler:
Add testing of erts_debug:df() to the emulator smoke tests
Speed up erts_debug:df()
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The byte_offset of sub-binaries wasn't taken into account for
ProcBins, subtly ruining the results. The test suite didn't catch
it since it didn't check for sub-binaries in particular, and only
checked for equality between variations -- not whether the output
was equal to the input.
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It is too easy to break the disassembler. Make sure that we notice.
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* siri/string-new-api: (28 commits)
hipe (test): Do not use deprecated functions in string(3)
dialyzer (test): Do not use deprecated functions in string(3)
eunit (test): Do not use deprecated functions in string(3)
system (test): Do not use deprecated functions in string(3)
system (test): Do not use deprecated functions in string(3)
mnesia (test): Do not use deprecated functions in string(3)
Deprecate old string functions
observer: Do not use deprecated functions in string(3)
common_test: Do not use deprecated functions in string(3)
eldap: Do not use deprecated functions in string(3)
et: Do not use deprecated functions in string(3)
os_mon: Do not use deprecated functions in string(3)
debugger: Do not use deprecated functions in string(3)
runtime_tools: Do not use deprecated functions in string(3)
asn1: Do not use deprecated functions in string(3)
compiler: Do not use deprecated functions in string(3)
sasl: Do not use deprecated functions in string(3)
reltool: Do not use deprecated functions in string(3)
kernel: Do not use deprecated functions in string(3)
hipe: Do not use deprecated functions in string(3)
...
Conflicts:
lib/eunit/src/eunit_lib.erl
lib/observer/src/crashdump_viewer.erl
lib/reltool/src/reltool_target.erl
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* sverker/on_load-on_load-bug/OTP-14612:
erts: Fix 'on_load' tracing bug for modules with -on_load
code_SUITE:on_load_trace_on_load
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* bjorn/erts/pack-combined:
Pack combined instructions
beam_makeops: Refactor code generation
Correct disassembly of select instructions
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* maint:
Document that the compiler may optimize away atoms
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Document that the compiler may optimize away atoms
OTP-14614
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* lukas/erts/remove-dirty-scheduler-defines/OTP-14613:
erts: Remove possibility to disable dirty schedulers
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* maint:
Updated OTP version
Update release notes
Update version numbers
inets: httpd correct server_name environment value
inets: httpd - Add chunk handling of client data
inets: Restore old behavior when parsing "+"
inets: prepare for release
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* maint-20:
Updated OTP version
Update release notes
Update version numbers
inets: httpd correct server_name environment value
inets: httpd - Add chunk handling of client data
inets: Restore old behavior when parsing "+"
inets: prepare for release
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The refactoring will simplify packing of combined instructions.
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Make sure to use the 'unpacked[-1]' when accessing the unpacked
arguments.
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* bjorn/erts/relative-jumps:
Pack failure labels in i_select_val2 and i_select_tuple_arity2
Optimize i_select_tuple_arity2 and is_select_lins
Rewrite select_val_bins so that its labels can be packed
Pack sequences of trailing 'f' operands
Implement packing of 'f' and 'j'
Make sure that mask literals are 64 bits
Use relative failure labels
Add information about offset to common group start position
Remove JUMP_OFFSET
Refactor instructions to support relative jumps
Introduce a new trace_jump/1 instruction for tracing
Avoid using $Src more than once
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Don't save a pointer to the default failure label. That could
relieve register pressure. Instead, if we'll need to signal an
error in i_select_tuple_arity2, delay to the execution phase.
That should be a clear win because i_select_tuple_arity2 very
rarely fails because of the term being selected is not a tuple.
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Pack sequences of trailing 'f' operands for instructions
such at jump_on_val or i_select_val_lins.
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Use the "ull" suffix for the mask literals instead of "ul"
to ensure that the literals are 64 bits also on Windows.
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Relative failure in itself is not an optimization, but we plan to
pack failure labels in the future to save memory.
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It has served its purpose.
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The following code could fail in the call to list_existing_atom/1:
String = atom_to_list(some_atom),
Atom = list_to_existing_atom(String)
because the compiler will rewrite the code to:
String = "some_atom",
Atom = list_to_existing_atom(String)
If some_atom is not used in another place, it will not exist.
The compiler could be updated to preserve the atom in this simple case,
but it would be hard to make sure that the compiler never loses atoms
that exist in the source text. It also difficult to imagine a
real world use case where this would be a problem. If an atom is
mentioned only in a way that the compiler can optimize away, is there
really any need to create the atom at all in list_to_existing_atom/1?
Therefore, it is better to place the responsibility that the atom exists
on the user of list_to_existing_atom/1. Update the documentation to
mention that the compiler may optimize away atoms.
https://bugs.erlang.org/browse/ERL-453
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* maint:
stdlib: Fix jumping to beginning or end of line
Fix del_chars not considering wide chars and update buffer length before calling write_buf
Make cp_pos_to_col function aware of the ANSI escape codes
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