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Diffstat (limited to 'venv/lib/python3.11/site-packages/greenlet/greenlet_slp_switch.hpp')
-rw-r--r-- | venv/lib/python3.11/site-packages/greenlet/greenlet_slp_switch.hpp | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/venv/lib/python3.11/site-packages/greenlet/greenlet_slp_switch.hpp b/venv/lib/python3.11/site-packages/greenlet/greenlet_slp_switch.hpp new file mode 100644 index 0000000..bd4b7ae --- /dev/null +++ b/venv/lib/python3.11/site-packages/greenlet/greenlet_slp_switch.hpp @@ -0,0 +1,99 @@ +#ifndef GREENLET_SLP_SWITCH_HPP +#define GREENLET_SLP_SWITCH_HPP + +#include "greenlet_compiler_compat.hpp" +#include "greenlet_refs.hpp" + +/* + * the following macros are spliced into the OS/compiler + * specific code, in order to simplify maintenance. + */ +// We can save about 10% of the time it takes to switch greenlets if +// we thread the thread state through the slp_save_state() and the +// following slp_restore_state() calls from +// slp_switch()->g_switchstack() (which already needs to access it). +// +// However: +// +// that requires changing the prototypes and implementations of the +// switching functions. If we just change the prototype of +// slp_switch() to accept the argument and update the macros, without +// changing the implementation of slp_switch(), we get crashes on +// 64-bit Linux and 32-bit x86 (for reasons that aren't 100% clear); +// on the other hand, 64-bit macOS seems to be fine. Also, 64-bit +// windows is an issue because slp_switch is written fully in assembly +// and currently ignores its argument so some code would have to be +// adjusted there to pass the argument on to the +// ``slp_save_state_asm()`` function (but interestingly, because of +// the calling convention, the extra argument is just ignored and +// things function fine, albeit slower, if we just modify +// ``slp_save_state_asm`()` to fetch the pointer to pass to the +// macro.) +// +// Our compromise is to use a *glabal*, untracked, weak, pointer +// to the necessary thread state during the process of switching only. +// This is safe because we're protected by the GIL, and if we're +// running this code, the thread isn't exiting. This also nets us a +// 10-12% speed improvement. + +static greenlet::Greenlet* volatile switching_thread_state = nullptr; + + +extern "C" { +static int GREENLET_NOINLINE(slp_save_state_trampoline)(char* stackref); +static void GREENLET_NOINLINE(slp_restore_state_trampoline)(); +} + + +#define SLP_SAVE_STATE(stackref, stsizediff) \ +do { \ + assert(switching_thread_state); \ + stackref += STACK_MAGIC; \ + if (slp_save_state_trampoline((char*)stackref)) \ + return -1; \ + if (!switching_thread_state->active()) \ + return 1; \ + stsizediff = switching_thread_state->stack_start() - (char*)stackref; \ +} while (0) + +#define SLP_RESTORE_STATE() slp_restore_state_trampoline() + +#define SLP_EVAL +extern "C" { +#define slp_switch GREENLET_NOINLINE(slp_switch) +#include "slp_platformselect.h" +} +#undef slp_switch + +#ifndef STACK_MAGIC +# error \ + "greenlet needs to be ported to this platform, or taught how to detect your compiler properly." +#endif /* !STACK_MAGIC */ + + + +#ifdef EXTERNAL_ASM +/* CCP addition: Make these functions, to be called from assembler. + * The token include file for the given platform should enable the + * EXTERNAL_ASM define so that this is included. + */ +extern "C" { +intptr_t +slp_save_state_asm(intptr_t* ref) +{ + intptr_t diff; + SLP_SAVE_STATE(ref, diff); + return diff; +} + +void +slp_restore_state_asm(void) +{ + SLP_RESTORE_STATE(); +} + +extern int slp_switch(void); +}; +#endif + +#endif |