Boundary symbols have a special name prefix:
* section$start$segname$sectname
* section$stop$segname$sectname
* segment$start$segname
* segment$stop$segname
and will resolve to either start or end of the respective
section/segment if found.
If not found, we return an error stating we couldn't find the
requested section/segment rather than silently failing and resolving
the address to 0 which seems to be the case with Apple's ld64.
There are two optimizations here, which work together to avoid a
pathological case.
The first optimization is that AstGen now records the result type of an
array multiplication expression where possible. This type is not used
according to the language specification, but instead as an optimization.
In the expression '.{x} ** 1000', if we know that the result must be an
array, then it is much more efficient to coerce the LHS to an array with
length 1 before doing the multiplication. Otherwise, we end up with a
1000-element tuple which we must coerce to an array by individually
extracting each field.
Secondly, the previous logic would repeatedly extract element/field
values from the LHS when initializing the result. This is unnecessary:
each element must only be extracted once, and the result reused.
These changes together give huge improvements to compiler performance on
a pathological case: AIR instructions go from 65551 to 15, and total AIR
bytes go from 1.86MiB to 264.57KiB. Codegen time spent on this function
(in a debug compiler build) goes from minutes to essentially zero.
Resolves: #17586
b3462b7 caused a regression in a third-party project, since it forced
resolution of field initializers for any field call 'foo.bar()', despite
this only being necessary when 'bar' is a comptime field.
See https://github.com/ziglang/zig/pull/17692#issuecomment-1802096734.
Previously the symbol tag field would remain `undefined` until it
was set during `flush`. However, the symbol's tag would be observed
earlier than where it was being set. We now set it to the explicit
tag `undefined` so this can be caught during debug. The symbol tag of
a decl will now also be set right after `updateDecl` and `updateFunc`.
Likewise, we now also set the `name` field during atom creation for
decls, as well as set the other fields to the max(u32) to ensure we
get a compiler crash during debug to ensure any misses will be caught.
There is no grantee that `copy_cqes` will return exactly wait_nr number of cqes.
If there are ready cqes it can return > 0 but < wait_nr number of cqes.
