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(Module &M,
  22                                         const TargetLibraryInfo &TLI) {
  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, TLI);
  30
  31   return Changed;
  32 }
  33
  34 PreservedAnalyses InferFunctionAttrsPass::run(Module &M,
  35                                               ModuleAnalysisManager &AM) {
  36   auto &TLI = AM.getResult<TargetLibraryAnalysis>(M);
  37
  38   if (!inferAllPrototypeAttributes(M, TLI))
  39     // If we didn't infer anything, preserve all analyses.
  40     return PreservedAnalyses::all();
  41
  42   // Otherwise, we may have changed fundamental function attributes, so clear
  43   // out all the passes.
  44   return PreservedAnalyses::none();
  45 }
  46
  47 namespace {
  48 struct InferFunctionAttrsLegacyPass : public ModulePass {
  49   static char ID; // Pass identification, replacement for typeid
  50   InferFunctionAttrsLegacyPass() : ModulePass(ID) {
  51     initializeInferFunctionAttrsLegacyPassPass(
  52         *PassRegistry::getPassRegistry());
  53   }
  54
  55   void getAnalysisUsage(AnalysisUsage &AU) const override {
  56     AU.addRequired<TargetLibraryInfoWrapperPass>();
  57   }
  58
  59   bool runOnModule(Module &M) override {
  60     if (skipModule(M))
  61       return false;
  62
  63     auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
  64     return inferAllPrototypeAttributes(M, TLI);
  65   }
  66 };
  67 }
  68
  69 char InferFunctionAttrsLegacyPass::ID = 0;
  70 INITIALIZE_PASS_BEGIN(InferFunctionAttrsLegacyPass, "inferattrs",
  71                       "Infer set function attributes", false, false)
  72 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
  73 INITIALIZE_PASS_END(InferFunctionAttrsLegacyPass, "inferattrs",
  74                     "Infer set function attributes", false, false)
  75
  76 Pass *llvm::createInferFunctionAttrsLegacyPass() {
  77   return new InferFunctionAttrsLegacyPass();
  78 }