Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0

1 files changed, 80 insertions, 0 deletions

diff --git a/clang-r353983/include/llvm/IR/PredIteratorCache.h b/clang-r353983/include/llvm/IR/PredIteratorCache.h
new file mode 100644
index 00000000..cc835277
--- /dev/null
+++ b/clang-r353983/include/llvm/IR/PredIteratorCache.h
@@ -0,0 +1,80 @@
+//===- PredIteratorCache.h - pred_iterator Cache ----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the PredIteratorCache class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_PREDITERATORCACHE_H
+#define LLVM_IR_PREDITERATORCACHE_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/Support/Allocator.h"
+
+namespace llvm {
+
+/// PredIteratorCache - This class is an extremely trivial cache for
+/// predecessor iterator queries.  This is useful for code that repeatedly
+/// wants the predecessor list for the same blocks.
+class PredIteratorCache {
+  /// BlockToPredsMap - Pointer to null-terminated list.
+  mutable DenseMap<BasicBlock *, BasicBlock **> BlockToPredsMap;
+  mutable DenseMap<BasicBlock *, unsigned> BlockToPredCountMap;
+
+  /// Memory - This is the space that holds cached preds.
+  BumpPtrAllocator Memory;
+
+private:
+  /// GetPreds - Get a cached list for the null-terminated predecessor list of
+  /// the specified block.  This can be used in a loop like this:
+  ///   for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI)
+  ///      use(*PI);
+  /// instead of:
+  /// for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+  BasicBlock **GetPreds(BasicBlock *BB) {
+    BasicBlock **&Entry = BlockToPredsMap[BB];
+    if (Entry)
+      return Entry;
+
+    SmallVector<BasicBlock *, 32> PredCache(pred_begin(BB), pred_end(BB));
+    PredCache.push_back(nullptr); // null terminator.
+
+    BlockToPredCountMap[BB] = PredCache.size() - 1;
+
+    Entry = Memory.Allocate<BasicBlock *>(PredCache.size());
+    std::copy(PredCache.begin(), PredCache.end(), Entry);
+    return Entry;
+  }
+
+  unsigned GetNumPreds(BasicBlock *BB) const {
+    auto Result = BlockToPredCountMap.find(BB);
+    if (Result != BlockToPredCountMap.end())
+      return Result->second;
+    return BlockToPredCountMap[BB] = std::distance(pred_begin(BB), pred_end(BB));
+  }
+
+public:
+  size_t size(BasicBlock *BB) const { return GetNumPreds(BB); }
+  ArrayRef<BasicBlock *> get(BasicBlock *BB) {
+    return makeArrayRef(GetPreds(BB), GetNumPreds(BB));
+  }
+
+  /// clear - Remove all information.
+  void clear() {
+    BlockToPredsMap.clear();
+    BlockToPredCountMap.clear();
+    Memory.Reset();
+  }
+};
+
+} // end namespace llvm
+
+#endif