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Keep accumulator lanes in locals in accumulate() #14

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Keep accumulator lanes in locals in accumulate() #14

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69 changes: 61 additions & 8 deletions lib/src/util.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,13 @@ void accumulate512(

/// Dart equivalent of the xxh3_accumulate function from XXH3. This function
/// performs [accumulate512] for each of the [stripes].
@pragma('vm:prefer-inline')
///
/// The loop body is a manually inlined [accumulate512]. The eight accumulator
/// lanes stay in unboxed local variables across stripes instead of going
/// through [acc] for every lane, which a call to [accumulate512] would require
/// since it can only update the lanes in memory. Not marked prefer-inline: it
/// runs once per block, and inlining a body this size exhausts the caller's
/// inlining budget, which leaves the typed data reads un-inlined.
void accumulate(
final Uint64List acc, {
required final ByteData input,
Expand All @@ -80,15 +86,62 @@ void accumulate(
final int inputOffset = 0,
final int secretOffset = 0,
}) {
int acc0 = acc[0];
int acc1 = acc[1];
int acc2 = acc[2];
int acc3 = acc[3];
int acc4 = acc[4];
int acc5 = acc[5];
int acc6 = acc[6];
int acc7 = acc[7];
int dataVal;
int dataKey;

for (int i = 0; i < stripes; i++) {
accumulate512(
acc,
input: input,
secret: secret,
inputOffset: (i * kStripeLength) + inputOffset,
secretOffset: (i * kSecretConsumeRate) + secretOffset,
);
final inOff = inputOffset + i * kStripeLength;
final secOff = secretOffset + i * kSecretConsumeRate;
dataVal = readLE64(input, inOff + 0);
dataKey = dataVal ^ readLE64(secret, secOff + 0);
acc1 += dataVal;
acc0 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
dataVal = readLE64(input, inOff + 8);
dataKey = dataVal ^ readLE64(secret, secOff + 8);
acc0 += dataVal;
acc1 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
dataVal = readLE64(input, inOff + 16);
dataKey = dataVal ^ readLE64(secret, secOff + 16);
acc3 += dataVal;
acc2 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
dataVal = readLE64(input, inOff + 24);
dataKey = dataVal ^ readLE64(secret, secOff + 24);
acc2 += dataVal;
acc3 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
dataVal = readLE64(input, inOff + 32);
dataKey = dataVal ^ readLE64(secret, secOff + 32);
acc5 += dataVal;
acc4 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
dataVal = readLE64(input, inOff + 40);
dataKey = dataVal ^ readLE64(secret, secOff + 40);
acc4 += dataVal;
acc5 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
dataVal = readLE64(input, inOff + 48);
dataKey = dataVal ^ readLE64(secret, secOff + 48);
acc7 += dataVal;
acc6 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
dataVal = readLE64(input, inOff + 56);
dataKey = dataVal ^ readLE64(secret, secOff + 56);
acc6 += dataVal;
acc7 += (dataKey & 0xFFFFFFFF) * (dataKey >>> 32);
}

acc[0] = acc0;
acc[1] = acc1;
acc[2] = acc2;
acc[3] = acc3;
acc[4] = acc4;
acc[5] = acc5;
acc[6] = acc6;
acc[7] = acc7;
}

/// Dart equivalent of the xxh3_avalanche.
Expand Down