dev backend: roc panic

[folkertdev]

proof of concept of roc_panic. I think a crash is the only thing that panics at the moment though, so still some work left to do after this to really get parity.

[lukewilliamboswell]

Here are the results of that test running on my Windows machine.

PS C:\Users\bosyl\Documents\GitHub\roc> cargo nextest-gen-dev a_crash
    Finished test [unoptimized + debuginfo] target(s) in 0.83s
    Starting 1 test across 2 binaries (851 skipped)
        PASS [   1.235s] test_gen::test_gen gen_primitives::a_crash
------------
     Summary [   1.236s] 1 test run: 1 passed, 851 skipped

[folkertdev]

ah yes it's probably a good idea to give a status update here:

crash now works with the dev backend: the message and the panic tag are sent over correctly. This now works for both linux and windows on x86_64. Linux was already tested on CI, and I've now added two tests (one that crashes, one that doesn't) on windows too so we don't regress.

On linux we can use the two return registers to send this information over to the setjmp call (which in roc terms returns a record of two u64 fields). For windows we had to get a bit more creative, because returning such a record is done via the stack. So, the setjmp/longjmp assembly is standard, except for how values are returned (and what/how many values).

[folkertdev]

can you shed a light on the constants here? maybe it is related to
argument_offset: X86_64WindowsFastcall::SHADOW_SPACE_SIZE as i32 + 16,?

[folkertdev]

the 8 is kind of a magic constant here...

[bhansconnect]

Skips over the return address on the stack?

[bhansconnect]

Looks great! exciting to see this working.

[bhansconnect]

wrapping malloc?

[folkertdev]

yeah, roc_getppid was used somehow in the builtins (I think)? so we needed to provide the symbol. I'll dig into this a bit, because it should not be required

[folkertdev]

I suspect it is these functions from expect.zig

extern fn roc_shm_open(name: *const i8, oflag: c_int, mode: c_uint) c_int;
extern fn roc_mmap(addr: ?*anyopaque, length: c_uint, prot: c_int, flags: c_int, fd: c_int, offset: c_uint) *anyopaque;
extern fn roc_getppid() c_int;

[bhansconnect]

Skips over the return address on the stack?