1//===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
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// This file implements the post-dominator construction algorithms.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Analysis/PostDominators.h"
14#include "llvm/IR/Function.h"
15#include "llvm/IR/Instructions.h"
16#include "llvm/IR/PassManager.h"
17#include "llvm/InitializePasses.h"
18#include "llvm/Pass.h"
19#include "llvm/Support/raw_ostream.h"
20
21using namespace llvm;
22
23#define DEBUG_TYPE "postdomtree"
24
25#ifdef EXPENSIVE_CHECKS
26static constexpr bool ExpensiveChecksEnabled = true;
27#else
28static constexpr bool ExpensiveChecksEnabled = false;
29#endif
30
31//===----------------------------------------------------------------------===//
32// PostDominatorTree Implementation
33//===----------------------------------------------------------------------===//
34
35char PostDominatorTreeWrapperPass::ID = 0;
36
37PostDominatorTreeWrapperPass::PostDominatorTreeWrapperPass()
38 : FunctionPass(ID) {}
39
40INITIALIZE_PASS(PostDominatorTreeWrapperPass, "postdomtree",
41 "Post-Dominator Tree Construction", true, true)
42
43bool PostDominatorTree::invalidate(Function &F, const PreservedAnalyses &PA,
44 FunctionAnalysisManager::Invalidator &) {
45 // Check whether the analysis, all analyses on functions, or the function's
46 // CFG have been preserved.
47 auto PAC = PA.getChecker<PostDominatorTreeAnalysis>();
48 return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
49 PAC.preservedSet<CFGAnalyses>());
50}
51
52bool PostDominatorTree::dominates(const Instruction *I1,
53 const Instruction *I2) const {
54 assert(I1 && I2 && "Expecting valid I1 and I2");
55
56 const BasicBlock *BB1 = I1->getParent();
57 const BasicBlock *BB2 = I2->getParent();
58
59 if (BB1 != BB2)
60 return Base::dominates(A: BB1, B: BB2);
61
62 // PHINodes in a block are unordered.
63 if (isa<PHINode>(Val: I1) && isa<PHINode>(Val: I2))
64 return false;
65
66 // Loop through the basic block until we find I1 or I2.
67 BasicBlock::const_iterator I = BB1->begin();
68 for (; &*I != I1 && &*I != I2; ++I)
69 /*empty*/;
70
71 return &*I == I2;
72}
73
74bool PostDominatorTreeWrapperPass::runOnFunction(Function &F) {
75 DT.recalculate(Func&: F);
76 return false;
77}
78
79void PostDominatorTreeWrapperPass::verifyAnalysis() const {
80 if (VerifyDomInfo)
81 assert(DT.verify(PostDominatorTree::VerificationLevel::Full));
82 else if (ExpensiveChecksEnabled)
83 assert(DT.verify(PostDominatorTree::VerificationLevel::Basic));
84}
85
86void PostDominatorTreeWrapperPass::print(raw_ostream &OS, const Module *) const {
87 DT.print(O&: OS);
88}
89
90FunctionPass* llvm::createPostDomTree() {
91 return new PostDominatorTreeWrapperPass();
92}
93
94AnalysisKey PostDominatorTreeAnalysis::Key;
95
96PostDominatorTree PostDominatorTreeAnalysis::run(Function &F,
97 FunctionAnalysisManager &) {
98 PostDominatorTree PDT(F);
99 return PDT;
100}
101
102PostDominatorTreePrinterPass::PostDominatorTreePrinterPass(raw_ostream &OS)
103 : OS(OS) {}
104
105PreservedAnalyses
106PostDominatorTreePrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
107 OS << "PostDominatorTree for function: " << F.getName() << "\n";
108 AM.getResult<PostDominatorTreeAnalysis>(IR&: F).print(O&: OS);
109
110 return PreservedAnalyses::all();
111}
112