[X86,ISEL] Fix X86 increment chain dependence calculation

Merging Load-add-store pattern into a increment op previously dropped
the load's chain from the instructions dependence if the store is
chained to a TokenFactor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293892 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 8ab4c0616880c6ebf3bb43d0b96dac5505640ef6..7f08d2dea9dc6f3e4140e965c192432bfa282ed2 100644 (file)
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -1905,6 +1905,8 @@ static bool isLoadIncOrDecStore(StoreSDNode *StoreNode, unsigned Opc,
       SDValue Op = Chain.getOperand(i);
       if (Op == Load.getValue(1)) {
         ChainCheck = true;
+        // Drop Load, but keep its chain. No cycle check necessary.
+        ChainOps.push_back(Load.getOperand(0));
         continue;
       }