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Refactor RunLengthEncodedBlock hash combination logic #19759

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merged 1 commit into from
Nov 20, 2023
Merged

Refactor RunLengthEncodedBlock hash combination logic #19759

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27 changes: 12 additions & 15 deletions core/trino-main/src/main/java/io/trino/operator/FlatHashStrategyCompiler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -443,16 +443,6 @@ private static MethodDefinition generateHashBlockVectorized(ClassDefinition defi
block,
position);

BytecodeExpression setHashExpression;
if (field.index() == 0) {
// hashes[index] = hash;
setHashExpression = hashes.setElement(index, hash);
}
else {
// hashes[index] = CombineHashFunction.getHash(hashes[index], hash);
setHashExpression = hashes.setElement(index, invokeStatic(CombineHashFunction.class, "getHash", long.class, hashes.getElement(index), hash));
}

BytecodeBlock rleHandling = new BytecodeBlock()
.append(new IfStatement("hash = block.isNull(position) ? NULL_HASH_CODE : hash(block, position)")
.condition(block.invoke("isNull", boolean.class, position))
Expand All @@ -463,11 +453,18 @@ private static MethodDefinition generateHashBlockVectorized(ClassDefinition defi
rleHandling.append(invokeStatic(Arrays.class, "fill", void.class, hashes, constantInt(0), length, hash));
}
else {
rleHandling.append(new ForLoop("for (int index = 0; index < length; index++) { hashes[index] = CombineHashFunction.getHash(hashes[index], hash); }")
.initialize(index.set(constantInt(0)))
.condition(lessThan(index, length))
.update(index.increment())
.body(setHashExpression));
// CombineHashFunction.combineAllHashesWithConstant(hashes, 0, length, hash)
rleHandling.append(invokeStatic(CombineHashFunction.class, "combineAllHashesWithConstant", void.class, hashes, constantInt(0), length, hash));
}

BytecodeExpression setHashExpression;
if (field.index() == 0) {
// hashes[index] = hash;
setHashExpression = hashes.setElement(index, hash);
}
else {
// hashes[index] = CombineHashFunction.getHash(hashes[index], hash);
setHashExpression = hashes.setElement(index, invokeStatic(CombineHashFunction.class, "getHash", long.class, hashes.getElement(index), hash));
Comment on lines +460 to +467
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Why did this move?

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Previously, the same hash assignment expression was used in the RLE loop as well as the normal block loop, so it was declared above both of them (RLE loop was defined first). Now it's only used in the normal block loop, so I moved it closer to it's usage site.

}

BytecodeBlock computeHashLoop = new BytecodeBlock()
Expand Down
13 changes: 13 additions & 0 deletions core/trino-main/src/main/java/io/trino/operator/scalar/CombineHashFunction.java
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Expand Up @@ -13,10 +13,13 @@
*/
package io.trino.operator.scalar;

import io.trino.annotation.UsedByGeneratedCode;
import io.trino.spi.function.ScalarFunction;
import io.trino.spi.function.SqlType;
import io.trino.spi.type.StandardTypes;

import static java.util.Objects.checkFromToIndex;

public final class CombineHashFunction
{
private CombineHashFunction() {}
Expand All @@ -27,4 +30,14 @@ public static long getHash(@SqlType(StandardTypes.BIGINT) long previousHashValue
{
return (31 * previousHashValue + value);
}

@UsedByGeneratedCode
public static void combineAllHashesWithConstant(long[] hashes, int fromIndex, int toIndex, long value)
{
checkFromToIndex(fromIndex, toIndex, hashes.length);

for (int i = 0; i < toIndex; i++) {
hashes[i] = (31 * hashes[i]) + value;
}
}
}