llvm/examples/OrcV2Examples/LLJITWithExecutorProcessControl/LLJITWithExecutorProcessControl.cpp

   1 //===- LLJITWithExecutorProcessControl.cpp - LLJIT example with EPC utils -===//
   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 // In this example we will use the lazy re-exports utility to lazily compile
  10 // IR modules. We will do this in seven steps:
  11 //
  12 // 1. Create an LLJIT instance.
  13 // 2. Install a transform so that we can see what is being compiled.
  14 // 3. Create an indirect stubs manager and lazy call-through manager.
  15 // 4. Add two modules that will be conditionally compiled, plus a main module.
  16 // 5. Add lazy-rexports of the symbols in the conditionally compiled modules.
  17 // 6. Dump the ExecutionSession state to see the symbol table prior to
  18 //    executing any code.
  19 // 7. Verify that only modules containing executed code are compiled.
  20 //
  21 //===----------------------------------------------------------------------===//
  22
  23 #include "llvm/ADT/StringMap.h"
  24 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
  25 #include "llvm/ExecutionEngine/Orc/EPCIndirectionUtils.h"
  26 #include "llvm/ExecutionEngine/Orc/ExecutorProcessControl.h"
  27 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
  28 #include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
  29 #include "llvm/ExecutionEngine/Orc/OrcABISupport.h"
  30 #include "llvm/Support/InitLLVM.h"
  31 #include "llvm/Support/TargetSelect.h"
  32 #include "llvm/Support/raw_ostream.h"
  33
  34 #include "../ExampleModules.h"
  35
  36 #include <future>
  37
  38 using namespace llvm;
  39 using namespace llvm::orc;
  40
  41 ExitOnError ExitOnErr;
  42
  43 // Example IR modules.
  44 //
  45 // Note that in the conditionally compiled modules, FooMod and BarMod, functions
  46 // have been given an _body suffix. This is to ensure that their names do not
  47 // clash with their lazy-reexports.
  48 // For clients who do not wish to rename function bodies (e.g. because they want
  49 // to re-use cached objects between static and JIT compiles) techniques exist to
  50 // avoid renaming. See the lazy-reexports section of the ORCv2 design doc.
  51
  52 const llvm::StringRef FooMod =
  53     R"(
  54   declare i32 @return1()
  55
  56   define i32 @foo_body() {
  57   entry:
  58     %0 = call i32 @return1()
  59     ret i32 %0
  60   }
  61 )";
  62
  63 const llvm::StringRef BarMod =
  64     R"(
  65   declare i32 @return2()
  66
  67   define i32 @bar_body() {
  68   entry:
  69     %0 = call i32 @return2()
  70     ret i32 %0
  71   }
  72 )";
  73
  74 const llvm::StringRef MainMod =
  75     R"(
  76
  77   define i32 @entry(i32 %argc) {
  78   entry:
  79     %and = and i32 %argc, 1
  80     %tobool = icmp eq i32 %and, 0
  81     br i1 %tobool, label %if.end, label %if.then
  82
  83   if.then:                                          ; preds = %entry
  84     %call = tail call i32 @foo() #2
  85     br label %return
  86
  87   if.end:                                           ; preds = %entry
  88     %call1 = tail call i32 @bar() #2
  89     br label %return
  90
  91   return:                                           ; preds = %if.end, %if.then
  92     %retval.0 = phi i32 [ %call, %if.then ], [ %call1, %if.end ]
  93     ret i32 %retval.0
  94   }
  95
  96   declare i32 @foo()
  97   declare i32 @bar()
  98 )";
  99
 100 extern "C" int32_t return1() { return 1; }
 101 extern "C" int32_t return2() { return 2; }
 102
 103 static void *reenter(void *Ctx, void *TrampolineAddr) {
 104   std::promise<void *> LandingAddressP;
 105   auto LandingAddressF = LandingAddressP.get_future();
 106
 107   auto *EPCIU = static_cast<EPCIndirectionUtils *>(Ctx);
 108   EPCIU->getLazyCallThroughManager().resolveTrampolineLandingAddress(
 109       ExecutorAddr::fromPtr(TrampolineAddr), [&](ExecutorAddr LandingAddress) {
 110         LandingAddressP.set_value(LandingAddress.toPtr<void *>());
 111       });
 112   return LandingAddressF.get();
 113 }
 114
 115 static void reportErrorAndExit() {
 116   errs() << "Unable to lazily compile function. Exiting.\n";
 117   exit(1);
 118 }
 119
 120 cl::list<std::string> InputArgv(cl::Positional,
 121                                 cl::desc("<program arguments>..."));
 122
 123 int main(int argc, char *argv[]) {
 124   // Initialize LLVM.
 125   InitLLVM X(argc, argv);
 126
 127   InitializeNativeTarget();
 128   InitializeNativeTargetAsmPrinter();
 129
 130   cl::ParseCommandLineOptions(argc, argv, "LLJITWithLazyReexports");
 131   ExitOnErr.setBanner(std::string(argv[0]) + ": ");
 132
 133   // (1) Create LLJIT instance.
 134   auto EPC = ExitOnErr(SelfExecutorProcessControl::Create());
 135   auto J = ExitOnErr(
 136       LLJITBuilder().setExecutorProcessControl(std::move(EPC)).create());
 137
 138   // (2) Install transform to print modules as they are compiled:
 139   J->getIRTransformLayer().setTransform(
 140       [](ThreadSafeModule TSM,
 141          const MaterializationResponsibility &R) -> Expected<ThreadSafeModule> {
 142         TSM.withModuleDo([](Module &M) { dbgs() << "---Compiling---\n" << M; });
 143         return std::move(TSM); // Not a redundant move: fix build on gcc-7.5
 144       });
 145
 146   // (3) Create stubs and call-through managers:
 147   auto EPCIU = ExitOnErr(EPCIndirectionUtils::Create(J->getExecutionSession()));
 148   ExitOnErr(EPCIU->writeResolverBlock(ExecutorAddr::fromPtr(&reenter),
 149                                       ExecutorAddr::fromPtr(EPCIU.get())));
 150   EPCIU->createLazyCallThroughManager(
 151       J->getExecutionSession(), ExecutorAddr::fromPtr(&reportErrorAndExit));
 152   auto ISM = EPCIU->createIndirectStubsManager();
 153
 154   // (4) Add modules.
 155   ExitOnErr(J->addIRModule(ExitOnErr(parseExampleModule(FooMod, "foo-mod"))));
 156   ExitOnErr(J->addIRModule(ExitOnErr(parseExampleModule(BarMod, "bar-mod"))));
 157   ExitOnErr(J->addIRModule(ExitOnErr(parseExampleModule(MainMod, "main-mod"))));
 158
 159   // (5) Add lazy reexports.
 160   MangleAndInterner Mangle(J->getExecutionSession(), J->getDataLayout());
 161   SymbolAliasMap ReExports(
 162       {{Mangle("foo"),
 163         {Mangle("foo_body"),
 164          JITSymbolFlags::Exported | JITSymbolFlags::Callable}},
 165        {Mangle("bar"),
 166         {Mangle("bar_body"),
 167          JITSymbolFlags::Exported | JITSymbolFlags::Callable}}});
 168   ExitOnErr(J->getMainJITDylib().define(
 169       lazyReexports(EPCIU->getLazyCallThroughManager(), *ISM,
 170                     J->getMainJITDylib(), std::move(ReExports))));
 171
 172   // (6) Dump the ExecutionSession state.
 173   dbgs() << "---Session state---\n";
 174   J->getExecutionSession().dump(dbgs());
 175   dbgs() << "\n";
 176
 177   // (7) Execute the JIT'd main function and pass the example's command line
 178   // arguments unmodified. This should cause either ExampleMod1 or ExampleMod2
 179   // to be compiled, and either "1" or "2" returned depending on the number of
 180   // arguments passed.
 181
 182   // Look up the JIT'd function, cast it to a function pointer, then call it.
 183   auto EntryAddr = ExitOnErr(J->lookup("entry"));
 184   auto *Entry = EntryAddr.toPtr<int(int)>();
 185
 186   int Result = Entry(argc);
 187   outs() << "---Result---\n"
 188          << "entry(" << argc << ") = " << Result << "\n";
 189
 190   // Destroy the EPCIndirectionUtils utility.
 191   ExitOnErr(EPCIU->cleanup());
 192
 193   return 0;
 194 }