ART: Replace expensive calls to Covers in reg alloc
LiveInterval::Covers is implemented as a linear-time search over
liveness ranges and can therefore be rather expensive and should be
avoided unless necessary. This patch replaces calls to Covers when
searching for a sibling with the cheaper IsDefinedAt call.
Change-Id: I93fc73529c15a518335f4cbdc3a0def52d9501e5
diff --git a/compiler/optimizing/ssa_liveness_analysis.h b/compiler/optimizing/ssa_liveness_analysis.h
index 98f98a2..beb4907 100644
--- a/compiler/optimizing/ssa_liveness_analysis.h
+++ b/compiler/optimizing/ssa_liveness_analysis.h
@@ -372,7 +372,11 @@
bool HasRegister() const { return register_ != kNoRegister; }
bool IsDeadAt(size_t position) const {
- return last_range_->GetEnd() <= position;
+ return GetEnd() <= position;
+ }
+
+ bool IsDefinedAt(size_t position) const {
+ return GetStart() <= position && !IsDeadAt(position);
}
bool Covers(size_t position) {
@@ -513,7 +517,7 @@
DCHECK(!is_fixed_);
DCHECK_GT(position, GetStart());
- if (last_range_->GetEnd() <= position) {
+ if (GetEnd() <= position) {
// This range dies before `position`, no need to split.
return nullptr;
}
@@ -643,8 +647,8 @@
// Returns the location of the interval following its siblings at `position`.
Location GetLocationAt(size_t position);
- // Finds the interval that covers `position`.
- const LiveInterval& GetIntervalAt(size_t position);
+ // Finds the sibling that is defined at `position`.
+ LiveInterval* GetSiblingAt(size_t position);
// Returns whether `other` and `this` share the same kind of register.
bool SameRegisterKind(Location other) const;