llvm/lib/Target/WebAssembly/WebAssemblyRefTypeMem2Local.cpp

   1 //=== WebAssemblyRefTypeMem2Local.cpp - WebAssembly RefType Mem2Local -----===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 ///
   9 /// \file
  10 /// Assign reference type allocas to local addrspace (addrspace(1)) so that
  11 /// their loads and stores can be lowered to local.gets/local.sets.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "Utils/WasmAddressSpaces.h"
  16 #include "Utils/WebAssemblyTypeUtilities.h"
  17 #include "WebAssembly.h"
  18 #include "llvm/IR/IRBuilder.h"
  19 #include "llvm/IR/InstVisitor.h"
  20 #include "llvm/IR/ValueHandle.h"
  21 #include "llvm/Pass.h"
  22 using namespace llvm;
  23
  24 #define DEBUG_TYPE "wasm-ref-type-mem2local"
  25
  26 namespace {
  27 class WebAssemblyRefTypeMem2Local final
  28     : public FunctionPass,
  29       public InstVisitor<WebAssemblyRefTypeMem2Local> {
  30   StringRef getPassName() const override {
  31     return "WebAssembly Reference Types Memory to Local";
  32   }
  33
  34   void getAnalysisUsage(AnalysisUsage &AU) const override {
  35     AU.setPreservesCFG();
  36     FunctionPass::getAnalysisUsage(AU);
  37   }
  38
  39   bool runOnFunction(Function &F) override;
  40   bool Changed = false;
  41
  42 public:
  43   static char ID;
  44   WebAssemblyRefTypeMem2Local() : FunctionPass(ID) {}
  45
  46   void visitAllocaInst(AllocaInst &AI);
  47 };
  48 } // End anonymous namespace
  49
  50 char WebAssemblyRefTypeMem2Local::ID = 0;
  51 INITIALIZE_PASS(WebAssemblyRefTypeMem2Local, DEBUG_TYPE,
  52                 "Assign reference type allocas to local address space", true,
  53                 false)
  54
  55 FunctionPass *llvm::createWebAssemblyRefTypeMem2Local() {
  56   return new WebAssemblyRefTypeMem2Local();
  57 }
  58
  59 void WebAssemblyRefTypeMem2Local::visitAllocaInst(AllocaInst &AI) {
  60   if (WebAssembly::isWebAssemblyReferenceType(AI.getAllocatedType())) {
  61     Changed = true;
  62     IRBuilder<> IRB(AI.getContext());
  63     IRB.SetInsertPoint(&AI);
  64     auto *NewAI = IRB.CreateAlloca(AI.getAllocatedType(),
  65                                    WebAssembly::WASM_ADDRESS_SPACE_VAR, nullptr,
  66                                    AI.getName() + ".var");
  67
  68     // The below is basically equivalent to AI.replaceAllUsesWith(NewAI), but we
  69     // cannot use it because it requires the old and new types be the same,
  70     // which is not true here because the address spaces are different.
  71     if (AI.hasValueHandle())
  72       ValueHandleBase::ValueIsRAUWd(&AI, NewAI);
  73     if (AI.isUsedByMetadata())
  74       ValueAsMetadata::handleRAUW(&AI, NewAI);
  75     while (!AI.materialized_use_empty()) {
  76       Use &U = *AI.materialized_use_begin();
  77       U.set(NewAI);
  78     }
  79
  80     AI.eraseFromParent();
  81   }
  82 }
  83
  84 bool WebAssemblyRefTypeMem2Local::runOnFunction(Function &F) {
  85   LLVM_DEBUG(dbgs() << "********** WebAssembly RefType Mem2Local **********\n"
  86                        "********** Function: "
  87                     << F.getName() << '\n');
  88
  89   if (F.getFnAttribute("target-features")
  90           .getValueAsString()
  91           .contains("+reference-types"))
  92     visit(F);
  93   return Changed;
  94 }