llvm/lib/Target/WebAssembly/WebAssemblyLowerRefTypesIntPtrConv.cpp

   1 //=== WebAssemblyLowerRefTypesIntPtrConv.cpp -
   2 //                     Lower IntToPtr and PtrToInt on Reference Types   ---===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9 ///
  10 /// \file
  11 /// Lowers IntToPtr and PtrToInt instructions on reference types to
  12 /// Trap instructions since they have been allowed to operate
  13 /// on non-integral pointers.
  14 ///
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "WebAssembly.h"
  18 #include "WebAssemblySubtarget.h"
  19 #include "llvm/IR/InstIterator.h"
  20 #include "llvm/Pass.h"
  21
  22 using namespace llvm;
  23
  24 #define DEBUG_TYPE "wasm-lower-reftypes-intptr-conv"
  25
  26 namespace {
  27 class WebAssemblyLowerRefTypesIntPtrConv final : public FunctionPass {
  28   StringRef getPassName() const override {
  29     return "WebAssembly Lower RefTypes Int-Ptr Conversions";
  30   }
  31
  32   static bool isRefType(Type *T);
  33
  34   bool runOnFunction(Function &MF) override;
  35
  36 public:
  37   static char ID; // Pass identification
  38   WebAssemblyLowerRefTypesIntPtrConv() : FunctionPass(ID) {}
  39 };
  40 } // end anonymous namespace
  41
  42 char WebAssemblyLowerRefTypesIntPtrConv::ID = 0;
  43 INITIALIZE_PASS(WebAssemblyLowerRefTypesIntPtrConv, DEBUG_TYPE,
  44                 "WebAssembly Lower RefTypes Int-Ptr Conversions", false, false)
  45
  46 FunctionPass *llvm::createWebAssemblyLowerRefTypesIntPtrConv() {
  47   return new WebAssemblyLowerRefTypesIntPtrConv();
  48 }
  49
  50 bool WebAssemblyLowerRefTypesIntPtrConv::isRefType(Type *T) {
  51   return WebAssemblyTargetLowering::isFuncrefType(T) ||
  52          WebAssemblyTargetLowering::isExternrefType(T);
  53 }
  54
  55 bool WebAssemblyLowerRefTypesIntPtrConv::runOnFunction(Function &F) {
  56   LLVM_DEBUG(dbgs() << "********** Lower RefTypes IntPtr Convs **********\n"
  57                        "********** Function: "
  58                     << F.getName() << '\n');
  59
  60   // This function will check for uses of ptrtoint and inttoptr on reference
  61   // types and replace them with a trap instruction.
  62   //
  63   // We replace the instruction by a trap instruction
  64   // and its uses by null in the case of inttoptr and 0 in the
  65   // case of ptrtoint.
  66   std::set<Instruction *> worklist;
  67
  68   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
  69     PtrToIntInst *PTI = dyn_cast<PtrToIntInst>(&*I);
  70     IntToPtrInst *ITP = dyn_cast<IntToPtrInst>(&*I);
  71     if (!(PTI && isRefType(PTI->getPointerOperand()->getType())) &&
  72         !(ITP && isRefType(ITP->getDestTy())))
  73       continue;
  74
  75     UndefValue *U = UndefValue::get(I->getType());
  76     I->replaceAllUsesWith(U);
  77
  78     Function *TrapIntrin =
  79         Intrinsic::getDeclaration(F.getParent(), Intrinsic::debugtrap);
  80     CallInst::Create(TrapIntrin, {}, "", &*I);
  81
  82     worklist.insert(&*I);
  83   }
  84
  85   // erase each instruction replaced by trap
  86   for (Instruction *I : worklist)
  87     I->eraseFromParent();
  88
  89   return !worklist.empty();
  90 }