llvm/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/InitializePasses.h"
  15 #include "llvm/Support/Debug.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 #include "llvm/Transforms/Utils/BuildLibCalls.h"
  18 #include "llvm/Transforms/Utils/Local.h"
  19 using namespace llvm;
  20
  21 #define DEBUG_TYPE "inferattrs"
  22
  23 static bool inferAllPrototypeAttributes(
  24     Module &M, function_ref<TargetLibraryInfo &(Function &)> GetTLI) {
  25   bool Changed = false;
  26
  27   for (Function &F : M.functions())
  28     // We only infer things using the prototype and the name; we don't need
  29     // definitions.  This ensures libfuncs are annotated and also allows our
  30     // CGSCC inference to avoid needing to duplicate the inference from other
  31     // attribute logic on all calls to declarations (as declarations aren't
  32     // explicitly visited by CGSCC passes in the new pass manager.)
  33     if (F.isDeclaration() && !F.hasOptNone()) {
  34       if (!F.hasFnAttribute(Attribute::NoBuiltin))
  35         Changed |= inferLibFuncAttributes(F, GetTLI(F));
  36       Changed |= inferAttributesFromOthers(F);
  37     }
  38
  39   return Changed;
  40 }
  41
  42 PreservedAnalyses InferFunctionAttrsPass::run(Module &M,
  43                                               ModuleAnalysisManager &AM) {
  44   FunctionAnalysisManager &FAM =
  45       AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
  46   auto GetTLI = [&FAM](Function &F) -> TargetLibraryInfo & {
  47     return FAM.getResult<TargetLibraryAnalysis>(F);
  48   };
  49
  50   if (!inferAllPrototypeAttributes(M, GetTLI))
  51     // If we didn't infer anything, preserve all analyses.
  52     return PreservedAnalyses::all();
  53
  54   // Otherwise, we may have changed fundamental function attributes, so clear
  55   // out all the passes.
  56   return PreservedAnalyses::none();
  57 }
  58
  59 namespace {
  60 struct InferFunctionAttrsLegacyPass : public ModulePass {
  61   static char ID; // Pass identification, replacement for typeid
  62   InferFunctionAttrsLegacyPass() : ModulePass(ID) {
  63     initializeInferFunctionAttrsLegacyPassPass(
  64         *PassRegistry::getPassRegistry());
  65   }
  66
  67   void getAnalysisUsage(AnalysisUsage &AU) const override {
  68     AU.addRequired<TargetLibraryInfoWrapperPass>();
  69   }
  70
  71   bool runOnModule(Module &M) override {
  72     if (skipModule(M))
  73       return false;
  74
  75     auto GetTLI = [this](Function &F) -> TargetLibraryInfo & {
  76       return this->getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
  77     };
  78     return inferAllPrototypeAttributes(M, GetTLI);
  79   }
  80 };
  81 }
  82
  83 char InferFunctionAttrsLegacyPass::ID = 0;
  84 INITIALIZE_PASS_BEGIN(InferFunctionAttrsLegacyPass, "inferattrs",
  85                       "Infer set function attributes", false, false)
  86 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
  87 INITIALIZE_PASS_END(InferFunctionAttrsLegacyPass, "inferattrs",
  88                     "Infer set function attributes", false, false)
  89
  90 Pass *llvm::createInferFunctionAttrsLegacyPass() {
  91   return new InferFunctionAttrsLegacyPass();
  92 }