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handle the array case consistently for simd_select_bitmask and simd_bitmask

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also move the two next to each other
This commit is contained in:
Ralf Jung 2023-12-03 14:51:31 +01:00
parent 56f50d53d1
commit 92b4ffc688
1 changed files with 45 additions and 43 deletions
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88
src/tools/miri/src/shims/intrinsics/simd.rs
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@ -405,6 +405,7 @@ enum Op {
this.write_immediate(*val, &dest)?;
}
}
// Variant of `select` that takes a bitmask rather than a "vector of bool".
"select_bitmask" => {
let [mask, yes, no] = check_arg_count(args)?;
let (yes, yes_len) = this.operand_to_simd(yes)?;
@ -412,6 +413,11 @@ enum Op {
let (dest, dest_len) = this.place_to_simd(dest)?;
let bitmask_len = dest_len.max(8);
// The mask must be an integer or an array.
assert!(
mask.layout.ty.is_integral()
|| matches!(mask.layout.ty.kind(), ty::Array(elemty, _) if elemty == &this.tcx.types.u8)
);
assert!(bitmask_len <= 64);
assert_eq!(bitmask_len, mask.layout.size.bits());
assert_eq!(dest_len, yes_len);
@ -419,23 +425,15 @@ enum Op {
let dest_len = u32::try_from(dest_len).unwrap();
let bitmask_len = u32::try_from(bitmask_len).unwrap();
// The mask can be a single integer or an array.
let mask: u64 = match mask.layout.ty.kind() {
ty::Int(..) | ty::Uint(..) =>
this.read_scalar(mask)?.to_bits(mask.layout.size)?.try_into().unwrap(),
ty::Array(elem, _) if matches!(elem.kind(), ty::Uint(ty::UintTy::U8)) => {
let mask_ty = this.machine.layouts.uint(mask.layout.size).unwrap();
let mask = mask.transmute(mask_ty, this)?;
this.read_scalar(&mask)?.to_bits(mask_ty.size)?.try_into().unwrap()
}
_ => bug!("simd_select_bitmask: invalid mask type {}", mask.layout.ty),
};
// To read the mask, we transmute it to an integer.
// That does the right thing wrt endianess.
let mask_ty = this.machine.layouts.uint(mask.layout.size).unwrap();
let mask = mask.transmute(mask_ty, this)?;
let mask: u64 = this.read_scalar(&mask)?.to_bits(mask_ty.size)?.try_into().unwrap();
for i in 0..dest_len {
let mask = mask
& 1u64
.checked_shl(simd_bitmask_index(i, dest_len, this.data_layout().endian))
.unwrap();
let bit_i = simd_bitmask_index(i, dest_len, this.data_layout().endian);
let mask = mask & 1u64.checked_shl(bit_i).unwrap();
let yes = this.read_immediate(&this.project_index(&yes, i.into())?)?;
let no = this.read_immediate(&this.project_index(&no, i.into())?)?;
let dest = this.project_index(&dest, i.into())?;
@ -445,6 +443,8 @@ enum Op {
}
for i in dest_len..bitmask_len {
// If the mask is "padded", ensure that padding is all-zero.
// This deliberately does not use `simd_bitmask_index`; these bits are outside
// the bitmask. It does not matter in which order we check them.
let mask = mask & 1u64.checked_shl(i).unwrap();
if mask != 0 {
throw_ub_format!(
@ -453,6 +453,36 @@ enum Op {
}
}
}
// Converts a "vector of bool" into a bitmask.
"bitmask" => {
let [op] = check_arg_count(args)?;
let (op, op_len) = this.operand_to_simd(op)?;
let bitmask_len = op_len.max(8);
// Returns either an unsigned integer or array of `u8`.
assert!(
dest.layout.ty.is_integral()
|| matches!(dest.layout.ty.kind(), ty::Array(elemty, _) if elemty == &this.tcx.types.u8)
);
assert!(bitmask_len <= 64);
assert_eq!(bitmask_len, dest.layout.size.bits());
let op_len = u32::try_from(op_len).unwrap();
let mut res = 0u64;
for i in 0..op_len {
let op = this.read_immediate(&this.project_index(&op, i.into())?)?;
if simd_element_to_bool(op)? {
res |= 1u64
.checked_shl(simd_bitmask_index(i, op_len, this.data_layout().endian))
.unwrap();
}
}
// We have to change the type of the place to be able to write `res` into it. This
// transmutes the integer to an array, which does the right thing wrt endianess.
let dest =
dest.transmute(this.machine.layouts.uint(dest.layout.size).unwrap(), this)?;
this.write_int(res, &dest)?;
}
"cast" | "as" | "cast_ptr" | "expose_addr" | "from_exposed_addr" => {
let [op] = check_arg_count(args)?;
let (op, op_len) = this.operand_to_simd(op)?;
@ -635,34 +665,6 @@ enum Op {
}
}
}
"bitmask" => {
let [op] = check_arg_count(args)?;
let (op, op_len) = this.operand_to_simd(op)?;
let bitmask_len = op_len.max(8);
// Returns either an unsigned integer or array of `u8`.
assert!(
dest.layout.ty.is_integral()
|| matches!(dest.layout.ty.kind(), ty::Array(elemty, _) if elemty == &this.tcx.types.u8)
);
assert!(bitmask_len <= 64);
assert_eq!(bitmask_len, dest.layout.size.bits());
let op_len = u32::try_from(op_len).unwrap();
let mut res = 0u64;
for i in 0..op_len {
let op = this.read_immediate(&this.project_index(&op, i.into())?)?;
if simd_element_to_bool(op)? {
res |= 1u64
.checked_shl(simd_bitmask_index(i, op_len, this.data_layout().endian))
.unwrap();
}
}
// We have to force the place type to be an int so that we can write `res` into it.
let mut dest = this.force_allocation(dest)?;
dest.layout = this.machine.layouts.uint(dest.layout.size).unwrap();
this.write_int(res, &dest)?;
}
name => throw_unsup_format!("unimplemented intrinsic: `simd_{name}`"),
}