contrib/llvm/lib/Transforms/Coroutines/CoroCleanup.cpp

   1 //===- CoroCleanup.cpp - Coroutine Cleanup Pass ---------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 // This pass lowers all remaining coroutine intrinsics.
  10 //===----------------------------------------------------------------------===//
  11
  12 #include "CoroInternal.h"
  13 #include "llvm/IR/IRBuilder.h"
  14 #include "llvm/IR/InstIterator.h"
  15 #include "llvm/IR/LegacyPassManager.h"
  16 #include "llvm/Pass.h"
  17 #include "llvm/Transforms/Scalar.h"
  18
  19 using namespace llvm;
  20
  21 #define DEBUG_TYPE "coro-cleanup"
  22
  23 namespace {
  24 // Created on demand if CoroCleanup pass has work to do.
  25 struct Lowerer : coro::LowererBase {
  26   IRBuilder<> Builder;
  27   Lowerer(Module &M) : LowererBase(M), Builder(Context) {}
  28   bool lowerRemainingCoroIntrinsics(Function &F);
  29 };
  30 }
  31
  32 static void simplifyCFG(Function &F) {
  33   llvm::legacy::FunctionPassManager FPM(F.getParent());
  34   FPM.add(createCFGSimplificationPass());
  35
  36   FPM.doInitialization();
  37   FPM.run(F);
  38   FPM.doFinalization();
  39 }
  40
  41 static void lowerSubFn(IRBuilder<> &Builder, CoroSubFnInst *SubFn) {
  42   Builder.SetInsertPoint(SubFn);
  43   Value *FrameRaw = SubFn->getFrame();
  44   int Index = SubFn->getIndex();
  45
  46   auto *FrameTy = StructType::get(
  47       SubFn->getContext(), {Builder.getInt8PtrTy(), Builder.getInt8PtrTy()});
  48   PointerType *FramePtrTy = FrameTy->getPointerTo();
  49
  50   Builder.SetInsertPoint(SubFn);
  51   auto *FramePtr = Builder.CreateBitCast(FrameRaw, FramePtrTy);
  52   auto *Gep = Builder.CreateConstInBoundsGEP2_32(FrameTy, FramePtr, 0, Index);
  53   auto *Load = Builder.CreateLoad(Gep);
  54
  55   SubFn->replaceAllUsesWith(Load);
  56 }
  57
  58 bool Lowerer::lowerRemainingCoroIntrinsics(Function &F) {
  59   bool Changed = false;
  60
  61   for (auto IB = inst_begin(F), E = inst_end(F); IB != E;) {
  62     Instruction &I = *IB++;
  63     if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
  64       switch (II->getIntrinsicID()) {
  65       default:
  66         continue;
  67       case Intrinsic::coro_begin:
  68         II->replaceAllUsesWith(II->getArgOperand(1));
  69         break;
  70       case Intrinsic::coro_free:
  71         II->replaceAllUsesWith(II->getArgOperand(1));
  72         break;
  73       case Intrinsic::coro_alloc:
  74         II->replaceAllUsesWith(ConstantInt::getTrue(Context));
  75         break;
  76       case Intrinsic::coro_id:
  77         II->replaceAllUsesWith(ConstantTokenNone::get(Context));
  78         break;
  79       case Intrinsic::coro_subfn_addr:
  80         lowerSubFn(Builder, cast<CoroSubFnInst>(II));
  81         break;
  82       }
  83       II->eraseFromParent();
  84       Changed = true;
  85     }
  86   }
  87
  88   if (Changed) {
  89     // After replacement were made we can cleanup the function body a little.
  90     simplifyCFG(F);
  91   }
  92   return Changed;
  93 }
  94
  95 //===----------------------------------------------------------------------===//
  96 //                              Top Level Driver
  97 //===----------------------------------------------------------------------===//
  98
  99 namespace {
 100
 101 struct CoroCleanup : FunctionPass {
 102   static char ID; // Pass identification, replacement for typeid
 103
 104   CoroCleanup() : FunctionPass(ID) {}
 105
 106   std::unique_ptr<Lowerer> L;
 107
 108   // This pass has work to do only if we find intrinsics we are going to lower
 109   // in the module.
 110   bool doInitialization(Module &M) override {
 111     if (coro::declaresIntrinsics(M, {"llvm.coro.alloc", "llvm.coro.begin",
 112                                      "llvm.coro.subfn.addr", "llvm.coro.free",
 113                                      "llvm.coro.id"}))
 114       L = llvm::make_unique<Lowerer>(M);
 115     return false;
 116   }
 117
 118   bool runOnFunction(Function &F) override {
 119     if (L)
 120       return L->lowerRemainingCoroIntrinsics(F);
 121     return false;
 122   }
 123   void getAnalysisUsage(AnalysisUsage &AU) const override {
 124     if (!L)
 125       AU.setPreservesAll();
 126   }
 127   StringRef getPassName() const override { return "Coroutine Cleanup"; }
 128 };
 129 }
 130
 131 char CoroCleanup::ID = 0;
 132 INITIALIZE_PASS(CoroCleanup, "coro-cleanup",
 133                 "Lower all coroutine related intrinsics", false, false)
 134
 135 Pass *llvm::createCoroCleanupPass() { return new CoroCleanup(); }