[LLVMdev] Terminator found in the middle of a basic block error

[J. Charles N. M.]

Problem resolved,
sound like a mistake in my source code.
Just forgot to manage my builders.

 ---
| J. Charles



2014-05-05 16:43 GMT+02:00 J. Charles N. M. <jcharles.nmbiada at gmail.com>:

> Hello,
> I am currently building a compilator for an extended CIL to LLVM with the
> OCaml's LLVM API.
>
> For all the branch statements, I need to create some basic block to
> represente the LLVM branchement.
> But after compilation, I got a module error
>
> See message error below :
>
> Terminator found in the middle of a basic block!
> label %lbl3
> Broken module found, compilation aborted!
> Aborted (core dumped)
>
> -------
> And here is the C source code follows by its compilation in LLVM IR
> representation.
>
> C Source:
> int f(void)
> {
>   int c;
>   c = 170;
>   if (c % 7 > 5) c = 7;
>   return c;
> }
>
> int main(void)
> {
>   int tmp;
>   tmp = f();
>   return tmp;
> }
>
> LLVM module :
> ; ModuleID = 'program'
>
> define i32 @f() {
> entry:
>   %c = alloca i32
>   store i32 170, i32* %c
>   %fclv2 = load i32* %c
>   %fclv3 = srem i32 %fclv2, 7
>   %fclv4 = icmp sgt i32 %fclv3, 5
>   br i1 %fclv4, label %lbl1, label %lbl2
>
> lbl1:                                             ; preds = %entry
>   store i32 7, i32* %c
>   br label %lbl3
>
> lbl2:                                             ; preds = %entry
>   br label %lbl3
>
> lbl3:                                             ; preds = %lbl2, %lbl1
>   store i32 7, i32* %c
>   %fclv5 = load i32* %c
>   ret i32 %fclv5
> }
>
> Until this optimized form does not work!
>
> define i32 @f() {
> entry:
>   %c = alloca i32
>   store i32 170, i32* %c
>   %fclv2 = load i32* %c
>   %fclv3 = srem i32 %fclv2, 7
>   %fclv4 = icmp sgt i32 %fclv3, 5
>   br i1 %fclv4, label %lbl1, label %lbl3
>
> lbl1:                                             ; preds = %entry
>   store i32 7, i32* %c
>   br label %lbl3
>
> lbl3:                                             ; preds = %entry, %lbl1
>   store i32 7, i32* %c
>   %fclv5 = load i32* %c
>   ret i32 %fclv5
> }
>
> I cannot understand why my module is corrupted.
> Reference  manuel says
> "[...] every basic block in a program ends with a “Terminator”
> instruction, which indicates which block should be executed after the
> current block is finished. These terminator instructions typically yield a
> ‘void‘ value: they produce control flow, not values (the one exception
> being the ‘invoke‘ instruction).
> The terminator instructions are: ‘ret‘, ‘br‘, ‘switch‘, ‘indirectbr‘,
> ‘invoke‘, ‘resume‘, and ‘unreachable‘."
>
> So whats happened here ?
> Thanks for your helps.
>  ---
> | J. Charles
>
>
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