From: drh <drh@noemail.net>
Date: Tue, 20 Sep 2016 22:04:05 +0000 (+0000)
Subject: Improved implementation of 64-bit signed integer multiply that correctly
X-Git-Tag: version-3.15.0~68
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=09952c6490fb1004055bd4a1c83d85fa781da1f2;p=thirdparty%2Fsqlite.git

Improved implementation of 64-bit signed integer multiply that correctly
detects overflow (and promotes to floating-point) in some corner cases.
Fix for ticket [1ec41379c9c1e400]

FossilOrigin-Name: db3ebd7c52cfc5fcc7be00f52e9d7c84719f7b93
---

diff --git a/manifest b/manifest
index 01075f300f..df03ff132c 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sharmless\scompiler\swarning.
-D 2016-09-20T17:49:01.524
+C Improved\simplementation\sof\s64-bit\ssigned\sinteger\smultiply\sthat\scorrectly\ndetects\soverflow\s(and\spromotes\sto\sfloating-point)\sin\ssome\scorner\scases.\nFix\sfor\sticket\s[1ec41379c9c1e400]
+D 2016-09-20T22:04:05.970
 F Makefile.in 6fd48ffcf7c2deea7499062d1f3747f986c19678
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc e1aa788e84f926e42239ee167c53f785bedacacd
@@ -451,7 +451,7 @@ F src/treeview.c f51b75a28b377adde9f79bc3deb6c7770bcf97c0
 F src/trigger.c 3419bb9862983d84d70735fb4c94b21b934cd0c5
 F src/update.c 8179e699dbd45b92934fd02d3d8e3732e8da8802
 F src/utf.c 699001c79f28e48e9bcdf8a463da029ea660540c
-F src/util.c 810ec3f22e2d1b62e66c30fe3621ebdedd23584d
+F src/util.c 3e2da6101888d073e79ecc6af5e0a2f70fa1e498
 F src/vacuum.c 913970b9d86dd6c2b8063ef1af421880f1464ec3
 F src/vdbe.c 0f87994593787575a4a23f932d27cb4588477436
 F src/vdbe.h c044be7050ac6bf596eecc6ab159f5dbc020a3b7
@@ -675,7 +675,7 @@ F test/exclusive.test 9a57bd66e39144b888ca75c309914fcdefb4e3f9
 F test/exclusive2.test 32798111aae78a5deec980eee383213f189df308
 F test/exec.test e949714dc127eaa5ecc7d723efec1ec27118fdd7
 F test/exists.test 79a75323c78f02bbe9c251ea502a092f9ef63dac
-F test/expr.test 79c3e7502d9e571553b85f0ecc8ff2ac7d0e4931
+F test/expr.test 66a2c9ac34f74f036faa4092f5402c7d3162fc93
 F test/extension01.test 00d13cec817f331a687a243e0e5a2d87b0e358c9
 F test/extraquick.test cb254400bd42bfb777ff675356aabf3287978f79
 F test/fallocate.test 3e979af17dfa7e5e9dda5eba1a696c04fa9d47f7
@@ -1525,7 +1525,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P bd3ecbb5c1977744321f4bbac79fd7e2e7c1b5ba
-R 9c6c154d94d3544c30252d0eac8d5092
-U mistachkin
-Z a981fdc618d99724c0721b182be1e085
+P 72429063956614975d90cae2a829cfa4296694da
+R 91d60e6e7ebec7104f81d972c645f360
+U drh
+Z 545cfa3e1675ae70fe7fd8b14cbd5249
diff --git a/manifest.uuid b/manifest.uuid
index 66c1131d07..55a4112105 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-72429063956614975d90cae2a829cfa4296694da
\ No newline at end of file
+db3ebd7c52cfc5fcc7be00f52e9d7c84719f7b93
\ No newline at end of file
diff --git a/src/util.c b/src/util.c
index db6163c3c7..e18b847578 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1305,36 +1305,21 @@ int sqlite3SubInt64(i64 *pA, i64 iB){
     return sqlite3AddInt64(pA, -iB);
   }
 }
-#define TWOPOWER32 (((i64)1)<<32)
-#define TWOPOWER31 (((i64)1)<<31)
 int sqlite3MulInt64(i64 *pA, i64 iB){
   i64 iA = *pA;
-  i64 iA1, iA0, iB1, iB0, r;
-
-  iA1 = iA/TWOPOWER32;
-  iA0 = iA % TWOPOWER32;
-  iB1 = iB/TWOPOWER32;
-  iB0 = iB % TWOPOWER32;
-  if( iA1==0 ){
-    if( iB1==0 ){
-      *pA *= iB;
-      return 0;
+  if( iB>0 ){
+    if( iA>LARGEST_INT64/iB ) return 1;
+    if( iA<SMALLEST_INT64/iB ) return 1;
+  }else if( iB<0 ){
+    if( iA>0 ){
+      if( iB<SMALLEST_INT64/iA ) return 1;
+    }else if( iA<0 ){
+      if( iB==SMALLEST_INT64 ) return 1;
+      if( iA==SMALLEST_INT64 ) return 1;
+      if( -iA>LARGEST_INT64/-iB ) return 1;
     }
-    r = iA0*iB1;
-  }else if( iB1==0 ){
-    r = iA1*iB0;
-  }else{
-    /* If both iA1 and iB1 are non-zero, overflow will result */
-    return 1;
   }
-  testcase( r==(-TWOPOWER31)-1 );
-  testcase( r==(-TWOPOWER31) );
-  testcase( r==TWOPOWER31 );
-  testcase( r==TWOPOWER31-1 );
-  if( r<(-TWOPOWER31) || r>=TWOPOWER31 ) return 1;
-  r *= TWOPOWER32;
-  if( sqlite3AddInt64(&r, iA0*iB0) ) return 1;
-  *pA = r;
+  *pA = iA*iB;
   return 0;
 }
 
diff --git a/test/expr.test b/test/expr.test
index 7d7b8ce5a7..7a6d477259 100644
--- a/test/expr.test
+++ b/test/expr.test
@@ -308,6 +308,33 @@ ifcapable floatingpoint {if {[working_64bit_int]} {
   test_realnum_expr expr-1.257\
       {i1=-4294967296, i2=-2147483647} {i1*i2}    9223372032559808512
 
+  test_realnum_expr expr-1.260\
+      {i1=3037000500, i2=3037000500} {i1*i2}      9.22337203700025e+18
+  test_realnum_expr expr-1.261\
+      {i1=3037000500, i2=-3037000500} {i1*i2}     -9.22337203700025e+18
+  test_realnum_expr expr-1.262\
+      {i1=-3037000500, i2=3037000500} {i1*i2}     -9.22337203700025e+18
+  test_realnum_expr expr-1.263\
+      {i1=-3037000500, i2=-3037000500} {i1*i2}    9.22337203700025e+18
+
+  test_realnum_expr expr-1.264\
+      {i1=3037000500, i2=3037000499} {i1*i2}      9223372033963249500
+  test_realnum_expr expr-1.265\
+      {i1=3037000500, i2=-3037000499} {i1*i2}     -9223372033963249500
+  test_realnum_expr expr-1.266\
+      {i1=-3037000500, i2=3037000499} {i1*i2}     -9223372033963249500
+  test_realnum_expr expr-1.267\
+      {i1=-3037000500, i2=-3037000499} {i1*i2}    9223372033963249500
+
+  test_realnum_expr expr-1.268\
+      {i1=3037000499, i2=3037000500} {i1*i2}      9223372033963249500
+  test_realnum_expr expr-1.269\
+      {i1=3037000499, i2=-3037000500} {i1*i2}     -9223372033963249500
+  test_realnum_expr expr-1.270\
+      {i1=-3037000499, i2=3037000500} {i1*i2}     -9223372033963249500
+  test_realnum_expr expr-1.271\
+      {i1=-3037000499, i2=-3037000500} {i1*i2}    9223372033963249500
+
 }}
 
 ifcapable floatingpoint {