lib/Transforms/IPO/InferFunctionAttrs.cpp

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