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 ) -> Option<CValue<'tcx>> {
  12     if lhs.layout().ty != fx.tcx.types.u128 && lhs.layout().ty != fx.tcx.types.i128 {
  13         return None;
  14     }
  15
  16     let lhs_val = lhs.load_scalar(fx);
  17     let rhs_val = rhs.load_scalar(fx);
  18
  19     let is_signed = type_sign(lhs.layout().ty);
  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             let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
  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             let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
  37             return Some(if is_signed {
  38                 fx.easy_call("__rust_i128_subo", &[lhs, rhs], out_ty)
  39             } else {
  40                 fx.easy_call("__rust_u128_subo", &[lhs, rhs], out_ty)
  41             })
  42         }
  43         BinOp::Offset => unreachable!("offset should only be used on pointers, not 128bit ints"),
  44         BinOp::Mul => {
  45             let res = if checked {
  46                 let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
  47                 if is_signed {
  48                     fx.easy_call("__rust_i128_mulo", &[lhs, rhs], out_ty)
  49                 } else {
  50                     fx.easy_call("__rust_u128_mulo", &[lhs, rhs], out_ty)
  51                 }
  52             } else {
  53                 let val_ty = if is_signed { fx.tcx.types.i128 } else { fx.tcx.types.u128 };
  54                 fx.easy_call("__multi3", &[lhs, rhs], val_ty)
  55             };
  56             return Some(res);
  57         }
  58         BinOp::Div => {
  59             assert!(!checked);
  60             if is_signed {
  61                 Some(fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128))
  62             } else {
  63                 Some(fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128))
  64             }
  65         }
  66         BinOp::Rem => {
  67             assert!(!checked);
  68             if is_signed {
  69                 Some(fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128))
  70             } else {
  71                 Some(fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128))
  72             }
  73         }
  74         BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
  75             assert!(!checked);
  76             return None;
  77         }
  78         BinOp::Shl | BinOp::Shr => {
  79             let is_overflow = if checked {
  80                 // rhs >= 128
  81
  82                 // FIXME support non 128bit rhs
  83                 /*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
  84                 let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
  85                 let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
  86                 let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
  87                 let is_overflow = fx.bcx.ins().bconst(types::B1, false);
  88
  89                 Some(fx.bcx.ins().bint(types::I8, is_overflow))
  90             } else {
  91                 None
  92             };
  93
  94             // Optimize `val >> 64`, because compiler_builtins uses it to deconstruct an 128bit
  95             // integer into its lsb and msb.
  96             // https://github.com/rust-lang-nursery/compiler-builtins/blob/79a6a1603d5672cbb9187ff41ff4d9b5048ac1cb/src/int/mod.rs#L217
  97             if let Some(64) = resolve_value_imm(fx.bcx.func, rhs_val) {
  98                 let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
  99                 let all_zeros = fx.bcx.ins().iconst(types::I64, 0);
 100                 let val = match (bin_op, is_signed) {
 101                     (BinOp::Shr, false) => {
 102                         let val = fx.bcx.ins().iconcat(lhs_msb, all_zeros);
 103                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.u128)))
 104                     }
 105                     (BinOp::Shr, true) => {
 106                         let sign = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, lhs_msb, 0);
 107                         let all_ones = fx.bcx.ins().iconst(types::I64, u64::max_value() as i64);
 108                         let all_sign_bits = fx.bcx.ins().select(sign, all_zeros, all_ones);
 109
 110                         let val = fx.bcx.ins().iconcat(lhs_msb, all_sign_bits);
 111                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.i128)))
 112                     }
 113                     (BinOp::Shl, _) => {
 114                         let val_ty = if is_signed { fx.tcx.types.i128 } else { fx.tcx.types.u128 };
 115                         let val = fx.bcx.ins().iconcat(all_zeros, lhs_lsb);
 116                         Some(CValue::by_val(val, fx.layout_of(val_ty)))
 117                     }
 118                     _ => None
 119                 };
 120                 if let Some(val) = val {
 121                     if let Some(is_overflow) = is_overflow {
 122                         let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 123                         let val = val.load_scalar(fx);
 124                         return Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 125                     } else {
 126                         return Some(val);
 127                     }
 128                 }
 129             }
 130
 131             let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
 132             let truncated_rhs = CValue::by_val(truncated_rhs, fx.layout_of(fx.tcx.types.u32));
 133             let val = match (bin_op, is_signed) {
 134                 (BinOp::Shl, false) => {
 135                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 136                 }
 137                 (BinOp::Shl, true) => {
 138                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 139                 }
 140                 (BinOp::Shr, false) => {
 141                     fx.easy_call("__lshrti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 142                 }
 143                 (BinOp::Shr, true) => {
 144                     fx.easy_call("__ashrti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 145                 }
 146                 (_, _) => unreachable!(),
 147             };
 148             if let Some(is_overflow) = is_overflow {
 149                 let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 150                 let val = val.load_scalar(fx);
 151                 Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 152             } else {
 153                 Some(val)
 154             }
 155         }
 156     }
 157 }