Another optimizer bug (*solved*)

[einar]

Ouch! This bug gave me a headache! It took me some time to figure out the reason my game was crashing...

Take a look at this sample:

Code:

sub test() asm call $fc12 di ld a, $fe ld i, a im 2 ei end asm end sub test()

Try compiling this sample above using:

Code:

zxb.exe -A -O2 prog.bas

And it will produce the expected result:

Code:

_test: push ix ld ix, 0 add ix, sp #line 1 call $fc12 di ld a, $fe ld i, a im 2 ei #line 7 _test__leave: ld sp, ix pop ix ret

However try compiling it again using:

Code:

zxb.exe -A -O3 prog.bas

Now the result won't make sense anymore:

Code:

_test: push ix ld ix, 0 add ix, sp #line 1 call $fc12 di im 2 ei #line 7 _test__leave: ld sp, ix pop ix ret

The problem is, the optimizer is supposed to try to optimize its own generated code only, not someone else's assembly code that it doesn't have enough information to understand!

[boriel]

Try and download the new version ZX BASIC 1.4.0s1902.

It's true the compiler should not optimize user's asm code. But at the moment it's not implemented.
However, the bug was it was not taking into account neither the I register nor the IM instruction. So it was a bug anyway.
Now your example works ok for me.

Can you try it, please??

[einar]

It works, thanks a lot!

[boriel]

It works, thanks a lot!

You're welcome!
A trick to avoid the compiler to optimize your code is to encode the asm using DEFB, DEFW (the bytes) but it's a so hard task... :roll: