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use rustc::ty::TyCtxt;
use rustc::mir::*;
use rustc_data_structures::indexed_vec::{Idx, IndexVec};
use transform::{MirPass, MirSource};
#[derive(PartialEq)]
pub enum AddCallGuards {
AllCallEdges,
CriticalCallEdges,
}
pub use self::AddCallGuards::*;
impl MirPass for AddCallGuards {
fn run_pass<'a, 'tcx>(&self,
_tcx: TyCtxt<'a, 'tcx, 'tcx>,
_src: MirSource,
mir: &mut Mir<'tcx>) {
self.add_call_guards(mir);
}
}
impl AddCallGuards {
pub fn add_call_guards(&self, mir: &mut Mir) {
let pred_count: IndexVec<_, _> =
mir.predecessors().iter().map(|ps| ps.len()).collect();
let mut new_blocks = Vec::new();
let cur_len = mir.basic_blocks().len();
for block in mir.basic_blocks_mut() {
match block.terminator {
Some(Terminator {
kind: TerminatorKind::Call {
destination: Some((_, ref mut destination)),
cleanup,
..
}, source_info
}) if pred_count[*destination] > 1 &&
(cleanup.is_some() || self == &AllCallEdges) =>
{
let call_guard = BasicBlockData {
statements: vec![],
is_cleanup: block.is_cleanup,
terminator: Some(Terminator {
source_info,
kind: TerminatorKind::Goto { target: *destination }
})
};
let idx = cur_len + new_blocks.len();
new_blocks.push(call_guard);
*destination = BasicBlock::new(idx);
}
_ => {}
}
}
debug!("Broke {} N edges", new_blocks.len());
mir.basic_blocks_mut().extend(new_blocks);
}
}