Unnamed temporaries

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#1

Hi,

I hope this is the right place to ask it, sorry if I’m wrong…

My compiler is generating this code:

(line numbers included) (Please ignore the extra br label %b0 and the whole b0)

...

  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

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

  66      br label %return
  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

  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 ; int
^

Why %4 ??? what I did wrong?

#2

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.

#3

Thank you so much,

removing then solved the problem.

I did not know thre where such a thing as anonymous blocks I thought llvm was going to ignore anything after a terminator instruction (br, ret, etc)

I’ll make my code generator “block aware” :stuck_out_tongue:

thank you again!!! :stuck_out_tongue: