ART: Fix critical edge splitting under try/catch
A critical edge would not be split if the predecessor ends with
TryBoundary. This would eventually trip liveness analysis because
a back edge block would have smaller liveness position than a nested
loop.
Another implication of this change is that an edge between a loop's
pre-header ending with TryBoundary and the header will be split,
guaranteeing that a pre-header always has just one successor.
Bug: 25493695
Bug: 25454012
Change-Id: I5a13b8bb74509b48f5d628906f7158af007f99ae
diff --git a/compiler/optimizing/graph_checker.cc b/compiler/optimizing/graph_checker.cc
index c32ef51..f77576d 100644
--- a/compiler/optimizing/graph_checker.cc
+++ b/compiler/optimizing/graph_checker.cc
@@ -460,12 +460,18 @@
int id = loop_header->GetBlockId();
HLoopInformation* loop_information = loop_header->GetLoopInformation();
- // Ensure the pre-header block is first in the list of
- // predecessors of a loop header.
+ // Ensure the pre-header block is first in the list of predecessors of a loop
+ // header and that the header block is its only successor.
if (!loop_header->IsLoopPreHeaderFirstPredecessor()) {
AddError(StringPrintf(
"Loop pre-header is not the first predecessor of the loop header %d.",
id));
+ } else if (loop_information->GetPreHeader()->GetSuccessors().size() != 1) {
+ AddError(StringPrintf(
+ "Loop pre-header %d of loop defined by header %d has %zu successors.",
+ loop_information->GetPreHeader()->GetBlockId(),
+ id,
+ loop_information->GetPreHeader()->GetSuccessors().size()));
}
// Ensure the loop header has only one incoming branch and the remaining
@@ -508,6 +514,13 @@
"Loop defined by header %d has an invalid back edge %d.",
id,
back_edge_id));
+ } else if (back_edge->GetLoopInformation() != loop_information) {
+ AddError(StringPrintf(
+ "Back edge %d of loop defined by header %d belongs to nested loop "
+ "with header %d.",
+ back_edge_id,
+ id,
+ back_edge->GetLoopInformation()->GetHeader()->GetBlockId()));
}
}
}