[Python-Dev] Why is Bytecode the way it is?
Chris King
squirrel at wpi.edu
Sat Jul 10 06:55:50 CEST 2004
While recently goofing around with the bytecode, I thought of doing
something like this:
case LOAD_CONST:
x = GETITEM(consts, oparg);
Py_INCREF(x);
+ if (*next_instr == RETURN_VAL) {
+ retval = x;
+ why = WHY_RETURN;
+ goto fast_block_end;
+ }
PUSH(x);
goto fast_next_opcode;
This would skip the stack and a trip through the loop without changing
the parser or the bytecode, and with a minimal amount of added code or
overhead. This could (of course) be applied to other opcodes, too.
Perhaps instead of littering the function with that block, a macro
"PUSH_MAYBE_RET" could be added that would replace the final PUSH in the
opcode's case block:
#define PUSH_MAYBE_RET { if (*next_instr == RETURN_VAL) { \
retval = x; \
why = WHY_RETURN; \
goto fast_block_end; } \
PUSH(x); }
Not sure how much this would help speed, if any.
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