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Ensure Panama float vector distance impls inlinable (#14031)
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This commit reduces the Panama vector distance float implementations to less than the maximum bytecode size of a hot method to be inlined (325).

E.g. Previously:  org.apache.lucene.internal.vectorization.PanamaVectorUtilSupport::dotProductBody (355 bytes)   failed to inline: callee is too large.

After: org.apache.lucene.internal.vectorization.PanamaVectorUtilSupport::dotProductBody (3xx bytes)   inline (hot)

This helps things a little.

Co-authored-by: Robert Muir <rmuir@apache.org>
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@ChrisHegarty @rmuir
ChrisHegarty and rmuir authored Dec 3, 2024
1 parent b2a10e3 commit 4f08f3d
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Showing 2 changed files with 50 additions and 36 deletions.
3 changes: 3 additions & 0 deletions lucene/CHANGES.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,9 @@ Optimizations
* GITHUB#14032: Speed up PostingsEnum when positions are requested.
(Adrien Grand)

* GITHUB#14031: Ensure Panama float vector distance impls inlinable.
(Robert Muir, Chris Hegarty)

Bug Fixes
---------------------
* GITHUB#13832: Fixed an issue where the DefaultPassageFormatter.format method did not format passages as intended
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83 changes: 47 additions & 36 deletions lucene/core/src/java21/org/apache/lucene/internal/vectorization/PanamaVectorUtilSupport.java
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,9 @@ final class PanamaVectorUtilSupport implements VectorUtilSupport {
}
}

// cached vector sizes for smaller method bodies
private static final int FLOAT_SPECIES_LENGTH = FLOAT_SPECIES.length();

// the way FMA should work! if available use it, otherwise fall back to mul/add
private static FloatVector fma(FloatVector a, FloatVector b, FloatVector c) {
if (Constants.HAS_FAST_VECTOR_FMA) {
Expand All @@ -99,7 +102,7 @@ public float dotProduct(float[] a, float[] b) {
float res = 0;

// if the array size is large (> 2x platform vector size), its worth the overhead to vectorize
if (a.length > 2 * FLOAT_SPECIES.length()) {
if (a.length > 2 * FLOAT_SPECIES_LENGTH) {
i += FLOAT_SPECIES.loopBound(a.length);
res += dotProductBody(a, b, i);
}
Expand All @@ -120,30 +123,33 @@ private float dotProductBody(float[] a, float[] b, int limit) {
FloatVector acc2 = FloatVector.zero(FLOAT_SPECIES);
FloatVector acc3 = FloatVector.zero(FLOAT_SPECIES);
FloatVector acc4 = FloatVector.zero(FLOAT_SPECIES);
int unrolledLimit = limit - 3 * FLOAT_SPECIES.length();
for (; i < unrolledLimit; i += 4 * FLOAT_SPECIES.length()) {
final int unrolledLimit = limit - 3 * FLOAT_SPECIES_LENGTH;
for (; i < unrolledLimit; i += 4 * FLOAT_SPECIES_LENGTH) {
// one
FloatVector va = FloatVector.fromArray(FLOAT_SPECIES, a, i);
FloatVector vb = FloatVector.fromArray(FLOAT_SPECIES, b, i);
acc1 = fma(va, vb, acc1);

// two
FloatVector vc = FloatVector.fromArray(FLOAT_SPECIES, a, i + FLOAT_SPECIES.length());
FloatVector vd = FloatVector.fromArray(FLOAT_SPECIES, b, i + FLOAT_SPECIES.length());
final int i2 = i + FLOAT_SPECIES_LENGTH;
FloatVector vc = FloatVector.fromArray(FLOAT_SPECIES, a, i2);
FloatVector vd = FloatVector.fromArray(FLOAT_SPECIES, b, i2);
acc2 = fma(vc, vd, acc2);

// three
FloatVector ve = FloatVector.fromArray(FLOAT_SPECIES, a, i + 2 * FLOAT_SPECIES.length());
FloatVector vf = FloatVector.fromArray(FLOAT_SPECIES, b, i + 2 * FLOAT_SPECIES.length());
final int i3 = i2 + FLOAT_SPECIES_LENGTH;
FloatVector ve = FloatVector.fromArray(FLOAT_SPECIES, a, i3);
FloatVector vf = FloatVector.fromArray(FLOAT_SPECIES, b, i3);
acc3 = fma(ve, vf, acc3);

// four
FloatVector vg = FloatVector.fromArray(FLOAT_SPECIES, a, i + 3 * FLOAT_SPECIES.length());
FloatVector vh = FloatVector.fromArray(FLOAT_SPECIES, b, i + 3 * FLOAT_SPECIES.length());
final int i4 = i3 + FLOAT_SPECIES_LENGTH;
FloatVector vg = FloatVector.fromArray(FLOAT_SPECIES, a, i4);
FloatVector vh = FloatVector.fromArray(FLOAT_SPECIES, b, i4);
acc4 = fma(vg, vh, acc4);
}
// vector tail: less scalar computations for unaligned sizes, esp with big vector sizes
for (; i < limit; i += FLOAT_SPECIES.length()) {
for (; i < limit; i += FLOAT_SPECIES_LENGTH) {
FloatVector va = FloatVector.fromArray(FLOAT_SPECIES, a, i);
FloatVector vb = FloatVector.fromArray(FLOAT_SPECIES, b, i);
acc1 = fma(va, vb, acc1);
Expand All @@ -162,7 +168,7 @@ public float cosine(float[] a, float[] b) {
float norm2 = 0;

// if the array size is large (> 2x platform vector size), its worth the overhead to vectorize
if (a.length > 2 * FLOAT_SPECIES.length()) {
if (a.length > 2 * FLOAT_SPECIES_LENGTH) {
i += FLOAT_SPECIES.loopBound(a.length);
float[] ret = cosineBody(a, b, i);
sum += ret[0];
Expand Down Expand Up @@ -190,8 +196,8 @@ private float[] cosineBody(float[] a, float[] b, int limit) {
FloatVector norm1_2 = FloatVector.zero(FLOAT_SPECIES);
FloatVector norm2_1 = FloatVector.zero(FLOAT_SPECIES);
FloatVector norm2_2 = FloatVector.zero(FLOAT_SPECIES);
int unrolledLimit = limit - FLOAT_SPECIES.length();
for (; i < unrolledLimit; i += 2 * FLOAT_SPECIES.length()) {
final int unrolledLimit = limit - FLOAT_SPECIES_LENGTH;
for (; i < unrolledLimit; i += 2 * FLOAT_SPECIES_LENGTH) {
// one
FloatVector va = FloatVector.fromArray(FLOAT_SPECIES, a, i);
FloatVector vb = FloatVector.fromArray(FLOAT_SPECIES, b, i);
Expand All @@ -200,14 +206,15 @@ private float[] cosineBody(float[] a, float[] b, int limit) {
norm2_1 = fma(vb, vb, norm2_1);

// two
FloatVector vc = FloatVector.fromArray(FLOAT_SPECIES, a, i + FLOAT_SPECIES.length());
FloatVector vd = FloatVector.fromArray(FLOAT_SPECIES, b, i + FLOAT_SPECIES.length());
final int i2 = i + FLOAT_SPECIES_LENGTH;
FloatVector vc = FloatVector.fromArray(FLOAT_SPECIES, a, i2);
FloatVector vd = FloatVector.fromArray(FLOAT_SPECIES, b, i2);
sum2 = fma(vc, vd, sum2);
norm1_2 = fma(vc, vc, norm1_2);
norm2_2 = fma(vd, vd, norm2_2);
}
// vector tail: less scalar computations for unaligned sizes, esp with big vector sizes
for (; i < limit; i += FLOAT_SPECIES.length()) {
for (; i < limit; i += FLOAT_SPECIES_LENGTH) {
FloatVector va = FloatVector.fromArray(FLOAT_SPECIES, a, i);
FloatVector vb = FloatVector.fromArray(FLOAT_SPECIES, b, i);
sum1 = fma(va, vb, sum1);
Expand All @@ -227,7 +234,7 @@ public float squareDistance(float[] a, float[] b) {
float res = 0;

// if the array size is large (> 2x platform vector size), its worth the overhead to vectorize
if (a.length > 2 * FLOAT_SPECIES.length()) {
if (a.length > 2 * FLOAT_SPECIES_LENGTH) {
i += FLOAT_SPECIES.loopBound(a.length);
res += squareDistanceBody(a, b, i);
}
Expand All @@ -240,6 +247,12 @@ public float squareDistance(float[] a, float[] b) {
return res;
}

/** helper: returns fma(a.sub(b), a.sub(b), c) */
private static FloatVector square(FloatVector a, FloatVector b, FloatVector c) {
FloatVector diff = a.sub(b);
return fma(diff, diff, c);
}

/** vectorized square distance body */
private float squareDistanceBody(float[] a, float[] b, int limit) {
int i = 0;
Expand All @@ -249,38 +262,36 @@ private float squareDistanceBody(float[] a, float[] b, int limit) {
FloatVector acc2 = FloatVector.zero(FLOAT_SPECIES);
FloatVector acc3 = FloatVector.zero(FLOAT_SPECIES);
FloatVector acc4 = FloatVector.zero(FLOAT_SPECIES);
int unrolledLimit = limit - 3 * FLOAT_SPECIES.length();
for (; i < unrolledLimit; i += 4 * FLOAT_SPECIES.length()) {
final int unrolledLimit = limit - 3 * FLOAT_SPECIES_LENGTH;
for (; i < unrolledLimit; i += 4 * FLOAT_SPECIES_LENGTH) {
// one
FloatVector va = FloatVector.fromArray(FLOAT_SPECIES, a, i);
FloatVector vb = FloatVector.fromArray(FLOAT_SPECIES, b, i);
FloatVector diff1 = va.sub(vb);
acc1 = fma(diff1, diff1, acc1);
acc1 = square(va, vb, acc1);

// two
FloatVector vc = FloatVector.fromArray(FLOAT_SPECIES, a, i + FLOAT_SPECIES.length());
FloatVector vd = FloatVector.fromArray(FLOAT_SPECIES, b, i + FLOAT_SPECIES.length());
FloatVector diff2 = vc.sub(vd);
acc2 = fma(diff2, diff2, acc2);
final int i2 = i + FLOAT_SPECIES_LENGTH;
FloatVector vc = FloatVector.fromArray(FLOAT_SPECIES, a, i2);
FloatVector vd = FloatVector.fromArray(FLOAT_SPECIES, b, i2);
acc2 = square(vc, vd, acc2);

// three
FloatVector ve = FloatVector.fromArray(FLOAT_SPECIES, a, i + 2 * FLOAT_SPECIES.length());
FloatVector vf = FloatVector.fromArray(FLOAT_SPECIES, b, i + 2 * FLOAT_SPECIES.length());
FloatVector diff3 = ve.sub(vf);
acc3 = fma(diff3, diff3, acc3);
final int i3 = i2 + FLOAT_SPECIES_LENGTH;
FloatVector ve = FloatVector.fromArray(FLOAT_SPECIES, a, i3);
FloatVector vf = FloatVector.fromArray(FLOAT_SPECIES, b, i3);
acc3 = square(ve, vf, acc3);

// four
FloatVector vg = FloatVector.fromArray(FLOAT_SPECIES, a, i + 3 * FLOAT_SPECIES.length());
FloatVector vh = FloatVector.fromArray(FLOAT_SPECIES, b, i + 3 * FLOAT_SPECIES.length());
FloatVector diff4 = vg.sub(vh);
acc4 = fma(diff4, diff4, acc4);
final int i4 = i3 + FLOAT_SPECIES_LENGTH;
FloatVector vg = FloatVector.fromArray(FLOAT_SPECIES, a, i4);
FloatVector vh = FloatVector.fromArray(FLOAT_SPECIES, b, i4);
acc4 = square(vg, vh, acc4);
}
// vector tail: less scalar computations for unaligned sizes, esp with big vector sizes
for (; i < limit; i += FLOAT_SPECIES.length()) {
for (; i < limit; i += FLOAT_SPECIES_LENGTH) {
FloatVector va = FloatVector.fromArray(FLOAT_SPECIES, a, i);
FloatVector vb = FloatVector.fromArray(FLOAT_SPECIES, b, i);
FloatVector diff = va.sub(vb);
acc1 = fma(diff, diff, acc1);
acc1 = square(va, vb, acc1);
}
// reduce
FloatVector res1 = acc1.add(acc2);
Expand Down

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