Quick: Avoid unnecessary GVN work in release builds.
In GVN's post-processing phase, compare LVNs only in debug
builds as they should be equal anyway.
Remove the Gate() from GVN cleanup pass and remove the
DCHECK() from MIRGraph::GlobalValueNumberingCleanup()
to make it a no-op if the GVN didn't run.
Bug: 16398693
Change-Id: Ia4f1e7e3ecf12d0305966c86e0e7dbae61dab0b7
diff --git a/compiler/dex/global_value_numbering.cc b/compiler/dex/global_value_numbering.cc
index 30e3ce0..e2b9987 100644
--- a/compiler/dex/global_value_numbering.cc
+++ b/compiler/dex/global_value_numbering.cc
@@ -128,8 +128,9 @@
++bbs_processed_;
merge_lvns_.clear();
- bool change = (lvns_[bb->id] == nullptr) || !lvns_[bb->id]->Equals(*work_lvn_);
+ bool change = false;
if (mode_ == kModeGvn) {
+ change = (lvns_[bb->id] == nullptr) || !lvns_[bb->id]->Equals(*work_lvn_);
// In GVN mode, keep the latest LVN even if Equals() indicates no change. This is
// to keep the correct values of fields that do not contribute to Equals() as long
// as they depend only on predecessor LVNs' fields that do contribute to Equals().
@@ -137,6 +138,9 @@
std::unique_ptr<const LocalValueNumbering> old_lvn(lvns_[bb->id]);
lvns_[bb->id] = work_lvn_.release();
} else {
+ DCHECK_EQ(mode_, kModeGvnPostProcessing); // kModeLvn doesn't use FinishBasicBlock().
+ DCHECK(lvns_[bb->id] != nullptr);
+ DCHECK(lvns_[bb->id]->Equals(*work_lvn_));
work_lvn_.reset();
}
return change;