138 lines · cpp
1//===--------- LLJITRemovableCode.cpp -- LLJIT with Code Removal ----------===//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-exception6//7//===----------------------------------------------------------------------===//8//9// In this example we will use an the resource management APIs to transfer10// ownership of modules, remove modules from a JITDylib, and then a whole11// JITDylib from the ExecutionSession.12//13//===----------------------------------------------------------------------===//14 15#include "llvm/ExecutionEngine/Orc/LLJIT.h"16#include "llvm/IR/LegacyPassManager.h"17#include "llvm/Pass.h"18#include "llvm/Support/InitLLVM.h"19#include "llvm/Support/TargetSelect.h"20#include "llvm/Support/raw_ostream.h"21#include "llvm/Transforms/IPO.h"22#include "llvm/Transforms/Scalar.h"23 24#include "../ExampleModules.h"25 26using namespace llvm;27using namespace llvm::orc;28 29ExitOnError ExitOnErr;30 31// Example IR modules.32//33// We will use a few modules containing no-op functions to demonstrate the code34// removal APIs.35 36const llvm::StringRef FooMod =37 R"(38 define void @foo() {39 entry:40 ret void41 }42)";43 44const llvm::StringRef BarMod =45 R"(46 define void @bar() {47 entry:48 ret void49 }50)";51 52const llvm::StringRef BazMod =53 R"(54 define void @baz() {55 entry:56 ret void57 }58)";59 60int main(int argc, char *argv[]) {61 // Initialize LLVM.62 InitLLVM X(argc, argv);63 64 InitializeNativeTarget();65 InitializeNativeTargetAsmPrinter();66 67 ExitOnErr.setBanner(std::string(argv[0]) + ": ");68 69 // (1) Create LLJIT instance.70 auto J = ExitOnErr(LLJITBuilder().create());71 72 // (2) Create a new JITDylib to use for this example.73 auto &JD = ExitOnErr(J->createJITDylib("JD"));74 75 // (3) Add the 'foo' module with no explicit resource tracker. The resources76 // for 'foo' will be tracked by the default tracker for JD. We will not be77 // able to free it separately, but its resources will still be freed when we78 // clear or remove JD.79 ExitOnErr(J->addIRModule(JD, ExitOnErr(parseExampleModule(FooMod, "foo"))));80 81 // (4) Create a tracker for the module 'bar' and use it to add that module.82 auto BarRT = JD.createResourceTracker();83 ExitOnErr(84 J->addIRModule(BarRT, ExitOnErr(parseExampleModule(BarMod, "bar"))));85 86 // (5) Create a tracker for the module 'baz' and use it to add that module.87 auto BazRT = JD.createResourceTracker();88 ExitOnErr(89 J->addIRModule(BazRT, ExitOnErr(parseExampleModule(BazMod, "baz"))));90 91 // (6) Print out the symbols in their initial state:92 auto PrintSymbol = [&](StringRef Name) {93 dbgs() << Name << " = ";94 if (auto Sym = J->lookup(JD, Name))95 dbgs() << *Sym << "\n";96 else97 dbgs() << "error: " << toString(Sym.takeError()) << "\n";98 };99 100 dbgs() << "Initially:\n";101 PrintSymbol("foo");102 PrintSymbol("bar");103 PrintSymbol("baz");104 105 // (7) Reset BazRT. This will implicitly transfer tracking of module baz to106 // JD's default resource tracker.107 dbgs() << "After implicitly transferring ownership of baz to JD's default "108 "tracker:\n";109 BazRT = nullptr;110 PrintSymbol("foo");111 PrintSymbol("bar");112 PrintSymbol("baz");113 114 // (8) Remove BarRT. This should remove the bar symbol.115 dbgs() << "After removing bar (lookup for bar should yield a missing symbol "116 "error):\n";117 ExitOnErr(BarRT->remove());118 PrintSymbol("foo");119 PrintSymbol("bar");120 PrintSymbol("baz");121 122 // (9) Clear JD. This should remove all symbols currently in the JITDylib.123 dbgs() << "After clearing JD (lookup should yield missing symbol errors for "124 "all symbols):\n";125 ExitOnErr(JD.clear());126 PrintSymbol("foo");127 PrintSymbol("bar");128 PrintSymbol("baz");129 130 // (10) Remove JD from the ExecutionSession. JD can no longer be used.131 dbgs() << "Removing JD.\n";132 ExitOnErr(J->getExecutionSession().removeJITDylib(JD));133 134 dbgs() << "done.\n";135 136 return 0;137}138