On Fri, 12 Apr 2013, Nicolas Cellier wrote:

> Once you recompileAll, they do not fail anymore.

Digging into the code a bit I found out that the pushTemp: bytecode is a 
hack to duplicate the value which will be assigned.

The generated code could be improved if Binding >> #value: would 
always return its argument. In that case the bytecode could follow the 
assignment chain directly:

78 <25> pushConstant: ##ActiveWorld
79 <26> pushConstant: ##ActiveHand
80 <27> pushConstant: ##ActiveEvent
81 <73> pushConstant: nil
82 <CA> send: value:
83 <CA> send: value:
84 <CA> send: value:
85 <87> pop

It doesn't seem to be a simple change though.


Levente

> Still the same problem, Compiler recompileAll will leave unbound CompiledMethod here and there.
> 
> 
> 2013/4/12 Levente Uzonyi <leves at elte.hu>
>       On Fri, 12 Apr 2013, Frank Shearar wrote:
>
>             This, and the other decompiler test failure, happens because of the
>             recent chained assignment work:
>
>             original snippet:
>
>                ActiveWorld := ActiveHand := ActiveEvent := nil.
>
>             decompiled version of sameL
>
>                ActiveEvent := nil.
>                ActiveHand := nil.
>                ActiveWorld := nil.
>
>             How to fix?
> 
> 
> The only method with this assignment chain in my image is MorphicProject
>             #saveState . The bytecodes for this line are:
> 
> 
> 73 <73> pushConstant: nil
> 74 <81 C5> storeIntoLit: ActiveEvent
> 76 <81 C6> storeIntoLit: ActiveHand
> 78 <82 C7> popIntoLit: ActiveWorld
> 
> And the decompiler can reproduce the original code.
> 
> If I recompile this method (which should have been done due to the Environments changes, but for some reason it hasn't happened yet), then there's a bug in the compiler. The bytecodes will be:
> 
> 78 <25> pushConstant: ##ActiveWorld
> 79 <73> pushConstant: nil
> 80 <27> pushConstant: ##ActiveEvent
> 81 <80 41> pushTemp: 1
> 83 <CA> send: value:
> 84 <87> pop
> 85 <26> pushConstant: ##ActiveHand
> 86 <80 41> pushTemp: 1
> 88 <CA> send: value:
> 89 <87> pop
> 90 <CA> send: value:
> 91 <87> pop
> 
> Which are obviously wrong.
> 
> Creating a new method with just a simple assignment chain:
> 
> foo
> 
>         GlobalA := GlobalB := $a
> 
> generetes:
> 
> 25 <20> pushConstant: ##GlobalA
> 26 <22> pushConstant: $a
> 27 <21> pushConstant: ##GlobalB
> 28 <80 41> pushTemp: 1
> 30 <CA> send: value:
> 31 <87> pop
> 32 <CA> send: value:
> 33 <87> pop
> 34 <78> returnSelf
> 
> Which still has the pushTemp: 1. But this method has 0 temporaries, so it's a compiler bug. I wonder how the decompiler can decompile anything
> meaningful from this, and how the VM doesn't crash.
> 
> 
> Levente
> 
>
>       frank
> 
> 
> 
> 
> 
>