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Merge pull request #2522 from terrelln/stack-reduction

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Reduce stack usage of ZSTD_buildCTable()
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Nick Terrell 2021-03-04 20:55:58 -08:00 committed by GitHub
commit e50f88ca4c
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1 changed files with 11 additions and 5 deletions
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16
lib/compress/zstd_compress_sequences.c
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@ -232,6 +232,11 @@ ZSTD_selectEncodingType(
return set_compressed; return set_compressed;
} }
typedef struct {
S16 norm[MaxSeq + 1];
U32 wksp[FSE_BUILD_CTABLE_WORKSPACE_SIZE_U32(MaxSeq, MaxFSELog)];
} ZSTD_BuildCTableWksp;
size_t size_t
ZSTD_buildCTable(void* dst, size_t dstCapacity, ZSTD_buildCTable(void* dst, size_t dstCapacity,
FSE_CTable* nextCTable, U32 FSELog, symbolEncodingType_e type, FSE_CTable* nextCTable, U32 FSELog, symbolEncodingType_e type,
@ -258,7 +263,7 @@ ZSTD_buildCTable(void* dst, size_t dstCapacity,
FORWARD_IF_ERROR(FSE_buildCTable_wksp(nextCTable, defaultNorm, defaultMax, defaultNormLog, entropyWorkspace, entropyWorkspaceSize), ""); /* note : could be pre-calculated */ FORWARD_IF_ERROR(FSE_buildCTable_wksp(nextCTable, defaultNorm, defaultMax, defaultNormLog, entropyWorkspace, entropyWorkspaceSize), ""); /* note : could be pre-calculated */
return 0; return 0;
case set_compressed: { case set_compressed: {
S16 norm[MaxSeq + 1]; ZSTD_BuildCTableWksp* wksp = (ZSTD_BuildCTableWksp*)entropyWorkspace;
size_t nbSeq_1 = nbSeq; size_t nbSeq_1 = nbSeq;
const U32 tableLog = FSE_optimalTableLog(FSELog, nbSeq, max); const U32 tableLog = FSE_optimalTableLog(FSELog, nbSeq, max);
if (count[codeTable[nbSeq-1]] > 1) { if (count[codeTable[nbSeq-1]] > 1) {
@ -266,11 +271,12 @@ ZSTD_buildCTable(void* dst, size_t dstCapacity,
nbSeq_1--; nbSeq_1--;
} }
assert(nbSeq_1 > 1); assert(nbSeq_1 > 1);
assert(entropyWorkspaceSize >= FSE_BUILD_CTABLE_WORKSPACE_SIZE(MaxSeq, MaxFSELog)); assert(entropyWorkspaceSize >= sizeof(ZSTD_BuildCTableWksp));
FORWARD_IF_ERROR(FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max, ZSTD_useLowProbCount(nbSeq_1)), ""); (void)entropyWorkspaceSize;
{ size_t const NCountSize = FSE_writeNCount(op, oend - op, norm, max, tableLog); /* overflow protected */ FORWARD_IF_ERROR(FSE_normalizeCount(wksp->norm, tableLog, count, nbSeq_1, max, ZSTD_useLowProbCount(nbSeq_1)), "");
{ size_t const NCountSize = FSE_writeNCount(op, oend - op, wksp->norm, max, tableLog); /* overflow protected */
FORWARD_IF_ERROR(NCountSize, "FSE_writeNCount failed"); FORWARD_IF_ERROR(NCountSize, "FSE_writeNCount failed");
FORWARD_IF_ERROR(FSE_buildCTable_wksp(nextCTable, norm, max, tableLog, entropyWorkspace, entropyWorkspaceSize), ""); FORWARD_IF_ERROR(FSE_buildCTable_wksp(nextCTable, wksp->norm, max, tableLog, wksp->wksp, sizeof(wksp->wksp)), "");
return NCountSize; return NCountSize;
} }
} }