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