Improve detection of lifetime holes.

The check concluding that the next use was in a successor
was too conservative: two blocks following each other
in terms of liveness are not necessarily predecessor/sucessor.

Change-Id: Ideec98046c812aa5fb63781141b5fde24c706d6d

1 files changed, 47 insertions, 0 deletions

diff --git a/compiler/optimizing/liveness_test.cc b/compiler/optimizing/liveness_test.cc
index 84b2e33ee7..2d861696bb 100644
--- a/compiler/optimizing/liveness_test.cc
+++ b/compiler/optimizing/liveness_test.cc
@@ -546,4 +546,51 @@ TEST(LivenessTest, Loop7) {
   TestCode(data, expected);
 }
 
+TEST(LivenessTest, Loop8) {
+  // var a = 0;
+  // while (a == a) {
+  //   a = a + a;
+  // }
+  // return a;
+  //
+  // We want to test that the ins of the loop exit
+  // does contain the phi.
+  // Bitsets are made of:
+  // (constant0, phi, add)
+  const char* expected =
+    "Block 0\n"
+    "  live in: (000)\n"
+    "  live out: (100)\n"
+    "  kill: (100)\n"
+    "Block 1\n"  // pre loop header
+    "  live in: (100)\n"
+    "  live out: (000)\n"
+    "  kill: (000)\n"
+    "Block 2\n"  // loop header
+    "  live in: (000)\n"
+    "  live out: (010)\n"
+    "  kill: (010)\n"
+    "Block 3\n"  // back edge
+    "  live in: (010)\n"
+    "  live out: (000)\n"
+    "  kill: (001)\n"
+    "Block 4\n"  // return block
+    "  live in: (010)\n"
+    "  live out: (000)\n"
+    "  kill: (000)\n"
+    "Block 5\n"  // exit block
+    "  live in: (000)\n"
+    "  live out: (000)\n"
+    "  kill: (000)\n";
+
+  const uint16_t data[] = ONE_REGISTER_CODE_ITEM(
+    Instruction::CONST_4 | 0 | 0,
+    Instruction::IF_EQ, 6,
+    Instruction::ADD_INT, 0, 0,
+    Instruction::GOTO | 0xFB00,
+    Instruction::RETURN | 0 << 8);
+
+  TestCode(data, expected);
+}
+
 }  // namespace art