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Mujoco_WASM/src/engine/engine_util_sparse.c
T
Yuval Tassa 7eb8231fda Represent only the lower triangle in Newton solver's reduced dof-dof matrix.
PiperOrigin-RevId: 712488529
Change-Id: Iad91c72654376539791d7856765a0d0ac9088251
2025-01-06 04:58:55 -08:00

915 lines
22 KiB
C

// Copyright 2021 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "engine/engine_util_sparse.h"
#include "engine/engine_util_sparse_avx.h" // IWYU pragma: keep
#include <string.h>
#include <mujoco/mjdata.h>
#include <mujoco/mjsan.h> // IWYU pragma: keep
#include <mujoco/mjtnum.h>
#include "engine/engine_io.h"
#include "engine/engine_util_blas.h"
#include "engine/engine_util_misc.h"
//------------------------------ sparse operations -------------------------------------------------
// dot-productX3, first vector is sparse; supernode of size 3
void mju_dotSparseX3(mjtNum* res0, mjtNum* res1, mjtNum* res2,
const mjtNum* vec10, const mjtNum* vec11, const mjtNum* vec12,
const mjtNum* vec2, int nnz1, const int* ind1) {
#ifdef mjUSEAVX
mju_dotSparseX3_avx(res0, res1, res2, vec10, vec11, vec12, vec2, nnz1, ind1);
#else
int i = 0;
// clear result
mjtNum RES0 = 0;
mjtNum RES1 = 0;
mjtNum RES2 = 0;
for (; i < nnz1; i++) {
mjtNum v2 = vec2[ind1[i]];
RES0 += vec10[i] * v2;
RES1 += vec11[i] * v2;
RES2 += vec12[i] * v2;
}
// copy result
*res0 = RES0;
*res1 = RES1;
*res2 = RES2;
#endif // mjUSEAVX
}
// dot-product, both vectors are sparse
// flg_unc2: is vec2 memory layout uncompressed
mjtNum mju_dotSparse2(const mjtNum* vec1, const mjtNum* vec2, int nnz1, const int* ind1, int nnz2,
const int* ind2, int flg_unc2) {
int i1 = 0, i2 = 0;
mjtNum res = 0;
// check for empty array
if (!nnz1 || !nnz2) {
return 0;
}
while (i1 < nnz1 && i2 < nnz2) {
// get current indices
int adr1 = ind1[i1], adr2 = ind2[i2];
// match: accumulate result, advance both
if (adr1 == adr2) {
if (flg_unc2) {
res += vec1[i1++] * vec2[adr2];
i2++;
} else {
res += vec1[i1++] * vec2[i2++];
}
}
// otherwise advance smaller
else if (adr1 < adr2) {
i1++;
} else {
i2++;
}
}
return res;
}
// convert matrix from dense to sparse
// nnz is size of res and colind, return 1 if too small, 0 otherwise
int mju_dense2sparse(mjtNum* res, const mjtNum* mat, int nr, int nc,
int* rownnz, int* rowadr, int* colind, int nnz) {
if (nnz <= 0) {
return 1;
}
int adr = 0;
// find non-zeros and construct sparse
for (int r=0; r < nr; r++) {
// init row
rownnz[r] = 0;
rowadr[r] = adr;
// find non-zeros
for (int c=0; c < nc; c++) {
if (mat[r*nc+c]) {
// check for out of bounds
if (adr >= nnz) {
return 1;
}
// record index and count
colind[adr] = c;
rownnz[r]++;
// copy element
res[adr++] = mat[r*nc+c];
}
}
}
return 0;
}
// convert matrix from sparse to dense
void mju_sparse2dense(mjtNum* res, const mjtNum* mat, int nr, int nc,
const int* rownnz, const int* rowadr, const int* colind) {
// clear
mju_zero(res, nr*nc);
// copy non-zeros
for (int r=0; r < nr; r++) {
for (int i=0; i < rownnz[r]; i++) {
res[r*nc + colind[rowadr[r]+i]] = mat[rowadr[r]+i];
}
}
}
// multiply sparse matrix and dense vector: res = mat * vec.
void mju_mulMatVecSparse(mjtNum* res, const mjtNum* mat, const mjtNum* vec,
int nr, const int* rownnz, const int* rowadr,
const int* colind, const int* rowsuper) {
#ifdef mjUSEAVX
mju_mulMatVecSparse_avx(res, mat, vec, nr, rownnz, rowadr, colind, rowsuper);
#else
// regular sparse dot-product
for (int r=0; r < nr; r++) {
res[r] = mju_dotSparse(mat+rowadr[r], vec, rownnz[r], colind+rowadr[r], /*flg_unc1=*/0);
}
#endif // mjUSEAVX
}
// multiply transposed sparse matrix and dense vector: res = mat' * vec.
void mju_mulMatTVecSparse(mjtNum* res, const mjtNum* mat, const mjtNum* vec, int nr, int nc,
const int* rownnz, const int* rowadr, const int* colind) {
// clear res
mju_zero(res, nc);
for (int i=0; i < nr; i++) {
mjtNum scl = vec[i];
// skip if 0
if (!scl) continue;
// add row scaled by the corresponding vector element
int nnz = rownnz[i];
int adr = rowadr[i];
const int* ind = colind + adr;
const mjtNum* row = mat + adr;
for (int j=0; j < nnz; j++) {
res[ind[j]] += row[j] * scl;
}
}
}
// res = res*scl1 + vec*scl2
static void mju_addToSclScl(mjtNum* res, const mjtNum* vec, mjtNum scl1, mjtNum scl2, int n) {
#ifdef mjUSEAVX
mju_addToSclScl_avx(res, vec, scl1, scl2, n);
#else
for (int i=0; i < n; i++) {
res[i] = res[i]*scl1 + vec[i]*scl2;
}
#endif // mjUSEAVX
}
// return 1 if vec1==vec2, 0 otherwise
static int mju_compare(const int* vec1, const int* vec2, int n) {
#ifdef mjUSEAVX
return mju_compare_avx(vec1, vec2, n);
#else
return !memcmp(vec1, vec2, n*sizeof(int));
#endif // mjUSEAVX
}
// count the number of non-zeros in the sum of two sparse vectors
int mju_combineSparseCount(int a_nnz, int b_nnz, const int* a_ind, const int* b_ind) {
int a = 0, b = 0, c_nnz = 0;
// count c_nnz: nonzero indices common to both a and b
while (a < a_nnz && b < b_nnz) {
// common index, increment everything
if (a_ind[a] == b_ind[b]) {
c_nnz++;
a++;
b++;
}
// update smallest index
else if (a_ind[a] < b_ind[b]) {
a++;
} else {
b++;
}
}
// union minus the intersection
return a_nnz + b_nnz - c_nnz;
}
// combine two sparse vectors: dst = a*dst + b*src, return nnz of result
int mju_combineSparse(mjtNum* dst, const mjtNum* src, mjtNum a, mjtNum b,
int dst_nnz, int src_nnz, int* dst_ind, const int* src_ind,
mjtNum* buf, int* buf_ind) {
// check for identical pattern
if (dst_nnz == src_nnz) {
if (mju_compare(dst_ind, src_ind, dst_nnz)) {
// combine mjtNum data directly
mju_addToSclScl(dst, src, a, b, dst_nnz);
return dst_nnz;
}
}
// copy dst into buf
if (dst_nnz) {
mju_copy(buf, dst, dst_nnz);
mju_copyInt(buf_ind, dst_ind, dst_nnz);
}
// prepare to merge buf and src into dst
int bi = 0, si = 0, nnz = 0;
int buf_nnz = dst_nnz;
// merge vectors
while (bi < buf_nnz && si < src_nnz) {
int badr = buf_ind[bi];
int sadr = src_ind[si];
if (badr == sadr) {
dst[nnz] = a*buf[bi++] + b*src[si++];
dst_ind[nnz++] = badr;
}
// buf only
else if (badr < sadr) {
dst[nnz] = a*buf[bi++];
dst_ind[nnz++] = badr;
}
// src only
else {
dst[nnz] = b*src[si++];
dst_ind[nnz++] = sadr;
}
}
// the rest of src only
while (si < src_nnz) {
dst[nnz] = b*src[si];
dst_ind[nnz++] = src_ind[si++];
}
// the rest of buf only
while (bi < buf_nnz) {
dst[nnz] = a*buf[bi];
dst_ind[nnz++] = buf_ind[bi++];
}
return nnz;
}
// incomplete combine sparse: dst = a*dst + b*src at common indices
void mju_combineSparseInc(mjtNum* dst, const mjtNum* src, int n, mjtNum a, mjtNum b,
int dst_nnz, int src_nnz, int* dst_ind, const int* src_ind) {
// check for identical pattern
if (dst_nnz == src_nnz) {
if (mju_compare(dst_ind, src_ind, dst_nnz)) {
// combine mjtNum data directly
mju_addToSclScl(dst, src, a, b, dst_nnz);
return;
}
}
// scale dst by a
if (a != 1) {
mju_scl(dst, dst, a, dst_nnz);
}
// prepare to merge
int di = 0, si = 0;
int dadr = di < dst_nnz ? dst_ind[di] : n+1;
int sadr = si < src_nnz ? src_ind[si] : n+1;
// add src*b at common indices
while (di < dst_nnz) {
// both
if (dadr == sadr) {
dst[di++] += b*src[si++];
dadr = di < dst_nnz ? dst_ind[di] : n+1;
sadr = si < src_nnz ? src_ind[si] : n+1;
}
// dst only
else if (dadr < sadr) {
di++;
dadr = di < dst_nnz ? dst_ind[di] : n+1;
}
// src only
else {
si++;
sadr = si < src_nnz ? src_ind[si] : n+1;
}
}
}
// dst += scl*src, only at common non-zero indices
void mju_addToSclSparseInc(mjtNum* dst, const mjtNum* src,
int nnzdst, const int* inddst,
int nnzsrc, const int* indsrc, mjtNum scl) {
if (!nnzdst || !nnzsrc) {
return;
}
int adrs = 0, adrd = 0, inds = indsrc[0], indd = inddst[0];
while (1) {
// common non-zero index
if (inds == indd) {
// add
dst[adrd] += scl * src[adrs];
// advance src
if (++adrs < nnzsrc) {
inds = indsrc[adrs];
} else {
return;
}
// advance dst
if (++adrd < nnzdst) {
indd = inddst[adrd];
} else {
return;
}
}
// src non-zero index smaller: advance src
else if (inds < indd) {
if (++adrs < nnzsrc) {
inds = indsrc[adrs];
} else {
return;
}
}
// dst non-zero index smaller: advance dst
else {
if (++adrd < nnzdst) {
indd = inddst[adrd];
} else {
return;
}
}
}
}
// add to sparse matrix: dst = dst + scl*src, return nnz of result
int mju_addToSparseMat(mjtNum* dst, const mjtNum* src, int n, int nrow, mjtNum scl,
int dst_nnz, int src_nnz, int* dst_ind, const int* src_ind,
mjtNum* buf, int* buf_ind) {
// check for identical pattern
if (dst_nnz == src_nnz) {
if (dst_nnz == 0) {
return 0;
}
if (mju_compare(dst_ind, src_ind, dst_nnz)) {
// combine mjtNum data directly
mju_addToScl(dst, src, scl, nrow*dst_nnz);
return dst_nnz;
}
}
// prepare to merge scr and dst into buf^T
int si = 0, di = 0, nnz = 0;
int sadr = src_nnz ? src_ind[0] : n+1;
int dadr = dst_nnz ? dst_ind[0] : n+1;
// merge matrices
while (si < src_nnz || di < dst_nnz) {
// both
if (sadr == dadr) {
for (int k=0; k < nrow; k++) {
buf[nrow*nnz + k] = dst[di + k*dst_nnz] + scl*src[si + k*src_nnz];
}
buf_ind[nnz++] = sadr;
si++;
di++;
sadr = si < src_nnz ? src_ind[si] : n+1;
dadr = di < dst_nnz ? dst_ind[di] : n+1;
}
// dst only
else if (dadr < sadr) {
for (int k=0; k < nrow; k++) {
buf[nrow*nnz + k] = dst[di + k*dst_nnz];
}
buf_ind[nnz++] = dadr;
di++;
dadr = di < dst_nnz ? dst_ind[di] : n+1;
}
// src only
else {
for (int k=0; k < nrow; k++) {
buf[nrow*nnz + k] = scl*src[si + k*src_nnz];
}
buf_ind[nnz++] = sadr;
si++;
sadr = si < src_nnz ? src_ind[si] : n+1;
}
}
// copy transposed buf into dst
mju_transpose(dst, buf, nnz, nrow);
mju_copyInt(dst_ind, buf_ind, nnz);
return nnz;
}
// add(merge) two chains
int mju_addChains(int* res, int n, int NV1, int NV2,
const int* chain1, const int* chain2) {
// check for identical pattern
if (NV1 == NV2) {
if (NV1 == 0) {
return 0;
}
if (mju_compare(chain1, chain2, NV1)) {
mju_copyInt(res, chain1, NV1);
return NV1;
}
}
// prepare to merge
int i1 = 0, i2 = 0, NV = 0;
int adr1 = NV1 ? chain1[0] : n+1;
int adr2 = NV2 ? chain2[0] : n+1;
// merge chains
while (i1 < NV1 || i2 < NV2) {
// both
if (adr1 == adr2) {
res[NV++] = adr1;
i1++;
i2++;
adr1 = i1 < NV1 ? chain1[i1] : n+1;
adr2 = i2 < NV2 ? chain2[i2] : n+1;
}
// chain1 only
else if (adr1 < adr2) {
res[NV++] = adr1;
i1++;
adr1 = i1 < NV1 ? chain1[i1] : n+1;
}
// chain2 only
else {
res[NV++] = adr2;
i2++;
adr2 = i2 < NV2 ? chain2[i2] : n+1;
}
}
return NV;
}
// compress layout of sparse matrix
void mju_compressSparse(mjtNum* mat, int nr, int nc, int* rownnz, int* rowadr, int* colind) {
rowadr[0] = 0;
int adr = rownnz[0];
for (int r=1; r < nr; r++) {
// save old rowadr, record new
int rowadr1 = rowadr[r];
rowadr[r] = adr;
// shift mat and mat_colind
for (int adr1=rowadr1; adr1 < rowadr1+rownnz[r]; adr1++) {
mat[adr] = mat[adr1];
colind[adr] = colind[adr1];
adr++;
}
}
}
// transpose sparse matrix
void mju_transposeSparse(mjtNum* res, const mjtNum* mat, int nr, int nc,
int* res_rownnz, int* res_rowadr, int* res_colind,
const int* rownnz, const int* rowadr, const int* colind) {
// clear number of non-zeros for each row of transposed
mju_zeroInt(res_rownnz, nc);
// count the number of non-zeros for each row of the transposed matrix
for (int r = 0; r < nr; r++) {
int start = rowadr[r];
int end = start + rownnz[r];
for (int j = start; j < end; j++) {
res_rownnz[colind[j]]++;
}
}
// compute the row addresses for the transposed matrix
res_rowadr[0] = 0;
for (int i = 1; i < nc; i++) {
res_rowadr[i] = res_rowadr[i-1] + res_rownnz[i-1];
}
// iterate through each non-zero entry of mat
for (int r = 0; r < nr; r++) {
int start = rowadr[r];
int end = start + rownnz[r];
for (int i = start; i < end; i++) {
// swap rows with columns and increment res_rowadr
int c = res_rowadr[colind[i]]++;
res_colind[c] = r;
if (res) {
res[c] = mat[i];
}
}
}
// shift back row addresses
for (int i = nc-1; i > 0; i--) {
res_rowadr[i] = res_rowadr[i-1];
}
res_rowadr[0] = 0;
}
// construct row supernodes
void mju_superSparse(int nr, int* rowsuper,
const int* rownnz, const int* rowadr, const int* colind) {
// no rows: nothing to do
if (!nr) {
return;
}
// find match to child
for (int r=0; r < nr-1; r++) {
// different number of nonzeros: cannot be a match
if (rownnz[r] != rownnz[r+1]) {
rowsuper[r] = 0;
}
// same number of nonzeros: compare colind vectors
else {
rowsuper[r] = mju_compare(colind+rowadr[r], colind+rowadr[r+1], rownnz[r]);
}
}
// clear last (by definition)
rowsuper[nr-1] = 0;
// accumulate in reverse
for (int r=nr-2; r >= 0; r--) {
if (rowsuper[r]) {
rowsuper[r] += rowsuper[r+1];
}
}
}
// precount res_rownnz and precompute res_rowadr for mju_sqrMatTDSparse
void mju_sqrMatTDSparseInit(int* res_rownnz, int* res_rowadr, int nr,
const int* rownnz, const int* rowadr, const int* colind,
const int* rownnzT, const int* rowadrT, const int* colindT,
const int* rowsuperT, mjData* d, int flg_upper) {
mj_markStack(d);
int* chain = mjSTACKALLOC(d, 2*nr, int);
int nchain = 0;
int* res_colind = NULL;
for (int r=0; r < nr; r++) {
// supernode; copy everything to next row
if (rowsuperT && r > 0 && rowsuperT[r-1] > 0) {
res_rownnz[r] = res_rownnz[r - 1];
// fill in upper triangle
if (flg_upper) {
for (int j=0; j < nchain; j++) {
res_rownnz[res_colind[j]]++;
}
}
// update chain with diagonal
if (rownnzT[r]) {
res_colind[nchain++] = r;
res_rownnz[r]++;
}
} else {
int inew = 0, iold = nr;
nchain = 0;
for (int i=0; i < rownnzT[r]; i++) {
int c = colindT[rowadrT[r] + i];
int adr = inew;
inew = iold;
iold = adr;
int nnewchain = 0;
adr = 0;
int end = rowadr[c] + rownnz[c];
for (int adr1=rowadr[c]; adr1 < end; adr1++) {
int col_mat = colind[adr1];
while (adr < nchain && chain[iold + adr] < col_mat && chain[iold + adr] <= r) {
chain[inew + nnewchain++] = chain[iold + adr++];
}
// skip upper triangle
if (col_mat > r) {
break;
}
if (adr < nchain && chain[iold + adr] == col_mat) {
adr++;
}
chain[inew + nnewchain++] = col_mat;
}
while (adr < nchain && chain[iold + adr] <= r) {
chain[inew + nnewchain++] = chain[iold + adr++];
}
nchain = nnewchain;
}
// only computed for lower triangle
res_rownnz[r] = nchain;
res_colind = chain + inew;
// update upper triangle
if (flg_upper) {
int nchain_end = nchain;
// avoid double counting
if (nchain > 0 && res_colind[nchain-1] == r) {
nchain_end = nchain - 1;
}
for (int j=0; j < nchain_end; j++) {
res_rownnz[res_colind[j]]++;
}
}
}
}
res_rowadr[0] = 0;
for (int r = 1; r < nr; r++) {
res_rowadr[r] = res_rowadr[r-1] + res_rownnz[r-1];
}
mj_freeStack(d);
}
// precompute res_rowadr for mju_sqrMatTDSparse using uncompressed memory
void mju_sqrMatTDUncompressedInit(int* res_rowadr, int nc) {
for (int r=0; r < nc; r++) {
res_rowadr[r] = r*nc;
}
}
// compute sparse M'*diag*M (diag=NULL: compute M'*M), res has uncompressed layout
// res_rowadr is required to be precomputed
void mju_sqrMatTDSparse(mjtNum* res, const mjtNum* mat, const mjtNum* matT,
const mjtNum* diag, int nr, int nc,
int* res_rownnz, const int* res_rowadr, int* res_colind,
const int* rownnz, const int* rowadr,
const int* colind, const int* rowsuper,
const int* rownnzT, const int* rowadrT,
const int* colindT, const int* rowsuperT,
mjData* d, int flg_upper) {
// allocate space for accumulation buffer and matT
mj_markStack(d);
// a dense row buffer that stores the current row in the resulting matrix
mjtNum* buffer = mjSTACKALLOC(d, nc, mjtNum);
// these mark the currently set columns in the dense row buffer,
// used for when creating the resulting sparse row
int* markers = mjSTACKALLOC(d, nc, int);
for (int i=0; i < nc; i++) {
int rowadr_i = res_rowadr[i];
int* cols = res_colind + rowadr_i;
res_rownnz[i] = 0;
buffer[i] = 0;
markers[i] = 0;
// if rowsuper, use the previous row sparsity structure
if (rowsuperT && i > 0 && rowsuperT[i-1]) {
res_rownnz[i] = res_rownnz[i-1];
mju_copyInt(cols, res_colind+res_rowadr[i-1], res_rownnz[i]);
}
// iterate through each row of M'
int adrT = rowadrT[i];
int end_r = adrT + rownnzT[i];
for (int r = adrT; r < end_r; r++) {
int t = colindT[r];
int adr = rowadr[t];
int end_c = adr + rownnz[t];
for (int c=adr; c < end_c; c++) {
int cc = colind[c];
// ignore upper triangle
if (cc > i) {
break;
}
// add value to buffer
if (diag) {
buffer[cc] += matT[r] * diag[t] * mat[c];
} else {
buffer[cc] += matT[r] * mat[c];
}
// only need to insert nnz if not marked
if (!markers[cc]) {
markers[cc] = 1;
// since i is the rightmost column, it can be inserted at the end
if (cc == i) {
cols[res_rownnz[i]++] = cc;
continue;
}
// insert col in order via binary search
int l = 0, h = res_rownnz[i];
while (l < h) {
int m = (l + h) >> 1;
if (cols[m] < cc) {
l = m + 1;
} else {
h = m;
}
}
// cc is the rightmost column so far, it can be inserted at the end
if (l == res_rownnz[i]) {
cols[l] = cc;
res_rownnz[i]++;
continue;
}
// move the cols to the right
h = res_rownnz[i];
while (l < h) {
cols[h] = cols[h-1];
h--;
}
// insert
cols[l] = cc;
res_rownnz[i]++;
}
}
}
end_r = res_rownnz[i];
// rowsuperT: reuse sparsity, copy into res
if (rowsuperT && rowsuperT[i]) {
for (int r=0; r < end_r; r++) {
int c = cols[r];
res[rowadr_i + r] = buffer[c];
buffer[c] = 0;
}
}
// clear out buffers, sparsity cannot be reused
else {
for (int r=0; r < end_r; r++) {
int c = cols[r];
int adr = rowadr_i + r;
res[adr] = buffer[c];
res_colind[adr] = c;
buffer[c] = 0;
markers[c] = 0;
}
}
}
// fill upper triangle
if (flg_upper) {
for (int i=0; i < nc; i++) {
int start = res_rowadr[i];
int end = start + res_rownnz[i] - 1;
for (int j=start; j < end; j++) {
int adr = res_rowadr[res_colind[j]] + res_rownnz[res_colind[j]]++;
res[adr] = res[j];
res_colind[adr] = i;
}
}
}
mj_freeStack(d);
}
// compute row non-zeros of reverse-Cholesky factor L, return total non-zeros
// based on ldl_symbolic from 'Algorithm 8xx: a concise sparse Cholesky factorization package'
// note: reads pattern from upper triangle
int mju_cholFactorNNZ(int* L_rownnz, const int* rownnz, const int* rowadr, const int* colind,
int n, mjData* d) {
mj_markStack(d);
int* parent = mjSTACKALLOC(d, n, int);
int* flag = mjSTACKALLOC(d, n, int);
// loop over rows in reverse order
for (int r = n - 1; r >= 0; r--) {
parent[r] = -1;
flag[r] = r;
L_rownnz[r] = 1; // start with 1 for diagonal
// loop over non-zero columns
int start = rowadr[r];
int end = start + rownnz[r];
for (int c = start; c < end; c++) {
int i = colind[c];
if (i > r) {
// traverse from i to ancestor, stop when row is flagged
while (flag[i] != r) {
// if not yet set, set parent to current row
if (parent[i] == -1) {
parent[i] = r;
}
// increment non-zeros, flag row i, advance to parent
L_rownnz[i]++;
flag[i] = r;
i = parent[i];
}
}
}
}
mj_freeStack(d);
// sum up all row non-zeros
int nnz = 0;
for (int r = 0; r < n; r++) {
nnz += L_rownnz[r];
}
return nnz;
}