On Tue, 27 Nov 2001, Chris Tutty wrote:
> MemHandle BlahGetNextItem(UInt16 * Index)
> {
> if (mBlahDB == NULL)
> return NULL;
>
> return DmQueryNextInCategory(mBlahDB, Index, mCategory);
> }
MemHandle BlahGetNextItem(UInt16 *Index)
{
MemHandle result = NULL;
// ErrFatalDisplayIf(mBlahDB == NULL, "bullocks, database is not open");
if (mBlahDB) result = DmQueryNextInCategory(mBlahDB, Index, mCategory);
return result;
}
try rewriting it.. :) also, if that doesn't work.. uncomment the
ErrFatalDisplayIf call :)
> which is set using an OpenBlahDB function called when the module
> is first accessed.
100% sure about this?
> This function is always returning NULL. In fact, the debugger only
> shows the '-' (showing an 'active' source line) beside the opening
> and closing braces and the 'return NULL' line. The only thing I
> can think of is that the compiler thinks that the test will always
> return true and is dead-stripping the rest of the function. The 'if'
> statement is never being executed.
>
> On the other hand the assembler seems to include it (my 15-year
> old memory of assembler suggests that a 'tst.l' followed by a 'bne'
> is a Branch on Not Equal and so would seem to be reasonable
> assembler for an if test against NULL) but the debugger clearly
> shows that variable as non-NULL and yet the test is being acted
> on as if true.
15-year old? hehe.. he's just perfect for the warez group! :)
[for all you know, maybe he is] :P
> This code is in a static library and is compiled with optimisation
> level set to 1. Having noticed this I've set the optimisation level
> to 0 (no deadstripping, among other things) and it seems to have
> fixed the problem (surprising how many things you find while
> carefully explaining the problem to someone else) but I don't see
> how this is valid behaviour for the optimiser.
>
> I've run into this kind of dead-stripping problem before with v6
> and fixed it by forcing a side-effect in the block being dead-stripped
> but seeing the same sort of problem in v7 worries me.
>
> So. Is it something stupid I'm doing or the compiler?
i think its probably the compiler, trying to be too smart.. :)
having multiple returns in a function can confuse the compiler
(not to mention it is bad programming) :P
just try rewriting the function a bit..
// az
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http://www.ardiri.com/
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