Revert the SelectionDAG optimization that makes
it impossible to create a MERGE_VALUES node with
only one result: sometimes it is useful to be able
to create a node with only one result out of one of
the results of a node with more than one result, for
example because the new node will eventually be used
to replace a one-result node using ReplaceAllUsesWith,
cf X86TargetLowering::ExpandFP_TO_SINT. On the other
hand, most users of MERGE_VALUES don't need this and
for them the optimization was valuable. So add a new
utility method getMergeValues for creating MERGE_VALUES
nodes which by default performs the optimization.
Change almost everywhere to use getMergeValues (and
tidy some stuff up at the same time).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52893 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 023be5c..6456fa3 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1983,8 +1983,7 @@
unsigned OpOpcode = Operand.Val->getOpcode();
switch (Opcode) {
case ISD::TokenFactor:
- case ISD::MERGE_VALUES:
- return Operand; // Factor or merge of one node? No need.
+ return Operand; // Factor of one node? No need.
case ISD::FP_ROUND: assert(0 && "Invalid method to make FP_ROUND node");
case ISD::FP_EXTEND:
assert(VT.isFloatingPoint() &&