Add synthesize uses at back edge.
This reduces the cost of linearizing the graph (hence removing
the notion of back edge). Since linear scan allocates/spills registers
based on next use, adding a use at a back edge ensures we do count
for loop uses.
Change-Id: Idaa882cb120edbdd08ca6bff142d326a8245bd14
diff --git a/compiler/optimizing/ssa_liveness_analysis.cc b/compiler/optimizing/ssa_liveness_analysis.cc
index b674f74..0bbcb30 100644
--- a/compiler/optimizing/ssa_liveness_analysis.cc
+++ b/compiler/optimizing/ssa_liveness_analysis.cc
@@ -341,7 +341,7 @@
size_t end = GetEnd();
while (use != nullptr && use->GetPosition() <= end) {
size_t use_position = use->GetPosition();
- if (use_position >= start) {
+ if (use_position >= start && !use->IsSynthesized()) {
HInstruction* user = use->GetUser();
size_t input_index = use->GetInputIndex();
if (user->IsPhi()) {