Struct Flags 

pub struct Flags {
    pub frame_pointer: bool,
    pub red_zone: bool,
    pub stack_clash: bool,
    pub landing: bool,
    pub profile: Profile,
    pub patch: Room,
    pub reorder: bool,
    pub reuse: bool,
    pub schedule: bool,
    pub accurate: Option<bool>,
}

What the command line says about a frame, as opposed to what the machine says.

Fields

frame_pointer: bool

Whether every function keeps a frame pointer, which -fno-omit-frame-pointer asks for.

red_zone: bool

Whether the red zone may be used, which -mno-red-zone and every kernel turns off.

stack_clash: bool

Whether a frame is taken a page at a time, which -fstack-clash-protection asks for.

landing: bool

Whether every address an indirect branch may arrive at opens with a landing pad, which -fcf-protection=branch asks for. That is every function, and every label of a function whose address the program took.

profile: Profile

Whether every function calls a profiler on the way in, which -pg asks for.

patch: Room

How much room every function opens with for a patcher, which -fpatchable-function-entry= asks for. See Room.

reorder: bool

Whether the blocks are put in the order the weights say rather than in the order the shape of the graph says, which -freorder-blocks asks for and every level above -O0 turns on. See crate::layout.

reuse: bool

Whether two things in the frame that are never both wanted may be the same bytes, which -fstack-reuse=none turns off. See crate::slots.

schedule: bool

Whether the instructions of a block are put in the order the machine finishes soonest, which -fschedule-insns2 asks for and every level from -O2 turns on. See crate::schedule.

accurate: Option<bool>

Whether the target’s timing model is believed about the machine’s units as well as about its latencies, which -Zcycle-accurate-model= says and the model itself answers otherwise.

None is a command line that did not say, which is nearly every one, and then the model’s own answer decides. It is here rather than only on the model because section 38.1 asks for a way to say the model is better or worse than it claims without editing the model, and because the measurement section 38.8 owes is the same corpus compiled both ways.

Trait Implementations

impl Clone for Flags

fn clone(&self) -> Flags

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Flags

impl Debug for Flags

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

Formats the value using the given formatter.

impl Default for Flags

fn default() -> Self

No frame pointer, the red zone allowed, the frame taken in one subtraction, no landing pad, no profiling, no room for a patcher, the blocks in the order the graph’s shape gives, nothing in the frame sharing with anything and no scheduling, which is what a convention that has a red zone says at -O0 when nobody on the command line has said otherwise.

impl Eq for Flags

impl PartialEq for Flags

fn eq(&self, other: &Flags) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Flags