[STLExtras] Add distance() for ranges, pred_size(), and succ_size()

This commit adds a wrapper for std::distance() which works with ranges.
As it would be a common case to write `distance(predecessors(BB))`, this
also introduces `pred_size()` and `succ_size()` helpers to make that
easier to write.

Differential Revision: https://reviews.llvm.org/D46668

llvm-svn: 332057

4 files changed, 7 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Scalar/GVNHoist.cpp b/llvm/lib/Transforms/Scalar/GVNHoist.cpp
index 663375b1416..a8b33d19d17 100644
--- a/llvm/lib/Transforms/Scalar/GVNHoist.cpp
+++ b/llvm/lib/Transforms/Scalar/GVNHoist.cpp
@@ -578,7 +578,7 @@ private:
 
   // Returns true when the values are flowing out to each edge.
   bool valueAnticipable(CHIArgs C, TerminatorInst *TI) const {
-    if (TI->getNumSuccessors() > (unsigned)std::distance(C.begin(), C.end()))
+    if (TI->getNumSuccessors() > (unsigned)distance(C))
       return false; // Not enough args in this CHI.
 
     for (auto CHI : C) {
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 4e02fc7da20..362ef73aa9b 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -945,10 +945,10 @@ static unsigned GetBestDestForJumpOnUndef(BasicBlock *BB) {
   unsigned MinSucc = 0;
   BasicBlock *TestBB = BBTerm->getSuccessor(MinSucc);
   // Compute the successor with the minimum number of predecessors.
-  unsigned MinNumPreds = std::distance(pred_begin(TestBB), pred_end(TestBB));
+  unsigned MinNumPreds = pred_size(TestBB);
   for (unsigned i = 1, e = BBTerm->getNumSuccessors(); i != e; ++i) {
     TestBB = BBTerm->getSuccessor(i);
-    unsigned NumPreds = std::distance(pred_begin(TestBB), pred_end(TestBB));
+    unsigned NumPreds = pred_size(TestBB);
     if (NumPreds < MinNumPreds) {
       MinSucc = i;
       MinNumPreds = NumPreds;
@@ -1648,8 +1648,7 @@ bool JumpThreadingPass::ProcessThreadableEdges(Value *Cond, BasicBlock *BB,
   // not thread. By doing so, we do not need to duplicate the current block and
   // also miss potential opportunities in case we dont/cant duplicate.
   if (OnlyDest && OnlyDest != MultipleDestSentinel) {
-    if (PredWithKnownDest ==
-        (size_t)std::distance(pred_begin(BB), pred_end(BB))) {
+    if (PredWithKnownDest == (size_t)pred_size(BB)) {
       bool SeenFirstBranchToOnlyDest = false;
       std::vector <DominatorTree::UpdateType> Updates;
       Updates.reserve(BB->getTerminator()->getNumSuccessors() - 1);
diff --git a/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp b/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
index 35e341f39a7..07d45144758 100644
--- a/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
+++ b/llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
@@ -285,8 +285,7 @@ bool MergedLoadStoreMotion::mergeStores(BasicBlock *T) {
     return false; // No. More than 2 predecessors.
 
   // #Instructions in Succ1 for Compile Time Control
-  int Size1 = std::distance(Pred1->instructionsWithoutDebug().begin(),
-                            Pred1->instructionsWithoutDebug().end());
+  int Size1 = distance(Pred1->instructionsWithoutDebug());
   int NStores = 0;
 
   for (BasicBlock::reverse_iterator RBI = Pred0->rbegin(), RBE = Pred0->rend();
diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index a97f6517cd5..bf851ef2e71 100644
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -966,7 +966,7 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &Cache) {
     auto MakeBaseInstPlaceholder = [](Instruction *I) -> Instruction* {
       if (isa<PHINode>(I)) {
         BasicBlock *BB = I->getParent();
-        int NumPreds = std::distance(pred_begin(BB), pred_end(BB));
+        int NumPreds = pred_size(BB);
         assert(NumPreds > 0 && "how did we reach here");
         std::string Name = suffixed_name_or(I, ".base", "base_phi");
         return PHINode::Create(I->getType(), NumPreds, Name, I);
@@ -1811,7 +1811,7 @@ static void relocationViaAlloca(
 
     SmallVector<Instruction *, 20> Uses;
     // PERF: trade a linear scan for repeated reallocation
-    Uses.reserve(std::distance(Def->user_begin(), Def->user_end()));
+    Uses.reserve(Def->getNumUses());
     for (User *U : Def->users()) {
       if (!isa<ConstantExpr>(U)) {
         // If the def has a ConstantExpr use, then the def is either a