Optimize calls to get2byte() in btree.c for almost a one-million cycle

performance gain and a few bytes less code.

FossilOrigin-Name: 41061f29969dc546c2702f7f412127070a4dd54593827692df93a83c939dfb61

diff --git a/manifest b/manifest
index bde62d44f69e6906e432696e7dabcf0d41a5adfa..65aab7e507f394a35043d4e9e57e2e1e7e30101f 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-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.
-D 2022-02-23T17:16:30.735
+C Optimize\scalls\sto\sget2byte()\sin\sbtree.c\sfor\salmost\sa\sone-million\scycle\nperformance\sgain\sand\sa\sfew\sbytes\sless\scode.
+D 2022-02-23T18:23:15.914
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -492,7 +492,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c a2891172438e385fdbe97c11c9745676bec54f518d4447090af97189fd8e52d7
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c 117808943727d27e38c69de4e79237e52c89ee40f6f1a70de4e6e14b5e596cbc
+F src/btree.c 35870e7059b2b5bd90b0e1ac482b632b41a81dbb9b466bc7c9f3e4086571391c
 F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
 F src/btreeInt.h 7282a6e77775f93a6eb78d3a41dab372a01a4ec1d93d3b4728d191d15fda42e2
 F src/build.c 9891c2160886cf7e344d7e8f1f7177f9612916c7c67ffeacd64cb34a92d387a8
@@ -1944,8 +1944,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 5aa9c3eb45514d5eb7b32696d25a9aeb7dad485e1ea5adb833fac6d1f2105f1a
-R 4a7be174abec3b1bd75c937cba4c1ec2
+P ece326db50201937eb688809df39edc7fb97413b4614d2e2e783418192f7b02a
+R 1c57a2dcd8f8c477175cc03c1d736930
 U drh
-Z 8b433f90acbe3d610b55829e1edc78df
+Z 34e99039e8cc6255862cb2a477919b3e
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index 12eedaa720b741176b9b555f920bdcfd7a12275e..3d1ba050420c3816162a3d5d191cc0e02581f74b 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-ece326db50201937eb688809df39edc7fb97413b4614d2e2e783418192f7b02a
\ No newline at end of file
+41061f29969dc546c2702f7f412127070a4dd54593827692df93a83c939dfb61
\ No newline at end of file

diff --git a/src/btree.c b/src/btree.c
index fb7f025a1634acc6e30a70ed1d8d5bd80c4ebb20..1d3acdc51d49b9faae78f372f289cf9a3394d164 100644 (file)
--- a/src/btree.c
+++ b/src/btree.c
@@ -1586,7 +1586,8 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
   const int hdr = pPg->hdrOffset;            /* Offset to page header */
   u8 * const aData = pPg->aData;             /* Page data */
   int iAddr = hdr + 1;                       /* Address of ptr to pc */
-  int pc = get2byte(&aData[iAddr]);          /* Address of a free slot */
+  u8 *pTmp = &aData[iAddr];                  /* Temporary ptr into aData[] */
+  int pc = get2byte(pTmp);                   /* Address of a free slot */
   int x;                                     /* Excess size of the slot */
   int maxPC = pPg->pBt->usableSize - nByte;  /* Max address for a usable slot */
   int size;                                  /* Size of the free slot */
@@ -1596,7 +1597,8 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
     /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
     ** freeblock form a big-endian integer which is the size of the freeblock
     ** in bytes, including the 4-byte header. */
-    size = get2byte(&aData[pc+2]);
+    pTmp = &aData[pc+2];
+    size = get2byte(pTmp);
     if( (x = size - nByte)>=0 ){
       testcase( x==4 );
       testcase( x==3 );
@@ -1621,7 +1623,8 @@ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
       return &aData[pc + x];
     }
     iAddr = pc;
-    pc = get2byte(&aData[pc]);
+    pTmp = &aData[pc];
+    pc = get2byte(pTmp);
     if( pc<=iAddr+size ){
       if( pc ){
         /* The next slot in the chain is not past the end of the current slot */
@@ -1655,6 +1658,7 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
   u8 * const data = pPage->aData;      /* Local cache of pPage->aData */
   int top;                             /* First byte of cell content area */
   int rc = SQLITE_OK;                  /* Integer return code */
+  u8 *pTmp;                            /* Temp ptr into data[] */
   int gap;        /* First byte of gap between cell pointers and cell content */
   
   assert( sqlite3PagerIswriteable(pPage->pDbPage) );
@@ -1673,7 +1677,8 @@ static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
   ** then the cell content offset of an empty page wants to be 65536.
   ** However, that integer is too large to be stored in a 2-byte unsigned
   ** integer, so a value of 0 is used in its place. */
-  top = get2byte(&data[hdr+5]);
+  pTmp = &data[hdr+5];
+  top = get2byte(pTmp);
   assert( top<=(int)pPage->pBt->usableSize ); /* by btreeComputeFreeSpace() */
   if( gap>top ){
     if( top==0 && pPage->pBt->usableSize==65536 ){
@@ -1755,6 +1760,7 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
   u16 x;                                /* Offset to cell content area */
   u32 iEnd = iStart + iSize;            /* First byte past the iStart buffer */
   unsigned char *data = pPage->aData;   /* Page content */
+  u8 *pTmp;                             /* Temporary ptr into data[] */
 
   assert( pPage->pBt!=0 );
   assert( sqlite3PagerIswriteable(pPage->pDbPage) );
@@ -1817,7 +1823,8 @@ static int freeSpace(MemPage *pPage, u16 iStart, u16 iSize){
     if( nFrag>data[hdr+7] ) return SQLITE_CORRUPT_PAGE(pPage);
     data[hdr+7] -= nFrag;
   }
-  x = get2byte(&data[hdr+5]);
+  pTmp = &data[hdr+5];
+  x = get2byte(pTmp);
   if( iStart<=x ){
     /* The new freeblock is at the beginning of the cell content area,
     ** so just extend the cell content area rather than create another