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 "Utils/WebAssemblyTypeUtilities.h"
  18 #include "WebAssembly.h"
  19 #include "WebAssemblySubtarget.h"
  20 #include "llvm/IR/InstIterator.h"
  21 #include "llvm/Pass.h"
  22 #include <set>
  23
  24 using namespace llvm;
  25
  26 #define DEBUG_TYPE "wasm-lower-reftypes-intptr-conv"
  27
  28 namespace {
  29 class WebAssemblyLowerRefTypesIntPtrConv final : public FunctionPass {
  30   StringRef getPassName() const override {
  31     return "WebAssembly Lower RefTypes Int-Ptr Conversions";
  32   }
  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::runOnFunction(Function &F) {
  51   LLVM_DEBUG(dbgs() << "********** Lower RefTypes IntPtr Convs **********\n"
  52                        "********** Function: "
  53                     << F.getName() << '\n');
  54
  55   // This function will check for uses of ptrtoint and inttoptr on reference
  56   // types and replace them with a trap instruction.
  57   //
  58   // We replace the instruction by a trap instruction
  59   // and its uses by null in the case of inttoptr and 0 in the
  60   // case of ptrtoint.
  61   std::set<Instruction *> worklist;
  62
  63   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
  64     PtrToIntInst *PTI = dyn_cast<PtrToIntInst>(&*I);
  65     IntToPtrInst *ITP = dyn_cast<IntToPtrInst>(&*I);
  66     if (!(PTI && WebAssembly::isWebAssemblyReferenceType(
  67                      PTI->getPointerOperand()->getType())) &&
  68         !(ITP && WebAssembly::isWebAssemblyReferenceType(ITP->getDestTy())))
  69       continue;
  70
  71     UndefValue *U = UndefValue::get(I->getType());
  72     I->replaceAllUsesWith(U);
  73
  74     Function *TrapIntrin =
  75         Intrinsic::getDeclaration(F.getParent(), Intrinsic::debugtrap);
  76     CallInst::Create(TrapIntrin, {}, "", I->getIterator());
  77
  78     worklist.insert(&*I);
  79   }
  80
  81   // erase each instruction replaced by trap
  82   for (Instruction *I : worklist)
  83     I->eraseFromParent();
  84
  85   return !worklist.empty();
  86 }