llvm/lib/Target/WebAssembly/WebAssemblyMCLowerPrePass.cpp

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