Merge "Do not record uses of unconstrained arguments in register allocation"
diff --git a/src/main/java/com/android/tools/r8/ir/regalloc/LinearScanRegisterAllocator.java b/src/main/java/com/android/tools/r8/ir/regalloc/LinearScanRegisterAllocator.java
index 1e010ce..31eb337 100644
--- a/src/main/java/com/android/tools/r8/ir/regalloc/LinearScanRegisterAllocator.java
+++ b/src/main/java/com/android/tools/r8/ir/regalloc/LinearScanRegisterAllocator.java
@@ -2176,7 +2176,22 @@
if (options.isGeneratingDex()) {
int inConstraint = instruction.maxInValueRegister();
LiveIntervals useIntervals = use.getLiveIntervals();
- useIntervals.addUse(new LiveIntervalsUse(instruction.getNumber(), inConstraint));
+ // Arguments are always kept in their original, incoming register. For every
+ // unconstrained use of an argument we therefore use its incoming register.
+ // As a result, we do not need to record that the argument is being used at the
+ // current instruction.
+ //
+ // For ranged invoke instructions that use a subset of the arguments in the current
+ // order, registering a use for the arguments at the invoke can cause us to run out of
+ // registers. That is because all arguments are forced back into a chosen register at
+ // all uses. Therefore, if we register a use of an argument where we can actually use
+ // it in the argument register, the register allocator would use two registers for the
+ // argument but in reality only use one.
+ boolean isUnconstrainedArgumentUse =
+ use.isArgument() && inConstraint == Constants.U16BIT_MAX;
+ if (!isUnconstrainedArgumentUse) {
+ useIntervals.addUse(new LiveIntervalsUse(instruction.getNumber(), inConstraint));
+ }
}
}
}
diff --git a/src/test/java/com/android/tools/r8/ir/regalloc/B77240639.java b/src/test/java/com/android/tools/r8/ir/regalloc/B77240639.java
index 440f4f3..28a6fa3 100644
--- a/src/test/java/com/android/tools/r8/ir/regalloc/B77240639.java
+++ b/src/test/java/com/android/tools/r8/ir/regalloc/B77240639.java
@@ -16,7 +16,6 @@
import org.junit.Test;
public class B77240639 extends TestBase {
- @Ignore("b/77240639")
@Test
public void test() throws Exception {
AndroidApp app = compileWithD8(readClasses(TestClass.class));
