Commit Graph

42 Commits

Author SHA1 Message Date
Damien George
7d5f697c38 py/emitglue: Add explicit cast of proto_fun to uint8_t pointer.
Otherwise C++ compilers may complain when this header is included in an
extern "C" block.

Signed-off-by: Damien George <damien@micropython.org>
2024-03-04 10:27:07 +11:00
Damien George
9e5b6972c7 py/emitglue: Make mp_emit_glue_assign_native's fun_data arg a const ptr.
It will only ever be read from, and in some cases (eg on esp8266) can
actually be in ROM.

Signed-off-by: Damien George <damien@micropython.org>
2024-02-22 11:27:33 +11:00
Damien George
def6ad4742 py/emitglue: Include fun_data_len in mp_raw_code_t only when saving.
Reduces the size of mp_raw_code_t in the case when MICROPY_DEBUG_PRINTERS
is enabled.

Signed-off-by: Damien George <damien@micropython.org>
2024-02-16 14:17:01 +11:00
Damien George
e2ff00e811 py/emitglue: Introduce mp_proto_fun_t as a more general mp_raw_code_t.
Allows bytecode itself to be used instead of an mp_raw_code_t in the simple
and common cases of a bytecode function without any children.

This can be used to further reduce frozen code size, and has the potential
to optimise other areas like importing.

Signed-off-by: Damien George <damien@micropython.org>
2024-02-16 14:17:01 +11:00
Damien George
5e3006f117 py/emitglue: Simplify mp_raw_code_t's kind and scope_flags members.
To simplify their access and reduce code size.

The `scope_flags` member is only ever used to determine if a function is a
generator or not, so make it reflect that fact as a bool type.

Signed-off-by: Damien George <damien@micropython.org>
2024-02-16 12:48:02 +11:00
Damien George
416465d81e py/emitglue: Provide a truncated mp_raw_code_t for non-asm code.
The `asm_n_pos_args` and `asm_type_sig` members of `mp_raw_code_t` are only
used for raw codes of type MP_CODE_NATIVE_ASM, which are rare, for example
in frozen code.  So using a truncated `mp_raw_code_t` in these cases helps
to reduce frozen code size on targets that have MICROPY_EMIT_INLINE_ASM
enabled.

With this, change in firmware size of RPI_PICO builds is -648.

Signed-off-by: Damien George <damien@micropython.org>
2024-02-16 12:48:02 +11:00
Damien George
39bf055d23 py/emitglue: Reorder and resize members of mp_raw_code_t.
The mp_raw_code_t struct has been reordered and some members resized.  The
`n_pos_args` member is renamed to `asm_n_pos_args`, and `type_sig` renamed
to `asm_type_sig` to indicate that these are used only for the inline-asm
emitters.  These two members are also grouped together in the struct.

The justifications for resizing the members are:
- `fun_data_len` can be 32-bits without issue
- `n_children` is already limited to 16-bits by
  `mp_emit_common_t::ct_cur_child`
- `scope_flags` is already limited to 16-bits by `scope_t::scope_flags`
- `prelude_offset` is already limited to 16-bits by the argument to
  `mp_emit_glue_assign_native()`
- it's reasonable to limit the maximim number of inline-asm arguments to 12
  (24 bits for `asm_type_sig` divided by 2)

This change helps to reduce frozen code size (and in some cases RAM usage)
in the following cases:
- 64-bit targets
- builds with MICROPY_PY_SYS_SETTRACE enabled
- builds with MICROPY_EMIT_MACHINE_CODE enabled but MICROPY_EMIT_INLINE_ASM
  disabled

With this change, unix 64-bit builds are -4080 bytes in size.  Bare-metal
ports like rp2 are unchanged (because mp_raw_code_t is still 32 bytes on
those 32-bit targets).

Signed-off-by: Damien George <damien@micropython.org>
2024-02-16 12:48:02 +11:00
Damien George
d4d53e9e11 py/emitnative: Access qstr values using indirection table qstr_table.
This changes the native emitter to access qstr values using the qstr
indirection table qstr_table, but only when generating native code that
will be saved to a .mpy file.  This makes the resulting native code fully
static, ie it does not require any fix-ups or rewriting when it is
imported.

The performance of native code is more or less unchanged.  Benchmark
results on PYBv1.0 (using --via-mpy and --emit native) are:

N=100 M=100          baseline -> this-commit     diff      diff% (error%)
bm_chaos.py            407.16 ->     411.85 :   +4.69 =  +1.152% (+/-0.01%)
bm_fannkuch.py         100.89 ->     101.20 :   +0.31 =  +0.307% (+/-0.01%)
bm_fft.py             3521.17 ->    3441.72 :  -79.45 =  -2.256% (+/-0.00%)
bm_float.py           6707.29 ->    6644.83 :  -62.46 =  -0.931% (+/-0.00%)
bm_hexiom.py            55.91 ->      55.41 :   -0.50 =  -0.894% (+/-0.00%)
bm_nqueens.py         5343.54 ->    5326.17 :  -17.37 =  -0.325% (+/-0.00%)
bm_pidigits.py         603.89 ->     632.79 :  +28.90 =  +4.786% (+/-0.33%)
core_qstr.py            64.18 ->      64.09 :   -0.09 =  -0.140% (+/-0.01%)
core_yield_from.py     313.61 ->     311.11 :   -2.50 =  -0.797% (+/-0.03%)
misc_aes.py            654.29 ->     659.75 :   +5.46 =  +0.834% (+/-0.02%)
misc_mandel.py        4205.10 ->    4272.08 :  +66.98 =  +1.593% (+/-0.01%)
misc_pystone.py       3077.79 ->    3128.39 :  +50.60 =  +1.644% (+/-0.01%)
misc_raytrace.py       388.45 ->     393.71 :   +5.26 =  +1.354% (+/-0.01%)
viper_call0.py         576.83 ->     566.76 :  -10.07 =  -1.746% (+/-0.05%)
viper_call1a.py        550.39 ->     540.12 :  -10.27 =  -1.866% (+/-0.11%)
viper_call1b.py        438.32 ->     432.09 :   -6.23 =  -1.421% (+/-0.11%)
viper_call1c.py        442.96 ->     436.11 :   -6.85 =  -1.546% (+/-0.08%)
viper_call2a.py        536.31 ->     527.37 :   -8.94 =  -1.667% (+/-0.04%)
viper_call2b.py        378.99 ->     377.50 :   -1.49 =  -0.393% (+/-0.08%)

Signed-off-by: Damien George <damien@micropython.org>
2022-05-23 15:43:06 +10:00
Damien George
f2040bfc7e py: Rework bytecode and .mpy file format to be mostly static data.
Background: .mpy files are precompiled .py files, built using mpy-cross,
that contain compiled bytecode functions (and can also contain machine
code). The benefit of using an .mpy file over a .py file is that they are
faster to import and take less memory when importing.  They are also
smaller on disk.

But the real benefit of .mpy files comes when they are frozen into the
firmware.  This is done by loading the .mpy file during compilation of the
firmware and turning it into a set of big C data structures (the job of
mpy-tool.py), which are then compiled and downloaded into the ROM of a
device.  These C data structures can be executed in-place, ie directly from
ROM.  This makes importing even faster because there is very little to do,
and also means such frozen modules take up much less RAM (because their
bytecode stays in ROM).

The downside of frozen code is that it requires recompiling and reflashing
the entire firmware.  This can be a big barrier to entry, slows down
development time, and makes it harder to do OTA updates of frozen code
(because the whole firmware must be updated).

This commit attempts to solve this problem by providing a solution that
sits between loading .mpy files into RAM and freezing them into the
firmware.  The .mpy file format has been reworked so that it consists of
data and bytecode which is mostly static and ready to run in-place.  If
these new .mpy files are located in flash/ROM which is memory addressable,
the .mpy file can be executed (mostly) in-place.

With this approach there is still a small amount of unpacking and linking
of the .mpy file that needs to be done when it's imported, but it's still
much better than loading an .mpy from disk into RAM (although not as good
as freezing .mpy files into the firmware).

The main trick to make static .mpy files is to adjust the bytecode so any
qstrs that it references now go through a lookup table to convert from
local qstr number in the module to global qstr number in the firmware.
That means the bytecode does not need linking/rewriting of qstrs when it's
loaded.  Instead only a small qstr table needs to be built (and put in RAM)
at import time.  This means the bytecode itself is static/constant and can
be used directly if it's in addressable memory.  Also the qstr string data
in the .mpy file, and some constant object data, can be used directly.
Note that the qstr table is global to the module (ie not per function).

In more detail, in the VM what used to be (schematically):

    qst = DECODE_QSTR_VALUE;

is now (schematically):

    idx = DECODE_QSTR_INDEX;
    qst = qstr_table[idx];

That allows the bytecode to be fixed at compile time and not need
relinking/rewriting of the qstr values.  Only qstr_table needs to be linked
when the .mpy is loaded.

Incidentally, this helps to reduce the size of bytecode because what used
to be 2-byte qstr values in the bytecode are now (mostly) 1-byte indices.
If the module uses the same qstr more than two times then the bytecode is
smaller than before.

The following changes are measured for this commit compared to the
previous (the baseline):
- average 7%-9% reduction in size of .mpy files
- frozen code size is reduced by about 5%-7%
- importing .py files uses about 5% less RAM in total
- importing .mpy files uses about 4% less RAM in total
- importing .py and .mpy files takes about the same time as before

The qstr indirection in the bytecode has only a small impact on VM
performance.  For stm32 on PYBv1.0 the performance change of this commit
is:

diff of scores (higher is better)
N=100 M=100             baseline -> this-commit  diff      diff% (error%)
bm_chaos.py               371.07 ->  357.39 :  -13.68 =  -3.687% (+/-0.02%)
bm_fannkuch.py             78.72 ->   77.49 :   -1.23 =  -1.563% (+/-0.01%)
bm_fft.py                2591.73 -> 2539.28 :  -52.45 =  -2.024% (+/-0.00%)
bm_float.py              6034.93 -> 5908.30 : -126.63 =  -2.098% (+/-0.01%)
bm_hexiom.py               48.96 ->   47.93 :   -1.03 =  -2.104% (+/-0.00%)
bm_nqueens.py            4510.63 -> 4459.94 :  -50.69 =  -1.124% (+/-0.00%)
bm_pidigits.py            650.28 ->  644.96 :   -5.32 =  -0.818% (+/-0.23%)
core_import_mpy_multi.py  564.77 ->  581.49 :  +16.72 =  +2.960% (+/-0.01%)
core_import_mpy_single.py  68.67 ->   67.16 :   -1.51 =  -2.199% (+/-0.01%)
core_qstr.py               64.16 ->   64.12 :   -0.04 =  -0.062% (+/-0.00%)
core_yield_from.py        362.58 ->  354.50 :   -8.08 =  -2.228% (+/-0.00%)
misc_aes.py               429.69 ->  405.59 :  -24.10 =  -5.609% (+/-0.01%)
misc_mandel.py           3485.13 -> 3416.51 :  -68.62 =  -1.969% (+/-0.00%)
misc_pystone.py          2496.53 -> 2405.56 :  -90.97 =  -3.644% (+/-0.01%)
misc_raytrace.py          381.47 ->  374.01 :   -7.46 =  -1.956% (+/-0.01%)
viper_call0.py            576.73 ->  572.49 :   -4.24 =  -0.735% (+/-0.04%)
viper_call1a.py           550.37 ->  546.21 :   -4.16 =  -0.756% (+/-0.09%)
viper_call1b.py           438.23 ->  435.68 :   -2.55 =  -0.582% (+/-0.06%)
viper_call1c.py           442.84 ->  440.04 :   -2.80 =  -0.632% (+/-0.08%)
viper_call2a.py           536.31 ->  532.35 :   -3.96 =  -0.738% (+/-0.06%)
viper_call2b.py           382.34 ->  377.07 :   -5.27 =  -1.378% (+/-0.03%)

And for unix on x64:

diff of scores (higher is better)
N=2000 M=2000        baseline -> this-commit     diff      diff% (error%)
bm_chaos.py          13594.20 ->  13073.84 :  -520.36 =  -3.828% (+/-5.44%)
bm_fannkuch.py          60.63 ->     59.58 :    -1.05 =  -1.732% (+/-3.01%)
bm_fft.py           112009.15 -> 111603.32 :  -405.83 =  -0.362% (+/-4.03%)
bm_float.py         246202.55 -> 247923.81 : +1721.26 =  +0.699% (+/-2.79%)
bm_hexiom.py           615.65 ->    617.21 :    +1.56 =  +0.253% (+/-1.64%)
bm_nqueens.py       215807.95 -> 215600.96 :  -206.99 =  -0.096% (+/-3.52%)
bm_pidigits.py        8246.74 ->   8422.82 :  +176.08 =  +2.135% (+/-3.64%)
misc_aes.py          16133.00 ->  16452.74 :  +319.74 =  +1.982% (+/-1.50%)
misc_mandel.py      128146.69 -> 130796.43 : +2649.74 =  +2.068% (+/-3.18%)
misc_pystone.py      83811.49 ->  83124.85 :  -686.64 =  -0.819% (+/-1.03%)
misc_raytrace.py     21688.02 ->  21385.10 :  -302.92 =  -1.397% (+/-3.20%)

The code size change is (firmware with a lot of frozen code benefits the
most):

       bare-arm:  +396 +0.697%
    minimal x86: +1595 +0.979% [incl +32(data)]
       unix x64: +2408 +0.470% [incl +800(data)]
    unix nanbox: +1396 +0.309% [incl -96(data)]
          stm32: -1256 -0.318% PYBV10
         cc3200:  +288 +0.157%
        esp8266:  -260 -0.037% GENERIC
          esp32:  -216 -0.014% GENERIC[incl -1072(data)]
            nrf:  +116 +0.067% pca10040
            rp2:  -664 -0.135% PICO
           samd:  +844 +0.607% ADAFRUIT_ITSYBITSY_M4_EXPRESS

As part of this change the .mpy file format version is bumped to version 6.
And mpy-tool.py has been improved to provide a good visualisation of the
contents of .mpy files.

In summary: this commit changes the bytecode to use qstr indirection, and
reworks the .mpy file format to be simpler and allow .mpy files to be
executed in-place.  Performance is not impacted too much.  Eventually it
will be possible to store such .mpy files in a linear, read-only, memory-
mappable filesystem so they can be executed from flash/ROM.  This will
essentially be able to replace frozen code for most applications.

Signed-off-by: Damien George <damien@micropython.org>
2022-02-24 18:08:43 +11:00
Milan Rossa
310b3d1b81 py: Integrate sys.settrace feature into the VM and runtime.
This commit adds support for sys.settrace, allowing to install Python
handlers to trace execution of Python code.  The interface follows CPython
as closely as possible.  The feature is disabled by default and can be
enabled via MICROPY_PY_SYS_SETTRACE.
2019-08-30 16:44:12 +10:00
Jun Wu
b152bbddd1 py: Define EMIT_MACHINE_CODE as EMIT_NATIVE || EMIT_INLINE_ASM.
The combination MICROPY_EMIT_NATIVE || MICROPY_EMIT_INLINE_ASM is used in
many places, so define a new macro for it.
2019-06-28 13:54:45 +10:00
Damien George
1396a026be py: Add support to save native, viper and asm code to .mpy files.
This commit adds support for saving and loading .mpy files that contain
native code (native, viper and inline-asm).  A lot of the ground work was
already done for this in the form of removing pointers from generated
native code.  The changes here are mainly to link in qstr values to the
native code, and change the format of .mpy files to contain native code
blocks (possibly mixed with bytecode).

A top-level summary:

- @micropython.native, @micropython.viper and @micropython.asm_thumb/
  asm_xtensa are now allowed in .py files when compiling to .mpy, and they
  work transparently to the user.

- Entire .py files can be compiled to native via mpy-cross -X emit=native
  and for the most part the generated .mpy files should work the same as
  their bytecode version.

- The .mpy file format is changed to 1) specify in the header if the file
  contains native code and if so the architecture (eg x86, ARMV7M, Xtensa);
  2) for each function block the kind of code is specified (bytecode,
  native, viper, asm).

- When native code is loaded from a .mpy file the native code must be
  modified (in place) to link qstr values in, just like bytecode (see
  py/persistentcode.c:arch_link_qstr() function).

In addition, this now defines a public, native ABI for dynamically loadable
native code generated by other languages, like C.
2019-03-08 15:53:05 +11:00
Damien George
636ed0ff8d py/emitglue: Remove union in mp_raw_code_t to combine bytecode & native. 2019-03-08 15:53:04 +11:00
Damien George
3751512e9d py/emit: Move MP_EMIT_OPT_xxx enums from compile.h to emitglue.h. 2018-09-15 12:17:09 +10:00
Damien George
5604b710c2 py/emitglue: When assigning bytecode only pass bytecode len if needed.
Most embedded targets will have this bit of the code disabled, saving a
small amount of code space.
2018-02-14 18:41:17 +11:00
Damien George
cf8e8c29e7 py/emitglue: Change type of bit-field to explicitly unsigned mp_uint_t.
Some compilers can treat enum types as signed, in which case 3 bits is not
enough to encode all mp_raw_code_kind_t values.  So change the type to
mp_uint_t.
2017-12-15 10:21:10 +11:00
Alexander Steffen
55f33240f3 all: Use the name MicroPython consistently in comments
There were several different spellings of MicroPython present in comments,
when there should be only one.
2017-07-31 18:35:40 +10:00
Alexander Steffen
299bc62586 all: Unify header guard usage.
The code conventions suggest using header guards, but do not define how
those should look like and instead point to existing files. However, not
all existing files follow the same scheme, sometimes omitting header guards
altogether, sometimes using non-standard names, making it easy to
accidentally pick a "wrong" example.

This commit ensures that all header files of the MicroPython project (that
were not simply copied from somewhere else) follow the same pattern, that
was already present in the majority of files, especially in the py folder.

The rules are as follows.

Naming convention:
* start with the words MICROPY_INCLUDED
* contain the full path to the file
* replace special characters with _

In addition, there are no empty lines before #ifndef, between #ifndef and
one empty line before #endif. #endif is followed by a comment containing
the name of the guard macro.

py/grammar.h cannot use header guards by design, since it has to be
included multiple times in a single C file. Several other files also do not
need header guards as they are only used internally and guaranteed to be
included only once:
* MICROPY_MPHALPORT_H
* mpconfigboard.h
* mpconfigport.h
* mpthreadport.h
* pin_defs_*.h
* qstrdefs*.h
2017-07-18 11:57:39 +10:00
Damien George
6810f2c134 py: Factor persistent code load/save funcs into persistentcode.[ch]. 2016-11-16 16:14:14 +11:00
Damien George
ed0c11236f py/emitglue: Make mp_raw_code_t* arguments constant pointers. 2016-04-13 16:05:43 +01:00
Damien George
6d24dc23b8 py/emitglue: Move typedef of mp_raw_code_t from .c to .h file.
It's needed by frozen bytecode.
2016-04-13 16:05:43 +01:00
Damien George
b5b1f2c527 py/emitglue: Add mp_raw_code_load_mem to load raw-code from memory. 2015-11-20 12:44:20 +00:00
Damien George
d8c834c95d py: Add MICROPY_PERSISTENT_CODE_LOAD/SAVE to load/save bytecode.
MICROPY_PERSISTENT_CODE must be enabled, and then enabling
MICROPY_PERSISTENT_CODE_LOAD/SAVE (either or both) will allow loading
and/or saving of code (at the moment just bytecode) from/to a .mpy file.
2015-11-13 12:49:18 +00:00
Damien George
713ea1800d py: Add constant table to bytecode.
Contains just argument names at the moment but makes it easy to add
arbitrary constants.
2015-11-13 12:49:18 +00:00
Damien George
3a3db4dcf0 py: Put all bytecode state (arg count, etc) in bytecode. 2015-11-13 12:49:18 +00:00
Damien George
9988618e0e py: Implement full func arg passing for native emitter.
This patch gets full function argument passing working with native
emitter.  Includes named args, keyword args, default args, var args
and var keyword args.  Fully Python compliant.

It reuses the bytecode mp_setup_code_state function to do all the hard
work.  This function is slightly adjusted to accommodate native calls,
and the native emitter is forced a bit to emit similar prelude and
code-info as bytecode.
2015-04-07 22:43:28 +01:00
Damien George
32444b759a py: Don't use anonymous unions, name them instead.
This makes the code (more) compatible with the C99 standard.
2015-01-24 23:14:12 +00:00
Damien George
51dfcb4bb7 py: Move to guarded includes, everywhere in py/ core.
Addresses issue #1022.
2015-01-01 20:32:09 +00:00
Paul Sokolovsky
8ab6f90674 py: Move to guarded includes for compile.h and related headers. 2014-12-27 16:12:17 +02:00
Damien George
1084b0f9c2 py: Store bytecode arg names in bytecode (were in own array).
This saves a lot of RAM for 2 reasons:

1. For functions that don't have default values, var args or var kw
args (which is a large number of functions in the general case), the
mp_obj_fun_bc_t type now fits in 1 GC block (previously needed 2 because
of the extra pointer to point to the arg_names array).  So this saves 16
bytes per function (32 bytes on 64-bit machines).

2. Combining separate memory regions generally saves RAM because the
unused bytes at the end of the GC block are saved for 1 of the blocks
(since that block doesn't exist on its own anymore).  So generally this
saves 8 bytes per function.

Tested by importing lots of modules:

- 64-bit Linux gave about an 8% RAM saving for 86k of used RAM.
- pyboard gave about a 6% RAM saving for 31k of used RAM.
2014-10-25 20:23:13 +01:00
Damien George
564963a170 py: Fix debug-printing of bytecode line numbers.
Also move the raw bytecode printing code from emitglue to mp_bytecode_print.
2014-10-24 14:42:50 +00:00
Damien George
3c658a4e75 py: Fix bug where GC collected native/viper/asm function data.
Because (for Thumb) a function pointer has the LSB set, pointers to
dynamic functions in RAM (eg native, viper or asm functions) were not
being traced by the GC.  This patch is a comprehensive fix for this.

Addresses issue #820.
2014-08-24 16:28:17 +01:00
Damien George
2ac4af6946 py: Allow viper to have type annotations.
Viper functions can now be annotated with the type of their arguments
and return value.  Eg:

@micropython.viper
def f(x:int) -> int:
    return x + 1
2014-08-15 16:45:41 +01:00
Damien George
915197a8f9 py: Remove emit_glue init and deinit. Needed only for debugging.
Debugging output for emit_glue now simplified so that the init and
deinit functions are no longer needed.
2014-05-12 23:11:14 +01:00
Damien George
ccc85ea0da py: Combine native emitters to 1 glue function; distinguish viper.
This patch simplifies the glue between native emitter and runtime,
and handles viper code like inline assember: return values are
converted to Python objects.

Fixes issue #531.
2014-05-10 13:40:46 +01:00
Damien George
3417bc2f25 py: Rename byte_code to bytecode everywhere.
bytecode is the more widely used.  See issue #590.
2014-05-10 10:36:38 +01:00
Damien George
04b9147e15 Add license header to (almost) all files.
Blanket wide to all .c and .h files.  Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.

Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.
2014-05-03 23:27:38 +01:00
Damien George
2827d62e8b py: Implement keyword-only args.
Implements 'def f(*, a)' and 'def f(*a, b)', but not default
keyword-only args, eg 'def f(*, a=1)'.

Partially addresses issue #524.
2014-04-27 15:50:52 +01:00
Damien George
3558f62fb5 py: Making closures now passes pointer to stack, not a tuple for vars.
Closed over variables are now passed on the stack, instead of creating a
tuple and passing that.  This way memory for the closed over variables
can be allocated within the closure object itself.  See issue #510 for
background.
2014-04-20 17:50:40 +01:00
Damien George
df8127a17e py: Remove unique_codes from emitglue.c. Replace with pointers.
Attempt to address issue #386.  unique_code_id's have been removed and
replaced with a pointer to the "raw code" information.  This pointer is
stored in the actual byte code (aligned, so the GC can trace it), so
that raw code (ie byte code, native code and inline assembler) is kept
only for as long as it is needed.  In memory it's now like a tree: the
outer module's byte code points directly to its children's raw code.  So
when the outer code gets freed, if there are no remaining functions that
need the raw code, then the children's code gets freed as well.

This is pretty much like CPython does it, except that CPython stores
indexes in the byte code rather than machine pointers.  These indices
index the per-function constant table in order to find the relevant
code.
2014-04-13 11:04:33 +01:00
Damien George
d1e443d0bc py: Free unique_code slot for outer module.
Partly (very partly!) addresses issue #386.  Most importantly, at the
REPL command line, each invocation does not now lead to increased memory
usage (unless you define a function/lambda).
2014-03-29 11:39:36 +00:00
Damien George
2326d52d20 py: Factor out code from runtime.c to emitglue.c. 2014-03-27 23:26:35 +00:00