| //===- StaticDataAnnotator - Annotate static data's section prefix --------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // To reason about module-wide data hotness in a module granularity, this file |
| // implements a module pass StaticDataAnnotator to work coordinately with the |
| // StaticDataSplitter pass. |
| // |
| // The StaticDataSplitter pass is a machine function pass. It analyzes data |
| // hotness based on code and adds counters in StaticDataProfileInfo via its |
| // wrapper pass StaticDataProfileInfoWrapper. |
| // The StaticDataProfileInfoWrapper sits in the middle between the |
| // StaticDataSplitter and StaticDataAnnotator passes. |
| // The StaticDataAnnotator pass is a module pass. It iterates global variables |
| // in the module, looks up counters from StaticDataProfileInfo and sets the |
| // section prefix based on profiles. |
| // |
| // The three-pass structure is implemented for practical reasons, to work around |
| // the limitation that a module pass based on legacy pass manager cannot make |
| // use of MachineBlockFrequencyInfo analysis. In the future, we can consider |
| // porting the StaticDataSplitter pass to a module-pass using the new pass |
| // manager framework. That way, analysis are lazily computed as opposed to |
| // eagerly scheduled, and a module pass can use MachineBlockFrequencyInfo. |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/ProfileSummaryInfo.h" |
| #include "llvm/Analysis/StaticDataProfileInfo.h" |
| #include "llvm/CodeGen/Passes.h" |
| #include "llvm/IR/Analysis.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/PassManager.h" |
| #include "llvm/InitializePasses.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| #define DEBUG_TYPE "static-data-annotator" |
| |
| using namespace llvm; |
| |
| /// A module pass which iterates global variables in the module and annotates |
| /// their section prefixes based on profile-driven analysis. |
| class StaticDataAnnotator : public ModulePass { |
| public: |
| static char ID; |
| |
| StaticDataProfileInfo *SDPI = nullptr; |
| const ProfileSummaryInfo *PSI = nullptr; |
| |
| StaticDataAnnotator() : ModulePass(ID) { |
| initializeStaticDataAnnotatorPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.addRequired<StaticDataProfileInfoWrapperPass>(); |
| AU.addRequired<ProfileSummaryInfoWrapperPass>(); |
| AU.setPreservesAll(); |
| ModulePass::getAnalysisUsage(AU); |
| } |
| |
| StringRef getPassName() const override { return "Static Data Annotator"; } |
| |
| bool runOnModule(Module &M) override; |
| }; |
| |
| bool StaticDataAnnotator::runOnModule(Module &M) { |
| SDPI = &getAnalysis<StaticDataProfileInfoWrapperPass>() |
| .getStaticDataProfileInfo(); |
| PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI(); |
| |
| if (!PSI->hasProfileSummary()) |
| return false; |
| |
| bool Changed = false; |
| for (auto &GV : M.globals()) { |
| if (GV.isDeclarationForLinker()) |
| continue; |
| |
| // The implementation below assumes prior passes don't set section prefixes, |
| // and specifically do 'assign' rather than 'update'. So report error if a |
| // section prefix is already set. |
| if (auto maybeSectionPrefix = GV.getSectionPrefix(); |
| maybeSectionPrefix && !maybeSectionPrefix->empty()) |
| llvm::report_fatal_error("Global variable " + GV.getName() + |
| " already has a section prefix " + |
| *maybeSectionPrefix); |
| |
| StringRef SectionPrefix = SDPI->getConstantSectionPrefix(&GV, PSI); |
| if (SectionPrefix.empty()) |
| continue; |
| |
| GV.setSectionPrefix(SectionPrefix); |
| Changed = true; |
| } |
| |
| return Changed; |
| } |
| |
| char StaticDataAnnotator::ID = 0; |
| |
| INITIALIZE_PASS(StaticDataAnnotator, DEBUG_TYPE, "Static Data Annotator", false, |
| false) |
| |
| ModulePass *llvm::createStaticDataAnnotatorPass() { |
| return new StaticDataAnnotator(); |
| } |