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fuzzbug fixes in stackifier

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This commit is contained in:
Chris Fallin 2021-12-15 20:04:06 -08:00
parent 250e922498
commit 1ace8713ed
1 changed files with 21 additions and 17 deletions
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38
src/backend/stackify.rs
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@ -184,6 +184,13 @@ impl Shape {
succ_pos, block_pos, order[succ_pos], order[block_pos]);
loop_header_to_end[succ_pos] = Some(end);
} else if succ_pos > block_pos + 1 {
log::trace!(
"forward edge: to RPO {} from RPO {} (to block {} from block {})",
succ_pos,
block_pos,
order[succ_pos],
order[block_pos]
);
forward_edges.push((block_pos, succ_pos));
}
}
@ -216,27 +223,24 @@ impl Shape {
log::trace!("loop_header_to_end = {:?}", loop_header_to_end);
log::trace!("loop_nest = {:?}", loop_nest);
// Look for irreducible edges. TODO: handle these by
// introducing label variables, then editing the region to
// refer to the canonical header block. Take care when jumping
// into multiple nested loops.
let loop_headers = loop_header_to_end
.iter()
.enumerate()
.filter(|(_, entry)| entry.is_some())
.map(|(header, _)| header)
.collect::<BTreeSet<_>>();
// Look for irreducible edges.
for &(from, to) in &forward_edges {
if let Some(&header_block) = loop_headers.range((from + 1)..to).next() {
panic!(
"Irreducible edge from block {} to block {}: jumps into loop with header block {}",
order[from], order[to], order[header_block]
);
let from_loop_nest = &loop_nest[from];
let to_loop_nest = &loop_nest[to];
for i in 0..to_loop_nest.len() {
if i >= from_loop_nest.len() || from_loop_nest[i] != to_loop_nest[i] {
// Entering a loop; the `to` must be the header.
let header_block = to_loop_nest[i].0;
if to != header_block {
panic!(
"Irreducible edge from RPO {} block {} to RPO {} block {}: jumps into loop with header RPO {} block {}",
from, order[from], to, order[to], header_block, order[header_block]
);
}
}
}
}
log::trace!("loop_headers = {:?}", loop_headers);
log::trace!("forward_edges = {:?}", forward_edges);
// Process forward edges: add "block-start count" to