Consider phis in basic block behavioral subsumption analysis
Change-Id: Ice49ec4d8ba212f3d5ae48b6b951a86484e9ca15
diff --git a/src/main/java/com/android/tools/r8/ir/analysis/equivalence/BasicBlockBehavioralSubsumption.java b/src/main/java/com/android/tools/r8/ir/analysis/equivalence/BasicBlockBehavioralSubsumption.java
index fce5100..94da205 100644
--- a/src/main/java/com/android/tools/r8/ir/analysis/equivalence/BasicBlockBehavioralSubsumption.java
+++ b/src/main/java/com/android/tools/r8/ir/analysis/equivalence/BasicBlockBehavioralSubsumption.java
@@ -16,9 +16,11 @@
import com.android.tools.r8.ir.code.DexItemBasedConstString;
import com.android.tools.r8.ir.code.Instruction;
import com.android.tools.r8.ir.code.InstructionIterator;
+import com.android.tools.r8.ir.code.Phi;
import com.android.tools.r8.ir.code.Return;
import com.android.tools.r8.ir.code.Value;
import com.android.tools.r8.utils.SetUtils;
+import java.util.List;
import java.util.Set;
/**
@@ -72,7 +74,8 @@
// If the other instruction is also a goto instruction, which targets the same block, then
// we are done.
if (targetBlock == otherTargetBlock) {
- return true;
+ return passesIdenticalValuesForPhis(
+ instruction.getBlock(), otherInstruction.getBlock(), targetBlock);
}
// Otherwise we continue the search from the two successor blocks.
otherIterator = otherTargetBlock.iterator();
@@ -204,4 +207,39 @@
return false;
}
+
+ private boolean passesIdenticalValuesForPhis(
+ BasicBlock block, BasicBlock other, BasicBlock blockWithPhis) {
+ if (block == other) {
+ return true;
+ }
+
+ int predecessorIndex = -1, otherPredecessorIndex = -1;
+ List<BasicBlock> predecessors = blockWithPhis.getPredecessors();
+ for (int i = 0; i < predecessors.size(); i++) {
+ BasicBlock predecessor = predecessors.get(i);
+ if (predecessor == block) {
+ predecessorIndex = i;
+ if (otherPredecessorIndex >= 0) {
+ break;
+ }
+ } else if (predecessor == other) {
+ otherPredecessorIndex = i;
+ if (predecessorIndex >= 0) {
+ break;
+ }
+ }
+ }
+
+ assert predecessorIndex >= 0;
+ assert otherPredecessorIndex >= 0;
+
+ for (Phi phi : blockWithPhis.getPhis()) {
+ if (!valuesAreIdentical(
+ phi.getOperand(predecessorIndex), phi.getOperand(otherPredecessorIndex))) {
+ return false;
+ }
+ }
+ return true;
+ }
}
