IssueTracker

Thank you for the report and reproduction. I can reproduce on a Android TV emulator.

Status of current findings.

This is related to the SplitReturnRewriter added in https://r8.googlesource.com/r8/+/0c68ba1dc945da74c2f72085b401fe46635b3fc9.

Not running this code pass on java.lang.Object androidx.collection.LruCache.remove(java.lang.Object) works around the issue. I used the following patch:

diff --git a/src/main/java/com/android/tools/r8/ir/conversion/passes/SplitReturnRewriter.java b/src/main/java/com/android/tools/r8/ir/conversion/passes/SplitReturnRewriter.java
index 157d26c66a..63e0f76064 100644
--- a/src/main/java/com/android/tools/r8/ir/conversion/passes/SplitReturnRewriter.java
+++ b/src/main/java/com/android/tools/r8/ir/conversion/passes/SplitReturnRewriter.java
@@ -43,6 +43,10 @@ public class SplitReturnRewriter extends CodeRewriterPass<AppInfo> {
 
   @Override
   protected CodeRewriterResult rewriteCode(IRCode code) {
+    if (code.context().toSourceString().equals(
+        "java.lang.Object androidx.collection.LruCache.remove(java.lang.Object)")) {
+      return CodeRewriterResult.NO_CHANGE;
+    }
     int color = colorExceptionHandlers(code);
     AffectedValues affectedValues = new AffectedValues();
     boolean changed = false;

Comparing the DEX with and without this patch shows one instruction diff in void androidx.leanback.widget.GridLayoutManager$2.addItem(java.lang.Object, int, int, int, int) where java.lang.Object androidx.collection.LruCache.remove(java.lang.Object) is inlined into.

Tracing the IR for void androidx.leanback.widget.GridLayoutManager$2.addItem(java.lang.Object, int, int, int, int) for the two versions shows that they start to deviate in second pass of IR after inserting assume instructions (SSA) with

block 29, pred-counts: 1, succ-count: 2, filled: true, sealed: false
predecessors: 28 
successors: 31 30  (no try/catch successors)
no phis
 #143:loadView;1762:addItem: -1: InstanceGet          v67 <- v136; field: androidx.collection.LruCache androidx.leanback.widget.ViewsStateBundle.mChildStates
                           : -1: Assume               v140 <- v67; lower bound: @Nullable androidx.collection.LruCache {}
                           : -1: SafeCheckCast        v131 <- v65; java.lang.String
                           : -1: Invoke-Virtual       v132 <- v140, v131; method: java.lang.Object androidx.collection.LruCache.remove(java.lang.String)
                           : -1: CheckCast            v69 <- v132; android.util.SparseArray
 #144:loadView;1762:addItem: -1: If                   v69 EQZ block 31 (fallthrough 30)

vs.

block 29, pred-counts: 1, succ-count: 2, filled: true, sealed: false
predecessors: 28 
successors: 31 30  (no try/catch successors)
no phis
 #143:loadView;1762:addItem: -1: InstanceGet          v67 <- v136; field: androidx.collection.LruCache androidx.leanback.widget.ViewsStateBundle.mChildStates
                           : -1: Assume               v140 <- v67; lower bound: @Nullable androidx.collection.LruCache {}
                           : -1: SafeCheckCast        v131 <- v65; java.lang.String
                           : -1: Invoke-Virtual       v132 <- v140, v131; method: java.lang.Object androidx.collection.LruCache.remove(java.lang.String)
                           : -1: Assume               v141 <- v132; not null
                           : -1: CheckCast            v69 <- v141; android.util.SparseArray
 #144:loadView;1762:addItem: -1: If                   v69 EQZ block 31 (fallthrough 30)

This is from computeDynamicReturnType concluding a dynamic return type of DynamicTypeWithUpperBound(@NotNull java.lang.Object {}).