Control instructions and overflow safety

Operand-free control instructions

The instruction set also includes two operand-free forms:

Both require a semicolon and have fixed layout sizes. pause is recognized as a two-byte sequence before a decoder reports an unknown byte. The end-to-end test checks both the binary and decoded listing:

ctest --test-dir build/windows-debug -C Debug -R "^encode.control$" --output-on-failure

Overflow-safe constant expressions

Constant expressions are evaluated with checked signed long long arithmetic before Kasm applies its signed 32-bit language limit. Addition, subtraction, and multiplication now reject intermediate overflow instead of relying on C signed overflow behavior. The semantic regression retains the successful precedence case and checks overflowing examples for all three operators:

ctest --test-dir build/windows-debug -C Debug -R "^semantic.expression$" --output-on-failure

Symbol-valued data remains a future layout feature at the time this checked-arithmetic behavior was added; as of 0.33.0, data directives can also resolve label expressions after layout — see Data directives and layout expressions.