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

1 files changed, 100 insertions, 0 deletions

diff --git a/clang-r353983/include/llvm/Analysis/IteratedDominanceFrontier.h b/clang-r353983/include/llvm/Analysis/IteratedDominanceFrontier.h
new file mode 100644
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+++ b/clang-r353983/include/llvm/Analysis/IteratedDominanceFrontier.h
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+//===- IteratedDominanceFrontier.h - Calculate IDF --------------*- 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// Compute iterated dominance frontiers using a linear time algorithm.
+///
+/// The algorithm used here is based on:
+///
+///   Sreedhar and Gao. A linear time algorithm for placing phi-nodes.
+///   In Proceedings of the 22nd ACM SIGPLAN-SIGACT Symposium on Principles of
+///   Programming Languages
+///   POPL '95. ACM, New York, NY, 62-73.
+///
+/// It has been modified to not explicitly use the DJ graph data structure and
+/// to directly compute pruned SSA using per-variable liveness information.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_IDF_H
+#define LLVM_ANALYSIS_IDF_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFGDiff.h"
+#include "llvm/IR/Dominators.h"
+
+namespace llvm {
+
+/// Determine the iterated dominance frontier, given a set of defining
+/// blocks, and optionally, a set of live-in blocks.
+///
+/// In turn, the results can be used to place phi nodes.
+///
+/// This algorithm is a linear time computation of Iterated Dominance Frontiers,
+/// pruned using the live-in set.
+/// By default, liveness is not used to prune the IDF computation.
+/// The template parameters should be either BasicBlock* or Inverse<BasicBlock
+/// *>, depending on if you want the forward or reverse IDF.
+template <class NodeTy, bool IsPostDom>
+class IDFCalculator {
+ public:
+   IDFCalculator(DominatorTreeBase<BasicBlock, IsPostDom> &DT)
+       : DT(DT), GD(nullptr), useLiveIn(false) {}
+
+   IDFCalculator(DominatorTreeBase<BasicBlock, IsPostDom> &DT,
+                 const GraphDiff<BasicBlock *, IsPostDom> *GD)
+       : DT(DT), GD(GD), useLiveIn(false) {}
+
+   /// Give the IDF calculator the set of blocks in which the value is
+   /// defined.  This is equivalent to the set of starting blocks it should be
+   /// calculating the IDF for (though later gets pruned based on liveness).
+   ///
+   /// Note: This set *must* live for the entire lifetime of the IDF calculator.
+   void setDefiningBlocks(const SmallPtrSetImpl<BasicBlock *> &Blocks) {
+     DefBlocks = &Blocks;
+   }
+
+  /// Give the IDF calculator the set of blocks in which the value is
+  /// live on entry to the block.   This is used to prune the IDF calculation to
+  /// not include blocks where any phi insertion would be dead.
+  ///
+  /// Note: This set *must* live for the entire lifetime of the IDF calculator.
+
+  void setLiveInBlocks(const SmallPtrSetImpl<BasicBlock *> &Blocks) {
+    LiveInBlocks = &Blocks;
+    useLiveIn = true;
+  }
+
+  /// Reset the live-in block set to be empty, and tell the IDF
+  /// calculator to not use liveness anymore.
+  void resetLiveInBlocks() {
+    LiveInBlocks = nullptr;
+    useLiveIn = false;
+  }
+
+  /// Calculate iterated dominance frontiers
+  ///
+  /// This uses the linear-time phi algorithm based on DJ-graphs mentioned in
+  /// the file-level comment.  It performs DF->IDF pruning using the live-in
+  /// set, to avoid computing the IDF for blocks where an inserted PHI node
+  /// would be dead.
+  void calculate(SmallVectorImpl<BasicBlock *> &IDFBlocks);
+
+private:
+ DominatorTreeBase<BasicBlock, IsPostDom> &DT;
+ const GraphDiff<BasicBlock *, IsPostDom> *GD;
+ bool useLiveIn;
+ const SmallPtrSetImpl<BasicBlock *> *LiveInBlocks;
+ const SmallPtrSetImpl<BasicBlock *> *DefBlocks;
+};
+typedef IDFCalculator<BasicBlock *, false> ForwardIDFCalculator;
+typedef IDFCalculator<Inverse<BasicBlock *>, true> ReverseIDFCalculator;
+}
+#endif