forked from rust-lang/rust
/
codegen_i128.rs
165 lines (155 loc) · 6.84 KB
/
codegen_i128.rs
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//! Replaces 128-bit operators with lang item calls
use crate::prelude::*;
pub(crate) fn maybe_codegen<'tcx>(
fx: &mut FunctionCx<'_, 'tcx, impl Backend>,
bin_op: BinOp,
checked: bool,
lhs: CValue<'tcx>,
rhs: CValue<'tcx>,
) -> Option<CValue<'tcx>> {
if lhs.layout().ty != fx.tcx.types.u128 && lhs.layout().ty != fx.tcx.types.i128 {
return None;
}
let lhs_val = lhs.load_scalar(fx);
let rhs_val = rhs.load_scalar(fx);
let is_signed = type_sign(lhs.layout().ty);
match bin_op {
BinOp::BitAnd | BinOp::BitOr | BinOp::BitXor => {
assert!(!checked);
return None;
}
BinOp::Add | BinOp::Sub if !checked => return None,
BinOp::Add => {
let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
return Some(if is_signed {
fx.easy_call("__rust_i128_addo", &[lhs, rhs], out_ty)
} else {
fx.easy_call("__rust_u128_addo", &[lhs, rhs], out_ty)
});
}
BinOp::Sub => {
let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
return Some(if is_signed {
fx.easy_call("__rust_i128_subo", &[lhs, rhs], out_ty)
} else {
fx.easy_call("__rust_u128_subo", &[lhs, rhs], out_ty)
});
}
BinOp::Offset => unreachable!("offset should only be used on pointers, not 128bit ints"),
BinOp::Mul => {
let res = if checked {
let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
if is_signed {
fx.easy_call("__rust_i128_mulo", &[lhs, rhs], out_ty)
} else {
fx.easy_call("__rust_u128_mulo", &[lhs, rhs], out_ty)
}
} else {
let val_ty = if is_signed {
fx.tcx.types.i128
} else {
fx.tcx.types.u128
};
fx.easy_call("__multi3", &[lhs, rhs], val_ty)
};
return Some(res);
}
BinOp::Div => {
assert!(!checked);
if is_signed {
Some(fx.easy_call("__divti3", &[lhs, rhs], fx.tcx.types.i128))
} else {
Some(fx.easy_call("__udivti3", &[lhs, rhs], fx.tcx.types.u128))
}
}
BinOp::Rem => {
assert!(!checked);
if is_signed {
Some(fx.easy_call("__modti3", &[lhs, rhs], fx.tcx.types.i128))
} else {
Some(fx.easy_call("__umodti3", &[lhs, rhs], fx.tcx.types.u128))
}
}
BinOp::Lt | BinOp::Le | BinOp::Eq | BinOp::Ge | BinOp::Gt | BinOp::Ne => {
assert!(!checked);
return None;
}
BinOp::Shl | BinOp::Shr => {
let is_overflow = if checked {
// rhs >= 128
// FIXME support non 128bit rhs
/*let (rhs_lsb, rhs_msb) = fx.bcx.ins().isplit(rhs_val);
let rhs_msb_gt_0 = fx.bcx.ins().icmp_imm(IntCC::NotEqual, rhs_msb, 0);
let rhs_lsb_ge_128 = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, rhs_lsb, 127);
let is_overflow = fx.bcx.ins().bor(rhs_msb_gt_0, rhs_lsb_ge_128);*/
let is_overflow = fx.bcx.ins().bconst(types::B1, false);
Some(fx.bcx.ins().bint(types::I8, is_overflow))
} else {
None
};
// Optimize `val >> 64`, because compiler_builtins uses it to deconstruct an 128bit
// integer into its lsb and msb.
// https://github.com/rust-lang-nursery/compiler-builtins/blob/79a6a1603d5672cbb9187ff41ff4d9b5048ac1cb/src/int/mod.rs#L217
if resolve_value_imm(fx.bcx.func, rhs_val) == Some(64) {
let (lhs_lsb, lhs_msb) = fx.bcx.ins().isplit(lhs_val);
let all_zeros = fx.bcx.ins().iconst(types::I64, 0);
let val = match (bin_op, is_signed) {
(BinOp::Shr, false) => {
let val = fx.bcx.ins().iconcat(lhs_msb, all_zeros);
Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.u128)))
}
(BinOp::Shr, true) => {
let sign = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, lhs_msb, 0);
let all_ones = fx.bcx.ins().iconst(types::I64, u64::MAX as i64);
let all_sign_bits = fx.bcx.ins().select(sign, all_zeros, all_ones);
let val = fx.bcx.ins().iconcat(lhs_msb, all_sign_bits);
Some(CValue::by_val(val, fx.layout_of(fx.tcx.types.i128)))
}
(BinOp::Shl, _) => {
let val_ty = if is_signed {
fx.tcx.types.i128
} else {
fx.tcx.types.u128
};
let val = fx.bcx.ins().iconcat(all_zeros, lhs_lsb);
Some(CValue::by_val(val, fx.layout_of(val_ty)))
}
_ => None,
};
if let Some(val) = val {
if let Some(is_overflow) = is_overflow {
let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
let val = val.load_scalar(fx);
return Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)));
} else {
return Some(val);
}
}
}
let truncated_rhs = clif_intcast(fx, rhs_val, types::I32, false);
let truncated_rhs = CValue::by_val(truncated_rhs, fx.layout_of(fx.tcx.types.u32));
let val = match (bin_op, is_signed) {
(BinOp::Shl, false) => {
fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
}
(BinOp::Shl, true) => {
fx.easy_call("__ashlti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
}
(BinOp::Shr, false) => {
fx.easy_call("__lshrti3", &[lhs, truncated_rhs], fx.tcx.types.u128)
}
(BinOp::Shr, true) => {
fx.easy_call("__ashrti3", &[lhs, truncated_rhs], fx.tcx.types.i128)
}
(_, _) => unreachable!(),
};
if let Some(is_overflow) = is_overflow {
let out_ty = fx.tcx.mk_tup([lhs.layout().ty, fx.tcx.types.bool].iter());
let val = val.load_scalar(fx);
Some(CValue::by_val_pair(val, is_overflow, fx.layout_of(out_ty)))
} else {
Some(val)
}
}
}
}