Struct cranelift::prelude::isa::BranchRange

pub struct BranchRange {
    pub origin: u8,
    pub bits: u8,
}

Constraints on the range of a branch instruction.

A branch instruction usually encodes its destination as a signed n-bit offset from an origin. The origin depends on the ISA and the specific instruction:

• RISC-V and ARM Aarch64 use the address of the branch instruction, origin = 0.
• x86 uses the address of the instruction following the branch, origin = 2 for a 2-byte branch instruction.
• ARM's A32 encoding uses the address of the branch instruction + 8 bytes, origin = 8.

Fields

origin: u8

Offset in bytes from the address of the branch instruction to the origin used for computing the branch displacement. This is the destination of a branch that encodes a 0 displacement.

bits: u8

Number of bits in the signed byte displacement encoded in the instruction. This does not account for branches that can only target aligned addresses.

Methods

impl BranchRange

pub fn contains(self, branch: u32, dest: u32) -> bool

Determine if this branch range can represent the range from branch to dest, where branch is the code offset of the branch instruction itself and dest is the code offset of the destination EBB header.

This method does not detect if the range is larger than 2 GB.

Trait Implementations

impl Clone for BranchRange

fn clone(&self) -> BranchRange

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for BranchRange

impl Debug for BranchRange

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.