[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

1 files changed, 1 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 8998503bc62..3817c80ae8c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1700,8 +1700,7 @@ SelectionDAGBuilder::getEdgeProbability(const MachineBasicBlock *Src,
   if (!BPI) {
     // If BPI is not available, set the default probability as 1 / N, where N is
     // the number of successors.
-    auto SuccSize = std::max<uint32_t>(
-        std::distance(succ_begin(SrcBB), succ_end(SrcBB)), 1);
+    auto SuccSize = std::max<uint32_t>(succ_size(SrcBB), 1);
     return BranchProbability(1, SuccSize);
   }
   return BPI->getEdgeProbability(SrcBB, DstBB);