compiler/rustc_codegen_cranelift/src/codegen_i128.rs

   1 //! Replaces 128-bit operators with lang item calls where necessary
   2
   3 use crate::prelude::*;
   4
   5 pub(crate) fn maybe_codegen<'tcx>(
   6     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
   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             None
  25         }
  26         BinOp::Add | BinOp::Sub if !checked => 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 {
  54                     fx.tcx.types.i128
  55                 } else {
  56                     fx.tcx.types.u128
  57                 };
  58                 fx.easy_call("__multi3", &[lhs, rhs], val_ty)
  59             };
  60             Some(res)
  61         }
  62         BinOp::Div => {
  63             assert!(!checked);
  64             if is_signed {
  65                 Some(fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128))
  66             } else {
  67                 Some(fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128))
  68             }
  69         }
  70         BinOp::Rem => {
  71             assert!(!checked);
  72             if is_signed {
  73                 Some(fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128))
  74             } else {
  75                 Some(fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128))
  76             }
  77         }
  78         BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
  79             assert!(!checked);
  80             None
  81         }
  82         BinOp::Shl | BinOp::Shr => {
  83             let is_overflow = if checked {
  84                 // rhs >= 128
  85
  86                 // FIXME support non 128bit rhs
  87                 /*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
  88                 let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
  89                 let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
  90                 let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
  91                 let is_overflow = fx.bcx.ins().bconst(types::B1, false);
  92
  93                 Some(fx.bcx.ins().bint(types::I8, is_overflow))
  94             } else {
  95                 None
  96             };
  97
  98             // Optimize `val >> 64`, because compiler_builtins uses it to deconstruct an 128bit
  99             // integer into its lsb and msb.
 100             // https://github.com/rust-lang-nursery/compiler-builtins/blob/79a6a1603d5672cbb9187ff41ff4d9b5048ac1cb/src/int/mod.rs#L217
 101             if resolve_value_imm(fx.bcx.func, rhs_val) == Some(64) {
 102                 let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
 103                 let all_zeros = fx.bcx.ins().iconst(types::I64, 0);
 104                 let val = match (bin_op, is_signed) {
 105                     (BinOp::Shr, false) => {
 106                         let val = fx.bcx.ins().iconcat(lhs_msb, all_zeros);
 107                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.u128)))
 108                     }
 109                     (BinOp::Shr, true) => {
 110                         let sign = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, lhs_msb, 0);
 111                         let all_ones = fx.bcx.ins().iconst(types::I64, u64::MAX as i64);
 112                         let all_sign_bits = fx.bcx.ins().select(sign, all_zeros, all_ones);
 113
 114                         let val = fx.bcx.ins().iconcat(lhs_msb, all_sign_bits);
 115                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.i128)))
 116                     }
 117                     (BinOp::Shl, _) => {
 118                         let val_ty = if is_signed {
 119                             fx.tcx.types.i128
 120                         } else {
 121                             fx.tcx.types.u128
 122                         };
 123                         let val = fx.bcx.ins().iconcat(all_zeros, lhs_lsb);
 124                         Some(CValue::by_val(val, fx.layout_of(val_ty)))
 125                     }
 126                     _ => None,
 127                 };
 128                 if let Some(val) = val {
 129                     if let Some(is_overflow) = is_overflow {
 130                         let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 131                         let val = val.load_scalar(fx);
 132                         return Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)));
 133                     } else {
 134                         return Some(val);
 135                     }
 136                 }
 137             }
 138
 139             let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
 140             let truncated_rhs = CValue::by_val(truncated_rhs, fx.layout_of(fx.tcx.types.u32));
 141             let val = match (bin_op, is_signed) {
 142                 (BinOp::Shl, false) => {
 143                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 144                 }
 145                 (BinOp::Shl, true) => {
 146                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 147                 }
 148                 (BinOp::Shr, false) => {
 149                     fx.easy_call("__lshrti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 150                 }
 151                 (BinOp::Shr, true) => {
 152                     fx.easy_call("__ashrti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 153                 }
 154                 (_, _) => unreachable!(),
 155             };
 156             if let Some(is_overflow) = is_overflow {
 157                 let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 158                 let val = val.load_scalar(fx);
 159                 Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 160             } else {
 161                 Some(val)
 162             }
 163         }
 164     }
 165 }