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use std::collections::{BTreeSet, HashMap, HashSet};
use std::rc::Rc;
use crate::compiler::codegen::codegen;
use crate::compiler::optimize::depgraph::{DepgraphKind, FunctionDependencyGraph};
use crate::compiler::optimize::{sexp_scale, SyntheticType};
use crate::compiler::{BasicCompileContext, CompileErr, CompileForm, CompilerOpts, HelperForm};
// Find the roots for the given function.
fn find_roots(
visited: &mut HashSet<Vec<u8>>,
root_set: &mut BTreeSet<Vec<u8>>,
depgraph: &FunctionDependencyGraph,
function: &[u8],
) {
if visited.contains(function) {
return;
}
visited.insert(function.to_vec());
// If it's non-inline, it's a root.
if let Some(f) = depgraph.helpers.get(function) {
if matches!(f.status, DepgraphKind::UserNonInline) {
root_set.insert(function.to_vec());
return;
}
}
if let Some(parents) = depgraph.parents(function) {
for p in parents.iter() {
find_roots(visited, root_set, depgraph, p);
}
}
}
pub(crate) fn stepping_over_24(opts: Rc<dyn CompilerOpts>) -> bool {
if let Some(s) = &opts.dialect().stepping {
return *s > 24;
}
opts.module_phase().is_some()
}
type VecOfRootSetTree<'a> = Vec<(&'a BTreeSet<Vec<u8>>, Vec<&'a Vec<u8>>)>;
// Should take a desugared program.
pub fn deinline_opt(
context: &mut BasicCompileContext,
opts: Rc<dyn CompilerOpts>,
mut compileform: CompileForm,
) -> Result<CompileForm, CompileErr> {
// Short circuit return: no helpers.
if compileform.helpers.is_empty() {
return Ok(compileform);
}
let is_module_compile = opts.module_phase().is_some();
// In module phase the inline/deinline size search below is a guaranteed
// no-op, so skip it. The `flip_helper` guard only permits the
// non-inline -> inline direction for `NoInlinePreference` synthetics when
// `is_module_compile` is true, and the module convention of keeping those
// synthetics non-inline means that direction is always strictly larger and
// therefore always rejected. Running the search anyway still pays
// O(functions) full code generations per root set -- each itself superlinear
// in program size -- which dominates compile time on large multi-export
// modules to the point that compilation appears to hang. Returning the
// unchanged program here is output-identical (the search never updates
// `best_compileform` in module phase) and removes the blow-up.
if is_module_compile {
return Ok(compileform);
}
let depgraph = FunctionDependencyGraph::new(&compileform);
let mut best_compileform = compileform.clone();
let generated_program = codegen(context, opts.clone(), &best_compileform)?;
let mut metric = sexp_scale(&generated_program);
let flip_helper = |h: &mut HelperForm| {
if let HelperForm::Defun(inline, defun) = h {
// Since the convention of module programs is non-inline for synthetics, no program
// in my test set lost weight by switching inline off after losing weight by switching
// it on, and the cost of this search can be high.
if matches!(&defun.synthetic, Some(SyntheticType::NoInlinePreference))
&& (!is_module_compile || !*inline)
{
*h = HelperForm::Defun(!*inline, defun.clone());
return true;
}
}
false
};
let helper_to_index: HashMap<Vec<u8>, usize> = compileform
.helpers
.iter()
.enumerate()
.map(|(i, h)| (h.name().to_vec(), i))
.collect();
// defun F -> Synthetic letbinding_$_1
// Synthetic letbinding_$_2 -> Synthetic letbinding_$_3
//
// defun H_inline ->
// Synthetic letbinding_$_4 -> Synthetic letbinding_$_5
// Synthetic letbinding_$_6
//
// defun G -> Synthetic letbinding_$_7 -> H_inline
//
// - Synthetic Roots -
//
// letbinding_$_1, letbinding_$_2, letbinding_$_7
// letbinding_$_4 is not a root, because it's in H_inline, called from G.
//
// So for each synthetic function, we traverse functions that depend on
// it as long as it's a synthetic function or a non-synthetic inline.
// The functions we reach are the roots.
//
// If any two roots share dependencies, they must be merged.
//
// So we take the set of each root and every synthetic function reachable
// from it and for each of those sets, we do the normal optimizataion loop.
// Find leaf synthetic functions by first finding leaf functions, then
// until we find a synthetic function, go up to each depended_on_by function
// until we reach a root.
//
// Remember the root this function belongs to.
let leaves: Vec<Vec<u8>> = depgraph
.leaves()
.iter()
.filter(|l| {
depgraph
.helpers
.get(&l.to_vec())
.map(|l| !matches!(l.status, DepgraphKind::UserNonInline))
.unwrap_or(false)
})
.cloned()
.collect();
let mut roots: HashMap<Vec<u8>, BTreeSet<Vec<u8>>> = HashMap::new();
// For each leaf, find roots.
for l in leaves.iter() {
let mut visited = HashSet::new();
let mut leaf_roots = BTreeSet::new();
find_roots(&mut visited, &mut leaf_roots, &depgraph, l);
if leaf_roots.is_empty() {
leaf_roots.insert(l.to_vec());
}
roots.insert(l.to_vec(), leaf_roots);
}
// Make a set of root sets to coalesce them.
let mut roots_set: HashSet<BTreeSet<Vec<u8>>> = HashSet::new();
for common_roots in roots.values() {
roots_set.insert(common_roots.clone());
}
// roots is a map from leaf inline to root container. We can use the roots_set
// with this collection to make a set of leaves reachable from each root set.
// Each root set is a set of functions that will change representation when
// inlining is changed so we have to handle each root set as a unit.
let mut root_set_to_leaf: HashMap<BTreeSet<Vec<u8>>, BTreeSet<Vec<u8>>> = roots_set
.iter()
.map(|root_set| (root_set.clone(), BTreeSet::new()))
.collect();
for l in leaves.iter() {
let root = if let Some(root) = roots.get(l) {
root.clone()
} else {
return Err(CompileErr(
compileform.loc.clone(),
"Error in deinline, depgraph gave a leaf that didn't yield a root".to_string(),
));
};
let from_root_set: Vec<BTreeSet<Vec<u8>>> = roots_set
.iter()
.filter(|r| {
let intersection_of_roots: HashSet<Vec<u8>> =
r.intersection(&root).cloned().collect();
!intersection_of_roots.is_empty()
})
.cloned()
.collect();
for root_set in from_root_set.iter() {
if let Some(leaf_set) = root_set_to_leaf.get_mut(root_set) {
leaf_set.insert(l.to_vec());
}
}
}
// Now collect the tree of synthetic functions rooted at any of the roots in
// each root set.
let root_set_to_inline_tree: HashMap<BTreeSet<Vec<u8>>, HashSet<Vec<u8>>> = root_set_to_leaf
.iter()
.map(|(root_set, leaves)| {
let mut full_tree_set = HashSet::new();
for root in root_set.iter() {
let mut full_tree = HashSet::new();
depgraph.get_full_depends_on(&mut full_tree, root);
full_tree_set = full_tree.union(&full_tree_set).cloned().collect();
}
if full_tree_set.is_empty() {
full_tree_set = leaves.iter().cloned().collect();
}
(root_set.clone(), full_tree_set)
})
.collect();
let mut root_set_to_inline_tree_vec: VecOfRootSetTree<'_> = root_set_to_inline_tree
.iter()
.map(|(k, function_set)| {
let mut fset_vec: Vec<&Vec<u8>> = function_set.iter().collect();
// Sort which normalizes order.
if stepping_over_24(opts.clone()) {
fset_vec.sort();
}
(k, fset_vec)
})
.collect();
// Sort which normalizes order.
if stepping_over_24(opts.clone()) {
root_set_to_inline_tree_vec.sort();
}
for (_, function_set) in root_set_to_inline_tree_vec.iter() {
loop {
let start_metric = metric;
for f in function_set.iter() {
// Get index of helper identified by this leaf name.
let i = if let Some(i) = helper_to_index.get(*f) {
*i
} else {
return Err(CompileErr(
compileform.loc.clone(),
"We have a helper name that has no index?".to_string(),
));
};
// Try flipped.
let old_helper = compileform.helpers[i].clone();
if !flip_helper(&mut compileform.helpers[i]) {
continue;
}
let maybe_smaller_program = codegen(context, opts.clone(), &compileform)?;
let new_metric = sexp_scale(&maybe_smaller_program);
// Don't keep this change if it made things worse.
if new_metric >= metric {
compileform.helpers[i] = old_helper;
} else {
metric = new_metric;
best_compileform = compileform.clone();
}
}
if start_metric == metric {
break;
}
}
}
Ok(best_compileform)
}