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>,
   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
  15         && lhs.layout().ty != fx.tcx.types.i128
  16         && rhs.layout().ty != fx.tcx.types.u128
  17         && rhs.layout().ty != fx.tcx.types.i128
  18     {
  19         return None;
  20     }
  21
  22     let lhs_val = lhs.load_scalar(fx);
  23     let rhs_val = rhs.load_scalar(fx);
  24
  25     let is_signed = type_sign(lhs.layout().ty);
  26
  27     match bin_op {
  28         BinOp::BitAnd | BinOp::BitOr | BinOp::BitXor => {
  29             assert!(!checked);
  30             None
  31         }
  32         BinOp::Add | BinOp::Sub if !checked => None,
  33         BinOp::Mul if !checked => {
  34             let val_ty = if is_signed {
  35                 fx.tcx.types.i128
  36             } else {
  37                 fx.tcx.types.u128
  38             };
  39             Some(fx.easy_call("__multi3", &[lhs, rhs], val_ty))
  40         }
  41         BinOp::Add | BinOp::Sub | BinOp::Mul => {
  42             assert!(checked);
  43             let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
  44             let out_place = CPlace::new_stack_slot(fx, fx.layout_of(out_ty));
  45             let param_types = vec![
  46                 AbiParam::special(pointer_ty(fx.tcx), ArgumentPurpose::StructReturn),
  47                 AbiParam::new(types::I128),
  48                 AbiParam::new(types::I128),
  49             ];
  50             let args = [
  51                 out_place.to_ptr().get_addr(fx),
  52                 lhs.load_scalar(fx),
  53                 rhs.load_scalar(fx),
  54             ];
  55             let name = match (bin_op, is_signed) {
  56                 (BinOp::Add, false) => "__rust_u128_addo",
  57                 (BinOp::Add, true) => "__rust_i128_addo",
  58                 (BinOp::Sub, false) => "__rust_u128_subo",
  59                 (BinOp::Sub, true) => "__rust_i128_subo",
  60                 (BinOp::Mul, false) => "__rust_u128_mulo",
  61                 (BinOp::Mul, true) => "__rust_i128_mulo",
  62                 _ => unreachable!(),
  63             };
  64             fx.lib_call(name, param_types, vec![], &args);
  65             Some(out_place.to_cvalue(fx))
  66         }
  67         BinOp::Offset => unreachable!("offset should only be used on pointers, not 128bit ints"),
  68         BinOp::Div => {
  69             assert!(!checked);
  70             if is_signed {
  71                 Some(fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128))
  72             } else {
  73                 Some(fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128))
  74             }
  75         }
  76         BinOp::Rem => {
  77             assert!(!checked);
  78             if is_signed {
  79                 Some(fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128))
  80             } else {
  81                 Some(fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128))
  82             }
  83         }
  84         BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
  85             assert!(!checked);
  86             None
  87         }
  88         BinOp::Shl | BinOp::Shr => {
  89             let is_overflow = if checked {
  90                 // rhs >= 128
  91
  92                 // FIXME support non 128bit rhs
  93                 /*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
  94                 let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
  95                 let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
  96                 let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
  97                 let is_overflow = fx.bcx.ins().bconst(types::B1, false);
  98
  99                 Some(fx.bcx.ins().bint(types::I8, is_overflow))
 100             } else {
 101                 None
 102             };
 103
 104             let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
 105             let val = match bin_op {
 106                 BinOp::Shl => fx.bcx.ins().ishl(lhs_val, truncated_rhs),
 107                 BinOp::Shr => {
 108                     if is_signed {
 109                         fx.bcx.ins().sshr(lhs_val, truncated_rhs)
 110                     } else {
 111                         fx.bcx.ins().ushr(lhs_val, truncated_rhs)
 112                     }
 113                 }
 114                 _ => unreachable!(),
 115             };
 116             if let Some(is_overflow) = is_overflow {
 117                 let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 118                 Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 119             } else {
 120                 Some(CValue::by_val(val, lhs.layout()))
 121             }
 122         }
 123     }
 124 }