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Get the sqlite3VdbeSerialGet() routine to run faster by avoiding the use

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of local variables.

FossilOrigin-Name: 8267d82174099e548a4f78d06af0c6324c89b83d
This commit is contained in:
drh
2014-08-22 14:34:05 +00:00
parent 3f5b199eb5
commit 14a924a5cd
4 changed files with 73 additions and 47 deletions
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89
src/vdbeaux.c
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@@ -2965,14 +2965,55 @@ u32 sqlite3VdbeSerialPut(u8 *buf, Mem *pMem, u32 serial_type){
/*
** Deserialize the data blob pointed to by buf as serial type serial_type
** and store the result in pMem. Return the number of bytes read.
**
** This function is implemented as two separate routines for performance.
** The few cases that require local variables are broken out into a separate
** routine so that in most cases the overhead of moving the stack pointer
** is avoided.
*/
u32 sqlite3VdbeSerialGet(
static u32 SQLITE_NOINLINE serialGet(
const unsigned char *buf, /* Buffer to deserialize from */
u32 serial_type, /* Serial type to deserialize */
Mem *pMem /* Memory cell to write value into */
){
u64 x;
u32 y;
u32 y = FOUR_BYTE_UINT(buf);
if( serial_type==4 ){
pMem->u.i = (i64)*(int*)&y;
pMem->flags = MEM_Int;
testcase( pMem->u.i<0 );
return 4;
}
x = (((u64)y)<<32)|FOUR_BYTE_UINT(buf+4);
if( serial_type==6 ){
pMem->u.i = *(i64*)&x;
pMem->flags = MEM_Int;
testcase( pMem->u.i<0 );
}else{
#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
/* Verify that integers and floating point values use the same
** byte order. Or, that if SQLITE_MIXED_ENDIAN_64BIT_FLOAT is
** defined that 64-bit floating point values really are mixed
** endian.
*/
static const u64 t1 = ((u64)0x3ff00000)<<32;
static const double r1 = 1.0;
u64 t2 = t1;
swapMixedEndianFloat(t2);
assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
#endif
assert( sizeof(x)==8 && sizeof(pMem->r)==8 );
swapMixedEndianFloat(x);
memcpy(&pMem->r, &x, sizeof(x));
pMem->flags = sqlite3IsNaN(pMem->r) ? MEM_Null : MEM_Real;
}
return 8;
}
u32 sqlite3VdbeSerialGet(
const unsigned char *buf, /* Buffer to deserialize from */
u32 serial_type, /* Serial type to deserialize */
Mem *pMem /* Memory cell to write value into */
){
switch( serial_type ){
case 10: /* Reserved for future use */
case 11: /* Reserved for future use */
@@ -2998,47 +3039,19 @@ u32 sqlite3VdbeSerialGet(
testcase( pMem->u.i<0 );
return 3;
}
case 4: { /* 4-byte signed integer */
y = FOUR_BYTE_UINT(buf);
pMem->u.i = (i64)*(int*)&y;
pMem->flags = MEM_Int;
testcase( pMem->u.i<0 );
return 4;
}
case 5: { /* 6-byte signed integer */
pMem->u.i = FOUR_BYTE_UINT(buf+2) + (((i64)1)<<32)*TWO_BYTE_INT(buf);
pMem->flags = MEM_Int;
testcase( pMem->u.i<0 );
return 6;
}
case 4: /* 4-byte signed integer */
case 6: /* 8-byte signed integer */
case 7: { /* IEEE floating point */
#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
/* Verify that integers and floating point values use the same
** byte order. Or, that if SQLITE_MIXED_ENDIAN_64BIT_FLOAT is
** defined that 64-bit floating point values really are mixed
** endian.
*/
static const u64 t1 = ((u64)0x3ff00000)<<32;
static const double r1 = 1.0;
u64 t2 = t1;
swapMixedEndianFloat(t2);
assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
#endif
x = FOUR_BYTE_UINT(buf);
y = FOUR_BYTE_UINT(buf+4);
x = (x<<32) | y;
if( serial_type==6 ){
pMem->u.i = *(i64*)&x;
pMem->flags = MEM_Int;
testcase( pMem->u.i<0 );
}else{
assert( sizeof(x)==8 && sizeof(pMem->r)==8 );
swapMixedEndianFloat(x);
memcpy(&pMem->r, &x, sizeof(x));
pMem->flags = sqlite3IsNaN(pMem->r) ? MEM_Null : MEM_Real;
}
return 8;
/* These three cases require local variables, so do them in a
** separate routine to avoid having to move the frame pointer in
** the common case */
return serialGet(buf,serial_type,pMem);
}
case 8: /* Integer 0 */
case 9: { /* Integer 1 */
@@ -3048,17 +3061,15 @@ u32 sqlite3VdbeSerialGet(
}
default: {
static const u16 aFlag[] = { MEM_Blob|MEM_Ephem, MEM_Str|MEM_Ephem };
u32 len = (serial_type-12)/2;
pMem->z = (char *)buf;
pMem->n = len;
pMem->n = (serial_type-12)/2;
pMem->xDel = 0;
pMem->flags = aFlag[serial_type&1];
return len;
return pMem->n;
}
}
return 0;
}
/*
** This routine is used to allocate sufficient space for an UnpackedRecord
** structure large enough to be used with sqlite3VdbeRecordUnpack() if