2015-11-24 14:07:49 +08:00
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//===- FunctionImport.cpp - ThinLTO Summary-based Function Import ---------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements Function import based on summaries.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO/FunctionImport.h"
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#include "llvm/ADT/StringSet.h"
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#include "llvm/IR/AutoUpgrade.h"
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#include "llvm/IR/DiagnosticPrinter.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IRReader/IRReader.h"
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#include "llvm/Linker/Linker.h"
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#include "llvm/Object/FunctionIndexObjectFile.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/SourceMgr.h"
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using namespace llvm;
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#define DEBUG_TYPE "function-import"
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// Load lazily a module from \p FileName in \p Context.
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static std::unique_ptr<Module> loadFile(const std::string &FileName,
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LLVMContext &Context) {
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SMDiagnostic Err;
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DEBUG(dbgs() << "Loading '" << FileName << "'\n");
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std::unique_ptr<Module> Result = getLazyIRFileModule(FileName, Err, Context);
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if (!Result) {
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Err.print("function-import", errs());
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return nullptr;
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}
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Result->materializeMetadata();
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UpgradeDebugInfo(*Result);
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return Result;
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}
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// Get a Module for \p FileName from the cache, or load it lazily.
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Module &FunctionImporter::getOrLoadModule(StringRef FileName) {
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auto &Module = ModuleMap[FileName];
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if (!Module)
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Module = loadFile(FileName, Context);
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return *Module;
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}
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// Automatically import functions in Module \p M based on the summaries index.
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//
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// The current implementation imports every called functions that exists in the
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// summaries index.
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bool FunctionImporter::importFunctions(Module &M) {
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assert(&Context == &M.getContext());
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bool Changed = false;
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/// First step is collecting the called functions and the one defined in this
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/// module.
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StringSet<> CalledFunctions;
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for (auto &F : M) {
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if (F.isDeclaration() || F.hasFnAttribute(Attribute::OptimizeNone))
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continue;
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for (auto &BB : F) {
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for (auto &I : BB) {
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if (isa<CallInst>(I)) {
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DEBUG(dbgs() << "Found a call: '" << I << "'\n");
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auto CalledFunction = cast<CallInst>(I).getCalledFunction();
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if (CalledFunction && CalledFunction->hasName() &&
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CalledFunction->isDeclaration())
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CalledFunctions.insert(CalledFunction->getName());
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}
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}
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}
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}
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/// Second step: for every call to an external function, try to import it.
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// Linker that will be used for importing function
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Linker L(&M, DiagnosticHandler);
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/// Insert initial called function set in a worklist, so that we can add
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/// transively called functions when importing.
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SmallVector<StringRef, 64> Worklist;
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for (auto &CalledFunction : CalledFunctions)
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Worklist.push_back(CalledFunction.first());
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while (!Worklist.empty()) {
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auto CalledFunctionName = Worklist.pop_back_val();
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DEBUG(dbgs() << "Process import for " << CalledFunctionName << "\n");
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// Try to get a summary for this function call.
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auto InfoList = Index.findFunctionInfoList(CalledFunctionName);
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if (InfoList == Index.end()) {
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DEBUG(dbgs() << "No summary for " << CalledFunctionName
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<< " Ignoring.\n");
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continue;
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}
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assert(!InfoList->second.empty() && "No summary, error at import?");
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// Comdat can have multiple entries, FIXME: what do we do with them?
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auto &Info = InfoList->second[0];
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assert(Info && "Nullptr in list, error importing summaries?\n");
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auto *Summary = Info->functionSummary();
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if (!Summary) {
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// FIXME: in case we are lazyloading summaries, we can do it now.
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dbgs() << "Missing summary for " << CalledFunctionName
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<< ", error at import?\n";
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llvm_unreachable("Missing summary");
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}
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//
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// No profitability notion right now, just import all the time...
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//
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// Get the module path from the summary.
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auto FileName = Summary->modulePath();
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DEBUG(dbgs() << "Importing " << CalledFunctionName << " from " << FileName
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<< "\n");
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// Get the module for the import (potentially from the cache).
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auto &Module = getOrLoadModule(FileName);
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// The function that we will import!
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GlobalValue *SGV = Module.getNamedValue(CalledFunctionName);
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2015-11-25 03:55:04 +08:00
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StringRef ImportFunctionName = CalledFunctionName;
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if (!SGV) {
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// Might be local in source Module, promoted/renamed in dest Module M.
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std::pair<StringRef, StringRef> Split =
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CalledFunctionName.split(".llvm.");
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SGV = Module.getNamedValue(Split.first);
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#ifndef NDEBUG
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// Assert that Split.second is module id
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uint64_t ModuleId;
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assert(!Split.second.getAsInteger(10, ModuleId));
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assert(ModuleId == Index.getModuleId(FileName));
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#endif
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}
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2015-11-24 14:07:49 +08:00
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Function *F = dyn_cast<Function>(SGV);
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if (!F && isa<GlobalAlias>(SGV)) {
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auto *SGA = dyn_cast<GlobalAlias>(SGV);
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F = dyn_cast<Function>(SGA->getBaseObject());
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2015-11-25 03:55:04 +08:00
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ImportFunctionName = F->getName();
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2015-11-24 14:07:49 +08:00
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}
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if (!F) {
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errs() << "Can't load function '" << CalledFunctionName << "' in Module '"
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<< FileName << "', error in the summary?\n";
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llvm_unreachable("Can't load function in Module");
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}
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2015-11-25 00:10:43 +08:00
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// We cannot import weak_any functions/aliases without possibly affecting
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// the order they are seen and selected by the linker, changing program
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2015-11-24 14:07:49 +08:00
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// semantics.
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2015-11-25 00:10:43 +08:00
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if (SGV->hasWeakAnyLinkage()) {
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DEBUG(dbgs() << "Ignoring import request for weak-any "
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<< (isa<Function>(SGV) ? "function " : "alias ")
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2015-11-24 14:07:49 +08:00
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<< CalledFunctionName << " from " << FileName << "\n");
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continue;
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}
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// Link in the specified function.
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if (L.linkInModule(&Module, Linker::Flags::None, &Index, F))
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report_fatal_error("Function Import: link error");
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2015-11-25 03:55:04 +08:00
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// Process the newly imported function and add callees to the worklist.
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GlobalValue *NewGV = M.getNamedValue(ImportFunctionName);
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assert(NewGV);
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Function *NewF = dyn_cast<Function>(NewGV);
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assert(NewF);
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for (auto &BB : *NewF) {
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for (auto &I : BB) {
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if (isa<CallInst>(I)) {
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DEBUG(dbgs() << "Found a call: '" << I << "'\n");
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auto CalledFunction = cast<CallInst>(I).getCalledFunction();
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// Insert any new external calls that have not already been
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// added to set/worklist.
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if (CalledFunction && CalledFunction->hasName() &&
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CalledFunction->isDeclaration() &&
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!CalledFunctions.count(CalledFunction->getName())) {
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CalledFunctions.insert(CalledFunction->getName());
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Worklist.push_back(CalledFunction->getName());
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}
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}
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}
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}
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2015-11-24 14:07:49 +08:00
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Changed = true;
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}
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return Changed;
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}
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/// Summary file to use for function importing when using -function-import from
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/// the command line.
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static cl::opt<std::string>
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SummaryFile("summary-file",
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cl::desc("The summary file to use for function importing."));
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static void diagnosticHandler(const DiagnosticInfo &DI) {
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raw_ostream &OS = errs();
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DiagnosticPrinterRawOStream DP(OS);
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DI.print(DP);
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OS << '\n';
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}
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/// Parse the function index out of an IR file and return the function
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/// index object if found, or nullptr if not.
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static std::unique_ptr<FunctionInfoIndex>
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getFunctionIndexForFile(StringRef Path, std::string &Error,
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DiagnosticHandlerFunction DiagnosticHandler) {
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std::unique_ptr<MemoryBuffer> Buffer;
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ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
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MemoryBuffer::getFile(Path);
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if (std::error_code EC = BufferOrErr.getError()) {
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Error = EC.message();
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return nullptr;
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}
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Buffer = std::move(BufferOrErr.get());
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ErrorOr<std::unique_ptr<object::FunctionIndexObjectFile>> ObjOrErr =
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object::FunctionIndexObjectFile::create(Buffer->getMemBufferRef(),
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DiagnosticHandler);
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if (std::error_code EC = ObjOrErr.getError()) {
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Error = EC.message();
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return nullptr;
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}
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return (*ObjOrErr)->takeIndex();
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}
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/// Pass that performs cross-module function import provided a summary file.
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class FunctionImportPass : public ModulePass {
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public:
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/// Pass identification, replacement for typeid
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static char ID;
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explicit FunctionImportPass() : ModulePass(ID) {}
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bool runOnModule(Module &M) override {
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if (SummaryFile.empty()) {
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report_fatal_error("error: -function-import requires -summary-file\n");
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}
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std::string Error;
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std::unique_ptr<FunctionInfoIndex> Index =
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getFunctionIndexForFile(SummaryFile, Error, diagnosticHandler);
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if (!Index) {
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errs() << "Error loading file '" << SummaryFile << "': " << Error << "\n";
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return false;
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}
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// Perform the import now.
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FunctionImporter Importer(M.getContext(), *Index, diagnosticHandler);
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return Importer.importFunctions(M);
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return false;
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}
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};
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char FunctionImportPass::ID = 0;
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INITIALIZE_PASS_BEGIN(FunctionImportPass, "function-import",
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"Summary Based Function Import", false, false)
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INITIALIZE_PASS_END(FunctionImportPass, "function-import",
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"Summary Based Function Import", false, false)
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namespace llvm {
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Pass *createFunctionImportPass() { return new FunctionImportPass(); }
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}
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