//===-- complex.cpp -------------------------------------------------------===//
//
//                         LDC – the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//

#include "gen/complex.h"

#include "dmd/declaration.h"
#include "dmd/errors.h"
#include "dmd/mtype.h"
#include "gen/binops.h"
#include "gen/dvalue.h"
#include "gen/irstate.h"
#include "gen/llvm.h"
#include "gen/llvmhelpers.h"
#include "gen/logger.h"
#include "gen/tollvm.h"

////////////////////////////////////////////////////////////////////////////////

llvm::StructType *DtoComplexType(Type *type) {
  Type *t = type->toBasetype();
  LLType *base = DtoComplexBaseType(t);
  LLType *types[] = {base, base};
  return llvm::StructType::get(gIR->context(), types, false);
}

LLType *DtoComplexBaseType(Type *t) {
  switch (t->toBasetype()->ty) {
  default:
    llvm_unreachable("Unexpected complex floating point type");
  case TY::Tcomplex32:
    return DtoType(Type::tfloat32);
  case TY::Tcomplex64:
    return DtoType(Type::tfloat64);
  case TY::Tcomplex80:
    return DtoType(Type::tfloat80);
  }
}

////////////////////////////////////////////////////////////////////////////////

LLConstant *DtoConstComplex(Type *_ty, real_t re, real_t im) {
  Type *base = nullptr;
  switch (_ty->toBasetype()->ty) {
  default:
    llvm_unreachable("Unexpected complex floating point type");
  case TY::Tcomplex32:
    base = Type::tfloat32;
    break;
  case TY::Tcomplex64:
    base = Type::tfloat64;
    break;
  case TY::Tcomplex80:
    base = Type::tfloat80;
    break;
  }

  LLConstant *inits[] = {DtoConstFP(base, re), DtoConstFP(base, im)};

  return llvm::ConstantStruct::get(DtoComplexType(_ty),
                                   llvm::ArrayRef<LLConstant *>(inits));
}

////////////////////////////////////////////////////////////////////////////////

DValue *DtoComplex(const Loc &loc, Type *to, DValue *val) {
  LLType *complexTy = DtoType(to);

  Type *baserety;
  Type *baseimty;
  switch (to->toBasetype()->ty) {
  default:
    llvm_unreachable("Unexpected complex floating point type");
  case TY::Tcomplex32:
    baserety = Type::tfloat32;
    baseimty = Type::timaginary32;
    break;
  case TY::Tcomplex64:
    baserety = Type::tfloat64;
    baseimty = Type::timaginary64;
    break;
  case TY::Tcomplex80:
    baserety = Type::tfloat80;
    baseimty = Type::timaginary80;
    break;
  }

  LLValue *re, *im;
  DtoGetComplexParts(loc, to, val, re, im);

  if (!re) {
    re = LLConstant::getNullValue(DtoType(baserety));
  }
  if (!im) {
    im = LLConstant::getNullValue(DtoType(baseimty));
  }

  LLValue *res = DtoAggrPair(complexTy, re, im);

  return new DImValue(to, res);
}

////////////////////////////////////////////////////////////////////////////////

void DtoComplexSet(LLValue *c, LLValue *re, LLValue *im) {
  DtoStore(re, DtoGEP(c, 0u, 0));
  DtoStore(im, DtoGEP(c, 0, 1));
}

////////////////////////////////////////////////////////////////////////////////

void DtoGetComplexParts(const Loc &loc, Type *to, DValue *val, DValue *&re,
                        DValue *&im) {
  Type *baserety;
  Type *baseimty;
  switch (to->toBasetype()->ty) {
  default:
    llvm_unreachable("Unexpected complex floating point type");
  case TY::Tcomplex32:
    baserety = Type::tfloat32;
    baseimty = Type::timaginary32;
    break;
  case TY::Tcomplex64:
    baserety = Type::tfloat64;
    baseimty = Type::timaginary64;
    break;
  case TY::Tcomplex80:
    baserety = Type::tfloat80;
    baseimty = Type::timaginary80;
    break;
  }

  Type *t = val->type->toBasetype();

  if (t->iscomplex()) {
    DValue *v = DtoCastComplex(loc, val, to);
    if (to->iscomplex()) {
      if (v->isLVal()) {
        LLValue *reVal = DtoGEP(DtoLVal(v), 0u, 0, ".re_part");
        LLValue *imVal = DtoGEP(DtoLVal(v), 0, 1, ".im_part");
        re = new DLValue(baserety, reVal);
        im = new DLValue(baseimty, imVal);
      } else {
        LLValue *reVal =
            gIR->ir->CreateExtractValue(DtoRVal(v), 0, ".re_part");
        LLValue *imVal =
            gIR->ir->CreateExtractValue(DtoRVal(v), 1, ".im_part");
        re = new DImValue(baserety, reVal);
        im = new DImValue(baseimty, imVal);
      }
    } else {
      DtoGetComplexParts(loc, to, v, re, im);
    }
  } else if (t->isimaginary()) {
    re = nullptr;
    im = DtoCastFloat(loc, val, baseimty);
  } else if (t->isfloating()) {
    re = DtoCastFloat(loc, val, baserety);
    im = nullptr;
  } else if (t->isintegral()) {
    re = DtoCastInt(loc, val, baserety);
    im = nullptr;
  } else {
    llvm_unreachable("Unexpected numeric type.");
  }
}

////////////////////////////////////////////////////////////////////////////////

void DtoGetComplexParts(const Loc &loc, Type *to, DValue *val, LLValue *&re,
                        LLValue *&im) {
  DValue *dre, *dim;
  DtoGetComplexParts(loc, to, val, dre, dim);
  re = dre ? DtoRVal(dre) : nullptr;
  im = dim ? DtoRVal(dim) : nullptr;
}

////////////////////////////////////////////////////////////////////////////////

DImValue *DtoComplexAdd(const Loc &loc, Type *type, DRValue *lhs,
                        DRValue *rhs) {
  llvm::Value *lhs_re, *lhs_im, *rhs_re, *rhs_im, *res_re, *res_im;

  // lhs values
  DtoGetComplexParts(loc, type, lhs, lhs_re, lhs_im);
  // rhs values
  DtoGetComplexParts(loc, type, rhs, rhs_re, rhs_im);

  // add up
  if (lhs_re && rhs_re) {
    res_re = gIR->ir->CreateFAdd(lhs_re, rhs_re);
  } else if (lhs_re) {
    res_re = lhs_re;
  } else { // either rhs_re or no re at all (then use any)
    res_re = rhs_re;
  }

  if (lhs_im && rhs_im) {
    res_im = gIR->ir->CreateFAdd(lhs_im, rhs_im);
  } else if (lhs_im) {
    res_im = lhs_im;
  } else { // either rhs_im or no im at all (then use any)
    res_im = rhs_im;
  }

  LLValue *res = DtoAggrPair(DtoType(type), res_re, res_im);
  return new DImValue(type, res);
}

////////////////////////////////////////////////////////////////////////////////

DImValue *DtoComplexMin(const Loc &loc, Type *type, DRValue *lhs,
                        DRValue *rhs) {
  llvm::Value *lhs_re, *lhs_im, *rhs_re, *rhs_im, *res_re, *res_im;

  // lhs values
  DtoGetComplexParts(loc, type, lhs, lhs_re, lhs_im);
  // rhs values
  DtoGetComplexParts(loc, type, rhs, rhs_re, rhs_im);

  // add up
  if (lhs_re && rhs_re) {
    res_re = gIR->ir->CreateFSub(lhs_re, rhs_re);
  } else if (lhs_re) {
    res_re = lhs_re;
  } else { // either rhs_re or no re at all (then use any)
    res_re = gIR->ir->CreateFNeg(rhs_re, "neg");
  }

  if (lhs_im && rhs_im) {
    res_im = gIR->ir->CreateFSub(lhs_im, rhs_im);
  } else if (lhs_im) {
    res_im = lhs_im;
  } else { // either rhs_im or no im at all (then use any)
    res_im = gIR->ir->CreateFNeg(rhs_im, "neg");
  }

  LLValue *res = DtoAggrPair(DtoType(type), res_re, res_im);
  return new DImValue(type, res);
}

////////////////////////////////////////////////////////////////////////////////

DImValue *DtoComplexMul(const Loc &loc, Type *type, DRValue *lhs,
                        DRValue *rhs) {
  llvm::Value *lhs_re, *lhs_im, *rhs_re, *rhs_im, *res_re, *res_im;

  // lhs values
  DtoGetComplexParts(loc, type, lhs, lhs_re, lhs_im);
  // rhs values
  DtoGetComplexParts(loc, type, rhs, rhs_re, rhs_im);

  // mul up
  llvm::Value *rere = nullptr;
  llvm::Value *reim = nullptr;
  llvm::Value *imre = nullptr;
  llvm::Value *imim = nullptr;

  if (lhs_re && rhs_re) {
    rere = gIR->ir->CreateFMul(lhs_re, rhs_re, "rere_mul");
  }
  if (lhs_re && rhs_im) {
    reim = gIR->ir->CreateFMul(lhs_re, rhs_im, "reim_mul");
  }
  if (lhs_im && rhs_re) {
    imre = gIR->ir->CreateFMul(lhs_im, rhs_re, "imre_mul");
  }
  if (lhs_im && rhs_im) {
    imim = gIR->ir->CreateFMul(lhs_im, rhs_im, "imim_mul");
  }

  if (rere && imim) {
    res_re = gIR->ir->CreateFSub(rere, imim, "rere_imim_sub");
  } else if (rere) {
    res_re = rere;
  } else if (imim) {
    res_re = gIR->ir->CreateFNeg(imim, "imim_neg");
  } else {
    res_re = lhs_re ? rhs_re : lhs_re; // null!
  }

  if (reim && imre) {
    res_im = gIR->ir->CreateFAdd(reim, imre, "reim_imre_add");
  } else if (reim) {
    res_im = reim;
  } else if (imre) {
    res_im = imre;
  } else {
    res_im = lhs_re ? rhs_im : lhs_re; // null!
  }

  LLValue *res = DtoAggrPair(DtoType(type), res_re, res_im);
  return new DImValue(type, res);
}

////////////////////////////////////////////////////////////////////////////////

DImValue *DtoComplexDiv(const Loc &loc, Type *type, DRValue *lhs,
                        DRValue *rhs) {
  llvm::Value *lhs_re, *lhs_im, *rhs_re, *rhs_im, *res_re, *res_im;

  // lhs values
  DtoGetComplexParts(loc, type, lhs, lhs_re, lhs_im);
  // rhs values
  DtoGetComplexParts(loc, type, rhs, rhs_re, rhs_im);

  // if divisor is only real, division is simple
  if (rhs_re && !rhs_im) {
    if (lhs_re) {
      res_re = gIR->ir->CreateFDiv(lhs_re, rhs_re, "re_divby_re");
    } else {
      res_re = lhs_re;
    }
    if (lhs_im) {
      res_im = gIR->ir->CreateFDiv(lhs_im, rhs_re, "im_divby_re");
    } else {
      res_im = lhs_im;
    }
  }
  // if divisor is only imaginary, division is simple too
  else if (!rhs_re && rhs_im) {
    if (lhs_re) {
      res_im = gIR->ir->CreateFNeg(
          gIR->ir->CreateFDiv(lhs_re, rhs_im, "re_divby_im"), "neg");
    } else {
      res_im = lhs_re;
    }
    if (lhs_im) {
      res_re = gIR->ir->CreateFDiv(lhs_im, rhs_im, "im_divby_im");
    } else {
      res_re = lhs_im;
    }
  }
  // full division
  else {
    llvm::Value *tmp1, *tmp2, *denom;

    if (lhs_re && lhs_im) {
      tmp1 = gIR->ir->CreateFMul(lhs_re, rhs_re, "rere");
      tmp2 = gIR->ir->CreateFMul(lhs_im, rhs_im, "imim");
      res_re = gIR->ir->CreateFAdd(tmp1, tmp2, "rere_plus_imim");

      tmp1 = gIR->ir->CreateFMul(lhs_re, rhs_im, "reim");
      tmp2 = gIR->ir->CreateFMul(lhs_im, rhs_re, "imre");
      res_im = gIR->ir->CreateFSub(tmp2, tmp1, "imre_sub_reim");
    } else if (lhs_re) {
      res_re = gIR->ir->CreateFMul(lhs_re, rhs_re, "rere");

      res_im = gIR->ir->CreateFMul(lhs_re, rhs_im, "reim");
      res_im = gIR->ir->CreateFNeg(res_im);
    } else if (lhs_im) {
      res_re = gIR->ir->CreateFMul(lhs_im, rhs_im, "imim");
      res_im = gIR->ir->CreateFMul(lhs_im, rhs_re, "imre");
    } else {
      llvm_unreachable("lhs has neither real nor imaginary part");
    }

    tmp1 = gIR->ir->CreateFMul(rhs_re, rhs_re, "rhs_resq");
    tmp2 = gIR->ir->CreateFMul(rhs_im, rhs_im, "rhs_imsq");
    denom = gIR->ir->CreateFAdd(tmp1, tmp2, "denom");

    res_re = gIR->ir->CreateFDiv(res_re, denom, "res_re");
    res_im = gIR->ir->CreateFDiv(res_im, denom, "res_im");
  }

  LLValue *res = DtoAggrPair(DtoType(type), res_re, res_im);
  return new DImValue(type, res);
}

////////////////////////////////////////////////////////////////////////////////

DImValue *DtoComplexMod(const Loc &loc, Type *type, DRValue *lhs,
                        DRValue *rhs) {
  llvm::Value *lhs_re, *lhs_im, *rhs_re, *rhs_im, *res_re, *res_im, *divisor;

  // lhs values
  DtoGetComplexParts(loc, type, lhs, lhs_re, lhs_im);
  // rhs values
  DtoGetComplexParts(loc, type, rhs, rhs_re, rhs_im);

  // Divisor can be real or imaginary but not complex
  assert((rhs_re != 0) ^ (rhs_im != 0));

  divisor = rhs_re ? rhs_re : rhs_im;
  res_re = lhs_re ? gIR->ir->CreateFRem(lhs_re, divisor) : lhs_re;
  res_im = lhs_re ? gIR->ir->CreateFRem(lhs_im, divisor) : lhs_im;

  LLValue *res = DtoAggrPair(DtoType(type), res_re, res_im);
  return new DImValue(type, res);
}

////////////////////////////////////////////////////////////////////////////////

DImValue *DtoComplexNeg(const Loc &loc, Type *type, DRValue *val) {
  llvm::Value *a, *b, *re, *im;

  // values
  DtoGetComplexParts(loc, type, val, a, b);

  // neg up
  assert(a && b);
  re = gIR->ir->CreateFNeg(a);
  im = gIR->ir->CreateFNeg(b);

  LLValue *res = DtoAggrPair(DtoType(type), re, im);
  return new DImValue(type, res);
}

////////////////////////////////////////////////////////////////////////////////

LLValue *DtoComplexEquals(const Loc &loc, TOK op, DValue *lhs, DValue *rhs) {
  DValue *lhs_re, *lhs_im, *rhs_re, *rhs_im;

  // lhs values
  DtoGetComplexParts(loc, lhs->type, lhs, lhs_re, lhs_im);
  // rhs values
  DtoGetComplexParts(loc, lhs->type, rhs, rhs_re, rhs_im);

  // (l.re==r.re && l.im==r.im) or (l.re!=r.re || l.im!=r.im)
  LLValue *b1 = DtoBinFloatsEquals(loc, lhs_re, rhs_re, op);
  LLValue *b2 = DtoBinFloatsEquals(loc, lhs_im, rhs_im, op);

  return (op == TOKequal || op == TOKidentity) ? gIR->ir->CreateAnd(b1, b2)
                                               : gIR->ir->CreateOr(b1, b2);
}

////////////////////////////////////////////////////////////////////////////////

DValue *DtoCastComplex(const Loc &loc, DValue *val, Type *_to) {
  Type *to = _to->toBasetype();
  Type *vty = val->type->toBasetype();
  if (to->iscomplex()) {
    if (vty->size() == to->size()) {
      return val;
    }

    llvm::Value *re, *im;
    DtoGetComplexParts(loc, val->type, val, re, im);
    LLType *toty = DtoComplexBaseType(to);

    if (to->size() < vty->size()) {
      re = gIR->ir->CreateFPTrunc(re, toty);
      im = gIR->ir->CreateFPTrunc(im, toty);
    } else {
      re = gIR->ir->CreateFPExt(re, toty);
      im = gIR->ir->CreateFPExt(im, toty);
    }

    LLValue *pair = DtoAggrPair(DtoType(_to), re, im);
    return new DImValue(_to, pair);
  }
  if (to->isimaginary()) {
    // FIXME: this loads both values, even when we only need one
    LLValue *v = DtoRVal(val);
    LLValue *impart = gIR->ir->CreateExtractValue(v, 1, ".im_part");
    Type *extractty;
    switch (vty->ty) {
    default:
      llvm_unreachable("Unexpected complex floating point type");
    case TY::Tcomplex32:
      extractty = Type::timaginary32;
      break;
    case TY::Tcomplex64:
      extractty = Type::timaginary64;
      break;
    case TY::Tcomplex80:
      extractty = Type::timaginary80;
      break;
    }
    auto im = new DImValue(extractty, impart);
    return DtoCastFloat(loc, im, to);
  }
  if (to->ty == TY::Tbool) {
    return new DImValue(
        _to, DtoComplexEquals(loc, TOKnotequal, val, DtoNullValue(vty)));
  }
  if (to->isfloating() || to->isintegral()) {
    // FIXME: this loads both values, even when we only need one
    LLValue *v = DtoRVal(val);
    LLValue *repart = gIR->ir->CreateExtractValue(v, 0, ".re_part");
    Type *extractty;
    switch (vty->ty) {
    default:
      llvm_unreachable("Unexpected complex floating point type");
    case TY::Tcomplex32:
      extractty = Type::tfloat32;
      break;
    case TY::Tcomplex64:
      extractty = Type::tfloat64;
      break;
    case TY::Tcomplex80:
      extractty = Type::tfloat80;
      break;
    }
    auto re = new DImValue(extractty, repart);
    return DtoCastFloat(loc, re, to);
  }
  error(loc, "Don't know how to cast `%s` to `%s`", vty->toChars(),
        to->toChars());
  fatal();
}