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 /// \brief This file defines an instruction selector for the WebAssembly target. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #include "WebAssembly.h" 16 #include "MCTargetDesc/WebAssemblyMCTargetDesc.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/MathExtras.h" 22 #include "llvm/Support/raw_ostream.h" 23 using namespace llvm; 24 25 #define DEBUG_TYPE "wasm-isel" 26 27 //===--------------------------------------------------------------------===// 28 /// WebAssembly-specific code to select WebAssembly machine instructions for 29 /// SelectionDAG operations. 30 /// 31 namespace { 32 class WebAssemblyDAGToDAGISel final : public SelectionDAGISel { 33 /// Keep a pointer to the WebAssemblySubtarget around so that we can make the 34 /// right decision when generating code for different targets. 35 const WebAssemblySubtarget *Subtarget; 36 37 bool ForCodeSize; 38 39 public: 40 WebAssemblyDAGToDAGISel(WebAssemblyTargetMachine &tm, 41 CodeGenOpt::Level OptLevel) 42 : SelectionDAGISel(tm, OptLevel), Subtarget(nullptr), ForCodeSize(false) { 43 } 44 45 const char *getPassName() const override { 46 return "WebAssembly Instruction Selection"; 47 } 48 49 bool runOnMachineFunction(MachineFunction &MF) override { 50 ForCodeSize = 51 MF.getFunction()->hasFnAttribute(Attribute::OptimizeForSize) || 52 MF.getFunction()->hasFnAttribute(Attribute::MinSize); 53 Subtarget = &MF.getSubtarget<WebAssemblySubtarget>(); 54 return SelectionDAGISel::runOnMachineFunction(MF); 55 } 56 57 SDNode *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 SDNode *WebAssemblyDAGToDAGISel::Select(SDNode *Node) { 71 // Dump information about the Node being selected. 72 DEBUG(errs() << "Selecting: "); 73 DEBUG(Node->dump(CurDAG)); 74 DEBUG(errs() << "\n"); 75 76 // If we have a custom node, we already have selected! 77 if (Node->isMachineOpcode()) { 78 DEBUG(errs() << "== "; Node->dump(CurDAG); errs() << "\n"); 79 Node->setNodeId(-1); 80 return nullptr; 81 } 82 83 // Few custom selection stuff. 84 SDNode *ResNode = nullptr; 85 EVT VT = Node->getValueType(0); 86 87 switch (Node->getOpcode()) { 88 default: 89 break; 90 // If we need WebAssembly-specific selection, it would go here. 91 (void)VT; 92 } 93 94 // Select the default instruction. 95 ResNode = SelectCode(Node); 96 97 DEBUG(errs() << "=> "); 98 if (ResNode == nullptr || ResNode == Node) 99 DEBUG(Node->dump(CurDAG)); 100 else 101 DEBUG(ResNode->dump(CurDAG)); 102 DEBUG(errs() << "\n"); 103 104 return ResNode; 105 } 106 107 bool WebAssemblyDAGToDAGISel::SelectInlineAsmMemoryOperand( 108 const SDValue &Op, unsigned ConstraintID, std::vector<SDValue> &OutOps) { 109 switch (ConstraintID) { 110 case InlineAsm::Constraint_i: 111 case InlineAsm::Constraint_m: 112 // We just support simple memory operands that just have a single address 113 // operand and need no special handling. 114 OutOps.push_back(Op); 115 return false; 116 default: 117 break; 118 } 119 120 return true; 121 } 122 123 /// This pass converts a legalized DAG into a WebAssembly-specific DAG, ready 124 /// for instruction scheduling. 125 FunctionPass *llvm::createWebAssemblyISelDag(WebAssemblyTargetMachine &TM, 126 CodeGenOpt::Level OptLevel) { 127 return new WebAssemblyDAGToDAGISel(TM, OptLevel); 128 } 129