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Replace the NOPUSH_MASKs with a bit-vector mechanism that can contain

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several different properties about each opcode. (CVS 4677)

FossilOrigin-Name: 042dcb9621934d0318a7c6e9cd08b20a569db367
This commit is contained in:
drh
2008-01-04 16:50:09 +00:00
parent dd2fb29be8
commit 3a40f696d4
6 changed files with 144 additions and 132 deletions
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44
src/vdbeaux.c
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@@ -232,48 +232,6 @@ void sqlite3VdbeResolveLabel(Vdbe *p, int x){
}
}
/*
** Return non-zero if opcode 'op' is guarenteed not to push more values
** onto the VDBE stack than it pops off.
*/
static int opcodeNoPush(u8 op){
/* The 10 NOPUSH_MASK_n constants are defined in the automatically
** generated header file opcodes.h. Each is a 16-bit bitmask, one
** bit corresponding to each opcode implemented by the virtual
** machine in vdbe.c. The bit is true if the word "no-push" appears
** in a comment on the same line as the "case OP_XXX:" in
** sqlite3VdbeExec() in vdbe.c.
**
** If the bit is true, then the corresponding opcode is guarenteed not
** to grow the stack when it is executed. Otherwise, it may grow the
** stack by at most one entry.
**
** NOPUSH_MASK_0 corresponds to opcodes 0 to 15. NOPUSH_MASK_1 contains
** one bit for opcodes 16 to 31, and so on.
**
** 16-bit bitmasks (rather than 32-bit) are specified in opcodes.h
** because the file is generated by an awk program. Awk manipulates
** all numbers as floating-point and we don't want to risk a rounding
** error if someone builds with an awk that uses (for example) 32-bit
** IEEE floats.
*/
static const u32 masks[5] = {
NOPUSH_MASK_0 + (((unsigned)NOPUSH_MASK_1)<<16),
NOPUSH_MASK_2 + (((unsigned)NOPUSH_MASK_3)<<16),
NOPUSH_MASK_4 + (((unsigned)NOPUSH_MASK_5)<<16),
NOPUSH_MASK_6 + (((unsigned)NOPUSH_MASK_7)<<16),
NOPUSH_MASK_8 + (((unsigned)NOPUSH_MASK_9)<<16)
};
assert( op<32*5 );
return (masks[op>>5] & (1<<(op&0x1F)));
}
#ifndef NDEBUG
int sqlite3VdbeOpcodeNoPush(u8 op){
return opcodeNoPush(op);
}
#endif
/*
** Loop through the program looking for P2 values that are negative.
** Each such value is a label. Resolve the label by setting the P2
@@ -338,7 +296,7 @@ static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs, int *pMaxStack){
if( n>nMaxArgs ) nMaxArgs = n;
#endif
}
if( opcodeNoPush(opcode) ){
if( !sqlite3VdbeOpcodeHasProperty(opcode, OPFLG_PUSH) ){
nMaxStack--;
}