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
24using namespace llvm;
25
26#define DEBUG_TYPE "wasm-lower-reftypes-intptr-conv"
27
28namespace {
29class 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
36public:
37  static char ID; // Pass identification
38  WebAssemblyLowerRefTypesIntPtrConv() : FunctionPass(ID) {}
39};
40} // end anonymous namespace
41
42char WebAssemblyLowerRefTypesIntPtrConv::ID = 0;
43INITIALIZE_PASS(WebAssemblyLowerRefTypesIntPtrConv, DEBUG_TYPE,
44                "WebAssembly Lower RefTypes Int-Ptr Conversions", false, false)
45
46FunctionPass *llvm::createWebAssemblyLowerRefTypesIntPtrConv() {
47  return new WebAssemblyLowerRefTypesIntPtrConv();
48}
49
50bool 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);
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}
87