CheckTailCallReturnConstraints is missing a check on the

incomming chain of the RETURN node. The incomming chain must
be the outgoing chain of the CALL node. This causes the
backend to identify tail calls that are not tail calls. This
patch fixes this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73387 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index ab4cd51..134a859 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2584,8 +2584,12 @@ bool TargetLowering::CheckTailCallReturnConstraints(CallSDNode *TheCall,
   // Check that operand of the RET node sources from the CALL node. The RET node
   // has at least two operands. Operand 0 holds the chain. Operand 1 holds the
   // value.
+  // Also we need to check that there is no code in between the call and the
+  // return. Hence we also check that the incomming chain to the return sources
+  // from the outgoing chain of the call.
   if (NumOps > 1 &&
-      IgnoreHarmlessInstructions(Ret.getOperand(1)) == SDValue(TheCall,0))
+      IgnoreHarmlessInstructions(Ret.getOperand(1)) == SDValue(TheCall,0) &&
+      Ret.getOperand(0) == SDValue(TheCall, TheCall->getNumValues()-1))
     return true;
   // void return: The RET node  has the chain result value of the CALL node as
   // input.