beam_validator: Strengthen validation of GC instructions

beam_validator did not verify that the Y registers were initialized
before executing the following instructions that could cause a GC:

    bs_append/8
    bs_init2/6
    bs_init_bits/6
    gc_bif1/5
    gc_bif2/6
    gc_bif3/7
    test_heap/2

That means that, for example, an incorrect optimization that replaced
an 'allocate_zero' instruction with an 'allocate' instruction when it
was not safe, would not be rejected by beam_validtor, but would
instead cause a crash or other undefined behavior at runtime.

Also fix a minor bug in beam_type exposed by the stronger checking.
When compiling from .S files, beam_type did not handle the
init/1 instruction and could produce unsafe code.

0 files changed, 0 insertions, 0 deletions