ScheduleDAGInstrs: In functions with tail calls PseudoSourceValues are not non-aliasing distinct objects

The code that builds the dependence graph assumes that two PseudoSourceValues
don't alias. In a tail calling function two FixedStackObjects might refer to the
same location. Worse 'immutable' fixed stack objects like function arguments are
not immutable and will be clobbered.

Change this so that a load from a FixedStackObject is not invariant in a tail
calling function and don't return a PseudoSourceValue for an instruction in tail
calling functions when building the dependence graph so that we handle function
arguments conservatively.

Fix for PR23459.

rdar://20740035

llvm-svn: 236916

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
index 9055e7ee532..ed5676c1fbb 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
@@ -637,8 +637,10 @@ HexagonTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   if (InFlag.getNode())
     Ops.push_back(InFlag);
 
-  if (isTailCall)
+  if (isTailCall) {
+    MF.getFrameInfo()->setHasTailCall();
     return DAG.getNode(HexagonISD::TC_RETURN, dl, NodeTys, Ops);
+  }
 
   int OpCode = doesNotReturn ? HexagonISD::CALLv3nr : HexagonISD::CALLv3;
   Chain = DAG.getNode(OpCode, dl, NodeTys, Ops);