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cranelift: Add narrower and wider constraints to the instruction DSL (#6013)

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* Add narrower and wider constraints to the instruction DSL

* Add docs to narrower/wider operands

* Update cranelift/codegen/meta/src/cdsl/instructions.rs

Co-authored-by: Jamey Sharp <jamey@minilop.net>

* Fix assertion message

* Simplify upper bounds for the wider constraint

* Remove additional unnecessary cases in the verifier

* Remove unused variables

* Remove changes to is_ctrl_typevar_candidate

These changes were only necessary when the type returned by an
instruction was a variable constrained by narrow or widen. As we have
switched to requiring that constraints must appear on argument types and
not return types, these changes were not longer necessary.

---------

Co-authored-by: Jamey Sharp <jamey@minilop.net>
This commit is contained in:
Trevor Elliott
2023-03-14 09:34:17 -07:00
committed by GitHub
parent 5c1b468648
commit f5ad74e546
6 changed files with 145 additions and 111 deletions
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2
cranelift/codegen/src/bitset.rs
View File

@@ -11,7 +11,7 @@ use core::mem::size_of;
use core::ops::{Add, BitOr, Shl, Sub};
/// A small bitset built on a single primitive integer type
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
#[cfg_attr(feature = "enable-serde", derive(serde::Serialize, serde::Deserialize))]
pub struct BitSet<T>(pub T);

58
cranelift/codegen/src/ir/instructions.rs
View File

@@ -575,12 +575,9 @@ impl OpcodeConstraints {
/// `ctrl_type`.
pub fn result_type(self, n: usize, ctrl_type: Type) -> Type {
debug_assert!(n < self.num_fixed_results(), "Invalid result index");
if let ResolvedConstraint::Bound(t) =
OPERAND_CONSTRAINTS[self.constraint_offset() + n].resolve(ctrl_type)
{
t
} else {
panic!("Result constraints can't be free");
match OPERAND_CONSTRAINTS[self.constraint_offset() + n].resolve(ctrl_type) {
ResolvedConstraint::Bound(t) => t,
ResolvedConstraint::Free(ts) => panic!("Result constraints can't be free: {:?}", ts),
}
}
@@ -614,7 +611,7 @@ type BitSet8 = BitSet<u8>;
type BitSet16 = BitSet<u16>;
/// A value type set describes the permitted set of types for a type variable.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ValueTypeSet {
/// Allowed lane sizes
pub lanes: BitSet16,
@@ -703,6 +700,12 @@ enum OperandConstraint {
/// This operands is `ctrlType.dynamic_to_vector()`.
DynamicToVector,
/// This operand is `ctrlType.narrower()`.
Narrower,
/// This operand is `ctrlType.wider()`.
Wider,
}
impl OperandConstraint {
@@ -766,6 +769,47 @@ impl OperandConstraint {
.dynamic_to_vector()
.expect("invalid type for dynamic_to_vector"),
),
Narrower => {
let ctrl_type_bits = ctrl_type.log2_lane_bits();
let mut tys = ValueTypeSet::default();
// We're testing scalar values, only.
tys.lanes = BitSet::from_range(0, 1);
if ctrl_type.is_int() {
// The upper bound in from_range is exclusive, so add one here get the closed
// interval of [I8, ctrl_type].
tys.ints = BitSet::from_range(3, ctrl_type_bits as u8 + 1);
} else if ctrl_type.is_float() {
// The upper bound in from_range is exclusive, so add one here get the closed
// interval of [F32, ctrl_type].
tys.floats = BitSet::from_range(5, ctrl_type_bits as u8 + 1);
} else {
panic!("The Narrower constraint only operates on floats or ints");
}
ResolvedConstraint::Free(tys)
}
Wider => {
let ctrl_type_bits = ctrl_type.log2_lane_bits();
let mut tys = ValueTypeSet::default();
// We're testing scalar values, only.
tys.lanes = BitSet::from_range(0, 1);
if ctrl_type.is_int() {
// The upper bound should include all types wider than `ctrl_type`, so we use
// `2^8` as the upper bound to define the closed range `[ctrl_type, I128]`.
tys.ints = BitSet::from_range(ctrl_type_bits as u8, 8);
} else if ctrl_type.is_float() {
// The upper bound should include all float types wider than `ctrl_type`, so we
// use `2^7` as the upper bound to define the closed range `[ctrl_type, F64]`.
tys.floats = BitSet::from_range(ctrl_type_bits as u8, 7);
} else {
panic!("The Wider constraint only operates on floats or ints");
}
ResolvedConstraint::Free(tys)
}
}
}
}

59
cranelift/codegen/src/verifier/mod.rs
View File

@@ -1191,7 +1191,7 @@ impl<'a> Verifier<'a> {
let _ = self.typecheck_fixed_args(inst, ctrl_type, errors);
let _ = self.typecheck_variable_args(inst, errors);
let _ = self.typecheck_return(inst, errors);
let _ = self.typecheck_special(inst, ctrl_type, errors);
let _ = self.typecheck_special(inst, errors);
Ok(())
}
@@ -1478,63 +1478,8 @@ impl<'a> Verifier<'a> {
// Check special-purpose type constraints that can't be expressed in the normal opcode
// constraints.
fn typecheck_special(
&self,
inst: Inst,
ctrl_type: Type,
errors: &mut VerifierErrors,
) -> VerifierStepResult<()> {
fn typecheck_special(&self, inst: Inst, errors: &mut VerifierErrors) -> VerifierStepResult<()> {
match self.func.dfg.insts[inst] {
ir::InstructionData::Unary { opcode, arg } => {
let arg_type = self.func.dfg.value_type(arg);
match opcode {
Opcode::Uextend | Opcode::Sextend | Opcode::Fpromote => {
if arg_type.lane_count() != ctrl_type.lane_count() {
return errors.nonfatal((
inst,
self.context(inst),
format!(
"input {} and output {} must have same number of lanes",
arg_type, ctrl_type,
),
));
}
if arg_type.lane_bits() >= ctrl_type.lane_bits() {
return errors.nonfatal((
inst,
self.context(inst),
format!(
"input {} must be smaller than output {}",
arg_type, ctrl_type,
),
));
}
}
Opcode::Ireduce | Opcode::Fdemote => {
if arg_type.lane_count() != ctrl_type.lane_count() {
return errors.nonfatal((
inst,
self.context(inst),
format!(
"input {} and output {} must have same number of lanes",
arg_type, ctrl_type,
),
));
}
if arg_type.lane_bits() <= ctrl_type.lane_bits() {
return errors.nonfatal((
inst,
self.context(inst),
format!(
"input {} must be larger than output {}",
arg_type, ctrl_type,
),
));
}
}
_ => {}
}
}
ir::InstructionData::TableAddr { table, arg, .. } => {
let index_type = self.func.dfg.value_type(arg);
let table_index_type = self.func.tables[table].index_type;