[LLVMdev] Unnamed temporaries

[Frits van Bommel]

On Fri, Mar 11, 2011 at 11:48 AM, Judison <judison at gmail.com> wrote:
> I hope this is the right place to ask it, sorry if I'm wrong...

It's the right place, though the IRC channel would have been good too.

> My compiler is generating this code:
>
> (line numbers included) (Please ignore the extra br label %b0 and the whole
> b0)

Sorry, but the extra branches can't be ignored since they are exactly
your problem.

>   54  define i32 @std_lang__rest() {
>   55    entry:
>   56      %ret = alloca i32                        ; <i32*> int*
>
>   57      %0 = icmp eq i32 4, 5                    ; <i1> boolean
>
>   58      br i1 %0, label %b0_t, label %b0_f
>
>   59    b0_t:
>   60      %1 = add i32 5, 2                        ; <i32> int
>
>   61      store i32 %1, i32* %ret
>   62      br label %return


This "br label %return" ended block %b0_t and automatically started a
new one. Since you didn't provide a label, it's named %2.

>
>   63      br label %b0
>   64    b0_f:
>   65      store i32 5, i32* %ret
>
>   66      br label %return

And here block %b0_f ends, and block %3 begins.

>   67      br label %b0
>
>   68    b0:
>   69      store i32 0, i32* %ret
>
>   70      br label %return
>   71    return:
>   72      %2 = load i32* %ret                      ; <i32> int

Leading to %4 being the next anonymous value here, not %2.

>
>   73      ret i32 %2
>   74  }
> ...
>
> llvm-as std_lang.ll
> llvm-as: std_lang.ll:72:5: error: instruction expected to be numbered '%4'
>     %2 = load i32* %ret                      ; <i32> int
>     ^
>
> Why %4 ??? what I did wrong?

You didn't realize there were anonymous blocks in your code, I'm guessing.