Optimize calls to get2byte() in btree.c for almost a one-million cycle
performance gain and a few bytes less code. FossilOrigin-Name: 41061f29969dc546c2702f7f412127070a4dd54593827692df93a83c939dfb61
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drh
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12
manifest
12
manifest
@ -1,5 +1,5 @@
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C Defer\sthe\scheck\sfor\serror\scheck\sPgno\szero\suntil\safter\sthe\spage\sfetch\smisses,\nto\sgain\sa\sfew\sCPU\scycles\sand\sa\ssmall\ssize\sreduction.
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D 2022-02-23T17:16:30.735
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C Optimize\scalls\sto\sget2byte()\sin\sbtree.c\sfor\salmost\sa\sone-million\scycle\nperformance\sgain\sand\sa\sfew\sbytes\sless\scode.
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D 2022-02-23T18:23:15.914
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F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
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F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
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F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
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@ -492,7 +492,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
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F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
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F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
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F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
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F src/btree.c 117808943727d27e38c69de4e79237e52c89ee40f6f1a70de4e6e14b5e596cbc
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F src/btree.c 35870e7059b2b5bd90b0e1ac482b632b41a81dbb9b466bc7c9f3e4086571391c
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F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
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F src/btreeInt.h 7282a6e77775f93a6eb78d3a41dab372a01a4ec1d93d3b4728d191d15fda42e2
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F src/build.c 9891c2160886cf7e344d7e8f1f7177f9612916c7c67ffeacd64cb34a92d387a8
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@ -1944,8 +1944,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
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F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
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F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
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R 4a7be174abec3b1bd75c937cba4c1ec2
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P ece326db50201937eb688809df39edc7fb97413b4614d2e2e783418192f7b02a
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R 1c57a2dcd8f8c477175cc03c1d736930
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U drh
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Z 8b433f90acbe3d610b55829e1edc78df
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Z 34e99039e8cc6255862cb2a477919b3e
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# Remove this line to create a well-formed Fossil manifest.
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@ -1 +1 @@
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ece326db50201937eb688809df39edc7fb97413b4614d2e2e783418192f7b02a
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41061f29969dc546c2702f7f412127070a4dd54593827692df93a83c939dfb61
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17
src/btree.c
17
src/btree.c
@ -1586,7 +1586,8 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
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const int hdr = pPg->hdrOffset; /* Offset to page header */
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u8 * const aData = pPg->aData; /* Page data */
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int iAddr = hdr + 1; /* Address of ptr to pc */
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int pc = get2byte(&aData[iAddr]); /* Address of a free slot */
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u8 *pTmp = &aData[iAddr]; /* Temporary ptr into aData[] */
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int pc = get2byte(pTmp); /* Address of a free slot */
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int x; /* Excess size of the slot */
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int maxPC = pPg->pBt->usableSize - nByte; /* Max address for a usable slot */
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int size; /* Size of the free slot */
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@ -1596,7 +1597,8 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
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/* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
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** freeblock form a big-endian integer which is the size of the freeblock
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** in bytes, including the 4-byte header. */
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size = get2byte(&aData[pc+2]);
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pTmp = &aData[pc+2];
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size = get2byte(pTmp);
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if( (x = size - nByte)>=0 ){
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testcase( x==4 );
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testcase( x==3 );
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@ -1621,7 +1623,8 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
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return &aData[pc + x];
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}
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iAddr = pc;
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pc = get2byte(&aData[pc]);
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pTmp = &aData[pc];
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pc = get2byte(pTmp);
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if( pc<=iAddr+size ){
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if( pc ){
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/* The next slot in the chain is not past the end of the current slot */
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@ -1655,6 +1658,7 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
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u8 * const data = pPage->aData; /* Local cache of pPage->aData */
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int top; /* First byte of cell content area */
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int rc = SQLITE_OK; /* Integer return code */
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u8 *pTmp; /* Temp ptr into data[] */
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int gap; /* First byte of gap between cell pointers and cell content */
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assert( sqlite3PagerIswriteable(pPage->pDbPage) );
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@ -1673,7 +1677,8 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
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** then the cell content offset of an empty page wants to be 65536.
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** However, that integer is too large to be stored in a 2-byte unsigned
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** integer, so a value of 0 is used in its place. */
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top = get2byte(&data[hdr+5]);
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pTmp = &data[hdr+5];
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top = get2byte(pTmp);
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assert( top<=(int)pPage->pBt->usableSize ); /* by btreeComputeFreeSpace() */
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if( gap>top ){
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if( top==0 && pPage->pBt->usableSize==65536 ){
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@ -1755,6 +1760,7 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
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u16 x; /* Offset to cell content area */
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u32 iEnd = iStart + iSize; /* First byte past the iStart buffer */
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unsigned char *data = pPage->aData; /* Page content */
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u8 *pTmp; /* Temporary ptr into data[] */
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assert( pPage->pBt!=0 );
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assert( sqlite3PagerIswriteable(pPage->pDbPage) );
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@ -1817,7 +1823,8 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
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if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_PAGE(pPage);
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data[hdr+7] -= nFrag;
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}
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x = get2byte(&data[hdr+5]);
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pTmp = &data[hdr+5];
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x = get2byte(pTmp);
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if( iStart<=x ){
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/* The new freeblock is at the beginning of the cell content area,
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** so just extend the cell content area rather than create another
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