LCOV - code coverage report
Current view: top level - include/llvm/Analysis - IteratedDominanceFrontier.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 5 48 10.4 %
Date: 2018-10-17 09:37:48 Functions: 0 10 0.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- IteratedDominanceFrontier.h - Calculate IDF --------------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : /// Compute iterated dominance frontiers using a linear time algorithm.
      11             : ///
      12             : /// The algorithm used here is based on:
      13             : ///
      14             : ///   Sreedhar and Gao. A linear time algorithm for placing phi-nodes.
      15             : ///   In Proceedings of the 22nd ACM SIGPLAN-SIGACT Symposium on Principles of
      16             : ///   Programming Languages
      17             : ///   POPL '95. ACM, New York, NY, 62-73.
      18             : ///
      19             : /// It has been modified to not explicitly use the DJ graph data structure and
      20             : /// to directly compute pruned SSA using per-variable liveness information.
      21             : //
      22             : //===----------------------------------------------------------------------===//
      23             : 
      24             : #ifndef LLVM_ANALYSIS_IDF_H
      25             : #define LLVM_ANALYSIS_IDF_H
      26             : 
      27             : #include "llvm/ADT/DenseMap.h"
      28             : #include "llvm/ADT/SmallPtrSet.h"
      29             : #include "llvm/ADT/SmallVector.h"
      30             : #include "llvm/IR/BasicBlock.h"
      31             : #include "llvm/IR/CFGDiff.h"
      32             : #include "llvm/IR/Dominators.h"
      33             : 
      34             : namespace llvm {
      35             : 
      36             : /// Determine the iterated dominance frontier, given a set of defining
      37             : /// blocks, and optionally, a set of live-in blocks.
      38             : ///
      39             : /// In turn, the results can be used to place phi nodes.
      40             : ///
      41             : /// This algorithm is a linear time computation of Iterated Dominance Frontiers,
      42             : /// pruned using the live-in set.
      43             : /// By default, liveness is not used to prune the IDF computation.
      44             : /// The template parameters should be either BasicBlock* or Inverse<BasicBlock
      45             : /// *>, depending on if you want the forward or reverse IDF.
      46             : template <class NodeTy, bool IsPostDom>
      47             : class IDFCalculator {
      48             :  public:
      49      104231 :    IDFCalculator(DominatorTreeBase<BasicBlock, IsPostDom> &DT)
      50      104231 :        : DT(DT), GD(nullptr), useLiveIn(false) {}
      51           0 : 
      52           0 :    IDFCalculator(DominatorTreeBase<BasicBlock, IsPostDom> &DT,
      53           0 :                  const GraphDiff<BasicBlock *, IsPostDom> *GD)
      54           0 :        : DT(DT), GD(GD), useLiveIn(false) {}
      55             : 
      56           0 :    /// Give the IDF calculator the set of blocks in which the value is
      57             :    /// defined.  This is equivalent to the set of starting blocks it should be
      58           0 :    /// calculating the IDF for (though later gets pruned based on liveness).
      59           0 :    ///
      60             :    /// Note: This set *must* live for the entire lifetime of the IDF calculator.
      61           0 :    void setDefiningBlocks(const SmallPtrSetImpl<BasicBlock *> &Blocks) {
      62       64239 :      DefBlocks = &Blocks;
      63           0 :    }
      64           0 : 
      65             :   /// Give the IDF calculator the set of blocks in which the value is
      66             :   /// live on entry to the block.   This is used to prune the IDF calculation to
      67             :   /// not include blocks where any phi insertion would be dead.
      68             :   ///
      69             :   /// Note: This set *must* live for the entire lifetime of the IDF calculator.
      70             : 
      71           0 :   void setLiveInBlocks(const SmallPtrSetImpl<BasicBlock *> &Blocks) {
      72       19476 :     LiveInBlocks = &Blocks;
      73       19476 :     useLiveIn = true;
      74           0 :   }
      75           0 : 
      76           0 :   /// Reset the live-in block set to be empty, and tell the IDF
      77           0 :   /// calculator to not use liveness anymore.
      78           0 :   void resetLiveInBlocks() {
      79           0 :     LiveInBlocks = nullptr;
      80           0 :     useLiveIn = false;
      81           0 :   }
      82             : 
      83             :   /// Calculate iterated dominance frontiers
      84             :   ///
      85             :   /// This uses the linear-time phi algorithm based on DJ-graphs mentioned in
      86             :   /// the file-level comment.  It performs DF->IDF pruning using the live-in
      87           0 :   /// set, to avoid computing the IDF for blocks where an inserted PHI node
      88           0 :   /// would be dead.
      89           0 :   void calculate(SmallVectorImpl<BasicBlock *> &IDFBlocks);
      90           0 : 
      91           0 : private:
      92           0 :  DominatorTreeBase<BasicBlock, IsPostDom> &DT;
      93           0 :  const GraphDiff<BasicBlock *, IsPostDom> *GD;
      94           0 :  bool useLiveIn;
      95           0 :  const SmallPtrSetImpl<BasicBlock *> *LiveInBlocks;
      96           0 :  const SmallPtrSetImpl<BasicBlock *> *DefBlocks;
      97           0 : };
      98           0 : typedef IDFCalculator<BasicBlock *, false> ForwardIDFCalculator;
      99             : typedef IDFCalculator<Inverse<BasicBlock *>, true> ReverseIDFCalculator;
     100             : }
     101             : #endif

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