commit 05543adc2b9f5f17590fd7465e2bf55bd408cd7f
author Christoffer Quist Adamsen <christofferqa@google.com> Mon Mar 21 14:09:23 2022 +0100
committer Christoffer Adamsen <christofferqa@google.com> Mon Mar 21 13:27:04 2022 +0000
tree 9b5adce149300375552f635f4b234b387f1ad9ff
parent 8bd8b45a52f95ec3e5407d233a03b268e19810e2

Disable loop unrolling

The loop unrolling seems to replace a phi by one of its operands leading to the use of a value that is not defined on all paths.

Bug: 225393424
Change-Id: I192a9980ab547c010365e42652ccb21f5cf448c9

src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java

diff --git a/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java b/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java
index 9cf8f31..3da2a7e 100644
--- a/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java
+++ b/src/main/java/com/android/tools/r8/ir/conversion/IRConverter.java
@@ -1313,7 +1313,7 @@
     codeRewriter.rewriteKnownArrayLengthCalls(code);
     timing.end();
     timing.begin("Natural Int Loop Remover");
-    naturalIntLoopRemover.run(code);
+    naturalIntLoopRemover.run(appView, code);
     timing.end();
     timing.begin("Rewrite AssertionError");
     codeRewriter.rewriteAssertionErrorTwoArgumentConstructor(code, options);

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

diff --git a/src/main/java/com/android/tools/r8/ir/optimize/NaturalIntLoopRemover.java b/src/main/java/com/android/tools/r8/ir/optimize/NaturalIntLoopRemover.java
index 9e0908a..0951ff9 100644
--- a/src/main/java/com/android/tools/r8/ir/optimize/NaturalIntLoopRemover.java
+++ b/src/main/java/com/android/tools/r8/ir/optimize/NaturalIntLoopRemover.java
@@ -5,6 +5,7 @@
 package com.android.tools.r8.ir.optimize;
 
 import com.android.tools.r8.errors.Unreachable;
+import com.android.tools.r8.graph.AppView;
 import com.android.tools.r8.ir.code.BasicBlock;
 import com.android.tools.r8.ir.code.Goto;
 import com.android.tools.r8.ir.code.IRCode;
@@ -28,7 +29,10 @@
  */
 public class NaturalIntLoopRemover {
 
-  public void run(IRCode code) {
+  public void run(AppView<?> appView, IRCode code) {
+    if (!appView.testing().enableExperimentalLoopUnrolling) {
+      return;
+    }
     boolean loopRemoved = false;
     for (BasicBlock comparisonBlockCandidate : code.blocks) {
       if (isComparisonBlock(comparisonBlockCandidate)) {

src/main/java/com/android/tools/r8/utils/InternalOptions.java

diff --git a/src/main/java/com/android/tools/r8/utils/InternalOptions.java b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
index e359381..dcf8dbd 100644
--- a/src/main/java/com/android/tools/r8/utils/InternalOptions.java
+++ b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
@@ -1764,6 +1764,7 @@
     public boolean enableEnumUnboxingDebugLogs = false;
     public boolean forceRedundantConstNumberRemoval = false;
     public boolean enableExperimentalDesugaredLibraryKeepRuleGenerator = false;
+    public boolean enableExperimentalLoopUnrolling = false;
     public boolean invertConditionals = false;
     public boolean placeExceptionalBlocksLast = false;
     public boolean dontCreateMarkerInD8 = false;

src/test/java/com/android/tools/r8/ir/optimize/loops/LoopWith1Iterations.java

diff --git a/src/test/java/com/android/tools/r8/ir/optimize/loops/LoopWith1Iterations.java b/src/test/java/com/android/tools/r8/ir/optimize/loops/LoopWith1Iterations.java
index dc3ca19..6bbfb60 100644
--- a/src/test/java/com/android/tools/r8/ir/optimize/loops/LoopWith1Iterations.java
+++ b/src/test/java/com/android/tools/r8/ir/optimize/loops/LoopWith1Iterations.java
@@ -33,6 +33,7 @@
         .setMinApi(parameters.getApiLevel())
         .addProgramClasses(Main.class)
         .addKeepMainRule(Main.class)
+        .addOptionsModification(options -> options.testing.enableExperimentalLoopUnrolling = true)
         .enableInliningAnnotations()
         .noMinification()
         .compile()