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Overview
| Comment: | Simplifications to the overflow-free multiplier. Also remove some commented-out code that was left in that subroutine by mistake on the previous check-in. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | 55fc25fdab61e6094289e068c343e012 |
| User & Date: | drh 2011-03-05 21:41:34 |
Context
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2011-03-06
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| 21:28 | Remove dead code identified by the clang static analyzer. check-in: 01a79d5a user: drh tags: trunk | |
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2011-03-05
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| 21:41 | Simplifications to the overflow-free multiplier. Also remove some commented-out code that was left in that subroutine by mistake on the previous check-in. check-in: 55fc25fd user: drh tags: trunk | |
| 20:59 | Fix all known instances of signed-integer overflow. Within SQL expressions, integer overflow now forces coercion to floating point. The shift operators work with any integer right-hand operand with negative values reversing the direction of the shift. check-in: abf21394 user: drh tags: trunk | |
Changes
Changes to src/util.c.
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}
#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;
// if( iB==1 ){ return 0; }
// if( iA==1 ){ *pA = iB; return 0; }
iA1 = iA/TWOPOWER32;
iA0 = iA % TWOPOWER32;
iB1 = iB/TWOPOWER32;
iB0 = iB % TWOPOWER32;
if( iA1*iB1 != 0 ) return 1;
r = iA1*iB0;
if( sqlite3AddInt64(&r, iA0*iB1) ) 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;
return 0;
}
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}
#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*iB1 != 0 ) return 1;
assert( iA1*iB0==0 || iA0*iB1==0 );
r = iA1*iB0 + iA0*iB1;
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;
return 0;
}
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