fact.ll

@str = internal constant [4 x i8] c"%d\0A\00"
                                                                                                                     
define void @main() nounwind {
  %fact = call i32 @fact.tr(i32 5)
  call i32 @printf( i8* getelementptr ([4 x i8]* @str, i32 0,i32 0), i32 %fact)
  ret void
}

; tail recurse
define i32 @fact.tr(i32 %n) nounwind {
  %fact = call i32 @fact0(i32 %n, i32 1)
  ret i32 %fact
}

define i32 @fact0(i32 %n, i32 %f) nounwind {
  %cond = icmp ule i32 %n, 1
  br i1 %cond, label %c1, label %c2

c1:
  ret i32 %f

c2:
  %f1 = mul i32 %n, %f
  %n1 = sub i32 %n, 1
  %r = call i32 @fact0(i32 %n1, i32 %f1)
  ret i32 %r
}


; non-tail-recurse
define i32 @fact.ntr(i32 %n) nounwind {
  %cond = icmp ule i32 %n, 1
  br i1 %cond, label %c1, label %c2

c1:
  ret i32 1

c2:
  %n1 = sub i32 %n, 1
  %fact1 = call i32 @fact.ntr(i32 %n1)
  %r = mul i32 %fact1, %n
  ret i32 %r
} 
  
declare i32 @printf(i8*, ...) nounwind