1 //===-- WebAssemblyMCLowerPrePass.cpp - Prepare for MC lower --------------===// 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 /// Some information in MC lowering / asm printing gets generated as 11 /// instructions get emitted, but may be necessary at the start, such as for 12 /// .globaltype declarations. This pass collects this information. 13 /// 14 //===----------------------------------------------------------------------===// 15 16 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" 17 #include "WebAssembly.h" 18 #include "WebAssemblyMachineFunctionInfo.h" 19 #include "WebAssemblySubtarget.h" 20 #include "WebAssemblyUtilities.h" 21 #include "llvm/ADT/SCCIterator.h" 22 #include "llvm/CodeGen/MachineFrameInfo.h" 23 #include "llvm/CodeGen/MachineFunction.h" 24 #include "llvm/CodeGen/MachineInstrBuilder.h" 25 #include "llvm/CodeGen/MachineLoopInfo.h" 26 #include "llvm/CodeGen/MachineModuleInfoImpls.h" 27 #include "llvm/CodeGen/MachineRegisterInfo.h" 28 #include "llvm/CodeGen/Passes.h" 29 #include "llvm/IR/Module.h" 30 #include "llvm/Support/Debug.h" 31 #include "llvm/Support/raw_ostream.h" 32 using namespace llvm; 33 34 #define DEBUG_TYPE "wasm-mclower-prepass" 35 36 namespace { 37 class WebAssemblyMCLowerPrePass final : public ModulePass { getPassName() const38 StringRef getPassName() const override { 39 return "WebAssembly MC Lower Pre Pass"; 40 } 41 getAnalysisUsage(AnalysisUsage & AU) const42 void getAnalysisUsage(AnalysisUsage &AU) const override { 43 AU.setPreservesCFG(); 44 ModulePass::getAnalysisUsage(AU); 45 } 46 47 bool runOnModule(Module &M) override; 48 49 public: 50 static char ID; // Pass identification, replacement for typeid WebAssemblyMCLowerPrePass()51 WebAssemblyMCLowerPrePass() : ModulePass(ID) {} 52 }; 53 } // end anonymous namespace 54 55 char WebAssemblyMCLowerPrePass::ID = 0; 56 INITIALIZE_PASS( 57 WebAssemblyMCLowerPrePass, DEBUG_TYPE, 58 "Collects information ahead of time for MC lowering", 59 false, false) 60 createWebAssemblyMCLowerPrePass()61ModulePass *llvm::createWebAssemblyMCLowerPrePass() { 62 return new WebAssemblyMCLowerPrePass(); 63 } 64 65 // NOTE: this is a ModulePass since we need to enforce that this code has run 66 // for all functions before AsmPrinter. If this way of doing things is ever 67 // suboptimal, we could opt to make it a MachineFunctionPass and instead use 68 // something like createBarrierNoopPass() to enforce ordering. 69 // 70 // The information stored here is essential for emitExternalDecls in the Wasm 71 // AsmPrinter runOnModule(Module & M)72bool WebAssemblyMCLowerPrePass::runOnModule(Module &M) { 73 auto *MMIWP = getAnalysisIfAvailable<MachineModuleInfoWrapperPass>(); 74 if (!MMIWP) 75 return true; 76 77 MachineModuleInfo &MMI = MMIWP->getMMI(); 78 MachineModuleInfoWasm &MMIW = MMI.getObjFileInfo<MachineModuleInfoWasm>(); 79 80 for (Function &F : M) { 81 MachineFunction *MF = MMI.getMachineFunction(F); 82 if (!MF) 83 continue; 84 85 LLVM_DEBUG(dbgs() << "********** MC Lower Pre Pass **********\n" 86 "********** Function: " 87 << MF->getName() << '\n'); 88 89 for (MachineBasicBlock &MBB : *MF) { 90 for (auto &MI : MBB) { 91 // FIXME: what should all be filtered out beyond these? 92 if (MI.isDebugInstr() || MI.isInlineAsm()) 93 continue; 94 for (MachineOperand &MO : MI.uses()) { 95 if (MO.isSymbol()) { 96 MMIW.MachineSymbolsUsed.insert(MO.getSymbolName()); 97 } 98 } 99 } 100 } 101 } 102 return true; 103 } 104