Algorithm that was supposed to go into recurse does not go into recurse

Question

I am pretty new to LLVM IR and I am trying to convert the following into LLVM IR

double sum(double *input, int n) {
  double result = input[0] + ... + input[n-1]
  return result
}

and this is what I have done:

    %free_func = type void (double*)*
    %list = type { %list*, double*, %free_func }



define double @sum(double* %ptr, i32 %n) {
entry:
    %var1 = alloca i32
    store i32 %n, i32* %var1
    %var2 = alloca double*
    store double* %ptr, double** %var2

    %conv1.1 = load i32, i32* %var1
    %tmp1 = icmp sle i32 %conv1.1, 0
    
    br i1 %tmp1, label %recurse, label %done

        
    recurse:
        
        %0 = bitcast double** %var2 to %list*       ; base field
        %1 = bitcast double** %var2 to %list**      ; next field
        %2 = bitcast double** %var2 to %list***     ; next next field

        %3 = bitcast %list* %0 to i16*
        %conv2.1 = load i16, i16* %3
        %4 = bitcast %list** %1 to i16*        
        %conv2.2 = load i16, i16* %4

        %tmp2 = add nsw i16 %conv2.2, %conv2.1    ; add base value & next value
        %tmp3 = alloca i16
        store i16 %tmp2, i16* %tmp3

        %5 = bitcast i16* %tmp3 to %list*         ; convert vector back to list
        store %list* %5, %list** %1               ; replace next value with sum
        %conv3.1 = load %list*, %list** %1        ; replace base with next
        %conv3.2 = load %list**, %list*** %2      ; replace next with next next
        %6 = bitcast %list* %conv3.1 to double*   ; convert list back to double

        %tmp5 = sub nsw i32 %conv1.1, 1

        %tmp6 = call double @sum(double* %6, i32 %tmp5) 

        ret double %tmp6

        
    done:
        
        %conv6.1 = load double, double* %ptr
        ret double %conv6.1

}

It seems to go straight to done without going through recurse and I am not sure what is wrong. May I ask for tips on how to make this work? Thank you and I am sorry if the code looks messy because I've only just started learning and am practising.