(store (op (load ...))) folding problem. In the generated matching code,

Chain is initially set to the chain operand of store node, when it reaches
load, if it matches the load then Chain is set to the chain operand of the
load.

However, if the matching code that follows this fails, isel moves on to the
next pattern but it does not restore Chain to the chain operand of the store.
So when it tries to match the next store / op / load pattern it would fail on
the Chain == load.getOperand(0) test.

The solution is for each chain operand to get a unique name. e.g. Chain10.

llvm-svn: 25931