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      1 //===-- VPlanHCFGBuilder.h --------------------------------------*- C++ -*-===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 ///
      9 /// \file
     10 /// This file defines the VPlanHCFGBuilder class which contains the public
     11 /// interface (buildHierarchicalCFG) to build a VPlan-based Hierarchical CFG
     12 /// (H-CFG) for an incoming IR.
     13 ///
     14 /// A H-CFG in VPlan is a control-flow graph whose nodes are VPBasicBlocks
     15 /// and/or VPRegionBlocks (i.e., other H-CFGs). The outermost H-CFG of a VPlan
     16 /// consists of a VPRegionBlock, denoted Top Region, which encloses any other
     17 /// VPBlockBase in the H-CFG. This guarantees that any VPBlockBase in the H-CFG
     18 /// other than the Top Region will have a parent VPRegionBlock and allows us
     19 /// to easily add more nodes before/after the main vector loop (such as the
     20 /// reduction epilogue).
     21 ///
     22 //===----------------------------------------------------------------------===//
     23 
     24 #ifndef LLVM_TRANSFORMS_VECTORIZE_VPLAN_VPLANHCFGBUILDER_H
     25 #define LLVM_TRANSFORMS_VECTORIZE_VPLAN_VPLANHCFGBUILDER_H
     26 
     27 #include "VPlan.h"
     28 #include "VPlanDominatorTree.h"
     29 #include "VPlanVerifier.h"
     30 
     31 namespace llvm {
     32 
     33 class Loop;
     34 class VPlanTestBase;
     35 
     36 /// Main class to build the VPlan H-CFG for an incoming IR.
     37 class VPlanHCFGBuilder {
     38   friend VPlanTestBase;
     39 
     40 private:
     41   // The outermost loop of the input loop nest considered for vectorization.
     42   Loop *TheLoop;
     43 
     44   // Loop Info analysis.
     45   LoopInfo *LI;
     46 
     47   // The VPlan that will contain the H-CFG we are building.
     48   VPlan &Plan;
     49 
     50   // VPlan verifier utility.
     51   VPlanVerifier Verifier;
     52 
     53   // Dominator analysis for VPlan plain CFG to be used in the
     54   // construction of the H-CFG. This analysis is no longer valid once regions
     55   // are introduced.
     56   VPDominatorTree VPDomTree;
     57 
     58   /// Build plain CFG for TheLoop. Return a new VPRegionBlock (TopRegion)
     59   /// enclosing the plain CFG.
     60   VPRegionBlock *buildPlainCFG();
     61 
     62 public:
     63   VPlanHCFGBuilder(Loop *Lp, LoopInfo *LI, VPlan &P)
     64       : TheLoop(Lp), LI(LI), Plan(P) {}
     65 
     66   /// Build H-CFG for TheLoop and update Plan accordingly.
     67   void buildHierarchicalCFG();
     68 };
     69 } // namespace llvm
     70 
     71 #endif // LLVM_TRANSFORMS_VECTORIZE_VPLAN_VPLANHCFGBUILDER_H
     72