WebAssemblyInstructionSelector.cpp

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//===- WebAssemblyInstructionSelector.cpp ------------------------*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This file implements the targeting of the InstructionSelector class for
/// WebAssembly.
/// \todo This should be generated by TableGen.
//===----------------------------------------------------------------------===//
 
#include "GISel/WebAssemblyRegisterBankInfo.h"
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "WebAssemblyRegisterInfo.h"
#include "WebAssemblySubtarget.h"
#include "WebAssemblyTargetMachine.h"
#include "llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h"
#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/IR/IntrinsicsWebAssembly.h"
 
#define DEBUG_TYPE "wasm-isel"
 
using namespace llvm;
 
namespace {
 
#define GET_GLOBALISEL_PREDICATE_BITSET
#include "WebAssemblyGenGlobalISel.inc"
#undef GET_GLOBALISEL_PREDICATE_BITSET
 
class WebAssemblyInstructionSelector : public InstructionSelector {
public:
  WebAssemblyInstructionSelector(const WebAssemblyTargetMachine &TM,
                                 const WebAssemblySubtarget &STI,
                                 const WebAssemblyRegisterBankInfo &RBI);
 
  bool select(MachineInstr &I) override;
 
  static const char *getName() { return DEBUG_TYPE; }
 
private:
  bool selectImpl(MachineInstr &I, CodeGenCoverage &CoverageInfo) const;
  bool selectCopy(MachineInstr &I, MachineRegisterInfo &MRI) const;
 
  const WebAssemblyTargetMachine &TM;
  // const WebAssemblySubtarget &STI;
  const WebAssemblyInstrInfo &TII;
  const WebAssemblyRegisterInfo &TRI;
  const WebAssemblyRegisterBankInfo &RBI;
 
#define GET_GLOBALISEL_PREDICATES_DECL
#include "WebAssemblyGenGlobalISel.inc"
#undef GET_GLOBALISEL_PREDICATES_DECL
 
#define GET_GLOBALISEL_TEMPORARIES_DECL
#include "WebAssemblyGenGlobalISel.inc"
#undef GET_GLOBALISEL_TEMPORARIES_DECL
};
 
} // end anonymous namespace
 
#define GET_GLOBALISEL_IMPL
#include "WebAssemblyGenGlobalISel.inc"
#undef GET_GLOBALISEL_IMPL
 
WebAssemblyInstructionSelector::WebAssemblyInstructionSelector(
    const WebAssemblyTargetMachine &TM, const WebAssemblySubtarget &STI,
    const WebAssemblyRegisterBankInfo &RBI)
    : TM(TM), /*STI(STI),*/ TII(*STI.getInstrInfo()),
      TRI(*STI.getRegisterInfo()), RBI(RBI),
 
#define GET_GLOBALISEL_PREDICATES_INIT
#include "WebAssemblyGenGlobalISel.inc"
#undef GET_GLOBALISEL_PREDICATES_INIT
#define GET_GLOBALISEL_TEMPORARIES_INIT
#include "WebAssemblyGenGlobalISel.inc"
#undef GET_GLOBALISEL_TEMPORARIES_INIT
{
}
 
bool WebAssemblyInstructionSelector::selectCopy(
    MachineInstr &I, MachineRegisterInfo &MRI) const {
  const TargetRegisterClass *DstRC =
      TRI.getConstrainedRegClassForOperand(I.getOperand(0), MRI);
  if (!DstRC)
    return false;
 
  const TargetRegisterClass *SrcRC =
      TRI.getConstrainedRegClassForOperand(I.getOperand(1), MRI);
  if (!SrcRC)
    return false;
 
  Register DstReg = I.getOperand(0).getReg();
  Register SrcReg = I.getOperand(1).getReg();
 
  if (DstReg.isVirtual())
    RBI.constrainGenericRegister(DstReg, *DstRC, MRI);
  if (SrcReg.isVirtual())
    RBI.constrainGenericRegister(SrcReg, *SrcRC, MRI);
 
  if (DstRC != SrcRC) {
    if (DstReg.isPhysical() || SrcReg.isPhysical())
      llvm_unreachable("COPY to/from SP[32/64] or FP[32/64] with mismatching "
                       "classes not currently supported");
 
    if (DstRC == &WebAssembly::I32RegClass &&
        SrcRC == &WebAssembly::F32RegClass) {
      I.setDesc(TII.get(WebAssembly::I32_REINTERPRET_F32));
      return true;
    }
    if (DstRC == &WebAssembly::F32RegClass &&
        SrcRC == &WebAssembly::I32RegClass) {
      I.setDesc(TII.get(WebAssembly::F32_REINTERPRET_I32));
      return true;
    }
    if (DstRC == &WebAssembly::I64RegClass &&
        SrcRC == &WebAssembly::F64RegClass) {
      I.setDesc(TII.get(WebAssembly::I64_REINTERPRET_F64));
      return true;
    }
    if (DstRC == &WebAssembly::F64RegClass &&
        SrcRC == &WebAssembly::I64RegClass) {
      I.setDesc(TII.get(WebAssembly::F64_REINTERPRET_I64));
      return true;
    }
 
    llvm_unreachable("COPY between unsupported reg classes.");
  }
 
  return true;
}
 
bool WebAssemblyInstructionSelector::select(MachineInstr &I) {
  MachineBasicBlock &MBB = *I.getParent();
  MachineFunction &MF = *MBB.getParent();
  MachineRegisterInfo &MRI = MF.getRegInfo();
 
  if (!I.isPreISelOpcode()) {
    if (I.isCopy())
      return selectCopy(I, MRI);
    return true;
  }
 
  if (selectImpl(I, *CoverageInfo))
    return true;
 
  using namespace TargetOpcode;
 
  switch (I.getOpcode()) {
  case G_IMPLICIT_DEF: {
    const Register DefReg = I.getOperand(0).getReg();
 
    const TargetRegisterClass *DefRC =
        TRI.getConstrainedRegClassForOperand(I.getOperand(0), MRI);
 
    if (!DefRC)
      return false;
 
    I.setDesc(TII.get(TargetOpcode::IMPLICIT_DEF));
    return RBI.constrainGenericRegister(DefReg, *DefRC, MRI) != nullptr;
  }
  default:
    break;
  }
 
  return false;
}
 
namespace llvm {
InstructionSelector *
createWebAssemblyInstructionSelector(const WebAssemblyTargetMachine &TM,
                                     const WebAssemblySubtarget &Subtarget,
                                     const WebAssemblyRegisterBankInfo &RBI) {
  return new WebAssemblyInstructionSelector(TM, Subtarget, RBI);
}
} // namespace llvm