1//===- InferFunctionAttrs.cpp - Infer implicit function attributes --------===//
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#include "llvm/Transforms/IPO/InferFunctionAttrs.h"
10#include "llvm/Analysis/TargetLibraryInfo.h"
11#include "llvm/IR/Function.h"
12#include "llvm/IR/LLVMContext.h"
13#include "llvm/IR/Module.h"
14#include "llvm/InitializePasses.h"
15#include "llvm/Support/Debug.h"
16#include "llvm/Support/raw_ostream.h"
17#include "llvm/Transforms/Utils/BuildLibCalls.h"
18using namespace llvm;
19
20#define DEBUG_TYPE "inferattrs"
21
22static bool inferAllPrototypeAttributes(
23    Module &M, function_ref<TargetLibraryInfo &(Function &)> GetTLI) {
24  bool Changed = false;
25
26  for (Function &F : M.functions())
27    // We only infer things using the prototype and the name; we don't need
28    // definitions.
29    if (F.isDeclaration() && !F.hasOptNone())
30      Changed |= inferLibFuncAttributes(F, GetTLI(F));
31
32  return Changed;
33}
34
35PreservedAnalyses InferFunctionAttrsPass::run(Module &M,
36                                              ModuleAnalysisManager &AM) {
37  FunctionAnalysisManager &FAM =
38      AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
39  auto GetTLI = [&FAM](Function &F) -> TargetLibraryInfo & {
40    return FAM.getResult<TargetLibraryAnalysis>(F);
41  };
42
43  if (!inferAllPrototypeAttributes(M, GetTLI))
44    // If we didn't infer anything, preserve all analyses.
45    return PreservedAnalyses::all();
46
47  // Otherwise, we may have changed fundamental function attributes, so clear
48  // out all the passes.
49  return PreservedAnalyses::none();
50}
51
52namespace {
53struct InferFunctionAttrsLegacyPass : public ModulePass {
54  static char ID; // Pass identification, replacement for typeid
55  InferFunctionAttrsLegacyPass() : ModulePass(ID) {
56    initializeInferFunctionAttrsLegacyPassPass(
57        *PassRegistry::getPassRegistry());
58  }
59
60  void getAnalysisUsage(AnalysisUsage &AU) const override {
61    AU.addRequired<TargetLibraryInfoWrapperPass>();
62  }
63
64  bool runOnModule(Module &M) override {
65    if (skipModule(M))
66      return false;
67
68    auto GetTLI = [this](Function &F) -> TargetLibraryInfo & {
69      return this->getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
70    };
71    return inferAllPrototypeAttributes(M, GetTLI);
72  }
73};
74}
75
76char InferFunctionAttrsLegacyPass::ID = 0;
77INITIALIZE_PASS_BEGIN(InferFunctionAttrsLegacyPass, "inferattrs",
78                      "Infer set function attributes", false, false)
79INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
80INITIALIZE_PASS_END(InferFunctionAttrsLegacyPass, "inferattrs",
81                    "Infer set function attributes", false, false)
82
83Pass *llvm::createInferFunctionAttrsLegacyPass() {
84  return new InferFunctionAttrsLegacyPass();
85}
86