From: drh <>
Date: Sun, 2 Jan 2022 16:48:00 +0000 (+0000)
Subject: Performance optimization in btreeParseCellPtr() by unrolling the loop that
X-Git-Tag: version-3.38.0~132
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=29bbc2b51f2477a5a45fe1a99cf56b5d7ea0ca82;p=thirdparty%2Fsqlite.git

Performance optimization in btreeParseCellPtr() by unrolling the loop that
decodes the rowid.

FossilOrigin-Name: fef72368a2eef5cb68ffc56e4f01be212d5e3318ebdb56a23ab26e1ef454272e
---

diff --git a/manifest b/manifest
index fee691766c..89b61494cb 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Small\sperformance\soptimization\sand\ssize\sreduction\sin\ssqlite3BtreeDelete().
-D 2022-01-02T14:55:43.095
+C Performance\soptimization\sin\sbtreeParseCellPtr()\sby\sunrolling\sthe\sloop\sthat\ndecodes\sthe\srowid.
+D 2022-01-02T16:48:00.312
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -491,7 +491,7 @@ F src/auth.c f4fa91b6a90bbc8e0d0f738aa284551739c9543a367071f55574681e0f24f8cf
 F src/backup.c 3014889fa06e20e6adfa0d07b60097eec1f6e5b06671625f476a714d2356513d
 F src/bitvec.c 7c849aac407230278445cb069bebc5f89bf2ddd87c5ed9459b070a9175707b3d
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c d4b6e026d85b47018dd4c31b42dd490ed22d4320917e705d6502e589d1a8227d
+F src/btree.c 75aed1a53f45c9020d57ead65397693fe28e408526c08d2b15803629619eb4b7
 F src/btree.h 74d64b8f28cfa4a894d14d4ed64fa432cd697b98b61708d4351482ae15913e22
 F src/btreeInt.h ee9348c4cb9077243b049edc93a82c1f32ca48baeabf2140d41362b9f9139ff7
 F src/build.c 6e16f7b539bfc55149a039bf0cda26b089640339df6147070b072df2d1c4f771
@@ -1936,8 +1936,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 5232c9777fe4fb13e1ecfe5b5d644e2c45d0514f95884dbed49a03fb9b67304c
-R aa110e7b5297811807e4f693fefdef54
+P da0af4dd9ba4180a16543fac1549fd4ccecdc66dcf6d275f77de21fd80708882
+R 8e54a2cff16f34421db02383c81bf96e
 U drh
-Z a31d2467491c7884583c9d9e2a7c5425
+Z 07304ae249bd8afb301d4ea202109e15
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 71edf50ae9..a2fb6d3baa 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-da0af4dd9ba4180a16543fac1549fd4ccecdc66dcf6d275f77de21fd80708882
\ No newline at end of file
+fef72368a2eef5cb68ffc56e4f01be212d5e3318ebdb56a23ab26e1ef454272e
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index 4f777f0f75..b99045c41e 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -1225,18 +1225,32 @@ static void btreeParseCellPtr(
   **
   **     pIter += getVarint(pIter, (u64*)&pInfo->nKey);
   **
-  ** The code is inlined to avoid a function call.
+  ** The code is inlined and the loop is unrolled for performance.
+  ** This routine is a high-runner.
   */
   iKey = *pIter;
   if( iKey>=0x80 ){
-    u8 *pEnd = &pIter[7];
-    iKey &= 0x7f;
-    while(1){
-      iKey = (iKey<<7) | (*++pIter & 0x7f);
-      if( (*pIter)<0x80 ) break;
-      if( pIter>=pEnd ){
-        iKey = (iKey<<8) | *++pIter;
-        break;
+    u8 x;
+    iKey = ((iKey&0x7f)<<7) | ((x = *++pIter) & 0x7f);
+    if( x>=0x80 ){
+      iKey = (iKey<<7) | ((x =*++pIter) & 0x7f);
+      if( x>=0x80 ){
+        iKey = (iKey<<7) | ((x = *++pIter) & 0x7f);
+        if( x>=0x80 ){
+          iKey = (iKey<<7) | ((x = *++pIter) & 0x7f);
+          if( x>=0x80 ){
+            iKey = (iKey<<7) | ((x = *++pIter) & 0x7f);
+            if( x>=0x80 ){
+              iKey = (iKey<<7) | ((x = *++pIter) & 0x7f);
+              if( x>=0x80 ){
+                iKey = (iKey<<7) | ((x = *++pIter) & 0x7f);
+                if( x>=0x80 ){
+                  iKey = (iKey<<8) | (*++pIter);
+                }
+              }
+            }
+          }
+        }
       }
     }
   }