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Handle many missing (step 2)

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Ben Edgington 2021-03-03 11:48:56 +00:00
parent 80af76581d
commit 8fbea3b3ef
6 changed files with 102 additions and 97 deletions
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14
src/c_kzg_util.c
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@ -122,3 +122,17 @@ C_KZG_RET new_g1_array_2(g1_t ***x, size_t n) {
C_KZG_RET new_g2_array(g2_t **x, size_t n) {
return c_kzg_malloc((void **)x, n * sizeof **x);
}
/**
* Allocate memory for an array of polynomial headers.
*
* @remark Free the space later using `free()`, after freeing the individual polynomials via #free_poly.
*
* @param[out] x Pointer to the allocated space
* @param[in] n The number of polynomial headers to be allocated
* @retval C_CZK_OK All is well
* @retval C_CZK_MALLOC Memory allocation failed
*/
C_KZG_RET new_poly_array(poly **x, size_t n) {
return c_kzg_malloc((void **)x, n * sizeof **x);
}

2
src/c_kzg_util.h
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@ -18,6 +18,7 @@
#include <stdlib.h> // free()
#include "c_kzg.h"
#include "poly.h"
C_KZG_RET c_kzg_malloc(void **p, size_t n);
C_KZG_RET new_uint64_array(uint64_t **x, size_t n);
@ -26,3 +27,4 @@ C_KZG_RET new_fr_array_2(fr_t ***x, size_t n);
C_KZG_RET new_g1_array(g1_t **x, size_t n);
C_KZG_RET new_g1_array_2(g1_t ***x, size_t n);
C_KZG_RET new_g2_array(g2_t **x, size_t n);
C_KZG_RET new_poly_array(poly **x, size_t n);

5
src/poly.h
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@ -16,6 +16,9 @@
/** @file poly.h */
#ifndef POLY_H
#define POLY_H
#include "c_kzg.h"
/**
@ -33,3 +36,5 @@ C_KZG_RET new_poly_long_div(poly *out, const poly *dividend, const poly *divisor
C_KZG_RET new_poly(poly *out, uint64_t length);
C_KZG_RET new_poly_with_coeffs(poly *out, const fr_t *coeffs, uint64_t length);
void free_poly(poly *p);
#endif // POLY_H

114
src/zero_poly.c
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@ -39,6 +39,8 @@
* @param[in] fs The FFT settings previously initialised with #new_fft_settings
* @retval C_CZK_OK All is well
* @retval C_CZK_BADARGS Invalid parameters were supplied
*
* @todo rework to pass polynomials in and out
*/
C_KZG_RET do_zero_poly_mul_leaf(fr_t *dst, uint64_t len_dst, const uint64_t *indices, uint64_t len_indices,
uint64_t stride, const FFTSettings *fs) {
@ -106,48 +108,38 @@ C_KZG_RET pad_p(fr_t *out, uint64_t out_len, const fr_t *p, uint64_t p_len) {
* @retval C_CZK_OK All is well
* @retval C_CZK_BADARGS Invalid parameters were supplied
* @retval C_CZK_ERROR An internal error occurred
*
* @todo Check if we can make `ps` a proper 2d array rather than an array of pointers to arrays.
*/
C_KZG_RET reduce_leaves(fr_t *dst, uint64_t len_dst, fr_t *scratch, uint64_t len_scratch, blst_fr **ps, uint64_t len_ps,
const uint64_t *len_p, const FFTSettings *fs) {
CHECK(is_power_of_two(len_dst));
CHECK(len_scratch >= 3 * len_dst);
CHECK(len_ps > 0);
// The degree of the output is the sum of the degrees of the input polynomials.
// TODO A more relaxed check should be ok: `len_ps * (len_p[0] - 1) < len_dst` (or even sum up the lengths)
// CHECK(len_ps * len_p[0] <= len_dst);
uint64_t total_length = 0;
for (int i = 0; i < len_ps; i++) {
total_length += len_p[i] - 1;
C_KZG_RET reduce_leaves(poly *out, uint64_t len_out, fr_t *scratch, uint64_t len_scratch, const poly *leaves,
uint64_t leaf_count, const FFTSettings *fs) {
CHECK(is_power_of_two(len_out));
CHECK(len_scratch >= 3 * len_out);
CHECK(leaf_count > 0);
// The degree of the output polynomial is the sum of the degrees of the input polynomials.
uint64_t out_degree = 0;
for (int i = 0; i < leaf_count; i++) {
out_degree += leaves[i].length - 1;
}
if (total_length + 1 > len_dst) {
printf("Total length: %lu, len dest: %lu\n", total_length, len_dst);
printf("\n");
for (int i = 0; i < len_ps; i++) {
printf("Len %d = %lu\n", i, len_p[i]);
}
}
CHECK(total_length + 1 <= len_dst);
CHECK(out_degree + 1 <= len_out);
// Split `scratch` up into three equally sized working arrays
fr_t *p_padded = scratch;
fr_t *mul_eval_ps = scratch + len_dst;
fr_t *p_eval = scratch + 2 * len_dst;
fr_t *mul_eval_ps = scratch + len_out;
fr_t *p_eval = scratch + 2 * len_out;
// Do the last leaf first: it may be shorter than the others and the padding can remain in place for the rest.
TRY(pad_p(p_padded, len_dst, ps[len_ps - 1], len_p[len_ps - 1]));
TRY(fft_fr(mul_eval_ps, p_padded, false, len_dst, fs));
TRY(pad_p(p_padded, len_out, leaves[leaf_count - 1].coeffs, leaves[leaf_count - 1].length));
TRY(fft_fr(mul_eval_ps, p_padded, false, len_out, fs));
for (uint64_t i = 0; i < len_ps - 1; i++) {
TRY(pad_p(p_padded, len_p[i], ps[i], len_p[i]));
TRY(fft_fr(p_eval, p_padded, false, len_dst, fs));
for (uint64_t j = 0; j < len_dst; j++) {
for (uint64_t i = 0; i < leaf_count - 1; i++) {
TRY(pad_p(p_padded, leaves[i].length, leaves[i].coeffs, leaves[i].length));
TRY(fft_fr(p_eval, p_padded, false, len_out, fs));
for (uint64_t j = 0; j < len_out; j++) {
fr_mul(&mul_eval_ps[j], &mul_eval_ps[j], &p_eval[j]);
}
}
TRY(fft_fr(dst, mul_eval_ps, true, len_dst, fs));
TRY(fft_fr(out->coeffs, mul_eval_ps, true, len_out, fs));
out->length = out_degree + 1;
return C_KZG_OK;
}
@ -163,7 +155,8 @@ C_KZG_RET reduce_leaves(fr_t *dst, uint64_t len_dst, fr_t *scratch, uint64_t len
*
* @remark Fails for very high numbers of missing indices. For example, with `fs.max_width = 256` and `length = 256`,
* this will fail for len_missing = 253 or more. In this case, `length` (and maybe `fs.max_width`) needs to be doubled.
* But this failure is probably OK for our use case.
* But this failure is probably OK for our use case. TODO: no longer true. But it does fail if the whole domain is
* missing. We know the answer for that case anyway.
*
* @remark Note that @p zero_poly is used as workspace during calculation.
*
@ -192,7 +185,7 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
}
return C_KZG_OK;
}
CHECK(len_missing < length); // The output would be larger than length otherwise
CHECK(len_missing < length); // The output would be larger than length otherwise, (TODO describe in docs)
CHECK(length <= fs->max_width);
CHECK(is_power_of_two(length));
@ -208,8 +201,8 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
TRY(fft_fr(zero_eval, zero_poly, false, length, fs));
*zero_poly_len = len_missing + 1;
} else {
// Work space for reducing the leaves - `zero_poly` is large enough due to the above check, so use that.
// fr_t *work = zero_poly;
// Work space for building and reducing the leaves
fr_t *work;
TRY(new_fr_array(&work, next_power_of_two(leaf_count * per_leaf_poly)));
@ -217,75 +210,62 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
// Just allocate pointers here since we're re-using `work` for the leaf processing
// Combining leaves can be done mostly in-place, using a scratchpad.
fr_t **leaves, *scratch, *reduced;
uint64_t *leaf_lengths;
TRY(new_fr_array_2(&leaves, leaf_count));
TRY(new_uint64_array(&leaf_lengths, leaf_count));
poly *leaves;
TRY(new_poly_array(&leaves, leaf_count));
uint64_t offset = 0, out_offset = 0, max = len_missing;
for (int i = 0; i < leaf_count; i++) {
uint64_t end = offset + per_leaf;
if (end > max) end = max;
leaves[i] = &work[out_offset];
leaf_lengths[i] = per_leaf_poly;
TRY(do_zero_poly_mul_leaf(leaves[i], per_leaf_poly, &missing_indices[offset], end - offset, domain_stride,
fs));
leaves[i].coeffs = &work[out_offset];
leaves[i].length = per_leaf_poly;
TRY(do_zero_poly_mul_leaf(leaves[i].coeffs, per_leaf_poly, &missing_indices[offset], end - offset,
domain_stride, fs));
offset += per_leaf;
out_offset += per_leaf_poly;
}
// Adjust the length of the last leaf
// leaf_lengths[leaf_count - 1] = 1 + len_missing % per_leaf;
leaf_lengths[leaf_count - 1] = 1 + len_missing - (leaf_count - 1) * per_leaf;
leaves[leaf_count - 1].length = 1 + len_missing - (leaf_count - 1) * per_leaf;
// Now reduce all the leaves to a single poly
int reduction_factor = 4; // must be a power of 2 (why?)
int reduction_factor = 4; // must be a power of 2 (TODO why?)
fr_t *scratch;
TRY(new_fr_array(&scratch, n * 3));
while (leaf_count > 1) {
uint64_t reduced_count = (leaf_count + reduction_factor - 1) / reduction_factor;
// All the leaves are the same length, except possibly the last leaf, but that's ok.
uint64_t leaf_size = next_power_of_two(leaf_lengths[0]);
uint64_t leaf_size = next_power_of_two(leaves[0].length);
for (uint64_t i = 0; i < reduced_count; i++) {
uint64_t start = i * reduction_factor;
uint64_t end = start + reduction_factor;
// E.g. if we *started* with 2 leaves, we won't have more than that since it is already a power
// of 2. If we had 3, it would have been rounded up anyway. So just pick the end
uint64_t out_end = end * leaf_size;
if (out_end > n) {
out_end = n;
}
reduced = work + start * leaf_size;
if (out_end > n) out_end = n;
fr_t *reduced = work + start * leaf_size;
uint64_t reduced_len = out_end - start * leaf_size;
if (reduced_len > length) reduced_len = length;
if (end > leaf_count) {
end = leaf_count;
}
if (end > leaf_count) end = leaf_count;
uint64_t leaves_slice_len = end - start;
if (leaves_slice_len > 1) {
TRY(reduce_leaves(reduced, reduced_len, scratch, n * 3, &leaves[start], leaves_slice_len,
&leaf_lengths[start], fs));
// leaf_lengths[i] = reduced_len;
// } else {
// leaf_lengths[i] = leaf_lengths[start];
leaves[i].coeffs = reduced;
TRY(reduce_leaves(&leaves[i], reduced_len, scratch, n * 3, &leaves[start], leaves_slice_len, fs));
} else {
leaves[i].coeffs = reduced;
leaves[i].length = leaves[start].length;
}
leaves[i] = reduced;
uint64_t total_length = 0;
for (int j = start; j < end; j++) {
total_length += leaf_lengths[j] - 1;
}
leaf_lengths[i] = total_length + 1;
}
leaf_count = reduced_count;
}
*zero_poly_len = leaf_lengths[0];
*zero_poly_len = leaves[0].length;
for (uint64_t i = 0; i < length; i++) {
zero_poly[i] = i < *zero_poly_len ? leaves[0][i] : fr_zero;
zero_poly[i] = i < *zero_poly_len ? leaves[0].coeffs[i] : fr_zero;
}
TRY(fft_fr(zero_eval, zero_poly, false, length, fs));
free(work);
free(leaves);
free(leaf_lengths);
free(scratch);
}

5
src/zero_poly.h
View File

@ -22,11 +22,12 @@
#include "c_kzg.h"
#include "fft_common.h"
#include "poly.h"
C_KZG_RET do_zero_poly_mul_leaf(fr_t *dst, uint64_t len_dst, const uint64_t *indices, uint64_t len_indices,
uint64_t stride, const FFTSettings *fs);
C_KZG_RET reduce_leaves(fr_t *dst, uint64_t len_dst, fr_t *scratch, uint64_t len_scratch, blst_fr **ps, uint64_t len_ps,
const uint64_t *len_p, const FFTSettings *fs);
C_KZG_RET reduce_leaves(poly *dst, uint64_t len_dst, fr_t *scratch, uint64_t len_scratch, const poly *leaves,
uint64_t leaf_count, const FFTSettings *fs);
C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, uint64_t *zero_poly_len, uint64_t length,
const uint64_t *missing_indices, uint64_t len_missing,
const FFTSettings *fs);

59
src/zero_poly_test.c
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@ -18,7 +18,6 @@
#include "c_kzg_util.h"
#include "test_util.h"
#include "zero_poly.h"
#include "poly.h"
#include "fft_fr.h"
#include "debug_util.h"
@ -64,22 +63,23 @@ uint64_t expected_poly_u64[16][4] = {
void test_reduce_leaves(void) {
FFTSettings fs;
TEST_CHECK(C_KZG_OK == new_fft_settings(&fs, 4));
fr_t from_tree_reduction[16], from_direct[9], scratch[48];
fr_t from_tree_reduction_coeffs[16], from_direct[9], scratch[48];
poly from_tree_reduction;
from_tree_reduction.coeffs = from_tree_reduction_coeffs;
// Via reduce_leaves
fr_t *leaves[4];
poly leaves[4];
fr_t leaf0[3], leaf1[3], leaf2[3], leaf3[3];
leaves[0] = leaf0;
leaves[1] = leaf1;
leaves[2] = leaf2;
leaves[3] = leaf3;
uint64_t leaf_lengths[] = {3, 3, 3, 3};
leaves[0].coeffs = leaf0, leaves[0].length = 3;
leaves[1].coeffs = leaf1, leaves[1].length = 3;
leaves[2].coeffs = leaf2, leaves[2].length = 3;
leaves[3].coeffs = leaf3, leaves[3].length = 3;
const uint64_t leaf_indices[4][2] = {{1, 3}, {7, 8}, {9, 10}, {12, 13}};
for (int i = 0; i < 4; i++) {
TEST_CHECK(C_KZG_OK == do_zero_poly_mul_leaf(leaves[i], 3, leaf_indices[i], 2, 1, &fs));
TEST_CHECK(C_KZG_OK == do_zero_poly_mul_leaf(leaves[i].coeffs, 3, leaf_indices[i], 2, 1, &fs));
}
TEST_CHECK(C_KZG_OK == reduce_leaves(from_tree_reduction, 16, scratch, 48, leaves, 4, leaf_lengths, &fs));
TEST_CHECK(C_KZG_OK == reduce_leaves(&from_tree_reduction, 16, scratch, 48, leaves, 4, &fs));
// Direct
uint64_t indices[] = {1, 3, 7, 8, 9, 10, 12, 13};
@ -87,7 +87,7 @@ void test_reduce_leaves(void) {
// Compare
for (int i = 0; i < 9; i++) {
TEST_CHECK(fr_equal(&from_tree_reduction[i], &from_direct[i]));
TEST_CHECK(fr_equal(&from_tree_reduction.coeffs[i], &from_direct[i]));
}
free_fft_settings(&fs);
@ -111,32 +111,32 @@ void reduce_leaves_random(void) {
shuffle(missing, point_count);
// Build the leaves
fr_t **leaves;
poly *leaves;
const int points_per_leaf = 63;
uint64_t indices[points_per_leaf];
uint64_t leaf_count = (missing_count + points_per_leaf - 1) / points_per_leaf;
uint64_t *leaf_lengths;
TEST_CHECK(C_KZG_OK == new_uint64_array(&leaf_lengths, leaf_count));
TEST_CHECK(C_KZG_OK == new_fr_array_2(&leaves, leaf_count));
TEST_CHECK(C_KZG_OK == new_poly_array(&leaves, leaf_count));
for (uint64_t i = 0; i < leaf_count; i++) {
uint64_t start = i * points_per_leaf;
uint64_t end = start + points_per_leaf;
if (end > missing_count) end = missing_count;
uint64_t leaf_size = end - start;
TEST_CHECK(C_KZG_OK == new_fr_array(&leaves[i], leaf_size + 1));
TEST_CHECK(C_KZG_OK == new_fr_array(&leaves[i].coeffs, leaf_size + 1));
for (int j = 0; j < leaf_size; j++) {
indices[j] = missing[i * points_per_leaf + j];
}
leaf_lengths[i] = leaf_size + 1;
TEST_CHECK(C_KZG_OK == do_zero_poly_mul_leaf(leaves[i], leaf_lengths[i], indices, leaf_size, 1, &fs));
leaves[i].length = leaf_size + 1;
TEST_CHECK(C_KZG_OK ==
do_zero_poly_mul_leaf(leaves[i].coeffs, leaves[i].length, indices, leaf_size, 1, &fs));
}
// From tree reduction
fr_t *from_tree_reduction, *scratch;
TEST_CHECK(C_KZG_OK == new_fr_array(&from_tree_reduction, point_count));
poly from_tree_reduction;
TEST_CHECK(C_KZG_OK == new_poly(&from_tree_reduction, point_count));
fr_t *scratch;
TEST_CHECK(C_KZG_OK == new_fr_array(&scratch, point_count * 3));
TEST_CHECK(C_KZG_OK == reduce_leaves(from_tree_reduction, point_count, scratch, point_count * 3, leaves,
leaf_count, leaf_lengths, &fs));
TEST_CHECK(C_KZG_OK == reduce_leaves(&from_tree_reduction, point_count, scratch, point_count * 3, leaves,
leaf_count, &fs));
// From direct
fr_t *from_direct;
@ -145,17 +145,16 @@ void reduce_leaves_random(void) {
fs.max_width / point_count, &fs));
for (uint64_t i = 0; i < missing_count + 1; i++) {
TEST_CHECK(fr_equal(&from_tree_reduction[i], &from_direct[i]));
TEST_CHECK(fr_equal(&from_tree_reduction.coeffs[i], &from_direct[i]));
}
free(from_tree_reduction);
free_poly(&from_tree_reduction);
free(from_direct);
free(scratch);
for (uint64_t i = 0; i < leaf_count; i++) {
free(leaves[i]);
free_poly(&leaves[i]);
}
free(leaves);
free(leaf_lengths);
free(missing);
free_fft_settings(&fs);
}
@ -274,6 +273,9 @@ void zero_poly_random(void) {
TEST_CHECK(C_KZG_OK == zero_polynomial_via_multiplication(zero_eval, zero_poly, &zero_poly_len,
fs.max_width, missing, len_missing, &fs));
TEST_CHECK(len_missing + 1 == zero_poly_len);
TEST_MSG("ZeroPolyLen: expected %d, got %lu", len_missing + 1, zero_poly_len);
poly p;
p.length = zero_poly_len;
p.coeffs = zero_poly;
@ -282,9 +284,10 @@ void zero_poly_random(void) {
fr_t out;
eval_poly(&out, &p, &fs.expanded_roots_of_unity[missing[i]]);
ret = TEST_CHECK(fr_is_zero(&out));
TEST_MSG("Failed for scale = %d, len_missing = %d, zero_poly_len = %lu", scale, len_missing,
zero_poly_len);
TEST_MSG("Failed for missing[%d] = %lu", i, missing[i]);
}
TEST_MSG("Failed for scale = %d, len_missing = %d, zero_poly_len = %lu", scale, len_missing, zero_poly_len);
fr_t *zero_eval_fft;
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_eval_fft, fs.max_width));
@ -373,7 +376,7 @@ void zero_poly_252(void) {
TEST_CHECK(C_KZG_OK == zero_polynomial_via_multiplication(zero_eval, zero_poly, &zero_poly_len, fs.max_width,
missing, len_missing, &fs));
TEST_CHECK(zero_poly_len == 253);
TEST_CHECK(253 == zero_poly_len);
TEST_MSG("ZeroPolyLen: expected %d, got %lu", len_missing + 1, zero_poly_len);
poly p;