Relax too strong DCHECK.

There may be a lifetime hole in the interval, which means the interval
does not cover the given position.

bug:27617589

Change-Id: Iabd2b3d82936bed498f87be1a01760210954f97e

5 files changed, 111 insertions, 1 deletions

diff --git a/compiler/optimizing/register_allocator.cc b/compiler/optimizing/register_allocator.cc
index b8d76b912e..48b7a97b72 100644
--- a/compiler/optimizing/register_allocator.cc
+++ b/compiler/optimizing/register_allocator.cc
@@ -1919,7 +1919,13 @@ void RegisterAllocator::Resolve() {
         BitVector* live = liveness_.GetLiveInSet(*block);
         for (uint32_t idx : live->Indexes()) {
           LiveInterval* interval = liveness_.GetInstructionFromSsaIndex(idx)->GetLiveInterval();
-          DCHECK(!interval->GetSiblingAt(block->GetLifetimeStart())->HasRegister());
+          LiveInterval* sibling = interval->GetSiblingAt(block->GetLifetimeStart());
+          // `GetSiblingAt` returns the sibling that contains a position, but there could be
+          // a lifetime hole in it. `CoversSlow` returns whether the interval is live at that
+          // position.
+          if (sibling->CoversSlow(block->GetLifetimeStart())) {
+            DCHECK(!sibling->HasRegister());
+          }
         }
       }
     } else {
diff --git a/test/588-checker-irreducible-lifetime-hole/expected.txt b/test/588-checker-irreducible-lifetime-hole/expected.txt
new file mode 100644
index 0000000000..d81cc0710e
--- /dev/null
+++ b/test/588-checker-irreducible-lifetime-hole/expected.txt
@@ -0,0 +1 @@
+42
diff --git a/test/588-checker-irreducible-lifetime-hole/info.txt b/test/588-checker-irreducible-lifetime-hole/info.txt
new file mode 100644
index 0000000000..a2861a9fd5
--- /dev/null
+++ b/test/588-checker-irreducible-lifetime-hole/info.txt
@@ -0,0 +1,3 @@
+Regression test for optimizing that used to have a too
+strong DCHECK in the presence of a combination of irreducible loops
+and try/catch.
diff --git a/test/588-checker-irreducible-lifetime-hole/smali/IrreducibleLoop.smali b/test/588-checker-irreducible-lifetime-hole/smali/IrreducibleLoop.smali
new file mode 100644
index 0000000000..207c77ef55
--- /dev/null
+++ b/test/588-checker-irreducible-lifetime-hole/smali/IrreducibleLoop.smali
@@ -0,0 +1,71 @@
+# Copyright (C) 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+.class public LIrreducibleLoop;
+
+.super Ljava/lang/Object;
+
+## CHECK-START-X86: int IrreducibleLoop.simpleLoop(int) dead_code_elimination (before)
+## CHECK-DAG: <<Method:(i|j)\d+>> CurrentMethod
+## CHECK-DAG: <<Constant:i\d+>>   IntConstant 42
+## CHECK-DAG:                     Goto irreducible:true
+## CHECK-DAG:                     InvokeStaticOrDirect [<<Constant>>,<<Method>>] loop:none
+## CHECK-DAG:                     InvokeStaticOrDirect [{{i\d+}},<<Method>>] loop:none
+.method public static simpleLoop(I)I
+   .registers 3
+   const/16 v0, 42
+   invoke-static {v0}, LIrreducibleLoop;->$noinline$m(I)V
+   if-eqz p0, :b22
+   goto :b34
+
+   :b34
+   goto :b20
+
+   :b20
+   if-nez p0, :b45
+   goto :b46
+
+   :b46
+   goto :b21
+
+   :b21
+   goto :b34
+
+   :b22
+   :try_start
+   div-int v0, v0, v0
+   :try_end
+   .catchall {:try_start .. :try_end} :b34
+   goto :b20
+
+   :b45
+   invoke-static {v0}, LIrreducibleLoop;->$noinline$m(I)V
+   goto :b26
+
+   :b26
+   return v0
+.end method
+
+.method public static $noinline$m(I)V
+   .registers 3
+   const/16 v0, 0
+   sget-boolean v1,LIrreducibleLoop;->doThrow:Z
+   if-eqz v1, :exit
+   # Prevent inlining.
+   throw v0
+   :exit
+   return-void
+.end method
+
+.field public static doThrow:Z
diff --git a/test/588-checker-irreducible-lifetime-hole/src/Main.java b/test/588-checker-irreducible-lifetime-hole/src/Main.java
new file mode 100644
index 0000000000..94e3357e5d
--- /dev/null
+++ b/test/588-checker-irreducible-lifetime-hole/src/Main.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.lang.reflect.Method;
+
+public class Main {
+  // Workaround for b/18051191.
+  class InnerClass {}
+
+  public static void main(String[] args) throws Exception {
+    Class<?> c = Class.forName("IrreducibleLoop");
+    Method m = c.getMethod("simpleLoop", int.class);
+    Object[] arguments = { 42 };
+    System.out.println(m.invoke(null, arguments));
+  }
+}