Hi,
On Mon, Nov 26, 2018 at 12:27:38PM +0100, Thomas De Schampheleire wrote:
> El mié., 21 nov. 2018 a las 15:46, Thomas De Schampheleire
> (<patrickdepinguin@xxxxxxxxx>) escribió:
> Modified code is:
>
> if( fg & MEM_Int ){
> sqlite3_snprintf(nByte, pMem->z, "%lld", pMem->u.i);
> }else{
> assert( fg & MEM_Real );
> asm volatile("" ::: "memory");
> sqlite3_snprintf(nByte, pMem->z, "%!.15g", pMem->u.r);
> }
>
> My question now becomes: is gcc allowed to optimize here (without the barrier)?
> Is gcc allowed to pre-load the floating point value pMem->u.r if it
> does not know yet that the value in the union is a floating-point
> value, knowing that a load of an invalid (integer) value could cause
> floating-point exceptions like underflow?
It depends on many things. We need to have some full, compilable source
code; know which target exactly; exact compiler flags used; what you saw
happen and why you think that is wrong. And then file it on
https://gcc.gnu.org/bugzilla please.
Segher
