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List of issues#2270 Value assignment and if checking
Author: 
shadow
shadowDate created:
Type: bug
Visibility: Everybody
Assigned to:
Labels: AS3Decompilation
State: closed 
> What steps will reproduce the problem?
code is here;
var _loc5_:Boolean;
if(_loc5_ = _loc6_.stack(param2))
{
stack_Cleanup(_loc6_,param2,param1);
}
pcode is here;
getlocal 6
getlocal2
callproperty QName(PackageNamespace(""),"stack"), 1
convert_b
dup
setlocal 5
iffalse ofs00f7
findpropstrict QName(PackageNamespace(""),"stack_Cleanup")
getlocal 6
getlocal2
getlocal1
callpropvoid QName(PackageNamespace(""),"stack_Cleanup"), 3
ofs00f7:
> What is the expected output? What do you see instead?
var _loc5_:Boolean = _loc6_.stack(param2);
if(_loc5_)
{
stack_Cleanup(_loc6_,param2,param1);
}
> What version of the product are you using? Is it "nightly build"? Which operating system
do you have?
21.0.1
> Please provide any additional information below. If the problem is related to a SWF
file, attach it here, otherwise we can't help you.
Wouldn't it be more correct to export the code in this way? I exported all the codes of a
game and there are errors in about 160 files in this way. it is impossible to fix them all
one by one :)
Your work is incredible. You are doing a great job.
Could you please provide sample SWF file?
I know I don't need it necessarily, but I'd like to investigate further more how it was
compiled.
It is clearly some kind of optimization.
How did you create such file?
I says "Adobe Flash Professional CS6 - build 481" in metadata.
I use the same build 481 and tried to compile such SWF
but my result is:
convert_b
setlocal1
getlocal1
iffalse ofsXXX
instead of your:
convert_b
dup
setlocal1
iffalse ofsXXX
Did you turned on some optimization? How?
Or you modified the p-code it by hand?
Can it be compiled this way using the Flash CS6?
Yes I edited the file in cs6 and then changed the code with JPEXs.
The game is normally developed with FlashDevelop. The game is about 14MB and has a lot of
code in it. Instead of throwing away the whole game file I chose to include a smaller test
file. I can upload the full game if you want.
Yes please, that would be great. Sorry for asking for that, but I'd like to see real world
example.
I still did not manage to compile it that way, even in FlashDevelop.
There must be some optimizer used.
You can find many examples in the screen_Level file in code.sndgames.ptd3.base. Like line
487, line 920, line 1498
PTD3.swf (31,711 KiB)Thank you for providing a SWF.
Also thank you for reporting this, I find this bug pretty crucial.
Now I know the reasons for this.
It is caused by optimization,
this optimization is done on local registers starting from number 4 and on.
It is because instruction "getlocal N" has more bytes than dup instruction and dup
instruction has same length as getlocal0,1,2,3.
The optimizer just changes:
setlocal N
getlocal N
to:
dup
setlocal N
which does the same, but with fewer bytes used.
Sample AS3 code to compile to reproduce this:
----------
var a:int = 1;
var b:int = 2;
var c:int = 3;
var d:int = 4;
var e:int = d + 5;
----------
(there must be more than 3 variables, that's why it did not work for single variable
examples)
FFDec was not prepared for this.
Luckily, in nightly 2852, I fixed it (or at least tried).
It should work now.
State: new→upgraded
I understood the logic now that you explained it to me. No matter how much I thought about
it, I wouldn't have thought of it :D
Thank you for the quick solution. Many people benefit from your work. You are awesome :)
Thanks :-).
It's now released as 21.0.2
State: upgraded→closed