When split functions is used, BOLT may skip tentative code layout
estimation in some cases, like:
- when there is no profile data for some blocks (ie cold blocks)
- when there are cold functions in lite mode
- when skip functions is used
However, when rewriting the binary we still need to compute PC-relative
distances between hot and cold basic blocks. Without cold layout
estimation, BOLT uses '0x0' as the address of the first cold block,
leading to incorrect estimations of any PC-relative addresses.
This affects large binaries as the relaxStub method expands more
branches than necessary using the short-jump sequence, at it wrongly
believes it has exceeded the branch distance boundary.
This increases code size with both a larger and slower sequence;
however,
performance regression is expected to be minimal since this only affects
any called cold code.
Example of such an unnecessary relaxation:
from:
```armasm
b .Ltmp1234
```
to:
```armasm
adrp x16, .Ltmp1234
add x16, x16, :lo12:.Ltmp1234
br x16
```
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