Line data    Source code

       1             : //- WebAssemblyISelDAGToDAG.cpp - A dag to dag inst selector for WebAssembly -//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : ///
      10             : /// \file
      11             : /// This file defines an instruction selector for the WebAssembly target.
      12             : ///
      13             : //===----------------------------------------------------------------------===//
      14             : 
      15             : #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
      16             : #include "WebAssembly.h"
      17             : #include "WebAssemblyTargetMachine.h"
      18             : #include "llvm/CodeGen/SelectionDAGISel.h"
      19             : #include "llvm/IR/Function.h" // To access function attributes.
      20             : #include "llvm/Support/Debug.h"
      21             : #include "llvm/Support/KnownBits.h"
      22             : #include "llvm/Support/MathExtras.h"
      23             : #include "llvm/Support/raw_ostream.h"
      24             : using namespace llvm;
      25             : 
      26             : #define DEBUG_TYPE "wasm-isel"
      27             : 
      28             : //===--------------------------------------------------------------------===//
      29             : /// WebAssembly-specific code to select WebAssembly machine instructions for
      30             : /// SelectionDAG operations.
      31             : ///
      32             : namespace {
      33             : class WebAssemblyDAGToDAGISel final : public SelectionDAGISel {
      34             :   /// Keep a pointer to the WebAssemblySubtarget around so that we can make the
      35             :   /// right decision when generating code for different targets.
      36             :   const WebAssemblySubtarget *Subtarget;
      37             : 
      38             :   bool ForCodeSize;
      39             : 
      40             : public:
      41             :   WebAssemblyDAGToDAGISel(WebAssemblyTargetMachine &tm,
      42             :                           CodeGenOpt::Level OptLevel)
      43         305 :       : SelectionDAGISel(tm, OptLevel), Subtarget(nullptr), ForCodeSize(false) {
      44             :   }
      45             : 
      46           0 :   StringRef getPassName() const override {
      47           0 :     return "WebAssembly Instruction Selection";
      48             :   }
      49             : 
      50        2987 :   bool runOnMachineFunction(MachineFunction &MF) override {
      51        5974 :     ForCodeSize = MF.getFunction().hasFnAttribute(Attribute::OptimizeForSize) ||
      52        2987 :                   MF.getFunction().hasFnAttribute(Attribute::MinSize);
      53        2987 :     Subtarget = &MF.getSubtarget<WebAssemblySubtarget>();
      54        2987 :     return SelectionDAGISel::runOnMachineFunction(MF);
      55             :   }
      56             : 
      57             :   void Select(SDNode *Node) override;
      58             : 
      59             :   bool SelectInlineAsmMemoryOperand(const SDValue &Op, unsigned ConstraintID,
      60             :                                     std::vector<SDValue> &OutOps) override;
      61             : 
      62             : // Include the pieces autogenerated from the target description.
      63             : #include "WebAssemblyGenDAGISel.inc"
      64             : 
      65             : private:
      66             :   // add select functions here...
      67             : };
      68             : } // end anonymous namespace
      69             : 
      70       42605 : void WebAssemblyDAGToDAGISel::Select(SDNode *Node) {
      71             :   // If we have a custom node, we already have selected!
      72       42605 :   if (Node->isMachineOpcode()) {
      73             :     LLVM_DEBUG(errs() << "== "; Node->dump(CurDAG); errs() << "\n");
      74             :     Node->setNodeId(-1);
      75           2 :     return;
      76             :   }
      77             : 
      78             :   // Few custom selection stuff. If we need WebAssembly-specific selection,
      79             :   // uncomment this block add corresponding case statements.
      80             :   /*
      81             :   switch (Node->getOpcode()) {
      82             :   default:
      83             :     break;
      84             :   }
      85             :   */
      86             : 
      87             :   // Select the default instruction.
      88             :   SelectCode(Node);
      89             : }
      90             : 
      91           0 : bool WebAssemblyDAGToDAGISel::SelectInlineAsmMemoryOperand(
      92             :     const SDValue &Op, unsigned ConstraintID, std::vector<SDValue> &OutOps) {
      93           0 :   switch (ConstraintID) {
      94           0 :   case InlineAsm::Constraint_i:
      95             :   case InlineAsm::Constraint_m:
      96             :     // We just support simple memory operands that just have a single address
      97             :     // operand and need no special handling.
      98           0 :     OutOps.push_back(Op);
      99           0 :     return false;
     100             :   default:
     101             :     break;
     102             :   }
     103             : 
     104             :   return true;
     105             : }
     106             : 
     107             : /// This pass converts a legalized DAG into a WebAssembly-specific DAG, ready
     108             : /// for instruction scheduling.
     109         305 : FunctionPass *llvm::createWebAssemblyISelDag(WebAssemblyTargetMachine &TM,
     110             :                                              CodeGenOpt::Level OptLevel) {
     111         305 :   return new WebAssemblyDAGToDAGISel(TM, OptLevel);
     112             : }