Handle String.<init> with a phi input.
We wrongly assumed only irreducible loops could lead
to this situation, but any loop can actually be in between
a String NewInstance and a String.<init>.
bug: 109666561
Test: 563-checker-fakestring
Change-Id: I018a22f7e22c15e140252544415f51d544f7cc13
diff --git a/compiler/optimizing/instruction_builder.cc b/compiler/optimizing/instruction_builder.cc
index 7cda6e9..4c72434 100644
--- a/compiler/optimizing/instruction_builder.cc
+++ b/compiler/optimizing/instruction_builder.cc
@@ -1308,29 +1308,25 @@
HInstruction* arg_this = LoadLocal(orig_this_reg, DataType::Type::kReference);
// Replacing the NewInstance might render it redundant. Keep a list of these
- // to be visited once it is clear whether it is has remaining uses.
+ // to be visited once it is clear whether it has remaining uses.
if (arg_this->IsNewInstance()) {
ssa_builder_->AddUninitializedString(arg_this->AsNewInstance());
- } else {
- // The only reason a HPhi can flow in a String.<init> is when there is an
- // irreducible loop, which will create HPhi for all dex registers at loop entry.
- DCHECK(arg_this->IsPhi());
- // TODO(b/109666561): Re-enable.
- // DCHECK(graph_->HasIrreducibleLoops());
- // Don't bother compiling a method in that situation. While we could look at all
- // phis related to the HNewInstance, it's not worth the trouble.
- MaybeRecordStat(compilation_stats_,
- MethodCompilationStat::kNotCompiledIrreducibleAndStringInit);
- return false;
- }
-
- // Walk over all vregs and replace any occurrence of `arg_this` with `invoke`.
- for (size_t vreg = 0, e = current_locals_->size(); vreg < e; ++vreg) {
- if ((*current_locals_)[vreg] == arg_this) {
- (*current_locals_)[vreg] = invoke;
+ // Walk over all vregs and replace any occurrence of `arg_this` with `invoke`.
+ for (size_t vreg = 0, e = current_locals_->size(); vreg < e; ++vreg) {
+ if ((*current_locals_)[vreg] == arg_this) {
+ (*current_locals_)[vreg] = invoke;
+ }
}
+ } else {
+ DCHECK(arg_this->IsPhi());
+ // We can get a phi as input of a String.<init> if there is a loop between the
+ // allocation and the String.<init> call. As we don't know which other phis might alias
+ // with `arg_this`, we keep a record of these phis and will analyze their inputs and
+ // uses once the inputs and users are populated (in ssa_builder.cc).
+ // Note: we only do this for phis, as it is a somewhat more expensive operation than
+ // what we're doing above when the input is the `HNewInstance`.
+ ssa_builder_->AddUninitializedStringPhi(arg_this->AsPhi(), invoke);
}
-
return true;
}