Files
wasmtime/cranelift/codegen/meta/src/cdsl/instructions.rs
2021-09-29 16:27:47 +02:00

756 lines
24 KiB
Rust

use cranelift_entity::{entity_impl, PrimaryMap};
use std::fmt;
use std::fmt::{Display, Error, Formatter};
use std::rc::Rc;
use crate::cdsl::camel_case;
use crate::cdsl::formats::InstructionFormat;
use crate::cdsl::operands::Operand;
use crate::cdsl::type_inference::Constraint;
use crate::cdsl::types::{LaneType, ReferenceType, ValueType};
use crate::cdsl::typevar::TypeVar;
use crate::shared::types::{Bool, Float, Int, Reference};
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub(crate) struct OpcodeNumber(u32);
entity_impl!(OpcodeNumber);
pub(crate) type AllInstructions = PrimaryMap<OpcodeNumber, Instruction>;
pub(crate) struct InstructionGroupBuilder<'all_inst> {
all_instructions: &'all_inst mut AllInstructions,
}
impl<'all_inst> InstructionGroupBuilder<'all_inst> {
pub fn new(all_instructions: &'all_inst mut AllInstructions) -> Self {
Self { all_instructions }
}
pub fn push(&mut self, builder: InstructionBuilder) {
let opcode_number = OpcodeNumber(self.all_instructions.next_key().as_u32());
let inst = builder.build(opcode_number);
self.all_instructions.push(inst);
}
}
/// Instructions can have parameters bound to them to specialize them for more specific encodings
/// (e.g. the encoding for adding two float types may be different than that of adding two
/// integer types)
pub(crate) trait Bindable {
/// Bind a parameter to an instruction
fn bind(&self, parameter: impl Into<BindParameter>) -> BoundInstruction;
}
#[derive(Debug)]
pub(crate) struct PolymorphicInfo {
pub use_typevar_operand: bool,
pub ctrl_typevar: TypeVar,
pub other_typevars: Vec<TypeVar>,
}
#[derive(Debug)]
pub(crate) struct InstructionContent {
/// Instruction mnemonic, also becomes opcode name.
pub name: String,
pub camel_name: String,
pub opcode_number: OpcodeNumber,
/// Documentation string.
pub doc: String,
/// Input operands. This can be a mix of SSA value operands and other operand kinds.
pub operands_in: Vec<Operand>,
/// Output operands. The output operands must be SSA values or `variable_args`.
pub operands_out: Vec<Operand>,
/// Instruction-specific TypeConstraints.
pub constraints: Vec<Constraint>,
/// Instruction format, automatically derived from the input operands.
pub format: Rc<InstructionFormat>,
/// One of the input or output operands is a free type variable. None if the instruction is not
/// polymorphic, set otherwise.
pub polymorphic_info: Option<PolymorphicInfo>,
/// Indices in operands_in of input operands that are values.
pub value_opnums: Vec<usize>,
/// Indices in operands_in of input operands that are immediates or entities.
pub imm_opnums: Vec<usize>,
/// Indices in operands_out of output operands that are values.
pub value_results: Vec<usize>,
/// True for instructions that terminate the block.
pub is_terminator: bool,
/// True for all branch or jump instructions.
pub is_branch: bool,
/// True for all indirect branch or jump instructions.',
pub is_indirect_branch: bool,
/// Is this a call instruction?
pub is_call: bool,
/// Is this a return instruction?
pub is_return: bool,
/// Is this a ghost instruction?
pub is_ghost: bool,
/// Can this instruction read from memory?
pub can_load: bool,
/// Can this instruction write to memory?
pub can_store: bool,
/// Can this instruction cause a trap?
pub can_trap: bool,
/// Does this instruction have other side effects besides can_* flags?
pub other_side_effects: bool,
/// Does this instruction write to CPU flags?
pub writes_cpu_flags: bool,
/// Should this opcode be considered to clobber all live registers, during regalloc?
pub clobbers_all_regs: bool,
}
impl InstructionContent {
pub fn snake_name(&self) -> &str {
if &self.name == "return" {
"return_"
} else {
&self.name
}
}
}
pub(crate) type Instruction = Rc<InstructionContent>;
impl Bindable for Instruction {
fn bind(&self, parameter: impl Into<BindParameter>) -> BoundInstruction {
BoundInstruction::new(self).bind(parameter)
}
}
impl fmt::Display for InstructionContent {
fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
if !self.operands_out.is_empty() {
let operands_out = self
.operands_out
.iter()
.map(|op| op.name)
.collect::<Vec<_>>()
.join(", ");
fmt.write_str(&operands_out)?;
fmt.write_str(" = ")?;
}
fmt.write_str(&self.name)?;
if !self.operands_in.is_empty() {
let operands_in = self
.operands_in
.iter()
.map(|op| op.name)
.collect::<Vec<_>>()
.join(", ");
fmt.write_str(" ")?;
fmt.write_str(&operands_in)?;
}
Ok(())
}
}
pub(crate) struct InstructionBuilder {
name: String,
doc: String,
format: Rc<InstructionFormat>,
operands_in: Option<Vec<Operand>>,
operands_out: Option<Vec<Operand>>,
constraints: Option<Vec<Constraint>>,
// See Instruction comments for the meaning of these fields.
is_terminator: bool,
is_branch: bool,
is_indirect_branch: bool,
is_call: bool,
is_return: bool,
is_ghost: bool,
can_load: bool,
can_store: bool,
can_trap: bool,
other_side_effects: bool,
clobbers_all_regs: bool,
}
impl InstructionBuilder {
pub fn new<S: Into<String>>(name: S, doc: S, format: &Rc<InstructionFormat>) -> Self {
Self {
name: name.into(),
doc: doc.into(),
format: format.clone(),
operands_in: None,
operands_out: None,
constraints: None,
is_terminator: false,
is_branch: false,
is_indirect_branch: false,
is_call: false,
is_return: false,
is_ghost: false,
can_load: false,
can_store: false,
can_trap: false,
other_side_effects: false,
clobbers_all_regs: false,
}
}
pub fn operands_in(mut self, operands: Vec<&Operand>) -> Self {
assert!(self.operands_in.is_none());
self.operands_in = Some(operands.iter().map(|x| (*x).clone()).collect());
self
}
pub fn operands_out(mut self, operands: Vec<&Operand>) -> Self {
assert!(self.operands_out.is_none());
self.operands_out = Some(operands.iter().map(|x| (*x).clone()).collect());
self
}
pub fn constraints(mut self, constraints: Vec<Constraint>) -> Self {
assert!(self.constraints.is_none());
self.constraints = Some(constraints);
self
}
#[allow(clippy::wrong_self_convention)]
pub fn is_terminator(mut self, val: bool) -> Self {
self.is_terminator = val;
self
}
#[allow(clippy::wrong_self_convention)]
pub fn is_branch(mut self, val: bool) -> Self {
self.is_branch = val;
self
}
#[allow(clippy::wrong_self_convention)]
pub fn is_indirect_branch(mut self, val: bool) -> Self {
self.is_indirect_branch = val;
self
}
#[allow(clippy::wrong_self_convention)]
pub fn is_call(mut self, val: bool) -> Self {
self.is_call = val;
self
}
#[allow(clippy::wrong_self_convention)]
pub fn is_return(mut self, val: bool) -> Self {
self.is_return = val;
self
}
#[allow(clippy::wrong_self_convention)]
pub fn is_ghost(mut self, val: bool) -> Self {
self.is_ghost = val;
self
}
pub fn can_load(mut self, val: bool) -> Self {
self.can_load = val;
self
}
pub fn can_store(mut self, val: bool) -> Self {
self.can_store = val;
self
}
pub fn can_trap(mut self, val: bool) -> Self {
self.can_trap = val;
self
}
pub fn other_side_effects(mut self, val: bool) -> Self {
self.other_side_effects = val;
self
}
fn build(self, opcode_number: OpcodeNumber) -> Instruction {
let operands_in = self.operands_in.unwrap_or_else(Vec::new);
let operands_out = self.operands_out.unwrap_or_else(Vec::new);
let mut value_opnums = Vec::new();
let mut imm_opnums = Vec::new();
for (i, op) in operands_in.iter().enumerate() {
if op.is_value() {
value_opnums.push(i);
} else if op.is_immediate_or_entityref() {
imm_opnums.push(i);
} else {
assert!(op.is_varargs());
}
}
let value_results = operands_out
.iter()
.enumerate()
.filter_map(|(i, op)| if op.is_value() { Some(i) } else { None })
.collect();
verify_format(&self.name, &operands_in, &self.format);
let polymorphic_info =
verify_polymorphic(&operands_in, &operands_out, &self.format, &value_opnums);
// Infer from output operands whether an instruction clobbers CPU flags or not.
let writes_cpu_flags = operands_out.iter().any(|op| op.is_cpu_flags());
let camel_name = camel_case(&self.name);
Rc::new(InstructionContent {
name: self.name,
camel_name,
opcode_number,
doc: self.doc,
operands_in,
operands_out,
constraints: self.constraints.unwrap_or_else(Vec::new),
format: self.format,
polymorphic_info,
value_opnums,
value_results,
imm_opnums,
is_terminator: self.is_terminator,
is_branch: self.is_branch,
is_indirect_branch: self.is_indirect_branch,
is_call: self.is_call,
is_return: self.is_return,
is_ghost: self.is_ghost,
can_load: self.can_load,
can_store: self.can_store,
can_trap: self.can_trap,
other_side_effects: self.other_side_effects,
writes_cpu_flags,
clobbers_all_regs: self.clobbers_all_regs,
})
}
}
/// An parameter used for binding instructions to specific types or values
pub(crate) enum BindParameter {
Lane(LaneType),
Reference(ReferenceType),
}
impl From<Int> for BindParameter {
fn from(ty: Int) -> Self {
BindParameter::Lane(ty.into())
}
}
impl From<Bool> for BindParameter {
fn from(ty: Bool) -> Self {
BindParameter::Lane(ty.into())
}
}
impl From<Float> for BindParameter {
fn from(ty: Float) -> Self {
BindParameter::Lane(ty.into())
}
}
impl From<LaneType> for BindParameter {
fn from(ty: LaneType) -> Self {
BindParameter::Lane(ty)
}
}
impl From<Reference> for BindParameter {
fn from(ty: Reference) -> Self {
BindParameter::Reference(ty.into())
}
}
#[derive(Clone)]
pub(crate) enum Immediate {}
impl Display for Immediate {
fn fmt(&self, _f: &mut Formatter) -> Result<(), Error> {
match self {
_ => panic!(),
}
}
}
#[derive(Clone)]
pub(crate) struct BoundInstruction {
pub inst: Instruction,
pub value_types: Vec<ValueType>,
pub immediate_values: Vec<Immediate>,
}
impl BoundInstruction {
/// Construct a new bound instruction (with nothing bound yet) from an instruction
fn new(inst: &Instruction) -> Self {
BoundInstruction {
inst: inst.clone(),
value_types: vec![],
immediate_values: vec![],
}
}
/// Verify that the bindings for a BoundInstruction are correct.
fn verify_bindings(&self) -> Result<(), String> {
// Verify that binding types to the instruction does not violate the polymorphic rules.
if !self.value_types.is_empty() {
match &self.inst.polymorphic_info {
Some(poly) => {
if self.value_types.len() > 1 + poly.other_typevars.len() {
return Err(format!(
"trying to bind too many types for {}",
self.inst.name
));
}
}
None => {
return Err(format!(
"trying to bind a type for {} which is not a polymorphic instruction",
self.inst.name
));
}
}
}
// Verify that only the right number of immediates are bound.
let immediate_count = self
.inst
.operands_in
.iter()
.filter(|o| o.is_immediate_or_entityref())
.count();
if self.immediate_values.len() > immediate_count {
return Err(format!(
"trying to bind too many immediates ({}) to instruction {} which only expects {} \
immediates",
self.immediate_values.len(),
self.inst.name,
immediate_count
));
}
Ok(())
}
}
impl Bindable for BoundInstruction {
fn bind(&self, parameter: impl Into<BindParameter>) -> BoundInstruction {
let mut modified = self.clone();
match parameter.into() {
BindParameter::Lane(lane_type) => modified.value_types.push(lane_type.into()),
BindParameter::Reference(reference_type) => {
modified.value_types.push(reference_type.into());
}
}
modified.verify_bindings().unwrap();
modified
}
}
/// Checks that the input operands actually match the given format.
fn verify_format(inst_name: &str, operands_in: &[Operand], format: &InstructionFormat) {
// A format is defined by:
// - its number of input value operands,
// - its number and names of input immediate operands,
// - whether it has a value list or not.
let mut num_values = 0;
let mut num_immediates = 0;
for operand in operands_in.iter() {
if operand.is_varargs() {
assert!(
format.has_value_list,
"instruction {} has varargs, but its format {} doesn't have a value list; you may \
need to use a different format.",
inst_name, format.name
);
}
if operand.is_value() {
num_values += 1;
}
if operand.is_immediate_or_entityref() {
if let Some(format_field) = format.imm_fields.get(num_immediates) {
assert_eq!(
format_field.kind.rust_field_name,
operand.kind.rust_field_name,
"{}th operand of {} should be {} (according to format), not {} (according to \
inst definition). You may need to use a different format.",
num_immediates,
inst_name,
format_field.kind.rust_field_name,
operand.kind.rust_field_name
);
num_immediates += 1;
}
}
}
assert_eq!(
num_values, format.num_value_operands,
"inst {} doesn't have as many value input operands as its format {} declares; you may need \
to use a different format.",
inst_name, format.name
);
assert_eq!(
num_immediates,
format.imm_fields.len(),
"inst {} doesn't have as many immediate input \
operands as its format {} declares; you may need to use a different format.",
inst_name,
format.name
);
}
/// Check if this instruction is polymorphic, and verify its use of type variables.
fn verify_polymorphic(
operands_in: &[Operand],
operands_out: &[Operand],
format: &InstructionFormat,
value_opnums: &[usize],
) -> Option<PolymorphicInfo> {
// The instruction is polymorphic if it has one free input or output operand.
let is_polymorphic = operands_in
.iter()
.any(|op| op.is_value() && op.type_var().unwrap().free_typevar().is_some())
|| operands_out
.iter()
.any(|op| op.is_value() && op.type_var().unwrap().free_typevar().is_some());
if !is_polymorphic {
return None;
}
// Verify the use of type variables.
let tv_op = format.typevar_operand;
let mut maybe_error_message = None;
if let Some(tv_op) = tv_op {
if tv_op < value_opnums.len() {
let op_num = value_opnums[tv_op];
let tv = operands_in[op_num].type_var().unwrap();
let free_typevar = tv.free_typevar();
if (free_typevar.is_some() && tv == &free_typevar.unwrap())
|| tv.singleton_type().is_some()
{
match is_ctrl_typevar_candidate(tv, &operands_in, &operands_out) {
Ok(other_typevars) => {
return Some(PolymorphicInfo {
use_typevar_operand: true,
ctrl_typevar: tv.clone(),
other_typevars,
});
}
Err(error_message) => {
maybe_error_message = Some(error_message);
}
}
}
}
};
// If we reached here, it means the type variable indicated as the typevar operand couldn't
// control every other input and output type variable. We need to look at the result type
// variables.
if operands_out.is_empty() {
// No result means no other possible type variable, so it's a type inference failure.
match maybe_error_message {
Some(msg) => panic!("{}", msg),
None => panic!("typevar_operand must be a free type variable"),
}
}
// Otherwise, try to infer the controlling type variable by looking at the first result.
let tv = operands_out[0].type_var().unwrap();
let free_typevar = tv.free_typevar();
if free_typevar.is_some() && tv != &free_typevar.unwrap() {
panic!("first result must be a free type variable");
}
// At this point, if the next unwrap() fails, it means the output type couldn't be used as a
// controlling type variable either; panicking is the right behavior.
let other_typevars = is_ctrl_typevar_candidate(tv, &operands_in, &operands_out).unwrap();
Some(PolymorphicInfo {
use_typevar_operand: false,
ctrl_typevar: tv.clone(),
other_typevars,
})
}
/// Verify that the use of TypeVars is consistent with `ctrl_typevar` as the controlling type
/// variable.
///
/// All polymorhic inputs must either be derived from `ctrl_typevar` or be independent free type
/// variables only used once.
///
/// All polymorphic results must be derived from `ctrl_typevar`.
///
/// Return a vector of other type variables used, or a string explaining what went wrong.
fn is_ctrl_typevar_candidate(
ctrl_typevar: &TypeVar,
operands_in: &[Operand],
operands_out: &[Operand],
) -> Result<Vec<TypeVar>, String> {
let mut other_typevars = Vec::new();
// Check value inputs.
for input in operands_in {
if !input.is_value() {
continue;
}
let typ = input.type_var().unwrap();
let free_typevar = typ.free_typevar();
// Non-polymorphic or derived from ctrl_typevar is OK.
if free_typevar.is_none() {
continue;
}
let free_typevar = free_typevar.unwrap();
if &free_typevar == ctrl_typevar {
continue;
}
// No other derived typevars allowed.
if typ != &free_typevar {
return Err(format!(
"{:?}: type variable {} must be derived from {:?} while it is derived from {:?}",
input, typ.name, ctrl_typevar, free_typevar
));
}
// Other free type variables can only be used once each.
for other_tv in &other_typevars {
if &free_typevar == other_tv {
return Err(format!(
"non-controlling type variable {} can't be used more than once",
free_typevar.name
));
}
}
other_typevars.push(free_typevar);
}
// Check outputs.
for result in operands_out {
if !result.is_value() {
continue;
}
let typ = result.type_var().unwrap();
let free_typevar = typ.free_typevar();
// Non-polymorphic or derived from ctrl_typevar is OK.
if free_typevar.is_none() || &free_typevar.unwrap() == ctrl_typevar {
continue;
}
return Err("type variable in output not derived from ctrl_typevar".into());
}
Ok(other_typevars)
}
#[cfg(test)]
mod test {
use super::*;
use crate::cdsl::formats::InstructionFormatBuilder;
use crate::cdsl::operands::{OperandKind, OperandKindFields};
use crate::cdsl::typevar::TypeSetBuilder;
use crate::shared::types::Int::{I32, I64};
fn field_to_operand(index: usize, field: OperandKindFields) -> Operand {
// Pretend the index string is &'static.
let name = Box::leak(index.to_string().into_boxed_str());
// Format's name / rust_type don't matter here.
let kind = OperandKind::new(name, name, field);
let operand = Operand::new(name, kind);
operand
}
fn field_to_operands(types: Vec<OperandKindFields>) -> Vec<Operand> {
types
.iter()
.enumerate()
.map(|(i, f)| field_to_operand(i, f.clone()))
.collect()
}
fn build_fake_instruction(
inputs: Vec<OperandKindFields>,
outputs: Vec<OperandKindFields>,
) -> Instruction {
// Setup a format from the input operands.
let mut format = InstructionFormatBuilder::new("fake");
for (i, f) in inputs.iter().enumerate() {
match f {
OperandKindFields::TypeVar(_) => format = format.value(),
OperandKindFields::ImmValue => {
format = format.imm(&field_to_operand(i, f.clone()).kind)
}
_ => {}
};
}
let format = format.build();
// Create the fake instruction.
InstructionBuilder::new("fake", "A fake instruction for testing.", &format)
.operands_in(field_to_operands(inputs).iter().collect())
.operands_out(field_to_operands(outputs).iter().collect())
.build(OpcodeNumber(42))
}
#[test]
fn ensure_bound_instructions_can_bind_lane_types() {
let type1 = TypeSetBuilder::new().ints(8..64).build();
let in1 = OperandKindFields::TypeVar(TypeVar::new("a", "...", type1));
let inst = build_fake_instruction(vec![in1], vec![]);
inst.bind(LaneType::Int(I32));
}
#[test]
fn ensure_bound_instructions_can_bind_immediates() {
let inst = build_fake_instruction(vec![OperandKindFields::ImmValue], vec![]);
let bound_inst = inst.bind(Immediate::IntCC(IntCC::Equal));
assert!(bound_inst.verify_bindings().is_ok());
}
#[test]
#[should_panic]
fn ensure_instructions_fail_to_bind() {
let inst = build_fake_instruction(vec![], vec![]);
inst.bind(BindParameter::Lane(LaneType::Int(I32)));
// Trying to bind to an instruction with no inputs should fail.
}
#[test]
#[should_panic]
fn ensure_bound_instructions_fail_to_bind_too_many_types() {
let type1 = TypeSetBuilder::new().ints(8..64).build();
let in1 = OperandKindFields::TypeVar(TypeVar::new("a", "...", type1));
let inst = build_fake_instruction(vec![in1], vec![]);
inst.bind(LaneType::Int(I32)).bind(LaneType::Int(I64));
}
#[test]
#[should_panic]
fn ensure_instructions_fail_to_bind_too_many_immediates() {
let inst = build_fake_instruction(vec![OperandKindFields::ImmValue], vec![]);
inst.bind(BindParameter::Immediate(Immediate::IntCC(IntCC::Equal)))
.bind(BindParameter::Immediate(Immediate::IntCC(IntCC::Equal)));
// Trying to bind too many immediates to an instruction should fail; note that the immediate
// values are nonsensical but irrelevant to the purpose of this test.
}
}