LiveIntervalAnalysis: findLastUseBefore() must ignore undef uses.

undef uses are no real uses of a register and must be ignored by
findLastUseBefore() so that handleMove() does not produce invalid live
intervals in some cases.

This fixed http://llvm.org/PR28083

llvm-svn: 272446

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/unittests/MI/LiveIntervalTest.cpp b/llvm/unittests/MI/LiveIntervalTest.cpp
index e4567363d39..e0b3d5529af 100644
--- a/llvm/unittests/MI/LiveIntervalTest.cpp
+++ b/llvm/unittests/MI/LiveIntervalTest.cpp
@@ -329,6 +329,30 @@ TEST(LiveIntervalTest, MoveUpValNos) {
   });
 }
 
+TEST(LiveIntervalTest, MoveOverUndefUse0) {
+  // findLastUseBefore() used by handleMoveUp() must ignore undef operands.
+  liveIntervalTest(
+"    %0 = IMPLICIT_DEF\n"
+"    NOOP\n"
+"    NOOP implicit undef %0\n"
+"    %0 = IMPLICIT_DEF implicit %0(tied-def 0)\n",
+  [](MachineFunction &MF, LiveIntervals &LIS) {
+    testHandleMove(MF, LIS, 3, 1);
+  });
+}
+
+TEST(LiveIntervalTest, MoveOverUndefUse1) {
+  // findLastUseBefore() used by handleMoveUp() must ignore undef operands.
+  liveIntervalTest(
+"    %rax = IMPLICIT_DEF\n"
+"    NOOP\n"
+"    NOOP implicit undef %rax\n"
+"    %rax = IMPLICIT_DEF implicit %rax(tied-def 0)\n",
+  [](MachineFunction &MF, LiveIntervals &LIS) {
+    testHandleMove(MF, LIS, 3, 1);
+  });
+}
+
 int main(int argc, char **argv) {
   ::testing::InitGoogleTest(&argc, argv);
   initLLVM();