C++ vs assembly code

[Pter0dactyl]

x=10; l= ++x + x++ + x
At first I thought evaluation takes place from right to left. So we have x=10
then, x++= 10 (later it will be converted to 11 for next evaluation)
then, ++x= 12 ( 11 +1) hence, we get, 12+10+10=32!
But I executed the program in three different compilers(g++ , turboC++ and DevC++) and I found that the answer is 33. I couldn't understand the its behind-the-scene working so I decided to deassemble the executable file and check its machine code to see if I could get anything out of it. Here's the machine code

mov [esp+0C],0000000A; this is variable x mov
 [esp+08],00000000; this is l cuz I initialised l to 0
 inc [esp+0C]
 mov eax,[esp+0C]
 add eax,eax
 add eax,[esp+0C] ;here we get accumulator register with value 33
 mov [esp+08],eax ;moving 33 to variable l

I cannot connect the C++ code with machine code. Can anyone help?

[Ispil]

Addition and prefix evaluate left-to-right, not right-to-left. Assignment evaluates right-to-left.

[keskiverto]

The code has undefined behaviour, so no matter what the compiler does, it is equally wrong.

y = ++x + x++ + x;
// is similar to
y = A + B + C;

// The A and B have to be evaluated before the first addition can be evaluated
// The order of evaluating A and B is up to implementation
// The C has to be evaluated before the second addtion, but can be evaluated before the first addition
// Therefore, the C can be before A and B, between them, or after them 

[Pter0dactyl]

@ispil: In that case it should evaluate to 11+11+12. That makes it 34 but it's evaluating to 33.
@keskiverto: Do you mean that the answer to such questions is unpredictable?

[keskiverto]

Yes.

See the sequence point rules: http://en.cppreference.com/w/cpp/language/eval_order

[Ispil]

Heh, I was trying to figure out whether it was undefined or not, but for some reason I blanked on that. Yes, the code here will change depending on where you compile it more than what you compile it with.

[TheHardew]

It has to be undefined, it changes x's value multiple times during the assignment.