Integer literals

Generated integers default to 1 rather than 0, and literals mix small values, arithmetic boundary values such as 2^31 − 1, and wide byte payloads.

1. Configuration

[generator]
max_integer_bytes = 16
# Closed integer terminal, and centre of small integer literals.
integer_base = 1
# Input bytes move a small integer literal within base ± spread.
integer_literal_spread = 4
# How integer literals decode: "wide" byte payloads, "small" values around integer_base,
# or "boundary" values such as 2^31 - 1 besides both.
integer_literals = "boundary"

Key	Meaning
integer_base	Value of a starved integer expression, and centre of small literals.
integer_literal_spread	Small literals lie in integer_base ± spread, 0..127.
integer_literals	"wide": every literal is a payload of up to max_integer_bytes. "small": half small, half wide. "boundary": half small, a quarter boundary values, a quarter wide.

2. Boundary values

-1, 0, 1, 2, 15, 16, 255, 256, 32767, 32768, 65536, 46340, 46341, 2^30, 2^31 − 1, −2^31, 2^31, −2^31 − 1, 2^63 − 1.

The last three lie outside TLC's signed 32-bit range. The shipped signature integer-literal-outside-tlc-range quarantines them when they occur as literals (known-defect signatures); overflow computed by arithmetic is checked.

Changing any of these keys reinterprets stored inputs: a corpus must keep the values it was created with.

Background

ADR 0012 records the design and the measurements behind it.