rust/src/num.rs
2024-05-17 20:33:02 -07:00

468 lines
18 KiB
Rust

//! Various operations on integer and floating-point numbers
use crate::prelude::*;
pub(crate) fn bin_op_to_intcc(bin_op: BinOp, signed: bool) -> Option<IntCC> {
use BinOp::*;
use IntCC::*;
Some(match bin_op {
Eq => Equal,
Lt => {
if signed {
SignedLessThan
} else {
UnsignedLessThan
}
}
Le => {
if signed {
SignedLessThanOrEqual
} else {
UnsignedLessThanOrEqual
}
}
Ne => NotEqual,
Ge => {
if signed {
SignedGreaterThanOrEqual
} else {
UnsignedGreaterThanOrEqual
}
}
Gt => {
if signed {
SignedGreaterThan
} else {
UnsignedGreaterThan
}
}
_ => return None,
})
}
fn codegen_three_way_compare<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
signed: bool,
lhs: Value,
rhs: Value,
) -> CValue<'tcx> {
// This emits `(lhs > rhs) - (lhs < rhs)`, which is cranelift's preferred form per
// <https://github.com/bytecodealliance/wasmtime/blob/8052bb9e3b792503b225f2a5b2ba3bc023bff462/cranelift/codegen/src/prelude_opt.isle#L41-L47>
let gt_cc = crate::num::bin_op_to_intcc(BinOp::Gt, signed).unwrap();
let lt_cc = crate::num::bin_op_to_intcc(BinOp::Lt, signed).unwrap();
let gt = fx.bcx.ins().icmp(gt_cc, lhs, rhs);
let lt = fx.bcx.ins().icmp(lt_cc, lhs, rhs);
let val = fx.bcx.ins().isub(gt, lt);
CValue::by_val(val, fx.layout_of(fx.tcx.ty_ordering_enum(Some(fx.mir.span))))
}
fn codegen_compare_bin_op<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
signed: bool,
lhs: Value,
rhs: Value,
) -> CValue<'tcx> {
if bin_op == BinOp::Cmp {
return codegen_three_way_compare(fx, signed, lhs, rhs);
}
let intcc = crate::num::bin_op_to_intcc(bin_op, signed).unwrap();
let val = fx.bcx.ins().icmp(intcc, lhs, rhs);
CValue::by_val(val, fx.layout_of(fx.tcx.types.bool))
}
pub(crate) fn codegen_binop<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
in_lhs: CValue<'tcx>,
in_rhs: CValue<'tcx>,
) -> CValue<'tcx> {
match bin_op {
BinOp::Eq | BinOp::Lt | BinOp::Le | BinOp::Ne | BinOp::Ge | BinOp::Gt | BinOp::Cmp => {
match in_lhs.layout().ty.kind() {
ty::Bool | ty::Uint(_) | ty::Int(_) | ty::Char => {
let signed = type_sign(in_lhs.layout().ty);
let lhs = in_lhs.load_scalar(fx);
let rhs = in_rhs.load_scalar(fx);
return codegen_compare_bin_op(fx, bin_op, signed, lhs, rhs);
}
_ => {}
}
}
_ => {}
}
match in_lhs.layout().ty.kind() {
ty::Bool => crate::num::codegen_bool_binop(fx, bin_op, in_lhs, in_rhs),
ty::Uint(_) | ty::Int(_) => crate::num::codegen_int_binop(fx, bin_op, in_lhs, in_rhs),
ty::Float(_) => crate::num::codegen_float_binop(fx, bin_op, in_lhs, in_rhs),
ty::RawPtr(..) | ty::FnPtr(..) => crate::num::codegen_ptr_binop(fx, bin_op, in_lhs, in_rhs),
_ => unreachable!("{:?}({:?}, {:?})", bin_op, in_lhs.layout().ty, in_rhs.layout().ty),
}
}
pub(crate) fn codegen_bool_binop<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
in_lhs: CValue<'tcx>,
in_rhs: CValue<'tcx>,
) -> CValue<'tcx> {
let lhs = in_lhs.load_scalar(fx);
let rhs = in_rhs.load_scalar(fx);
let b = fx.bcx.ins();
let res = match bin_op {
BinOp::BitXor => b.bxor(lhs, rhs),
BinOp::BitAnd => b.band(lhs, rhs),
BinOp::BitOr => b.bor(lhs, rhs),
// Compare binops handles by `codegen_binop`.
_ => unreachable!("{:?}({:?}, {:?})", bin_op, in_lhs, in_rhs),
};
CValue::by_val(res, fx.layout_of(fx.tcx.types.bool))
}
pub(crate) fn codegen_int_binop<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
in_lhs: CValue<'tcx>,
in_rhs: CValue<'tcx>,
) -> CValue<'tcx> {
if !matches!(bin_op, BinOp::Shl | BinOp::ShlUnchecked | BinOp::Shr | BinOp::ShrUnchecked) {
assert_eq!(
in_lhs.layout().ty,
in_rhs.layout().ty,
"int binop requires lhs and rhs of same type"
);
}
if let Some(res) = crate::codegen_i128::maybe_codegen(fx, bin_op, in_lhs, in_rhs) {
return res;
}
let signed = type_sign(in_lhs.layout().ty);
let lhs = in_lhs.load_scalar(fx);
let rhs = in_rhs.load_scalar(fx);
let b = fx.bcx.ins();
// FIXME trap on overflow for the Unchecked versions
let val = match bin_op {
BinOp::Add | BinOp::AddUnchecked => b.iadd(lhs, rhs),
BinOp::Sub | BinOp::SubUnchecked => b.isub(lhs, rhs),
BinOp::Mul | BinOp::MulUnchecked => b.imul(lhs, rhs),
BinOp::Div => {
if signed {
b.sdiv(lhs, rhs)
} else {
b.udiv(lhs, rhs)
}
}
BinOp::Rem => {
if signed {
b.srem(lhs, rhs)
} else {
b.urem(lhs, rhs)
}
}
BinOp::BitXor => b.bxor(lhs, rhs),
BinOp::BitAnd => b.band(lhs, rhs),
BinOp::BitOr => b.bor(lhs, rhs),
BinOp::Shl | BinOp::ShlUnchecked => b.ishl(lhs, rhs),
BinOp::Shr | BinOp::ShrUnchecked => {
if signed {
b.sshr(lhs, rhs)
} else {
b.ushr(lhs, rhs)
}
}
BinOp::Offset => unreachable!("Offset is not an integer operation"),
BinOp::AddWithOverflow | BinOp::SubWithOverflow | BinOp::MulWithOverflow => {
unreachable!("Overflow binops handled by `codegen_checked_int_binop`")
}
// Compare binops handles by `codegen_binop`.
BinOp::Eq | BinOp::Ne | BinOp::Lt | BinOp::Le | BinOp::Gt | BinOp::Ge | BinOp::Cmp => {
unreachable!("{:?}({:?}, {:?})", bin_op, in_lhs.layout().ty, in_rhs.layout().ty);
}
};
CValue::by_val(val, in_lhs.layout())
}
pub(crate) fn codegen_checked_int_binop<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
in_lhs: CValue<'tcx>,
in_rhs: CValue<'tcx>,
) -> CValue<'tcx> {
let lhs = in_lhs.load_scalar(fx);
let rhs = in_rhs.load_scalar(fx);
if let Some(res) = crate::codegen_i128::maybe_codegen_checked(fx, bin_op, in_lhs, in_rhs) {
return res;
}
let signed = type_sign(in_lhs.layout().ty);
let (res, has_overflow) = match bin_op {
BinOp::Add => {
/*let (val, c_out) = fx.bcx.ins().iadd_cout(lhs, rhs);
(val, c_out)*/
// FIXME(CraneStation/cranelift#849) legalize iadd_cout for i8 and i16
let val = fx.bcx.ins().iadd(lhs, rhs);
let has_overflow = if !signed {
fx.bcx.ins().icmp(IntCC::UnsignedLessThan, val, lhs)
} else {
let rhs_is_negative = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, rhs, 0);
let slt = fx.bcx.ins().icmp(IntCC::SignedLessThan, val, lhs);
fx.bcx.ins().bxor(rhs_is_negative, slt)
};
(val, has_overflow)
}
BinOp::Sub => {
/*let (val, b_out) = fx.bcx.ins().isub_bout(lhs, rhs);
(val, b_out)*/
// FIXME(CraneStation/cranelift#849) legalize isub_bout for i8 and i16
let val = fx.bcx.ins().isub(lhs, rhs);
let has_overflow = if !signed {
fx.bcx.ins().icmp(IntCC::UnsignedGreaterThan, val, lhs)
} else {
let rhs_is_negative = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, rhs, 0);
let sgt = fx.bcx.ins().icmp(IntCC::SignedGreaterThan, val, lhs);
fx.bcx.ins().bxor(rhs_is_negative, sgt)
};
(val, has_overflow)
}
BinOp::Mul => {
let ty = fx.bcx.func.dfg.value_type(lhs);
match ty {
types::I8 | types::I16 | types::I32 if !signed => {
let lhs = fx.bcx.ins().uextend(ty.double_width().unwrap(), lhs);
let rhs = fx.bcx.ins().uextend(ty.double_width().unwrap(), rhs);
let val = fx.bcx.ins().imul(lhs, rhs);
let has_overflow = fx.bcx.ins().icmp_imm(
IntCC::UnsignedGreaterThan,
val,
(1 << ty.bits()) - 1,
);
let val = fx.bcx.ins().ireduce(ty, val);
(val, has_overflow)
}
types::I8 | types::I16 | types::I32 if signed => {
let lhs = fx.bcx.ins().sextend(ty.double_width().unwrap(), lhs);
let rhs = fx.bcx.ins().sextend(ty.double_width().unwrap(), rhs);
let val = fx.bcx.ins().imul(lhs, rhs);
let has_underflow =
fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, val, -(1 << (ty.bits() - 1)));
let has_overflow = fx.bcx.ins().icmp_imm(
IntCC::SignedGreaterThan,
val,
(1 << (ty.bits() - 1)) - 1,
);
let val = fx.bcx.ins().ireduce(ty, val);
(val, fx.bcx.ins().bor(has_underflow, has_overflow))
}
types::I64 => {
let val = fx.bcx.ins().imul(lhs, rhs);
let has_overflow = if !signed {
let val_hi = fx.bcx.ins().umulhi(lhs, rhs);
fx.bcx.ins().icmp_imm(IntCC::NotEqual, val_hi, 0)
} else {
// Based on LLVM's instruction sequence for compiling
// a.checked_mul(b).is_some() to riscv64gc:
// mulh a2, a0, a1
// mul a0, a0, a1
// srai a0, a0, 63
// xor a0, a0, a2
// snez a0, a0
let val_hi = fx.bcx.ins().smulhi(lhs, rhs);
let val_sign = fx.bcx.ins().sshr_imm(val, i64::from(ty.bits() - 1));
let xor = fx.bcx.ins().bxor(val_hi, val_sign);
fx.bcx.ins().icmp_imm(IntCC::NotEqual, xor, 0)
};
(val, has_overflow)
}
types::I128 => {
unreachable!("i128 should have been handled by codegen_i128::maybe_codegen")
}
_ => unreachable!("invalid non-integer type {}", ty),
}
}
_ => bug!("binop {:?} on checked int/uint lhs: {:?} rhs: {:?}", bin_op, in_lhs, in_rhs),
};
let out_layout = fx.layout_of(Ty::new_tup(fx.tcx, &[in_lhs.layout().ty, fx.tcx.types.bool]));
CValue::by_val_pair(res, has_overflow, out_layout)
}
pub(crate) fn codegen_saturating_int_binop<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
lhs: CValue<'tcx>,
rhs: CValue<'tcx>,
) -> CValue<'tcx> {
assert_eq!(lhs.layout().ty, rhs.layout().ty);
let signed = type_sign(lhs.layout().ty);
let clif_ty = fx.clif_type(lhs.layout().ty).unwrap();
let (min, max) = type_min_max_value(&mut fx.bcx, clif_ty, signed);
let checked_res = crate::num::codegen_checked_int_binop(fx, bin_op, lhs, rhs);
let (val, has_overflow) = checked_res.load_scalar_pair(fx);
let val = match (bin_op, signed) {
(BinOp::Add, false) => fx.bcx.ins().select(has_overflow, max, val),
(BinOp::Sub, false) => fx.bcx.ins().select(has_overflow, min, val),
(BinOp::Add, true) => {
let rhs = rhs.load_scalar(fx);
let rhs_ge_zero = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThanOrEqual, rhs, 0);
let sat_val = fx.bcx.ins().select(rhs_ge_zero, max, min);
fx.bcx.ins().select(has_overflow, sat_val, val)
}
(BinOp::Sub, true) => {
let rhs = rhs.load_scalar(fx);
let rhs_ge_zero = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThanOrEqual, rhs, 0);
let sat_val = fx.bcx.ins().select(rhs_ge_zero, min, max);
fx.bcx.ins().select(has_overflow, sat_val, val)
}
_ => unreachable!(),
};
CValue::by_val(val, lhs.layout())
}
pub(crate) fn codegen_float_binop<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
in_lhs: CValue<'tcx>,
in_rhs: CValue<'tcx>,
) -> CValue<'tcx> {
assert_eq!(in_lhs.layout().ty, in_rhs.layout().ty);
let lhs = in_lhs.load_scalar(fx);
let rhs = in_rhs.load_scalar(fx);
let b = fx.bcx.ins();
let res = match bin_op {
BinOp::Add => b.fadd(lhs, rhs),
BinOp::Sub => b.fsub(lhs, rhs),
BinOp::Mul => b.fmul(lhs, rhs),
BinOp::Div => b.fdiv(lhs, rhs),
BinOp::Rem => {
let (name, ty) = match in_lhs.layout().ty.kind() {
ty::Float(FloatTy::F32) => ("fmodf", types::F32),
ty::Float(FloatTy::F64) => ("fmod", types::F64),
_ => bug!(),
};
let ret_val = fx.lib_call(
name,
vec![AbiParam::new(ty), AbiParam::new(ty)],
vec![AbiParam::new(ty)],
&[lhs, rhs],
)[0];
return CValue::by_val(ret_val, in_lhs.layout());
}
BinOp::Eq | BinOp::Lt | BinOp::Le | BinOp::Ne | BinOp::Ge | BinOp::Gt => {
let fltcc = match bin_op {
BinOp::Eq => FloatCC::Equal,
BinOp::Lt => FloatCC::LessThan,
BinOp::Le => FloatCC::LessThanOrEqual,
BinOp::Ne => FloatCC::NotEqual,
BinOp::Ge => FloatCC::GreaterThanOrEqual,
BinOp::Gt => FloatCC::GreaterThan,
_ => unreachable!(),
};
let val = fx.bcx.ins().fcmp(fltcc, lhs, rhs);
return CValue::by_val(val, fx.layout_of(fx.tcx.types.bool));
}
_ => unreachable!("{:?}({:?}, {:?})", bin_op, in_lhs, in_rhs),
};
CValue::by_val(res, in_lhs.layout())
}
pub(crate) fn codegen_ptr_binop<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
bin_op: BinOp,
in_lhs: CValue<'tcx>,
in_rhs: CValue<'tcx>,
) -> CValue<'tcx> {
let is_thin_ptr =
in_lhs.layout().ty.builtin_deref(true).map(|ty| !has_ptr_meta(fx.tcx, ty)).unwrap_or(true);
if is_thin_ptr {
match bin_op {
BinOp::Eq | BinOp::Lt | BinOp::Le | BinOp::Ne | BinOp::Ge | BinOp::Gt => {
let lhs = in_lhs.load_scalar(fx);
let rhs = in_rhs.load_scalar(fx);
codegen_compare_bin_op(fx, bin_op, false, lhs, rhs)
}
BinOp::Offset => {
let pointee_ty = in_lhs.layout().ty.builtin_deref(true).unwrap();
let (base, offset) = (in_lhs, in_rhs.load_scalar(fx));
let pointee_size = fx.layout_of(pointee_ty).size.bytes();
let ptr_diff = fx.bcx.ins().imul_imm(offset, pointee_size as i64);
let base_val = base.load_scalar(fx);
let res = fx.bcx.ins().iadd(base_val, ptr_diff);
CValue::by_val(res, base.layout())
}
_ => unreachable!("{:?}({:?}, {:?})", bin_op, in_lhs, in_rhs),
}
} else {
let (lhs_ptr, lhs_extra) = in_lhs.load_scalar_pair(fx);
let (rhs_ptr, rhs_extra) = in_rhs.load_scalar_pair(fx);
let res = match bin_op {
BinOp::Eq => {
let ptr_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_ptr, rhs_ptr);
let extra_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_extra, rhs_extra);
fx.bcx.ins().band(ptr_eq, extra_eq)
}
BinOp::Ne => {
let ptr_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_ptr, rhs_ptr);
let extra_ne = fx.bcx.ins().icmp(IntCC::NotEqual, lhs_extra, rhs_extra);
fx.bcx.ins().bor(ptr_ne, extra_ne)
}
BinOp::Lt | BinOp::Le | BinOp::Ge | BinOp::Gt => {
let ptr_eq = fx.bcx.ins().icmp(IntCC::Equal, lhs_ptr, rhs_ptr);
let ptr_cmp =
fx.bcx.ins().icmp(bin_op_to_intcc(bin_op, false).unwrap(), lhs_ptr, rhs_ptr);
let extra_cmp = fx.bcx.ins().icmp(
bin_op_to_intcc(bin_op, false).unwrap(),
lhs_extra,
rhs_extra,
);
fx.bcx.ins().select(ptr_eq, extra_cmp, ptr_cmp)
}
_ => panic!("bin_op {:?} on ptr", bin_op),
};
CValue::by_val(res, fx.layout_of(fx.tcx.types.bool))
}
}
// In Rust floating point min and max don't propagate NaN. In Cranelift they do however.
// For this reason it is necessary to use `a.is_nan() ? b : (a >= b ? b : a)` for `minnumf*`
// and `a.is_nan() ? b : (a <= b ? b : a)` for `maxnumf*`. NaN checks are done by comparing
// a float against itself. Only in case of NaN is it not equal to itself.
pub(crate) fn codegen_float_min(fx: &mut FunctionCx<'_, '_, '_>, a: Value, b: Value) -> Value {
let a_is_nan = fx.bcx.ins().fcmp(FloatCC::NotEqual, a, a);
let a_ge_b = fx.bcx.ins().fcmp(FloatCC::GreaterThanOrEqual, a, b);
let temp = fx.bcx.ins().select(a_ge_b, b, a);
fx.bcx.ins().select(a_is_nan, b, temp)
}
pub(crate) fn codegen_float_max(fx: &mut FunctionCx<'_, '_, '_>, a: Value, b: Value) -> Value {
let a_is_nan = fx.bcx.ins().fcmp(FloatCC::NotEqual, a, a);
let a_le_b = fx.bcx.ins().fcmp(FloatCC::LessThanOrEqual, a, b);
let temp = fx.bcx.ins().select(a_le_b, b, a);
fx.bcx.ins().select(a_is_nan, b, temp)
}