e2338edb47 didn't *quite* do it, the call sites of all switch prong related
functions now have to do their part too and be a little more precise about
what kind of prong they're currently analyzing.
Also removes some unused/unnecessary stuff.
This commit aims to simplify and de-duplicate the logic required for
semantically analyzing `switch` expressions.
The core logic has been moved to `analyzeSwitchBlock`, `resolveSwitchBlock`
and `finishSwitchBlock` and has been rewritten around the new iterator-based
API exposed by `Zir.UnwrappedSwitchBlock`.
All validation logic and switch prong item resolution have been moved to
`validateSwitchBlock`, which produces a `ValidatedSwitchBlock` containing
all the necessary information for further analysis.
`Zir.UnwrappedSwitchBlock`, `ValidatedSwitchBlock` and `SwitchOperand`
replace `SwitchProngAnalysis` while adding more flexibility, mainly for
better integration with `switch_block_err_union`.
`analyzeSwitchBlock` has an explicit code path for OPV types which lowers
them to either a `block`-`br` or a `loop`-`repeat` construct instead of a
switch. Backends expect `switch` to actually have an operand that exists
at runtime, so this is a bug fix and avoids further special cases in the
rest of the switch logic.
`resolveSwitchBlock` and `finishSwitchBr` exclusively deal with operands
which can have more than one value, at comptime and at runtime respectively.
This commit also reworks `RangeSet` to be an unmanaged container and adds
`Air.SwitchBr.BranchHints` to offload some complexity from Sema to there
and save a few bytes of memory in the process.
Additionally, some new features have been implemented:
- decl literals and everything else requiring a result type (`@enumFromInt`!)
may now be used as switch prong items
- union tag captures are now allowed for all prongs, not just `inline` ones
- switch prongs may contain errors which are not in the error set being
switched on, if these prongs contain `=> comptime unreachable`
and some bugs have been fixed:
- lots of issues with switching on OPV types are now fixed
- the rules around unreachable `else` prongs when switching on errors now
apply to *any* switch on an error, not just to `switch_block_err_union`,
and are applied properly based on the AST
- switching on `void` no longer requires an `else` prong unconditionally
- lazy values are properly resolved before any comparisons with prong items
- evaluation order between all kinds of switch statements is now the same,
with or without label
If both are used, 'else' handles named members and '_' handles
unnamed members. In this case the 'else' prong will be unrolled
to an explicit case containing all remaining named values.
Mainly affects ZIR representation of switch_block[_ref]
and special prong (detection) logic for switch.
Adds a new SpecialProng tag 'absorbing_under' that allows
specifying additional explicit tags in a '_' prong which
are respected when checking that every value is handled
during semantic analysis but are not transformed into AIR
and instead 'absorbed' by the '_' branch.
Updated solution is future proof for arbitary size integer handling for both strategies .br_table lowering if switch case is dense, .br_if base jump table if values are too sparse.
Reorganize how the binOp and genBinOp functions work.
I've spent quite a while here reading exactly through the spec and so many
tests are enabled because of several critical issues the old design had.
There are some regressions that will take a long time to figure out individually
so I will ignore them for now, and pray they get fixed by themselves. When
we're closer to 100% passing is when I will start diving into them one-by-one.
- implements `airSlice`, `airBitAnd`, `airBitOr`, `airShr`.
- got a basic design going for the `airErrorName` but for some reason it simply returns
empty bytes. will investigate further.
- only generating `.got.zig` entries when not compiling an object or shared library
- reduced the total amount of ops a mnemonic can have to 3, simplifying the logic
