[Xtensa] Fix fp16 conversion

[gerekon]

No description provided.

[gerekon]

@andreisfr @sstefan1 PTAL
@kassane FYI

[sstefan1]

I suggest using update_llc_test_checks.py for generating check lines. Otherwise LGTM!

[gerekon]

@sstefan1

I suggest using update_llc_test_checks.py for generating check lines. Otherwise LGTM!

Actually I used it to generate initial test case. But after that I removed instructions and left only ones related to conversion functions calls as it is done for ARM. But looks like that code is 9 years old, so it was written before the first version of update_llc_test_checks.py was implemented.

So. Ok. I will re-generate checks for easier maintenance in future.

[kassane]

This change didn't give me the error mentioned in the issue.

But, now:

$> ./out/zig-x86_64-linux-musl-baseline/zig cc -target xtensa-freestanding -mcpu=esp32 start.c
LLVM Emit Object... error: <unknown>:0: Undefined temporary symbol .LBB385_2