1//===- Inliner.h - Inliner pass and infrastructure --------------*- 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#ifndef LLVM_TRANSFORMS_IPO_INLINER_H
10#define LLVM_TRANSFORMS_IPO_INLINER_H
11
12#include "llvm/Analysis/CGSCCPassManager.h"
13#include "llvm/Analysis/CallGraphSCCPass.h"
14#include "llvm/Analysis/InlineCost.h"
15#include "llvm/Analysis/LazyCallGraph.h"
16#include "llvm/IR/CallSite.h"
17#include "llvm/IR/PassManager.h"
18#include "llvm/Transforms/Utils/ImportedFunctionsInliningStatistics.h"
19#include <utility>
20
21namespace llvm {
22
23class AssumptionCacheTracker;
24class CallGraph;
25class ProfileSummaryInfo;
26
27/// This class contains all of the helper code which is used to perform the
28/// inlining operations that do not depend on the policy. It contains the core
29/// bottom-up inlining infrastructure that specific inliner passes use.
30struct LegacyInlinerBase : public CallGraphSCCPass {
31  explicit LegacyInlinerBase(char &ID);
32  explicit LegacyInlinerBase(char &ID, bool InsertLifetime);
33
34  /// For this class, we declare that we require and preserve the call graph.
35  /// If the derived class implements this method, it should always explicitly
36  /// call the implementation here.
37  void getAnalysisUsage(AnalysisUsage &Info) const override;
38
39  bool doInitialization(CallGraph &CG) override;
40
41  /// Main run interface method, this implements the interface required by the
42  /// Pass class.
43  bool runOnSCC(CallGraphSCC &SCC) override;
44
45  using llvm::Pass::doFinalization;
46
47  /// Remove now-dead linkonce functions at the end of processing to avoid
48  /// breaking the SCC traversal.
49  bool doFinalization(CallGraph &CG) override;
50
51  /// This method must be implemented by the subclass to determine the cost of
52  /// inlining the specified call site.  If the cost returned is greater than
53  /// the current inline threshold, the call site is not inlined.
54  virtual InlineCost getInlineCost(CallSite CS) = 0;
55
56  /// Remove dead functions.
57  ///
58  /// This also includes a hack in the form of the 'AlwaysInlineOnly' flag
59  /// which restricts it to deleting functions with an 'AlwaysInline'
60  /// attribute. This is useful for the InlineAlways pass that only wants to
61  /// deal with that subset of the functions.
62  bool removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly = false);
63
64  /// This function performs the main work of the pass.  The default of
65  /// Inlinter::runOnSCC() calls skipSCC() before calling this method, but
66  /// derived classes which cannot be skipped can override that method and call
67  /// this function unconditionally.
68  bool inlineCalls(CallGraphSCC &SCC);
69
70private:
71  // Insert @llvm.lifetime intrinsics.
72  bool InsertLifetime = true;
73
74protected:
75  AssumptionCacheTracker *ACT;
76  ProfileSummaryInfo *PSI;
77  ImportedFunctionsInliningStatistics ImportedFunctionsStats;
78};
79
80/// The inliner pass for the new pass manager.
81///
82/// This pass wires together the inlining utilities and the inline cost
83/// analysis into a CGSCC pass. It considers every call in every function in
84/// the SCC and tries to inline if profitable. It can be tuned with a number of
85/// parameters to control what cost model is used and what tradeoffs are made
86/// when making the decision.
87///
88/// It should be noted that the legacy inliners do considerably more than this
89/// inliner pass does. They provide logic for manually merging allocas, and
90/// doing considerable DCE including the DCE of dead functions. This pass makes
91/// every attempt to be simpler. DCE of functions requires complex reasoning
92/// about comdat groups, etc. Instead, it is expected that other more focused
93/// passes be composed to achieve the same end result.
94class InlinerPass : public PassInfoMixin<InlinerPass> {
95public:
96  InlinerPass(InlineParams Params = getInlineParams())
97      : Params(std::move(Params)) {}
98  ~InlinerPass();
99  InlinerPass(InlinerPass &&Arg)
100      : Params(std::move(Arg.Params)),
101        ImportedFunctionsStats(std::move(Arg.ImportedFunctionsStats)) {}
102
103  PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
104                        LazyCallGraph &CG, CGSCCUpdateResult &UR);
105
106private:
107  InlineParams Params;
108  std::unique_ptr<ImportedFunctionsInliningStatistics> ImportedFunctionsStats;
109};
110
111} // end namespace llvm
112
113#endif // LLVM_TRANSFORMS_IPO_INLINER_H
114