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Optimize some checkElements* implementations #3123

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merged 5 commits into from
Nov 2, 2023
Merged

Optimize some checkElements* implementations #3123

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0cc79bb
remove call through checkElementsEqualGenerated (about 10% faster)
kainino0x Oct 31, 2023
e0604f3
split checkElementsPassPredicate in half (about 40% faster??)
kainino0x Oct 31, 2023
8c1aad0
Implement checkElementsEqual/Generated directly (about 10% faster)
kainino0x Oct 31, 2023
08a2ec5
comment
kainino0x Oct 31, 2023
fa3967a
Merge branch 'main' into checkElements-optimizations
kainino0x Nov 2, 2023
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81 changes: 72 additions & 9 deletions src/webgpu/util/check_contents.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,28 @@ export function checkElementsEqual(
): ErrorWithExtra | undefined {
assert(actual.constructor === expected.constructor, 'TypedArray type mismatch');
assert(actual.length === expected.length, 'size mismatch');
return checkElementsEqualGenerated(actual, i => expected[i]);
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Hmmm... I would be interested to see if the change here where instead of creating an additional generator, we are now just comparing the arrays is the real culprit of the speed up? (Sort of the only thing that seems to really have changed functionally?)

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I measured these changes separately - see the commit messages. The largest speedup was from just splitting the check function in half.


let failedElementsFirstMaybe: number | undefined = undefined;
/** Sparse array with `true` for elements that failed. */
const failedElements: (true | undefined)[] = [];
for (let i = 0; i < actual.length; ++i) {
if (actual[i] !== expected[i]) {
failedElementsFirstMaybe ??= i;
failedElements[i] = true;
}
}

if (failedElementsFirstMaybe === undefined) {
return undefined;
}

const failedElementsFirst = failedElementsFirstMaybe;
return failCheckElements({
actual,
failedElements,
failedElementsFirst,
predicatePrinter: [{ leftHeader: 'expected ==', getValueForCell: index => expected[index] }],
});
}

/**
Expand Down Expand Up @@ -117,11 +138,29 @@ export function checkElementsEqualGenerated(
actual: TypedArrayBufferView,
generator: CheckElementsGenerator
): ErrorWithExtra | undefined {
const error = checkElementsPassPredicate(actual, (index, value) => value === generator(index), {
let failedElementsFirstMaybe: number | undefined = undefined;
/** Sparse array with `true` for elements that failed. */
const failedElements: (true | undefined)[] = [];
for (let i = 0; i < actual.length; ++i) {
if (actual[i] !== generator(i)) {
failedElementsFirstMaybe ??= i;
failedElements[i] = true;
}
}

if (failedElementsFirstMaybe === undefined) {
return undefined;
}

const failedElementsFirst = failedElementsFirstMaybe;
const error = failCheckElements({
actual,
failedElements,
failedElementsFirst,
predicatePrinter: [{ leftHeader: 'expected ==', getValueForCell: index => generator(index) }],
});
// If there was an error, extend it with additional extras.
return error ? new ErrorWithExtra(error, () => ({ generator })) : undefined;
// Add more extras to the error.
return new ErrorWithExtra(error, () => ({ generator }));
}

/**
Expand All @@ -133,14 +172,10 @@ export function checkElementsPassPredicate(
predicate: CheckElementsPredicate,
{ predicatePrinter }: { predicatePrinter?: CheckElementsSupplementalTableRows }
): ErrorWithExtra | undefined {
const size = actual.length;
const ctor = actual.constructor as TypedArrayBufferViewConstructor;
const printAsFloat = ctor === Float16Array || ctor === Float32Array || ctor === Float64Array;

let failedElementsFirstMaybe: number | undefined = undefined;
/** Sparse array with `true` for elements that failed. */
const failedElements: (true | undefined)[] = [];
for (let i = 0; i < size; ++i) {
for (let i = 0; i < actual.length; ++i) {
if (!predicate(i, actual[i])) {
failedElementsFirstMaybe ??= i;
failedElements[i] = true;
Expand All @@ -150,7 +185,35 @@ export function checkElementsPassPredicate(
if (failedElementsFirstMaybe === undefined) {
return undefined;
}

const failedElementsFirst = failedElementsFirstMaybe;
return failCheckElements({ actual, failedElements, failedElementsFirst, predicatePrinter });
}

interface CheckElementsFailOpts {
actual: TypedArrayBufferView;
failedElements: (true | undefined)[];
failedElementsFirst: number;
predicatePrinter?: CheckElementsSupplementalTableRows;
}

/**
* Implements the failure case of some checkElementsX helpers above. This allows those functions to
* implement their checks directly without too many function indirections in between.
*
* Note: Separating this into its own function significantly speeds up the non-error case in
* Chromium (though this may be V8-specific behavior).
*/
function failCheckElements({
actual,
failedElements,
failedElementsFirst,
predicatePrinter,
}: CheckElementsFailOpts): ErrorWithExtra {
const size = actual.length;
const ctor = actual.constructor as TypedArrayBufferViewConstructor;
const printAsFloat = ctor === Float16Array || ctor === Float32Array || ctor === Float64Array;

const failedElementsLast = failedElements.length - 1;

// Include one extra non-failed element at the beginning and end (if they exist), for context.
Expand Down