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                     let oflow_place = CPlace::new_stack_slot(fx, fx.tcx.types.i32);
  34                     let oflow_addr = oflow_place.to_addr(fx);
  35                     let oflow_addr = CValue::by_val(oflow_addr, fx.layout_of(fx.tcx.mk_mut_ptr(fx.tcx.types.i32)));
  36                     let val = fx.easy_call("__muloti4", &[lhs, rhs, oflow_addr], fx.tcx.types.i128);
  37                     let val = val.load_scalar(fx);
  38                     let oflow = oflow_place.to_cvalue(fx).load_scalar(fx);
  39                     let oflow = fx.bcx.ins().icmp_imm(IntCC::NotEqual, oflow, 0);
  40                     let oflow = fx.bcx.ins().bint(types::I8, oflow);
  41                     CValue::by_val_pair(val, oflow, fx.layout_of(out_ty))
  42                 } else {
  43                     // FIXME implement it
  44                 let out_layout = fx.layout_of(out_ty);
  45                     return Some(crate::trap::trap_unreachable_ret_value(fx, out_layout, format!("unimplemented 128bit checked binop unsigned mul")));
  46                 }
  47             } else {
  48                 let val_ty = if is_signed { fx.tcx.types.i128 } else { fx.tcx.types.u128 };
  49                 fx.easy_call("__multi3", &[lhs, rhs], val_ty)
  50             };
  51             return Some(res);
  52         }
  53         BinOp::Div => {
  54             let res = if checked {
  55                 // FIXME implement it
  56                 let out_layout = fx.layout_of(out_ty);
  57                 return Some(crate::trap::trap_unreachable_ret_value(fx, out_layout, format!("unimplemented 128bit checked binop div")));
  58             } else {
  59                 if is_signed {
  60                     fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128)
  61                 } else {
  62                     fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128)
  63                 }
  64             };
  65             return Some(res);
  66         }
  67         BinOp::Rem => {
  68             let res = if checked {
  69                 // FIXME implement it
  70                 let out_layout = fx.layout_of(out_ty);
  71                 return Some(crate::trap::trap_unreachable_ret_value(fx, out_layout, format!("unimplemented 128bit checked binop rem")));
  72             } else {
  73                 if is_signed {
  74                     fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128)
  75                 } else {
  76                     fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128)
  77                 }
  78             };
  79             return Some(res);
  80         }
  81         BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
  82             assert!(!checked);
  83             let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
  84             let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
  85             let res = match (bin_op, is_signed) {
  86                 (BinOp::Eq, _) => {
  87                     let lsb_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_lsb, rhs_lsb);
  88                     let msb_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_msb, rhs_msb);
  89                     fx.bcx.ins().band(lsb_eq, msb_eq)
  90                 }
  91                 (BinOp::Ne, _) => {
  92                     let lsb_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_lsb, rhs_lsb);
  93                     let msb_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_msb, rhs_msb);
  94                     fx.bcx.ins().bor(lsb_ne, msb_ne)
  95                 }
  96                 _ => {
  97                     // FIXME implement it
  98                     let out_layout = fx.layout_of(out_ty);
  99                     return Some(crate::trap::trap_unreachable_ret_value(fx, out_layout, format!("unimplemented 128bit binop {:?}", bin_op)));
 100                 },
 101             };
 102
 103             let res = fx.bcx.ins().bint(types::I8, res);
 104             let res = CValue::by_val(res, fx.layout_of(fx.tcx.types.bool));
 105             return Some(res);
 106         }
 107         BinOp::Shl | BinOp::Shr => {
 108             let is_overflow = if checked {
 109                 // rhs >= 128
 110
 111                 // FIXME support non 128bit rhs
 112                 /*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
 113                 let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
 114                 let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
 115                 let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
 116                 let is_overflow = fx.bcx.ins().bconst(types::B1, false);
 117
 118                 Some(fx.bcx.ins().bint(types::I8, is_overflow))
 119             } else {
 120                 None
 121             };
 122
 123             // Optimize `val >> 64`, because compiler_builtins uses it to deconstruct an 128bit
 124             // integer into its lsb and msb.
 125             // https://github.com/rust-lang-nursery/compiler-builtins/blob/79a6a1603d5672cbb9187ff41ff4d9b5048ac1cb/src/int/mod.rs#L217
 126             if let Some(64) = resolve_value_imm(fx.bcx.func, rhs_val) {
 127                 let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
 128                 let all_zeros = fx.bcx.ins().iconst(types::I64, 0);
 129                 let val = match (bin_op, is_signed) {
 130                     (BinOp::Shr, false) => {
 131                         let val = fx.bcx.ins().iconcat(lhs_msb, all_zeros);
 132                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.u128)))
 133                     }
 134                     (BinOp::Shr, true) => {
 135                         let sign = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, lhs_msb, 0);
 136                         let all_ones = fx.bcx.ins().iconst(types::I64, u64::max_value() as i64);
 137                         let all_sign_bits = fx.bcx.ins().select(sign, all_zeros, all_ones);
 138
 139                         let val = fx.bcx.ins().iconcat(lhs_msb, all_sign_bits);
 140                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.i128)))
 141                     }
 142                     (BinOp::Shl, _) => {
 143                         let val = fx.bcx.ins().iconcat(all_zeros, lhs_lsb);
 144                         Some(CValue::by_val(val, fx.layout_of(out_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 }