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