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>,
   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 { fx.tcx.types.i128 } else { fx.tcx.types.u128 };
  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 = [out_place.to_ptr().get_addr(fx), lhs.load_scalar(fx), rhs.load_scalar(fx)];
  47             let name = match (bin_op, is_signed) {
  48                 (BinOp::Add, false) => "__rust_u128_addo",
  49                 (BinOp::Add, true) => "__rust_i128_addo",
  50                 (BinOp::Sub, false) => "__rust_u128_subo",
  51                 (BinOp::Sub, true) => "__rust_i128_subo",
  52                 (BinOp::Mul, false) => "__rust_u128_mulo",
  53                 (BinOp::Mul, true) => "__rust_i128_mulo",
  54                 _ => unreachable!(),
  55             };
  56             fx.lib_call(name, param_types, vec![], &args);
  57             Some(out_place.to_cvalue(fx))
  58         }
  59         BinOp::Offset => unreachable!("offset should only be used on pointers, not 128bit ints"),
  60         BinOp::Div => {
  61             assert!(!checked);
  62             if is_signed {
  63                 Some(fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128))
  64             } else {
  65                 Some(fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128))
  66             }
  67         }
  68         BinOp::Rem => {
  69             assert!(!checked);
  70             if is_signed {
  71                 Some(fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128))
  72             } else {
  73                 Some(fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128))
  74             }
  75         }
  76         BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
  77             assert!(!checked);
  78             None
  79         }
  80         BinOp::Shl | BinOp::Shr => {
  81             let is_overflow = if checked {
  82                 // rhs >= 128
  83
  84                 // FIXME support non 128bit rhs
  85                 /*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
  86                 let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
  87                 let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
  88                 let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
  89                 let is_overflow = fx.bcx.ins().bconst(types::B1, false);
  90
  91                 Some(fx.bcx.ins().bint(types::I8, is_overflow))
  92             } else {
  93                 None
  94             };
  95
  96             let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
  97             let val = match bin_op {
  98                 BinOp::Shl => fx.bcx.ins().ishl(lhs_val, truncated_rhs),
  99                 BinOp::Shr => {
 100                     if is_signed {
 101                         fx.bcx.ins().sshr(lhs_val, truncated_rhs)
 102                     } else {
 103                         fx.bcx.ins().ushr(lhs_val, truncated_rhs)
 104                     }
 105                 }
 106                 _ => unreachable!(),
 107             };
 108             if let Some(is_overflow) = is_overflow {
 109                 let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 110                 Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 111             } else {
 112                 Some(CValue::by_val(val, lhs.layout()))
 113             }
 114         }
 115     }
 116 }