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Rollup merge of #122247 - notriddle:notriddle/search-unbox-limit, r=G…
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…uillaumeGomez

rustdoc-search: depth limit `T<U>` -> `U` unboxing

Profiler output:
https://notriddle.com/rustdoc-html-demo-9/search-unbox-limit/ (the only significant change is that one of the `rust` tests went from 378416ms to 16ms).

This is a performance enhancement aimed at a problem I found while using type-driven search on the Rust compiler. It is caused by [`Interner`], a trait with 41 associated types, many of which recurse back to `Self` again.

This caused search.js to struggle. It eventually terminates, after about 10 minutes of turning my PC into a space header, but it's doing `41!` unifications and that's too slow.

[`Interner`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/trait.Interner.html
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@matthiaskrgr
matthiaskrgr authored Mar 14, 2024
2 parents 7997ef4 + fa5b9f0 commit a95e2f9
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Showing 4 changed files with 366 additions and 31 deletions.
138 changes: 107 additions & 31 deletions src/librustdoc/html/static/js/search.js
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Original file line number Diff line number Diff line change
Expand Up @@ -81,6 +81,13 @@ const longItemTypes = [
const TY_GENERIC = itemTypes.indexOf("generic");
const ROOT_PATH = typeof window !== "undefined" ? window.rootPath : "../";

// Hard limit on how deep to recurse into generics when doing type-driven search.
// This needs limited, partially because
// a search for `Ty` shouldn't match `WithInfcx<ParamEnvAnd<Vec<ConstTy<Interner<Ty=Ty>>>>>`,
// but mostly because this is the simplest and most principled way to limit the number
// of permutations we need to check.
const UNBOXING_LIMIT = 5;

// In the search display, allows to switch between tabs.
function printTab(nb) {
let iter = 0;
Expand Down Expand Up @@ -1458,10 +1465,23 @@ function initSearch(rawSearchIndex) {
* @param {Map<number,number>|null} mgensIn
* - Map functions generics to query generics (never modified).
* @param {null|Map<number,number> -> bool} solutionCb - Called for each `mgens` solution.
* @param {number} unboxingDepth
* - Limit checks that Ty matches Vec<Ty>,
* but not Vec<ParamEnvAnd<WithInfcx<ConstTy<Interner<Ty=Ty>>>>>
*
* @return {boolean} - Returns true if a match, false otherwise.
*/
function unifyFunctionTypes(fnTypesIn, queryElems, whereClause, mgensIn, solutionCb) {
function unifyFunctionTypes(
fnTypesIn,
queryElems,
whereClause,
mgensIn,
solutionCb,
unboxingDepth
) {
if (unboxingDepth >= UNBOXING_LIMIT) {
return false;
}
/**
* @type Map<integer, integer>|null
*/
Expand All @@ -1480,7 +1500,7 @@ function initSearch(rawSearchIndex) {
&& queryElems[0].bindings.size === 0) {
const queryElem = queryElems[0];
for (const fnType of fnTypesIn) {
if (!unifyFunctionTypeIsMatchCandidate(fnType, queryElem, whereClause, mgens)) {
if (!unifyFunctionTypeIsMatchCandidate(fnType, queryElem, mgens)) {
continue;
}
if (fnType.id < 0 && queryElem.id < 0) {
Expand All @@ -1499,7 +1519,13 @@ function initSearch(rawSearchIndex) {
}
}
for (const fnType of fnTypesIn) {
if (!unifyFunctionTypeIsUnboxCandidate(fnType, queryElem, whereClause, mgens)) {
if (!unifyFunctionTypeIsUnboxCandidate(
fnType,
queryElem,
whereClause,
mgens,
unboxingDepth + 1
)) {
continue;
}
if (fnType.id < 0) {
Expand All @@ -1514,7 +1540,8 @@ function initSearch(rawSearchIndex) {
queryElems,
whereClause,
mgensScratch,
solutionCb
solutionCb,
unboxingDepth + 1
)) {
return true;
}
Expand All @@ -1523,7 +1550,8 @@ function initSearch(rawSearchIndex) {
queryElems,
whereClause,
mgens ? new Map(mgens) : null,
solutionCb
solutionCb,
unboxingDepth + 1
)) {
return true;
}
Expand Down Expand Up @@ -1559,7 +1587,7 @@ function initSearch(rawSearchIndex) {
let queryElemsTmp = null;
for (let i = flast; i >= 0; i -= 1) {
const fnType = fnTypes[i];
if (!unifyFunctionTypeIsMatchCandidate(fnType, queryElem, whereClause, mgens)) {
if (!unifyFunctionTypeIsMatchCandidate(fnType, queryElem, mgens)) {
continue;
}
let mgensScratch;
Expand Down Expand Up @@ -1596,7 +1624,8 @@ function initSearch(rawSearchIndex) {
fnType,
queryElem,
whereClause,
mgensScratch
mgensScratch,
unboxingDepth
);
if (!solution) {
return false;
Expand All @@ -1608,14 +1637,16 @@ function initSearch(rawSearchIndex) {
queryElem.generics,
whereClause,
simplifiedMgens,
solutionCb
solutionCb,
unboxingDepth
);
if (passesUnification) {
return true;
}
}
return false;
}
},
unboxingDepth
);
if (passesUnification) {
return true;
Expand All @@ -1627,7 +1658,13 @@ function initSearch(rawSearchIndex) {
}
for (let i = flast; i >= 0; i -= 1) {
const fnType = fnTypes[i];
if (!unifyFunctionTypeIsUnboxCandidate(fnType, queryElem, whereClause, mgens)) {
if (!unifyFunctionTypeIsUnboxCandidate(
fnType,
queryElem,
whereClause,
mgens,
unboxingDepth + 1
)) {
continue;
}
let mgensScratch;
Expand All @@ -1651,7 +1688,8 @@ function initSearch(rawSearchIndex) {
queryElems,
whereClause,
mgensScratch,
solutionCb
solutionCb,
unboxingDepth + 1
);
if (passesUnification) {
return true;
Expand All @@ -1670,11 +1708,10 @@ function initSearch(rawSearchIndex) {
*
* @param {FunctionType} fnType
* @param {QueryElement} queryElem
* @param {[FunctionSearchType]} whereClause - Trait bounds for generic items.
* @param {Map<number,number>|null} mgensIn - Map functions generics to query generics.
* @returns {boolean}
*/
function unifyFunctionTypeIsMatchCandidate(fnType, queryElem, whereClause, mgensIn) {
function unifyFunctionTypeIsMatchCandidate(fnType, queryElem, mgensIn) {
// type filters look like `trait:Read` or `enum:Result`
if (!typePassesFilter(queryElem.typeFilter, fnType.ty)) {
return false;
Expand Down Expand Up @@ -1775,9 +1812,16 @@ function initSearch(rawSearchIndex) {
* @param {[FunctionType]} whereClause - Trait bounds for generic items.
* @param {Map<number,number>} mgensIn - Map functions generics to query generics.
* Never modified.
* @param {number} unboxingDepth
* @returns {false|{mgens: [Map<number,number>], simplifiedGenerics: [FunctionType]}}
*/
function unifyFunctionTypeCheckBindings(fnType, queryElem, whereClause, mgensIn) {
function unifyFunctionTypeCheckBindings(
fnType,
queryElem,
whereClause,
mgensIn,
unboxingDepth
) {
if (fnType.bindings.size < queryElem.bindings.size) {
return false;
}
Expand All @@ -1804,7 +1848,8 @@ function initSearch(rawSearchIndex) {
// return `false` makes unifyFunctionTypes return the full set of
// possible solutions
return false;
}
},
unboxingDepth
);
return newSolutions;
});
Expand Down Expand Up @@ -1834,9 +1879,19 @@ function initSearch(rawSearchIndex) {
* @param {QueryElement} queryElem
* @param {[FunctionType]} whereClause - Trait bounds for generic items.
* @param {Map<number,number>|null} mgens - Map functions generics to query generics.
* @param {number} unboxingDepth
* @returns {boolean}
*/
function unifyFunctionTypeIsUnboxCandidate(fnType, queryElem, whereClause, mgens) {
function unifyFunctionTypeIsUnboxCandidate(
fnType,
queryElem,
whereClause,
mgens,
unboxingDepth
) {
if (unboxingDepth >= UNBOXING_LIMIT) {
return false;
}
if (fnType.id < 0 && queryElem.id >= 0) {
if (!whereClause) {
return false;
Expand All @@ -1858,14 +1913,21 @@ function initSearch(rawSearchIndex) {
whereClause[(-fnType.id) - 1],
queryElem,
whereClause,
mgensTmp
mgensTmp,
unboxingDepth
);
} else if (fnType.generics.length > 0 || fnType.bindings.size > 0) {
const simplifiedGenerics = [
...fnType.generics,
...Array.from(fnType.bindings.values()).flat(),
];
return checkIfInList(simplifiedGenerics, queryElem, whereClause, mgens);
return checkIfInList(
simplifiedGenerics,
queryElem,
whereClause,
mgens,
unboxingDepth
);
}
return false;
}
Expand All @@ -1877,13 +1939,14 @@ function initSearch(rawSearchIndex) {
* @param {Array<FunctionType>} list
* @param {QueryElement} elem - The element from the parsed query.
* @param {[FunctionType]} whereClause - Trait bounds for generic items.
* @param {Map<number,number>|null} mgens - Map functions generics to query generics.
* @param {Map<number,number>|null} mgens - Map functions generics to query generics.
* @param {number} unboxingDepth
*
* @return {boolean} - Returns true if found, false otherwise.
*/
function checkIfInList(list, elem, whereClause, mgens) {
function checkIfInList(list, elem, whereClause, mgens, unboxingDepth) {
for (const entry of list) {
if (checkType(entry, elem, whereClause, mgens)) {
if (checkType(entry, elem, whereClause, mgens, unboxingDepth)) {
return true;
}
}
Expand All @@ -1897,14 +1960,23 @@ function initSearch(rawSearchIndex) {
* @param {Row} row
* @param {QueryElement} elem - The element from the parsed query.
* @param {[FunctionType]} whereClause - Trait bounds for generic items.
* @param {Map<number,number>|null} mgens - Map functions generics to query generics.
* @param {Map<number,number>|null} mgens - Map functions generics to query generics.
*
* @return {boolean} - Returns true if the type matches, false otherwise.
*/
function checkType(row, elem, whereClause, mgens) {
function checkType(row, elem, whereClause, mgens, unboxingDepth) {
if (unboxingDepth >= UNBOXING_LIMIT) {
return false;
}
if (row.bindings.size === 0 && elem.bindings.size === 0) {
if (elem.id < 0) {
return row.id < 0 || checkIfInList(row.generics, elem, whereClause, mgens);
if (elem.id < 0 && mgens === null) {
return row.id < 0 || checkIfInList(
row.generics,
elem,
whereClause,
mgens,
unboxingDepth + 1
);
}
if (row.id > 0 && elem.id > 0 && elem.pathWithoutLast.length === 0 &&
typePassesFilter(elem.typeFilter, row.ty) && elem.generics.length === 0 &&
Expand All @@ -1916,11 +1988,12 @@ function initSearch(rawSearchIndex) {
row.generics,
elem,
whereClause,
mgens
mgens,
unboxingDepth
);
}
}
return unifyFunctionTypes([row], [elem], whereClause, mgens);
return unifyFunctionTypes([row], [elem], whereClause, mgens, null, unboxingDepth);
}

/**
Expand Down Expand Up @@ -2135,9 +2208,9 @@ function initSearch(rawSearchIndex) {
);
if (tfpDist !== null) {
const in_args = row.type && row.type.inputs
&& checkIfInList(row.type.inputs, elem, row.type.where_clause);
&& checkIfInList(row.type.inputs, elem, row.type.where_clause, null, 0);
const returned = row.type && row.type.output
&& checkIfInList(row.type.output, elem, row.type.where_clause);
&& checkIfInList(row.type.output, elem, row.type.where_clause, null, 0);
if (in_args) {
results_in_args.max_dist = Math.max(results_in_args.max_dist || 0, tfpDist);
const maxDist = results_in_args.size < MAX_RESULTS ?
Expand Down Expand Up @@ -2223,9 +2296,12 @@ function initSearch(rawSearchIndex) {
row.type.output,
parsedQuery.returned,
row.type.where_clause,
mgens
mgens,
null,
0 // unboxing depth
);
}
},
0 // unboxing depth
)) {
return;
}
Expand Down
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