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 "VPlanDominatorTree.h"
28 #include "VPlanVerifier.h"
29 
30 namespace llvm {
31 
32 class Loop;
33 class LoopInfo;
34 class VPRegionBlock;
35 class VPlan;
36 class VPlanTestBase;
37 
38 /// Main class to build the VPlan H-CFG for an incoming IR.
39 class VPlanHCFGBuilder {
40   friend VPlanTestBase;
41 
42 private:
43   // The outermost loop of the input loop nest considered for vectorization.
44   Loop *TheLoop;
45 
46   // Loop Info analysis.
47   LoopInfo *LI;
48 
49   // The VPlan that will contain the H-CFG we are building.
50   VPlan &Plan;
51 
52   // VPlan verifier utility.
53   VPlanVerifier Verifier;
54 
55   // Dominator analysis for VPlan plain CFG to be used in the
56   // construction of the H-CFG. This analysis is no longer valid once regions
57   // are introduced.
58   VPDominatorTree VPDomTree;
59 
60   /// Build plain CFG for TheLoop. Return the pre-header VPBasicBlock connected
61   /// to a new VPRegionBlock (TopRegion) enclosing the plain CFG.
62   VPBasicBlock *buildPlainCFG();
63 
64 public:
65   VPlanHCFGBuilder(Loop *Lp, LoopInfo *LI, VPlan &P)
66       : TheLoop(Lp), LI(LI), Plan(P) {}
67 
68   /// Build H-CFG for TheLoop and update Plan accordingly.
69   void buildHierarchicalCFG();
70 };
71 } // namespace llvm
72 
73 #endif // LLVM_TRANSFORMS_VECTORIZE_VPLAN_VPLANHCFGBUILDER_H
74