[CodeLayout] Refactor std::vector uses, namespace, and EdgeCountT. NFC

* Place types and functions in the llvm::codelayout namespace
* Change EdgeCountT from pair<pair<uint64_t, uint64_t>, uint64_t> to a struct and utilize structured bindings.
  It is not conventional to use the "T" suffix for structure types.
* Remove a redundant copy in ChainT::merge.
* Change {ExtTSPImpl,CDSortImpl}::run to use return value instead of an output parameter
* Rename applyCDSLayout to computeCacheDirectedLayout: (a) avoid rare
  abbreviation "CDS" (cache-directed sort) (b) "compute" is more conventional
  for the specific use case
* Change the parameter types from std::vector to ArrayRef so that
  SmallVector arguments can be used.
* Similarly, rename applyExtTspLayout to computeExtTspLayout.

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D159526

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
index 24f0197..603c0e9 100644
--- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
@@ -3501,7 +3501,7 @@ void MachineBlockPlacement::applyExtTsp() {
 
   auto BlockSizes = std::vector<uint64_t>(F->size());
   auto BlockCounts = std::vector<uint64_t>(F->size());
-  std::vector<EdgeCountT> JumpCounts;
+  std::vector<codelayout::EdgeCount> JumpCounts;
   for (MachineBasicBlock &MBB : *F) {
     // Getting the block frequency.
     BlockFrequency BlockFreq = MBFI->getBlockFreq(&MBB);
@@ -3520,8 +3520,8 @@ void MachineBlockPlacement::applyExtTsp() {
     for (MachineBasicBlock *Succ : MBB.successors()) {
       auto EP = MBPI->getEdgeProbability(&MBB, Succ);
       BlockFrequency JumpFreq = BlockFreq * EP;
-      auto Jump = std::make_pair(BlockIndex[&MBB], BlockIndex[Succ]);
-      JumpCounts.push_back(std::make_pair(Jump, JumpFreq.getFrequency()));
+      JumpCounts.push_back(
+          {BlockIndex[&MBB], BlockIndex[Succ], JumpFreq.getFrequency()});
     }
   }
 
@@ -3534,7 +3534,7 @@ void MachineBlockPlacement::applyExtTsp() {
                        calcExtTspScore(BlockSizes, BlockCounts, JumpCounts)));
 
   // Run the layout algorithm.
-  auto NewOrder = applyExtTspLayout(BlockSizes, BlockCounts, JumpCounts);
+  auto NewOrder = computeExtTspLayout(BlockSizes, BlockCounts, JumpCounts);
   std::vector<const MachineBasicBlock *> NewBlockOrder;
   NewBlockOrder.reserve(F->size());
   for (uint64_t Node : NewOrder) {