rust/src/analyze.rs
Bastian Kauschke 56e63805be update cg_clif
2020-11-16 22:42:09 +01:00

62 lines
1.8 KiB
Rust

//! SSA analysis
use crate::prelude::*;
use rustc_index::vec::IndexVec;
use rustc_middle::mir::StatementKind::*;
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub(crate) enum SsaKind {
NotSsa,
Ssa,
}
pub(crate) fn analyze(fx: &FunctionCx<'_, '_, impl Module>) -> IndexVec<Local, SsaKind> {
let mut flag_map = fx
.mir
.local_decls
.iter()
.map(|local_decl| {
let ty = fx.monomorphize(local_decl.ty);
if fx.clif_type(ty).is_some() || fx.clif_pair_type(ty).is_some() {
SsaKind::Ssa
} else {
SsaKind::NotSsa
}
})
.collect::<IndexVec<Local, SsaKind>>();
for bb in fx.mir.basic_blocks().iter() {
for stmt in bb.statements.iter() {
match &stmt.kind {
Assign(place_and_rval) => match &place_and_rval.1 {
Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
not_ssa(&mut flag_map, place.local)
}
_ => {}
},
_ => {}
}
}
match &bb.terminator().kind {
TerminatorKind::Call { destination, .. } => {
if let Some((dest_place, _dest_bb)) = destination {
let dest_layout = fx
.layout_of(fx.monomorphize(&dest_place.ty(&fx.mir.local_decls, fx.tcx).ty));
if !crate::abi::can_return_to_ssa_var(fx.tcx, dest_layout) {
not_ssa(&mut flag_map, dest_place.local)
}
}
}
_ => {}
}
}
flag_map
}
fn not_ssa(flag_map: &mut IndexVec<Local, SsaKind>, local: Local) {
flag_map[local] = SsaKind::NotSsa;
}