The main difference between = and != is how null values are handled.
SQLite passes a flag "NULLEQ" to Eq and Ne to disambiguate that.
In the presence of that flag, NULL = NULL.
Some prep work is done to make sure we can pass a flag instead of a
boolean to Eq and Ne. I looked into the bitflags crate but got a bit
scared with the list of dependencies.
skip rows
Emit Integer, OffsetLimit instructions for offset, and define function to emit IfPosinstruction to skip rows
Emit IfPos instructions to handle offset for simple select
Emit IfPos to handle offset for select with order by
Moved repeated emit_offset function call into emit_select_result
TLDR: no need to call either of:
program.emit_insn_with_label_dependency() -> just call program.emit_insn()
program.defer_label_resolution() -> just call program.resolve_label()
Changes:
- make BranchOffset an explicit enum (Label, Offset, Placeholder)
- remove program.emit_insn_with_label_dependency() - label dependency is automatically detected
- for label to offset mapping, use a hashmap from label(negative i32) to offset (positive u32)
- resolve all labels in program.build()
- remove program.defer_label_resolution() - all labels are resolved in build()
