Fix GVN to handle normal paths leading to catch entry.
When the catch block is empty, the catch entry is actually
the normal path block after the try block. Fix the LVN
merge for catch entries that didn't expect it during GVN.
Bug: 16360024
(cherry-picked from 11ca61259be6ec8e03eaff1e98905232728b3d45)
Change-Id: Ifc771edfec702ab2f0ff50bf7f8e69c846d13a46
diff --git a/compiler/dex/global_value_numbering_test.cc b/compiler/dex/global_value_numbering_test.cc
index 40bd983..18adbab 100644
--- a/compiler/dex/global_value_numbering_test.cc
+++ b/compiler/dex/global_value_numbering_test.cc
@@ -2090,4 +2090,28 @@
EXPECT_EQ(value_names_[3], value_names_[14]);
}
+TEST_F(GlobalValueNumberingTest, NormalPathToCatchEntry) {
+ // When there's an empty catch block, all the exception paths lead to the next block in
+ // the normal path and we can also have normal "taken" or "fall-through" branches to that
+ // path. Check that LocalValueNumbering::PruneNonAliasingRefsForCatch() can handle it.
+ static const BBDef bbs[] = {
+ DEF_BB(kNullBlock, DEF_SUCC0(), DEF_PRED0()),
+ DEF_BB(kEntryBlock, DEF_SUCC1(3), DEF_PRED0()),
+ DEF_BB(kExitBlock, DEF_SUCC0(), DEF_PRED1(4)),
+ DEF_BB(kDalvikByteCode, DEF_SUCC1(4), DEF_PRED1(1)),
+ DEF_BB(kDalvikByteCode, DEF_SUCC1(5), DEF_PRED1(3)),
+ DEF_BB(kDalvikByteCode, DEF_SUCC1(2), DEF_PRED2(3, 4)),
+ };
+ static const MIRDef mirs[] = {
+ DEF_INVOKE1(4, Instruction::INVOKE_STATIC, 100u),
+ };
+ PrepareBasicBlocks(bbs);
+ BasicBlock* catch_handler = cu_.mir_graph->GetBasicBlock(5u);
+ catch_handler->catch_entry = true;
+ BasicBlock* merge_block = cu_.mir_graph->GetBasicBlock(4u);
+ std::swap(merge_block->taken, merge_block->fall_through);
+ PrepareMIRs(mirs);
+ PerformGVN();
+}
+
} // namespace art
diff --git a/compiler/dex/local_value_numbering.cc b/compiler/dex/local_value_numbering.cc
index d5fd6fe..ef893fe 100644
--- a/compiler/dex/local_value_numbering.cc
+++ b/compiler/dex/local_value_numbering.cc
@@ -445,6 +445,11 @@
void LocalValueNumbering::PruneNonAliasingRefsForCatch() {
for (const LocalValueNumbering* lvn : gvn_->merge_lvns_) {
const BasicBlock* bb = gvn_->GetBasicBlock(lvn->Id());
+ if (UNLIKELY(bb->taken == id_) || UNLIKELY(bb->fall_through == id_)) {
+ // Non-exceptional path to a catch handler means that the catch block was actually
+ // empty and all exceptional paths lead to the shared path after that empty block.
+ continue;
+ }
DCHECK_EQ(bb->taken, kNullBlock);
DCHECK_NE(bb->fall_through, kNullBlock);
const BasicBlock* fall_through_bb = gvn_->GetBasicBlock(bb->fall_through);