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/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index b1c0b85e500..a3743d452e0 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -1847,8 +1847,10 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
     Ops.push_back(InFlag);
 
   SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
-  if (isTailCall)
+  if (isTailCall) {
+    MF.getFrameInfo()->setHasTailCall();
     return DAG.getNode(ARMISD::TC_RETURN, dl, NodeTys, Ops);
+  }
 
   // Returns a chain and a flag for retval copy to use.
   Chain = DAG.getNode(CallOpc, dl, NodeTys, Ops);