compiler/rustc_codegen_cranelift/src/codegen_i128.rs

   1 //! Replaces 128-bit operators with lang item calls where necessary
   2
   3 use cranelift_codegen::ir::ArgumentPurpose;
   4
   5 use crate::prelude::*;
   6
   7 pub(crate) fn maybe_codegen<'tcx>(
   8     fx: &mut FunctionCx<'_, 'tcx, impl Module>,
   9     bin_op: BinOp,
  10     checked: bool,
  11     lhs: CValue<'tcx>,
  12     rhs: CValue<'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     let is_signed = type_sign(lhs.layout().ty);
  22
  23     match bin_op {
  24         BinOp::BitAnd | BinOp::BitOr | BinOp::BitXor => {
  25             assert!(!checked);
  26             None
  27         }
  28         BinOp::Add | BinOp::Sub if !checked => None,
  29         BinOp::Mul if !checked => {
  30             let val_ty = if is_signed {
  31                 fx.tcx.types.i128
  32             } else {
  33                 fx.tcx.types.u128
  34             };
  35             Some(fx.easy_call("__multi3", &[lhs, rhs], val_ty))
  36         }
  37         BinOp::Add | BinOp::Sub | BinOp::Mul => {
  38             assert!(checked);
  39             let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
  40             let out_place = CPlace::new_stack_slot(fx, fx.layout_of(out_ty));
  41             let param_types = vec![
  42                 AbiParam::special(pointer_ty(fx.tcx), ArgumentPurpose::StructReturn),
  43                 AbiParam::new(types::I128),
  44                 AbiParam::new(types::I128),
  45             ];
  46             let args = [
  47                 out_place.to_ptr().get_addr(fx),
  48                 lhs.load_scalar(fx),
  49                 rhs.load_scalar(fx),
  50             ];
  51             let name = match (bin_op, is_signed) {
  52                 (BinOp::Add, false) => "__rust_u128_addo",
  53                 (BinOp::Add, true) => "__rust_i128_addo",
  54                 (BinOp::Sub, false) => "__rust_u128_subo",
  55                 (BinOp::Sub, true) => "__rust_i128_subo",
  56                 (BinOp::Mul, false) => "__rust_u128_mulo",
  57                 (BinOp::Mul, true) => "__rust_i128_mulo",
  58                 _ => unreachable!(),
  59             };
  60             fx.lib_call(name, param_types, vec![], &args);
  61             Some(out_place.to_cvalue(fx))
  62         }
  63         BinOp::Offset => unreachable!("offset should only be used on pointers, not 128bit ints"),
  64         BinOp::Div => {
  65             assert!(!checked);
  66             if is_signed {
  67                 Some(fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128))
  68             } else {
  69                 Some(fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128))
  70             }
  71         }
  72         BinOp::Rem => {
  73             assert!(!checked);
  74             if is_signed {
  75                 Some(fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128))
  76             } else {
  77                 Some(fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128))
  78             }
  79         }
  80         BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
  81             assert!(!checked);
  82             None
  83         }
  84         BinOp::Shl | BinOp::Shr => {
  85             let is_overflow = if checked {
  86                 // rhs >= 128
  87
  88                 // FIXME support non 128bit rhs
  89                 /*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
  90                 let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
  91                 let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
  92                 let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
  93                 let is_overflow = fx.bcx.ins().bconst(types::B1, false);
  94
  95                 Some(fx.bcx.ins().bint(types::I8, is_overflow))
  96             } else {
  97                 None
  98             };
  99
 100             // Optimize `val >> 64`, because compiler_builtins uses it to deconstruct an 128bit
 101             // integer into its lsb and msb.
 102             // https://github.com/rust-lang-nursery/compiler-builtins/blob/79a6a1603d5672cbb9187ff41ff4d9b5048ac1cb/src/int/mod.rs#L217
 103             if resolve_value_imm(fx.bcx.func, rhs_val) == Some(64) {
 104                 let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
 105                 let all_zeros = fx.bcx.ins().iconst(types::I64, 0);
 106                 let val = match (bin_op, is_signed) {
 107                     (BinOp::Shr, false) => {
 108                         let val = fx.bcx.ins().iconcat(lhs_msb, all_zeros);
 109                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.u128)))
 110                     }
 111                     (BinOp::Shr, true) => {
 112                         let sign = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, lhs_msb, 0);
 113                         let all_ones = fx.bcx.ins().iconst(types::I64, u64::MAX as i64);
 114                         let all_sign_bits = fx.bcx.ins().select(sign, all_zeros, all_ones);
 115
 116                         let val = fx.bcx.ins().iconcat(lhs_msb, all_sign_bits);
 117                         Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.i128)))
 118                     }
 119                     (BinOp::Shl, _) => {
 120                         let val_ty = if is_signed {
 121                             fx.tcx.types.i128
 122                         } else {
 123                             fx.tcx.types.u128
 124                         };
 125                         let val = fx.bcx.ins().iconcat(all_zeros, lhs_lsb);
 126                         Some(CValue::by_val(val, fx.layout_of(val_ty)))
 127                     }
 128                     _ => None,
 129                 };
 130                 if let Some(val) = val {
 131                     if let Some(is_overflow) = is_overflow {
 132                         let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 133                         let val = val.load_scalar(fx);
 134                         return Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)));
 135                     } else {
 136                         return Some(val);
 137                     }
 138                 }
 139             }
 140
 141             let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
 142             let truncated_rhs = CValue::by_val(truncated_rhs, fx.layout_of(fx.tcx.types.u32));
 143             let val = match (bin_op, is_signed) {
 144                 (BinOp::Shl, false) => {
 145                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 146                 }
 147                 (BinOp::Shl, true) => {
 148                     fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 149                 }
 150                 (BinOp::Shr, false) => {
 151                     fx.easy_call("__lshrti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
 152                 }
 153                 (BinOp::Shr, true) => {
 154                     fx.easy_call("__ashrti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
 155                 }
 156                 (_, _) => unreachable!(),
 157             };
 158             if let Some(is_overflow) = is_overflow {
 159                 let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 160                 let val = val.load_scalar(fx);
 161                 Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 162             } else {
 163                 Some(val)
 164             }
 165         }
 166     }
 167 }