So these constant objects can be loaded by dereferencing the REG_FUN_TABLE
pointer instead of loading immediate values. This reduces the size of
generated native code (when such constants are used), and means that
pointers to these constants are no longer stored in the assembly code.
The maximum index into mp_fun_table is currently less than 1024 and should
stay that way to keep things efficient for all architectures, so there is
no need to handle loading the pointer directly via a literal in this
function.
All architectures now have a dedicated register to hold the pointer to the
native function table mp_fun_table, and so they all need to load this
register at the start of the native function. This commit makes the
loading of this register uniform across architectures by passing the
pointer in the constant table for the native function, and then loading the
register from the constant table. Doing it this way means that the pointer
is not stored in the assembly code, helping to make the code more portable.
Instead of storing the function pointer directly in the assembly code.
This makes the generated code more independent of the runtime (so easier to
relocate the code), and reduces the generated code size.
The esp register is always a fixed distance below ebp, and using esp to
reference locals on the stack frees up the ebp register for general purpose
use (which is important for an architecture with only 8 user registers).
Instead of storing the function pointer directly in the assembly code.
This makes the generated code more independent of the runtime (so easier to
relocate the code), and reduces the generated code size.
The rsp register is always a fixed distance below rbp, and using rsp to
reference locals on the stack frees up the rbp register for general purpose
use.
This commit adds first class support for yield and yield-from in the native
emitter, including send and throw support, and yields enclosed in exception
handlers (which requires pulling down the NLR stack before yielding, then
rebuilding it when resuming).
This has been fully tested and is working on unix x86 and x86-64, and
stm32. Also basic tests have been done with the esp8266 port. Performance
of existing native code is unchanged.
The nlr_buf_t doesn't need to be part of the Python value stack (as it was
before this commit), it's simpler to have it separated as auxiliary state
that lives on the C stack. This will help adding yield support because in
that case the nlr_buf_t and Python value stack live in separate memory
areas (C stack and heap respectively).
Instead of at end of state, n_state - 1. It was originally (way back in
v1.0) put at the end of the state because the VM didn't have a pointer to
the start. But now that the VM takes a mp_code_state_t pointer it does
have a pointer to the start of the state so can put the exception object
there.
This commit saves about 30 bytes of code on all architectures, and, more
importantly, reduces C-stack usage by a couple of words (8 bytes on Thumb2
and 16 bytes on x86-64) for every (non-generator) call of a bytecode
function because fun_bc_call no longer needs to remember the n_state
variable.
Damien George