Needs of feature that disabling optimization pipeline in runtime

[corona10]

@iritkatriel
This feature is needed for debugging or experimentation when handling optimized bytecode.
When I want to take a look at the sequence of bytecodes that is optimized with the specific pipeline but not all pipelines, I need to disable several pipelines from

cpython/Python/flowgraph.c

Lines 1843 to 1851 in 30b4e9f

	RETURN_IF_ERROR(check_cfg(g));
	RETURN_IF_ERROR(inline_small_or_no_lineno_blocks(g->g_entryblock));
	RETURN_IF_ERROR(remove_unreachable(g->g_entryblock));
	RETURN_IF_ERROR(resolve_line_numbers(g, firstlineno));
	RETURN_IF_ERROR(optimize_load_const(const_cache, g, consts));
	for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
	RETURN_IF_ERROR(optimize_basic_block(const_cache, b, consts));
	}
	RETURN_IF_ERROR(remove_redundant_nops_and_pairs(g->g_entryblock));

and rebuild the CPython it's pretty painful because when I want to change the combination of optimization than I should rebuild CPython every time.

It would be great if there is a way to disable specific optimization pipelines at runtime when I want.
Above example is just one specific case and sometime I want to disable all _PyCfg_OptimizeCodeUnit or part of _PyCfg_OptimizeCodeUnit.

This is what I wanted to ask about at the PyCon and will happy to see your opinion about this.