src/codegen_i128.rs

   1 //! Replaces 128-bit operators with lang item calls
   2
   3 use crate::prelude::*;
   4
   5 pub fn maybe_codegen<'a, 'tcx>(
   6     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
   7     bin_op: BinOp,
   8     checked: bool,
   9     lhs: CValue<'tcx>,
  10     rhs: CValue<'tcx>,
  11     out_ty: Ty<'tcx>,
  12 ) -> Option<CValue<'tcx>> {
  13     if lhs.layout().ty != fx.tcx.types.u128 && lhs.layout().ty != fx.tcx.types.i128 {
  14         return None;
  15     }
  16
  17     let lhs_val = lhs.load_scalar(fx);
  18     let rhs_val = rhs.load_scalar(fx);
  19
  20     let is_signed = type_sign(lhs.layout().ty);
  21
  22     match bin_op {
  23         BinOp::BitAnd | BinOp::BitOr | BinOp::BitXor => {
  24             assert!(!checked);
  25             return None;
  26         }
  27         BinOp::Add | BinOp::Sub if !checked => return None,
  28         BinOp::Add => {
  29             return Some(if is_signed {
  30                 fx.easy_call("__rust_i128_addo", &[lhs, rhs], out_ty)
  31             } else {
  32                 fx.easy_call("__rust_u128_addo", &[lhs, rhs], out_ty)
  33             })
  34         }
  35         BinOp::Sub => {
  36             return Some(if is_signed {
  37                 fx.easy_call("__rust_i128_subo", &[lhs, rhs], out_ty)
  38             } else {
  39                 fx.easy_call("__rust_u128_subo", &[lhs, rhs], out_ty)
  40             })
  41         }
  42         BinOp::Offset => unreachable!("offset should only be used on pointers, not 128bit ints"),
  43         BinOp::Mul => {
  44             let res = if checked {
  45                 if is_signed {
  46                     fx.easy_call("__rust_i128_mulo", &[lhs, rhs], out_ty)
  47                 } else {
  48                     fx.easy_call("__rust_u128_mulo", &[lhs, rhs], out_ty)
  49                 }
  50             } else {
  51                 let val_ty = if is_signed { fx.tcx.types.i128 } else { fx.tcx.types.u128 };
  52                 fx.easy_call("__multi3", &[lhs, rhs], val_ty)
  53             };
  54             return Some(res);
  55         }
  56         BinOp::Div => {
  57             assert!(!checked);
  58             if is_signed {
  59                 Some(fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128))
  60             } else {
  61                 Some(fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128))
  62             }
  63         }
  64         BinOp::Rem => {
  65             assert!(!checked);
  66             if is_signed {
  67                 Some(fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128))
  68             } else {
  69                 Some(fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128))
  70             }
  71         }
  72         BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
  73             assert!(!checked);
  74             let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
  75             let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
  76
  77             let res = match bin_op {
  78                 BinOp::Eq => {
  79                     let lsb_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_lsb, rhs_lsb);
  80                     let msb_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_msb, rhs_msb);
  81                     fx.bcx.ins().band(lsb_eq, msb_eq)
  82                 }
  83                 BinOp::Ne => {
  84                     let lsb_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_lsb, rhs_lsb);
  85                     let msb_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_msb, rhs_msb);
  86                     fx.bcx.ins().bor(lsb_ne, msb_ne)
  87                 }
  88                 _ => {
  89                     // if msb_eq {
  90                     //     lsb_cc
  91                     // } else {
  92                     //     msb_cc
  93                     // }
  94                     let cc = match (bin_op, is_signed) {
  95                         (BinOp::Ge, false) => IntCC::UnsignedGreaterThanOrEqual,
  96                         (BinOp::Gt, false) => IntCC::UnsignedGreaterThan,
  97                         (BinOp::Lt, false) => IntCC::UnsignedLessThan,
  98                         (BinOp::Le, false) => IntCC::UnsignedLessThanOrEqual,
  99
 100                         (BinOp::Ge, true) => IntCC::SignedGreaterThanOrEqual,
 101                         (BinOp::Gt, true) => IntCC::SignedGreaterThan,
 102                         (BinOp::Lt, true) => IntCC::SignedLessThan,
 103                         (BinOp::Le, true) => IntCC::SignedLessThanOrEqual,
 104                         _ => unreachable!(),
 105                     };
 106
 107                     let msb_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_msb, rhs_msb);
 108                     let lsb_cc = fx.bcx.ins().icmp(cc, lhs_lsb, rhs_lsb);
 109                     let msb_cc = fx.bcx.ins().icmp(cc, lhs_msb, rhs_msb);
 110
 111                     fx.bcx.ins().select(msb_eq, lsb_cc, msb_cc)
 112                 }
 113             };
 114
 115             let res = fx.bcx.ins().bint(types::I8, res);
 116             let res = CValue::by_val(res, fx.layout_of(fx.tcx.types.bool));
 117             return Some(res);
 118         }
 119         BinOp::Shl | BinOp::Shr => {
 120             let is_overflow = if checked {
 121                 // rhs >= 128
 122
 123                 // FIXME support non 128bit rhs
 124                 /*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
 125                 let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
 126                 let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
 127                 let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
 128                 let is_overflow = fx.bcx.ins().bconst(types::B1, false);
 129
 130                 Some(fx.bcx.ins().bint(types::I8, is_overflow))
 131             } else {
 132                 None
 133             };
 134
 135             // Optimize `val >> 64`, because compiler_builtins uses it to deconstruct an 128bit
 136             // integer into its lsb and msb.
 137             // https://github.com/rust-lang-nursery/compiler-builtins/blob/79a6a1603d5672cbb9187ff41ff4d9b5048ac1cb/src/int/mod.rs#L217
 138             if let Some(64) = resolve_value_imm(fx.bcx.func, rhs_val) {
 139                 let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
 140                 let all_zeros = fx.bcx.ins().iconst(types::I64, 0);
 141                 let val = match (bin_op, is_signed) {
 142                     (BinOp::Shr, false) => {
 143                         let val = fx.bcx.ins().iconcat(lhs_msb, all_zeros);
 144                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.u128)))
 145                     }
 146                     (BinOp::Shr, true) => {
 147                         let sign = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, lhs_msb, 0);
 148                         let all_ones = fx.bcx.ins().iconst(types::I64, u64::max_value() as i64);
 149                         let all_sign_bits = fx.bcx.ins().select(sign, all_zeros, all_ones);
 150
 151                         let val = fx.bcx.ins().iconcat(lhs_msb, all_sign_bits);
 152                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.i128)))
 153                     }
 154                     (BinOp::Shl, _) => {
 155                         let val_ty = if is_signed { fx.tcx.types.i128 } else { fx.tcx.types.u128 };
 156                         let val = fx.bcx.ins().iconcat(all_zeros, lhs_lsb);
 157                         Some(CValue::by_val(val, fx.layout_of(val_ty)))
 158                     }
 159                     _ => None
 160                 };
 161                 if let Some(val) = val {
 162                     if let Some(is_overflow) = is_overflow {
 163                         let val = val.load_scalar(fx);
 164                         return Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 165                     } else {
 166                         return Some(val);
 167                     }
 168                 }
 169             }
 170
 171             let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
 172             let truncated_rhs = CValue::by_val(truncated_rhs, fx.layout_of(fx.tcx.types.u32));
 173             let val = match (bin_op, is_signed) {
 174                 (BinOp::Shl, false) => {
 175                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 176                 }
 177                 (BinOp::Shl, true) => {
 178                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 179                 }
 180                 (BinOp::Shr, false) => {
 181                     fx.easy_call("__lshrti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 182                 }
 183                 (BinOp::Shr, true) => {
 184                     fx.easy_call("__ashrti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 185                 }
 186                 (_, _) => unreachable!(),
 187             };
 188             if let Some(is_overflow) = is_overflow {
 189                 let val = val.load_scalar(fx);
 190                 Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 191             } else {
 192                 Some(val)
 193             }
 194         }
 195     }
 196 }