Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>

This is to be consistent with StringSet and ultimately with the standard
library's associative container insert function.

This lead to updating SmallSet::insert to return pair<iterator, bool>,
and then to update SmallPtrSet::insert to return pair<iterator, bool>,
and then to update all the existing users of those functions...

llvm-svn: 222334
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index e8e4da5..e93bdaf 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -7649,7 +7649,7 @@
   // nodes just above the top-level loads and token factors.
   while (!Queue.empty()) {
     SDNode *ChainNext = Queue.pop_back_val();
-    if (!Visited.insert(ChainNext))
+    if (!Visited.insert(ChainNext).second)
       continue;
 
     if (MemSDNode *ChainLD = dyn_cast<MemSDNode>(ChainNext)) {
@@ -7680,7 +7680,7 @@
        
     while (!Queue.empty()) {
       SDNode *LoadRoot = Queue.pop_back_val();
-      if (!Visited.insert(LoadRoot))
+      if (!Visited.insert(LoadRoot).second)
         continue;
 
       if (MemSDNode *ChainLD = dyn_cast<MemSDNode>(LoadRoot))
@@ -7810,7 +7810,7 @@
     SDValue BinOp = BinOps.back();
     BinOps.pop_back();
 
-    if (!Visited.insert(BinOp.getNode()))
+    if (!Visited.insert(BinOp.getNode()).second)
       continue;
 
     PromOps.push_back(BinOp);
@@ -8024,7 +8024,7 @@
     SDValue BinOp = BinOps.back();
     BinOps.pop_back();
 
-    if (!Visited.insert(BinOp.getNode()))
+    if (!Visited.insert(BinOp.getNode()).second)
       continue;
 
     PromOps.push_back(BinOp);