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clif.rs
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clif.rs
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//! Cranelift code generation for frawk programs.
//!
//! A few notes on how frawk typed IR is translated into CLIF (from which cranelift can JIT machine
//! code):
//! * Integers are I64s
//! * Floats are F64s
//! * Strings are I128s
//! * Maps are I64s (pointers, in actuality, but we have no need for cranelift's special handling
//! of reference types)
//! * Iterators are separate variables for the base pointer, the current offset, and the length of
//! the array of keys. We can get away without packaging these together into their own stack slots
//! because iterators are always local to the current function scope.
//!
//! Global variables are allocated on the entry function's stack and passed as extra function
//! parameters to the main function and UDFs. We include metadata in [`VarRef`] to ensure we can
//! emit separate code for assignments into global and local variables, as necessary.
//!
//! Strings are passed "by reference" to functions, so we explicitly allocate string variables on
//! the stack and then pass pointers to them.
use cranelift::prelude::*;
use cranelift_codegen::ir::StackSlot;
use cranelift_jit::{JITBuilder, JITModule};
use cranelift_module::{default_libcall_names, FuncId, Linkage, Module};
use hashbrown::HashMap;
use smallvec::{smallvec, SmallVec};
use crate::builtins;
use crate::bytecode::Accum;
use crate::codegen::{
intrinsics, Backend, CodeGenerator, Config, Handles, Jit, Op, Ref, Sig, StrReg,
};
use crate::common::{traverse, CompileError, Either, FileSpec, NodeIx, NumTy, Result, Stage};
use crate::compile::{self, Typer};
use crate::runtime::{self, UniqueStr};
use std::convert::TryFrom;
use std::mem;
/// Information about a user-defined function needed by callers.
#[derive(Clone)]
struct FuncInfo {
globals: SmallVec<[Ref; 2]>,
func_id: FuncId,
}
const PLACEHOLDER: Ref = (compile::UNUSED, compile::Ty::Null);
// for debugging
const DUMP_IR: bool = false;
/// After a function is declared, some additional information is required to map parameters to
/// variables. `Prelude` contains that information.
struct Prelude {
/// The Cranelift-level signature for the function
sig: Signature,
/// The frawk-level Refs corresponding to each of the parameters enumerated in `sig`. Includes
/// a placeholder for the final parameter containing the frawk runtime for more convenient
/// iteration.
refs: SmallVec<[Ref; 4]>,
/// The number of parameters that contain "true function arguments". These are passed first.
/// The rest of the parameters correspond to global variables and the runtime. Because the
/// runtime is always the last parameter, a single offset is enough to identify all three
/// classes of parameters.
n_args: usize,
}
/// A cranelift [`Variable`] with frawk-specific metadata
#[derive(Clone)]
struct VarRef {
var: Variable,
kind: VarKind,
}
/// The different kinds of variables we track
#[derive(Copy, Clone)]
enum VarKind {
/// Variables defined locally in the a function. Under some circumstances, we do not drop these
/// variables (e.g. at join points, or when returning them from a function).
Local { skip_drop: bool },
/// frawk-level function parameters. These are treated very similarly to local variables with
/// skip_drop set to true, the only difference is that parameters are reffed before being
/// returned from a function, whereas we simply skip dropping.
Param,
/// Global variables. These are treated specially throughout, as even integers and floats are
/// passed by reference. Like params, these are reffed before being returned.
Global,
}
impl VarKind {
fn skip_drop(&mut self) {
if let VarKind::Local { skip_drop } = self {
*skip_drop = true;
}
}
}
/// Iterator-specific variable state. This is treated differently from [`VarRef`] because iterators
/// function in a much more restricted context when compared with variables.
#[derive(Clone)]
struct IterState {
// NB: a more compact representation would just be to store `start` and `end`, but we need to
// hold onto the true `start` in order to free the memory.
bytes: Variable, // int, the length of the map multiplied by the type size
cur: Variable, // int, the current byte offset of the iteration
base: Variable, // pointer
}
/// Function-level state
struct Frame {
vars: HashMap<Ref, VarRef>,
iters: HashMap<Ref, IterState>,
header_actions: Vec<EntryDeclaration>,
runtime: Variable,
// The entry block is the entry to the function. It is filled in first and contains argument
// initialization code. It jumps unconditionally to the header block.
entry_block: Block,
// The header block is filled in last. It contains any local variable initializations, we
// "discover" which initializations are required during code generation.
//
// Neither the entry block nor the header block contain any explicit branches, but Cranelift
// requires that basic blocks are in a more-or-less finished state before jumping away from
// them (LLVM does not have this restriction, so the code for that backend is structured
// somewhat differently).
header_block: Block,
n_params: usize,
n_vars: usize,
}
/// Function-independent data used in compilation
struct Shared {
module: JITModule,
func_ids: Vec<Option<FuncInfo>>,
external_funcs: HashMap<*const u8, FuncId>,
// We need cranelift Signatures for declaring external functions. We put them here to reuse
// them across calls to `register_external_fn`.
sig: Signature,
handles: Handles,
}
/// Toplevel information
pub(crate) struct Generator {
shared: Shared,
ctx: FunctionBuilderContext,
cctx: codegen::Context,
funcs: Vec<Option<Prelude>>,
mains: Stage<FuncId>,
}
/// The state required for generating code for the function at `f`.
struct View<'a> {
f: Frame,
builder: FunctionBuilder<'a>,
shared: &'a mut Shared,
}
/// A specification of a declaration to append to the top of the function.
///
/// We cannot simply `switch_to_block` back to the entry block as we do in LLVM and append the
/// instructions immediately as we discover they are needed because the Cranelift frontend requires
/// that the current block is fully terminated before we can switch to another one.
struct EntryDeclaration {
var: Variable,
ty: compile::Ty,
}
/// Map frawk-level type to its type when passed as a parameter to a cranelift function.
///
/// Iterator types are disallowed; they are never passed as function parameterse.
fn ty_to_param(ty: compile::Ty, ptr_ty: Type) -> Result<AbiParam> {
use compile::Ty::*;
let clif_ty = match ty {
Null | Int => types::I64,
Float => types::F64,
MapIntInt | MapIntFloat | MapIntStr | MapStrInt | MapStrFloat | MapStrStr | Str => ptr_ty,
IterInt | IterStr => return err!("attempt to take iterator as parameter"),
// We assume that null parameters are omitted from the argument list ahead of time
// Null => return err!("attempt to take null as parameter"),
};
Ok(AbiParam::new(clif_ty))
}
/// Map frawk-level types to a cranelift-level type.
///
/// Iterator types are disallowed; they do not correspond to a single type in cranelift and must be
/// handled specially.
fn ty_to_clifty(ty: compile::Ty, ptr_ty: Type) -> Result<Type> {
use compile::Ty::*;
match ty {
Null | Int => Ok(types::I64),
Float => Ok(types::F64),
Str => Ok(types::I128),
MapIntInt | MapIntFloat | MapIntStr => Ok(ptr_ty),
MapStrInt | MapStrFloat | MapStrStr => Ok(ptr_ty),
IterInt | IterStr => err!("taking type of an iterator"),
}
}
impl Jit for Generator {
fn main_pointers(&mut self) -> Result<Stage<*const u8>> {
Ok(self
.mains
.map_ref(|id| self.shared.module.get_finalized_function(*id)))
}
}
fn jit_builder() -> Result<JITBuilder> {
// Adapted from the cranelift source.
let mut flag_builder = settings::builder();
cfg_if::cfg_if! {
if #[cfg(target_arch = "aarch64")] {
// See https://github.com/bytecodealliance/wasmtime/issues/2735
flag_builder.set("is_pic", "false").unwrap();
// Notes from cranelift source: "On at least AArch64, 'colocated' calls use
// shorter-range relocations, which might not reach all definitions; we
// can't handle that here, so we require long-range relocation types."
flag_builder.set("use_colocated_libcalls", "false").unwrap();
} else {
flag_builder.set("is_pic", "true").unwrap();
}
}
let isa_builder = cranelift_native::builder()
.map_err(|msg| err_raw!("host machine is not supported by cranelift: {}", msg))?;
flag_builder.enable("enable_llvm_abi_extensions").unwrap();
let isa = isa_builder
.finish(settings::Flags::new(flag_builder))
.map_err(|e| err_raw!("failed to initialize cranelift isa: {:?}", e))?;
Ok(JITBuilder::with_isa(isa, default_libcall_names()))
}
impl Generator {
pub(crate) fn init(typer: &mut Typer, _config: Config) -> Result<Generator> {
let builder = jit_builder()?;
let mut regstate = RegistrationState { builder };
intrinsics::register_all(&mut regstate)?;
let module = JITModule::new(regstate.builder);
let cctx = module.make_context();
let shared = Shared {
module,
func_ids: Default::default(),
external_funcs: Default::default(),
sig: cctx.func.signature.clone(),
handles: Default::default(),
};
let mut global = Generator {
shared,
ctx: FunctionBuilderContext::new(),
cctx,
funcs: Default::default(),
// placeholder
mains: Stage::Main(FuncId::from_u32(0)),
};
global.define_functions(typer)?;
let stage = match typer.stage() {
Stage::Main(main) => Stage::Main(global.define_main_function("__frawk_main", main)?),
Stage::Par {
begin,
main_loop,
end,
} => Stage::Par {
begin: traverse(
begin.map(|off| global.define_main_function("__frawk_begin", off)),
)?,
main_loop: traverse(
main_loop.map(|off| global.define_main_function("__frawk_main_loop", off)),
)?,
end: traverse(end.map(|off| global.define_main_function("__frawk_end", off)))?,
},
};
global.mains = stage;
global
.shared
.module
.finalize_definitions()
.map_err(|err| CompileError(format!("{}", err)))?;
Ok(global)
}
/// We get a set of UDFs that are idenfitied as "toplevel" or "main", but these will probably
/// reference global variables, which we have compiled to take as function parameters. This
/// method allocates those globals on the stack (while still taking a pointer to the runtime as
/// a parameter) and then calls into that function.
fn define_main_function(&mut self, name: &str, udf: usize) -> Result<FuncId> {
// first, synthesize a `Prelude` matching a main function. This is pretty simple.
let mut sig = Signature::new(self.cctx.func.signature.call_conv);
let ptr_ty = self.shared.module.target_config().pointer_type();
sig.params.push(AbiParam::new(ptr_ty));
let res = self
.shared
.module
.declare_function(name, Linkage::Export, &sig)
.map_err(|e| CompileError(format!("failed to declare main function: {}", e)))?;
let prelude = Prelude {
sig,
refs: smallvec![PLACEHOLDER],
n_args: 0,
};
// And now we allocate global variables. First, grab the globals we need from the FuncInfo
// stored for `udf`.
let globals = self.shared.func_ids[udf].as_ref().unwrap().globals.clone();
// We'll keep track of these variables and their types so we can drop them at the end.
let mut vars = Vec::with_capacity(globals.len());
// We'll reuse the existing function building machinery.
let mut view = self.create_view(prelude);
view.builder.switch_to_block(view.f.header_block);
view.builder.seal_block(view.f.header_block);
// Now, build each global variable "by hand". Allocate a variable for it, assign it to the
// address of a default value of the type in question on the stack.
for (reg, ty) in globals {
let var = Variable::new(view.f.n_vars);
vars.push((var, ty));
view.f.n_vars += 1;
let cl_ty = view.get_ty(ty);
let ptr_ty = view.ptr_to(cl_ty);
view.builder.declare_var(var, ptr_ty);
let slot = view.stack_slot_bytes(cl_ty.lane_bits() / 8);
let default = view.default_value(ty)?;
if let compile::Ty::Str = ty {
view.store_string(slot, default);
} else {
view.builder.ins().stack_store(default, slot, 0);
}
let addr = view.builder.ins().stack_addr(ptr_ty, slot, 0);
view.builder.def_var(var, addr);
view.f.vars.insert(
(reg, ty),
VarRef {
var,
kind: VarKind::Global,
},
);
}
view.call_udf(NumTy::try_from(udf).expect("function Id too large"), &[])?;
for (var, ty) in vars {
let val = view.builder.use_var(var);
view.drop_val(ty, val);
}
view.builder.ins().return_(&[]);
view.builder.finalize();
self.define_cur_function(res)?;
Ok(res)
}
fn define_cur_function(&mut self, id: FuncId) -> Result<()> {
self.shared
.module
.define_function(id, &mut self.cctx)
.map_err(|e| CompileError(e.to_string()))?;
self.shared.module.clear_context(&mut self.cctx);
Ok(())
}
fn define_functions(&mut self, typer: &mut Typer) -> Result<()> {
self.declare_local_funcs(typer)?;
for (i, frame) in typer.frames.iter().enumerate() {
if let Some(prelude) = self.funcs[i].take() {
let mut view = self.create_view(prelude);
if i == 0 {
intrinsics::register_all(&mut view)?;
}
view.gen_function_body(frame)?;
// func_id and prelude entries should be initialized in lockstep.
let id = self.shared.func_ids[i].as_ref().unwrap().func_id;
self.define_cur_function(id)?;
}
}
Ok(())
}
/// Initialize a new user-defined function and prepare it for full code generation.
fn create_view(&mut self, Prelude { sig, refs, n_args }: Prelude) -> View {
// Initialize a frame for the function at the given offset, declare variables corresponding
// to globals and params, return a View to proceed with the rest of code generation.
let n_params = sig.params.len();
let param_tys: SmallVec<[(Ref, Type); 5]> = refs
.iter()
.cloned()
.zip(sig.params.iter().map(|p| p.value_type))
.collect();
self.cctx.func.signature = sig;
let mut builder = FunctionBuilder::new(&mut self.cctx.func, &mut self.ctx);
let entry_block = builder.create_block();
let header_block = builder.create_block();
let mut res = View {
f: Frame {
n_params,
entry_block,
header_block,
// this will get overwritten in process_args
runtime: Variable::new(0),
n_vars: 0,
vars: Default::default(),
iters: Default::default(),
header_actions: Default::default(),
},
builder,
shared: &mut self.shared,
};
res.process_args(param_tys.into_iter(), n_args);
res
}
/// Declare non-main functions and generate corresponding [`Prelude`]s, but do not generate
/// their bodies.
fn declare_local_funcs(&mut self, typer: &mut Typer) -> Result<()> {
let globals = typer.get_global_refs();
let cc = self.cctx.func.signature.call_conv;
let ptr_ty = self.shared.module.target_config().pointer_type();
for (i, (info, refs)) in typer.func_info.iter().zip(globals.iter()).enumerate() {
if !typer.frames[i].is_called {
self.funcs.push(None);
self.shared.func_ids.push(None);
continue;
}
let mut sig = Signature::new(cc);
let total_args = info.arg_tys.len() + refs.len() + 1 /* runtime */;
sig.params.reserve(total_args);
// Used in FuncInfo to let callers know which values to pass.
let mut globals = SmallVec::with_capacity(refs.len());
let mut arg_refs = SmallVec::with_capacity(total_args);
// Used in Prelude to provide enough information to initialize variables corresponding
// to function parameters
let n_args = info.arg_tys.len();
let name = format!("udf{}", i);
// Build up a signature; there are three parts to a user-defined function parameter
// list (in order):
// 1. Function-level parameters,
// 2. Pointers to global variables required by the function,
// 3. A pointer to the runtime variable
//
// All functions are typed to return a single value.
for r in typer.frames[i]
.arg_regs
.iter()
.cloned()
.zip(info.arg_tys.iter().cloned())
{
let param = ty_to_param(r.1, ptr_ty)?;
sig.params.push(param);
arg_refs.push(r);
}
for r in refs.iter().cloned() {
globals.push(r);
// All globals are passed as pointers
sig.params.push(AbiParam::new(ptr_ty));
arg_refs.push(r);
}
// Put a placeholder in for the last argument
arg_refs.push(PLACEHOLDER);
sig.params.push(AbiParam::new(ptr_ty)); // runtime
sig.returns
.push(AbiParam::new(ty_to_clifty(info.ret_ty, ptr_ty)?));
// Now, to create a function and prelude
let func_id = self
.shared
.module
.declare_function(name.as_str(), Linkage::Local, &sig)
.map_err(|e| CompileError(format!("cranelift module error: {}", e)))?;
self.funcs.push(Some(Prelude {
sig,
n_args,
refs: arg_refs,
}));
self.shared
.func_ids
.push(Some(FuncInfo { globals, func_id }));
}
Ok(())
}
}
macro_rules! external {
($name:ident) => {
crate::codegen::intrinsics::$name as *const u8
};
}
impl<'a> View<'a> {
fn stack_slot_bytes(&mut self, bytes: u32) -> StackSlot {
debug_assert!(bytes > 0); // This signals a bug; all frawk types have positive size.
let data = StackSlotData::new(StackSlotKind::ExplicitSlot, bytes);
self.builder.create_sized_stack_slot(data)
}
fn gen_function_body(mut self, insts: &compile::Frame) -> Result<()> {
let nodes = insts.cfg.raw_nodes();
let bbs: Vec<_> = (0..nodes.len())
.map(|_| self.builder.create_block())
.collect();
let mut to_visit: Vec<_> = (0..nodes.len()).collect();
let mut to_visit_next = Vec::with_capacity(1);
for round in 0..2 {
for i in to_visit.drain(..) {
let node = &nodes[i];
if node.weight.exit && round == 0 {
// We defer processing exit nodes to the end.
to_visit_next.push(i);
continue;
}
self.builder.switch_to_block(bbs[i]);
for inst in &node.weight.insts {
match inst {
Either::Left(ll) => self.gen_ll_inst(ll)?,
Either::Right(hl) => self.gen_hl_inst(hl)?,
}
}
// branch-related metadata
let mut tcase = None;
let mut ecase = None;
let mut walker = insts.cfg.neighbors(NodeIx::new(i)).detach();
while let Some(e) = walker.next_edge(&insts.cfg) {
let (_, next) = insts.cfg.edge_endpoints(e).unwrap();
let bb = bbs[next.index()];
if let Some(e) = *insts.cfg.edge_weight(e).unwrap() {
tcase = Some(((e, compile::Ty::Int), bb));
} else {
ecase = Some(bb);
}
// Now scan any phi nodes in the successor block for references back to the current
// one. If we find one, we issue an assignment, though we skip the drop as it will
// be covered by predecessor blocks (alternatively, we could issue a "mov" here,
// but this does less work).
//
// NB We could avoid scanning duplicate Phis here by tracking dependencies a bit
// more carefully, but in practice the extra work done seems fairly low given the
// CFGs that we generate at time of writing.
for inst in &nodes[next.index()].weight.insts {
if let Either::Right(compile::HighLevel::Phi(dst_reg, ty, preds)) = inst {
for src_reg in preds.iter().filter_map(|(bb, reg)| {
if bb.index() == i {
Some(*reg)
} else {
None
}
}) {
self.mov_inner(*ty, *dst_reg, src_reg, /*skip_drop=*/ false)?;
}
} else {
// We can bail out once we see the first non-phi instruction. Those all go
// at the top
break;
}
}
}
if let Some(ecase) = ecase {
self.branch(tcase, ecase)?;
}
}
mem::swap(&mut to_visit, &mut to_visit_next);
}
// Finally, fill in our "header block" containing variable initializations and jump to
// bbs[0].
self.builder.switch_to_block(self.f.header_block);
self.builder.seal_block(self.f.header_block);
self.execute_actions()?;
self.builder.ins().jump(bbs[0], &[]);
self.builder.seal_all_blocks();
if DUMP_IR {
eprintln!("{}", self.builder.func);
}
self.builder.finalize();
Ok(())
}
/// If `tcase` is set, jump to the given block if the given value is non-zero. Regardless, jump
/// unconditionally to `ecase`.
fn branch(&mut self, tcase: Option<(Ref, Block)>, ecase: Block) -> Result<()> {
if let Some((cond, b)) = tcase {
let cv = self.get_val(cond)?;
self.builder.ins().brif(cv, b, &[], ecase, &[]);
} else {
self.builder.ins().jump(ecase, &[]);
}
Ok(())
}
/// Assign each incoming parameter to a Variable and an appropriate binding in the `vars` map.
///
/// n_args signifies the length of the prefix of `param_tys` corresponding to
/// frawk-function-level parameters, where the remaining arguments contain global variables and
/// a pointer to the runtime.
fn process_args(&mut self, param_tys: impl Iterator<Item = (Ref, Type)>, n_args: usize) {
self.builder
.append_block_params_for_function_params(self.f.entry_block);
self.builder.switch_to_block(self.f.entry_block);
self.builder.seal_block(self.f.entry_block);
// need to copy params because we borrow builder mutably in the loop body.
let params: SmallVec<[Value; 5]> = self
.builder
.block_params(self.f.entry_block)
.iter()
.cloned()
.collect();
for (i, (val, (rf, ty))) in params.into_iter().zip(param_tys).enumerate() {
let var = Variable::new(self.f.n_vars);
self.f.n_vars += 1;
self.builder.declare_var(var, ty);
self.builder.def_var(var, val);
if i == self.f.n_params - 1 {
// runtime
self.f.runtime = var;
} else if i >= n_args {
// global
self.f.vars.insert(
rf,
VarRef {
var,
kind: VarKind::Global,
},
);
} else {
// normal arg. These behave like normal variables, except we do not drop them (they
// are, in effect, borrowed).
self.f.vars.insert(
rf,
VarRef {
var,
kind: VarKind::Param,
},
);
}
}
self.builder.ins().jump(self.f.header_block, &[]);
}
/// Issue end-of-function drop instructions to all local variables that have (a) a non-trivial
/// drop procedure and (b) have not been marked `skip_drop`.
fn drop_all(&mut self) {
let mut drops = Vec::new();
for ((_, ty), VarRef { var, kind }) in self.f.vars.iter() {
if let VarKind::Local { skip_drop: false } = kind {
use compile::Ty::*;
let drop_fn = match ty {
MapIntInt => external!(drop_intint),
MapIntFloat => external!(drop_intfloat),
MapIntStr => external!(drop_intstr),
MapStrInt => external!(drop_strint),
MapStrFloat => external!(drop_strfloat),
MapStrStr => external!(drop_strstr),
Str => external!(drop_str),
_ => continue,
};
let val = self.builder.use_var(*var);
drops.push((drop_fn, val));
}
}
for (drop_fn, val) in drops {
// NB: We could probably refactor call_external_void to only borrow non-f.vars fields
// and then avoid the auxiliary vector, but life is short, and we will only call this
// function once per live UDF.
self.call_external_void(drop_fn, &[val]);
}
}
/// Call a frawk-level (as opposed to builtin/external) function.
fn call_udf(&mut self, id: NumTy, args: &[Ref]) -> Result<Value> {
let mut to_pass = SmallVec::<[Value; 6]>::with_capacity(args.len() + 1);
for arg in args.iter().cloned() {
let v = self.get_val(arg)?;
to_pass.push(v);
}
let FuncInfo { globals, func_id } = self.shared.func_ids[id as usize]
.as_ref()
.expect("all referenced functions must be declared");
for global in globals {
// We don't use get_val here because we want to pass the pointer to the global, and
// get_val will issue a load.
match self.f.vars.get(global) {
Some(VarRef {
var,
kind: VarKind::Global,
..
}) => {
to_pass.push(self.builder.use_var(*var));
}
_ => return err!("internal error, functions disagree on if reference is global"),
}
}
to_pass.push(self.builder.use_var(self.f.runtime));
let fref = self
.shared
.module
.declare_func_in_func(*func_id, self.builder.func);
let call_inst = self.builder.ins().call(fref, &to_pass[..]);
Ok(self
.builder
.inst_results(call_inst)
.iter()
.cloned()
.next()
.expect("all UDFs must return a value"))
}
/// Translate a high-level instruction. If the instruction is a `Ret`, we return the returned
/// value for further processing. We want to process returns last because we can only be sure
/// that the `drop_all` method will catch all relevant local variables once we have processed
/// all of the other instructions.
fn gen_hl_inst(&mut self, inst: &compile::HighLevel) -> Result<()> {
use compile::HighLevel::*;
match inst {
Call {
func_id,
dst_reg,
dst_ty,
args,
} => {
let res = self.call_udf(*func_id, args.as_slice())?;
self.bind_val((*dst_reg, *dst_ty), res)?;
Ok(())
}
Ret(reg, ty) => {
let mut v = self.get_val((*reg, *ty))?;
let test = self.f.vars.get_mut(&(*reg, *ty)).map(|x| {
// if this is a local, we want to avoid dropping it.
x.kind.skip_drop();
&x.kind
});
if let Some(VarKind::Param) | Some(VarKind::Global) = test {
// This was passed in as a parameter, so us returning it will introduce a new
// reference.
self.ref_val(*ty, v);
}
if let compile::Ty::Str = ty {
let str_ty = self.get_ty(*ty);
v = self.builder.ins().load(str_ty, MemFlags::trusted(), v, 0);
}
self.drop_all();
self.builder.ins().return_(&[v]);
Ok(())
}
DropIter(reg, ty) => {
use compile::Ty::*;
let drop_fn = match ty {
IterInt => external!(drop_iter_int),
IterStr => external!(drop_iter_str),
_ => return err!("can only drop iterators, got {:?}", ty),
};
let IterState { base, bytes, .. } = self.get_iter((*reg, *ty))?;
let base = self.builder.use_var(base);
let bytes = self.builder.use_var(bytes);
let key_ty = self.get_ty(ty.iter()?);
let len = self.div_by_type_size(key_ty, bytes)?;
self.call_external_void(drop_fn, &[base, len]);
Ok(())
}
// Phis are handled in predecessor blocks
Phi(..) => Ok(()),
}
}
fn default_value(&mut self, ty: compile::Ty) -> Result<Value> {
use compile::Ty::*;
match ty {
Null | Int => Ok(self.const_int(0)),
Float => Ok(self.builder.ins().f64const(0.0)),
Str => {
// cranelift does not currently support iconst for I128
let zero64 = self.builder.ins().iconst(types::I64, 0);
Ok(self.builder.ins().iconcat(zero64, zero64))
}
MapIntInt | MapIntFloat | MapIntStr | MapStrInt | MapStrFloat | MapStrStr => {
let alloc_fn = match ty {
MapIntInt => external!(alloc_intint),
MapIntFloat => external!(alloc_intfloat),
MapIntStr => external!(alloc_intstr),
MapStrInt => external!(alloc_strint),
MapStrFloat => external!(alloc_strfloat),
MapStrStr => external!(alloc_strstr),
_ => unreachable!(),
};
Ok(self.call_external(alloc_fn, &[]))
}
IterInt | IterStr => err!("iterators do not have default values"),
}
}
fn store_string(&mut self, ss: StackSlot, v: Value) {
let str_ty = self.get_ty(compile::Ty::Str);
let ptr_ty = self.ptr_to(str_ty);
// We get an error if we do a direct stack_store here
let addr = self.builder.ins().stack_addr(ptr_ty, ss, 0);
self.builder.ins().store(MemFlags::trusted(), v, addr, 0);
}
fn execute_actions(&mut self) -> Result<()> {
let header_actions = mem::take(&mut self.f.header_actions);
for EntryDeclaration { var, ty } in header_actions {
use compile::Ty::*;
let cl_ty = self.get_ty(ty);
let default_v = self.default_value(ty)?;
match ty {
Null | Int | Float => {
self.builder.def_var(var, default_v);
}
Str => {
// allocate a stack slot for the string, then assign var to point to that
// slot.
let ptr_ty = self.ptr_to(cl_ty);
let slot = self.stack_slot_bytes(mem::size_of::<runtime::Str>() as u32);
let addr = self.builder.ins().stack_addr(ptr_ty, slot, 0);
self.builder.def_var(var, addr);
self.store_string(slot, default_v);
}
MapIntInt | MapIntFloat | MapIntStr | MapStrInt | MapStrFloat | MapStrStr => {
self.builder.def_var(var, default_v);
}
IterInt | IterStr => return err!("attempting to default-initialize iterator type"),
}
}
Ok(())
}
/// Initialize the `Variable` associated with a non-iterator local variable of type `ty`.
fn declare_local(&mut self, ty: compile::Ty) -> Result<Variable> {
use compile::Ty::*;
let next_var = Variable::new(self.f.n_vars);
self.f.n_vars += 1;
let cl_ty = self.get_ty(ty);
// Remember to allocate/initialize this variable in the header
self.f
.header_actions
.push(EntryDeclaration { ty, var: next_var });
match ty {
Null | Int | Float => {
self.builder.declare_var(next_var, cl_ty);
}
Str => {
let ptr_ty = self.ptr_to(cl_ty);
self.builder.declare_var(next_var, ptr_ty);
}
MapIntInt | MapIntFloat | MapIntStr | MapStrInt | MapStrFloat | MapStrStr => {
self.builder.declare_var(next_var, cl_ty);
}
IterInt | IterStr => return err!("iterators cannot be declared"),
}
Ok(next_var)
}
/// Construct an [`IterState`] corresponding to an iterator of type `ty`.
fn declare_iterator(&mut self, ty: compile::Ty) -> Result<IterState> {
use compile::Ty::*;
match ty {
IterStr | IterInt => {
let bytes = Variable::new(self.f.n_vars);
let cur = Variable::new(self.f.n_vars + 1);
let base = Variable::new(self.f.n_vars + 2);
self.f.n_vars += 3;
self.builder.declare_var(bytes, types::I64);
self.builder.declare_var(cur, types::I64);
self.builder.declare_var(base, self.void_ptr_ty());
Ok(IterState { bytes, cur, base })
}
Null | Int | Float | Str | MapIntInt | MapIntFloat | MapIntStr | MapStrInt
| MapStrFloat | MapStrStr => err!(
"attempting to declare iterator variable for non-iterator type: {:?}",
ty
),
}
}
/// Increment the refcount of the value `v` of type `ty`.
///
/// If `ty` is not an array or string type, this method is a noop.
fn ref_val(&mut self, ty: compile::Ty, v: Value) {
use compile::Ty::*;
let func = match ty {
MapIntInt | MapIntFloat | MapIntStr | MapStrInt | MapStrFloat | MapStrStr => {
external!(ref_map)
}
Str => external!(ref_str),
Null | Int | Float | IterInt | IterStr => return,
};
self.call_external_void(func, &[v]);
}
/// Decrement the refcount of the value `v` of type `ty`.
///
/// If `ty` is not an array or string type, this method is a noop.
fn drop_val(&mut self, ty: compile::Ty, v: Value) {
use compile::Ty::*;
let func = match ty {
MapIntInt => external!(drop_intint),
MapIntFloat => external!(drop_intfloat),
MapIntStr => external!(drop_intstr),
MapStrInt => external!(drop_strint),
MapStrFloat => external!(drop_strfloat),
MapStrStr => external!(drop_strstr),
Str => external!(drop_str),
Null | Int | Float | IterInt | IterStr => return,
};
self.call_external_void(func, &[v]);
}
/// Call and external function that returns a value.
///
/// Panics if `func` has not been registered as an external function, or if it was not
/// registered as returning a single value.
fn call_external(&mut self, func: *const u8, args: &[Value]) -> Value {
let inst = self.call_inst(func, args);
let mut iter = self.builder.inst_results(inst).iter().cloned();
let ret = iter.next().expect("expected return value");
// For now, we expect all functions to have a single return value.
debug_assert!(iter.next().is_none());
ret
}
/// Call and external function that does not return a value.
///
/// Panics if `func` has not been registered as an external function, or if it was not
/// registered as returning a single value.
fn call_external_void(&mut self, func: *const u8, args: &[Value]) {
let _inst = self.call_inst(func, args);
debug_assert!(self.builder.inst_results(_inst).iter().next().is_none());
}
fn call_inst(&mut self, func: *const u8, args: &[Value]) -> cranelift_codegen::ir::Inst {
let id = self.shared.external_funcs[&func];
let fref = self
.shared
.module
.declare_func_in_func(id, self.builder.func);
self.builder.ins().call(fref, args)
}
/// frawk does not have booleans, so for now we always convert the results of comparison
/// operations back to integers.
///
/// NB: It would be interesting and likely useful to add a "bool" type (with consequent
/// coercions).
fn bool_to_int(&mut self, b: Value) -> Value {
let int_ty = self.get_ty(compile::Ty::Int);
let zero = self.builder.ins().iconst(int_ty, 0);
let one = self.builder.ins().iconst(int_ty, 1);
self.builder.ins().select(b, one, zero)
}
/// Generate a new value according to the comparison instruction, applied to `l` and `r`, which
/// are assumed to be floating point values if `is_float` and (signed, as is the case in frawk)
/// integer values otherwise.
///
/// As with the LLVM, we use the "ordered" variants on comparison: the ones that return false
/// if either operand is NaN.
fn cmp(&mut self, op: crate::codegen::Cmp, is_float: bool, l: Value, r: Value) -> Value {
use crate::codegen::Cmp::*;
let res = if is_float {
match op {
Eq => self.builder.ins().fcmp(FloatCC::Equal, l, r),
Lte => self.builder.ins().fcmp(FloatCC::LessThanOrEqual, l, r),
Lt => self.builder.ins().fcmp(FloatCC::LessThan, l, r),
Gte => self.builder.ins().fcmp(FloatCC::GreaterThanOrEqual, l, r),
Gt => self.builder.ins().fcmp(FloatCC::GreaterThan, l, r),
}
} else {
match op {
Eq => self.builder.ins().icmp(IntCC::Equal, l, r),
Lte => self.builder.ins().icmp(IntCC::SignedLessThanOrEqual, l, r),
Lt => self.builder.ins().icmp(IntCC::SignedLessThan, l, r),
Gte => self
.builder
.ins()
.icmp(IntCC::SignedGreaterThanOrEqual, l, r),
Gt => self.builder.ins().icmp(IntCC::SignedGreaterThan, l, r),
}
};
self.bool_to_int(res)
}
/// Generate a new value according to the operation specified in `op`.
///
/// We assume that `args` contains floating point or signed integer values depending on the
/// value of `is_float`. Panics if args has the wrong arity.
fn arith(&mut self, op: crate::codegen::Arith, is_float: bool, args: &[Value]) -> Value {
use crate::codegen::Arith::*;
if is_float {
match op {
Mul => self.builder.ins().fmul(args[0], args[1]),
Minus => self.builder.ins().fsub(args[0], args[1]),
Add => self.builder.ins().fadd(args[0], args[1]),
// No floating-point modulo in cranelift?
Mod => self.call_external(external!(_frawk_fprem), args),
Neg => self.builder.ins().fneg(args[0]),
}
} else {