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             let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
 101             let val = match bin_op {
 102                 BinOp::Shl => fx.bcx.ins().ishl(lhs_val, truncated_rhs),
 103                 BinOp::Shr => {
 104                     if is_signed {
 105                         fx.bcx.ins().sshr(lhs_val, truncated_rhs)
 106                     } else {
 107                         fx.bcx.ins().ushr(lhs_val, truncated_rhs)
 108                     }
 109                 }
 110                 _ => unreachable!(),
 111             };
 112             if let Some(is_overflow) = is_overflow {
 113                 let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
 114                 Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
 115             } else {
 116                 Some(CValue::by_val(val, lhs.layout()))
 117             }
 118         }
 119     }
 120 }