ART: Delete catch phis for undefined vregs.
SSA builder assumed that (eagerly created) catch phis for undefined
vregs must be dead and will be deleted by dead phi elimination. This,
however, does not hold for --debuggable because the catch phis might
be revived for their environment uses. This patch modifies the builder
to delete the phis itself.
Bug: 24054676
Change-Id: Iaa5f2487ff1c38353b44cb89c709bbff1ecd73cc
diff --git a/compiler/optimizing/ssa_builder.cc b/compiler/optimizing/ssa_builder.cc
index 9dcbea0..6f71ea3 100644
--- a/compiler/optimizing/ssa_builder.cc
+++ b/compiler/optimizing/ssa_builder.cc
@@ -577,12 +577,28 @@
const HTryBoundary& try_entry =
instruction->GetBlock()->GetTryCatchInformation()->GetTryEntry();
for (HExceptionHandlerIterator it(try_entry); !it.Done(); it.Advance()) {
- ArenaVector<HInstruction*>* handler_locals = GetLocalsFor(it.Current());
+ HBasicBlock* catch_block = it.Current();
+ ArenaVector<HInstruction*>* handler_locals = GetLocalsFor(catch_block);
DCHECK_EQ(handler_locals->size(), current_locals_->size());
- for (size_t i = 0, e = current_locals_->size(); i < e; ++i) {
- HInstruction* local_value = (*current_locals_)[i];
- if (local_value != nullptr) {
- (*handler_locals)[i]->AsPhi()->AddInput(local_value);
+ for (size_t vreg = 0, e = current_locals_->size(); vreg < e; ++vreg) {
+ HInstruction* handler_value = (*handler_locals)[vreg];
+ if (handler_value == nullptr) {
+ // Vreg was undefined at a previously encountered throwing instruction
+ // and the catch phi was deleted. Do not record the local value.
+ continue;
+ }
+ DCHECK(handler_value->IsPhi());
+
+ HInstruction* local_value = (*current_locals_)[vreg];
+ if (local_value == nullptr) {
+ // This is the first instruction throwing into `catch_block` where
+ // `vreg` is undefined. Delete the catch phi.
+ catch_block->RemovePhi(handler_value->AsPhi());
+ (*handler_locals)[vreg] = nullptr;
+ } else {
+ // Vreg has been defined at all instructions throwing into `catch_block`
+ // encountered so far. Record the local value in the catch phi.
+ handler_value->AsPhi()->AddInput(local_value);
}
}
}