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
23using namespace llvm;
24
25#define DEBUG_TYPE "wasm-lower-reftypes-intptr-conv"
26
27namespace {
28class WebAssemblyLowerRefTypesIntPtrConv final : public FunctionPass {
29  StringRef getPassName() const override {
30    return "WebAssembly Lower RefTypes Int-Ptr Conversions";
31  }
32
33  bool runOnFunction(Function &MF) override;
34
35public:
36  static char ID; // Pass identification
37  WebAssemblyLowerRefTypesIntPtrConv() : FunctionPass(ID) {}
38};
39} // end anonymous namespace
40
41char WebAssemblyLowerRefTypesIntPtrConv::ID = 0;
42INITIALIZE_PASS(WebAssemblyLowerRefTypesIntPtrConv, DEBUG_TYPE,
43                "WebAssembly Lower RefTypes Int-Ptr Conversions", false, false)
44
45FunctionPass *llvm::createWebAssemblyLowerRefTypesIntPtrConv() {
46  return new WebAssemblyLowerRefTypesIntPtrConv();
47}
48
49bool WebAssemblyLowerRefTypesIntPtrConv::runOnFunction(Function &F) {
50  LLVM_DEBUG(dbgs() << "********** Lower RefTypes IntPtr Convs **********\n"
51                       "********** Function: "
52                    << F.getName() << '\n');
53
54  // This function will check for uses of ptrtoint and inttoptr on reference
55  // types and replace them with a trap instruction.
56  //
57  // We replace the instruction by a trap instruction
58  // and its uses by null in the case of inttoptr and 0 in the
59  // case of ptrtoint.
60  std::set<Instruction *> worklist;
61
62  for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
63    PtrToIntInst *PTI = dyn_cast<PtrToIntInst>(&*I);
64    IntToPtrInst *ITP = dyn_cast<IntToPtrInst>(&*I);
65    if (!(PTI && WebAssembly::isRefType(PTI->getPointerOperand()->getType())) &&
66        !(ITP && WebAssembly::isRefType(ITP->getDestTy())))
67      continue;
68
69    UndefValue *U = UndefValue::get(I->getType());
70    I->replaceAllUsesWith(U);
71
72    Function *TrapIntrin =
73        Intrinsic::getDeclaration(F.getParent(), Intrinsic::debugtrap);
74    CallInst::Create(TrapIntrin, {}, "", &*I);
75
76    worklist.insert(&*I);
77  }
78
79  // erase each instruction replaced by trap
80  for (Instruction *I : worklist)
81    I->eraseFromParent();
82
83  return !worklist.empty();
84}
85