Missing return on nullptr check

[apach301]

Hi,

I found possible null pointer dereference with Svace static analyzer.

A return statement is missing for nullptr check of variable DI at utils/TableGen/Common/CodeGenDAGPatterns.cpp:

llvm-project/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp

Lines 3393 to 3398 in b2c5e9b

	if (Pat->isLeaf()) {
	DefInit *DI = dyn_cast<DefInit>(Pat->getLeafValue());
	if (!DI)
	I.error("Input $" + Pat->getName() + " must be an identifier!");
	Rec = DI->getDef();
	} else {