Merge "Do not remove instruction with debug information"

src/main/java/com/android/tools/r8/ir/code/IRCodeInstructionsIterator.java

diff --git a/src/main/java/com/android/tools/r8/ir/code/IRCodeInstructionsIterator.java b/src/main/java/com/android/tools/r8/ir/code/IRCodeInstructionsIterator.java
index 760a7ed..1390620 100644
--- a/src/main/java/com/android/tools/r8/ir/code/IRCodeInstructionsIterator.java
+++ b/src/main/java/com/android/tools/r8/ir/code/IRCodeInstructionsIterator.java
@@ -51,4 +51,9 @@
   public void replaceCurrentInstruction(Instruction newInstruction) {
     instructionIterator.replaceCurrentInstruction(newInstruction);
   }
+
+  @Override
+  public void removeOrReplaceByNop() {
+    instructionIterator.removeOrReplaceByNop();
+  }
 }

src/main/java/com/android/tools/r8/ir/code/InstructionIterator.java

diff --git a/src/main/java/com/android/tools/r8/ir/code/InstructionIterator.java b/src/main/java/com/android/tools/r8/ir/code/InstructionIterator.java
index 2cb8185..56d81a2 100644
--- a/src/main/java/com/android/tools/r8/ir/code/InstructionIterator.java
+++ b/src/main/java/com/android/tools/r8/ir/code/InstructionIterator.java
@@ -31,4 +31,10 @@
    * @param instruction The instruction to add.
    */
   void add(Instruction instruction);
+
+  /**
+   * Safe removal function that will insert a Nop to take over the debug values if any are
+   * associated with the current instruction.
+   */
+  void removeOrReplaceByNop();
 }

src/main/java/com/android/tools/r8/ir/optimize/CodeRewriter.java

diff --git a/src/main/java/com/android/tools/r8/ir/optimize/CodeRewriter.java b/src/main/java/com/android/tools/r8/ir/optimize/CodeRewriter.java
index 20f272a..fbde02b 100644
--- a/src/main/java/com/android/tools/r8/ir/optimize/CodeRewriter.java
+++ b/src/main/java/com/android/tools/r8/ir/optimize/CodeRewriter.java
@@ -91,7 +91,6 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.IdentityHashMap;
-import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.ListIterator;
@@ -1088,7 +1087,7 @@
             user -> user.isCheckCast()
                 && user.asCheckCast().getType().isSubtypeOf(checkCast.getType(), appInfo))) {
           checkCast.outValue().replaceUsers(checkCast.inValues().get(0));
-          it.remove();
+          it.removeOrReplaceByNop();
         }
       }
     }
@@ -1537,7 +1536,7 @@
 
     for (int i = 0; i < dominatorTree.getSortedBlocks().length; i++) {
       BasicBlock block = dominatorTree.getSortedBlocks()[i];
-      Iterator<Instruction> iterator = block.iterator();
+      InstructionListIterator iterator = block.listIterator();
       while (iterator.hasNext()) {
         Instruction instruction = iterator.next();
         if (instruction.isBinop()
@@ -1552,7 +1551,7 @@
                   shareCatchHandlers(instruction, candidate.definition)) {
                 instruction.outValue().replaceUsers(candidate);
                 eliminated = true;
-                iterator.remove();
+                iterator.removeOrReplaceByNop();
                 break;  // Don't try any more candidates.
               }
             }