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/Transforms/InstCombine/InstCombinePHI.cpp b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
index 6983a90..794263a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -511,7 +511,7 @@
   if (!PN->hasOneUse()) return false;
 
   // Remember this node, and if we find the cycle, return.
-  if (!PotentiallyDeadPHIs.insert(PN))
+  if (!PotentiallyDeadPHIs.insert(PN).second)
     return true;
 
   // Don't scan crazily complex things.
@@ -530,7 +530,7 @@
 static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
                            SmallPtrSetImpl<PHINode*> &ValueEqualPHIs) {
   // See if we already saw this PHI node.
-  if (!ValueEqualPHIs.insert(PN))
+  if (!ValueEqualPHIs.insert(PN).second)
     return true;
 
   // Don't scan crazily complex things.
@@ -654,7 +654,7 @@
 
       // If the user is a PHI, inspect its uses recursively.
       if (PHINode *UserPN = dyn_cast<PHINode>(UserI)) {
-        if (PHIsInspected.insert(UserPN))
+        if (PHIsInspected.insert(UserPN).second)
           PHIsToSlice.push_back(UserPN);
         continue;
       }