1 //===-- RISCVISelDAGToDAG.cpp - A dag to dag inst selector for RISCV ------===//
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 // This file defines an instruction selector for the RISCV target.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "RISCV.h"
15 #include "MCTargetDesc/RISCVMCTargetDesc.h"
16 #include "RISCVTargetMachine.h"
17 #include "llvm/CodeGen/SelectionDAGISel.h"
18 #include "llvm/Support/Debug.h"
19 #include "llvm/Support/MathExtras.h"
20 #include "llvm/Support/raw_ostream.h"
21 using namespace llvm;
22 
23 #define DEBUG_TYPE "riscv-isel"
24 
25 // RISCV-specific code to select RISCV machine instructions for
26 // SelectionDAG operations.
27 namespace {
28 class RISCVDAGToDAGISel final : public SelectionDAGISel {
29 public:
30   explicit RISCVDAGToDAGISel(RISCVTargetMachine &TargetMachine)
31       : SelectionDAGISel(TargetMachine) {}
32 
33   StringRef getPassName() const override {
34     return "RISCV DAG->DAG Pattern Instruction Selection";
35   }
36 
37   void Select(SDNode *Node) override;
38 
39 // Include the pieces autogenerated from the target description.
40 #include "RISCVGenDAGISel.inc"
41 };
42 }
43 
44 void RISCVDAGToDAGISel::Select(SDNode *Node) {
45   // Dump information about the Node being selected.
46   DEBUG(dbgs() << "Selecting: "; Node->dump(CurDAG); dbgs() << "\n");
47 
48   // If we have a custom node, we have already selected
49   if (Node->isMachineOpcode()) {
50     DEBUG(dbgs() << "== "; Node->dump(CurDAG); dbgs() << "\n");
51     Node->setNodeId(-1);
52     return;
53   }
54 
55   // Select the default instruction.
56   SelectCode(Node);
57 }
58 
59 // This pass converts a legalized DAG into a RISCV-specific DAG, ready
60 // for instruction scheduling.
61 FunctionPass *llvm::createRISCVISelDag(RISCVTargetMachine &TM) {
62   return new RISCVDAGToDAGISel(TM);
63 }
64