fact.ll

define private i64 @fact(i64 %n) {
entry:
  %n1 = alloca i64
  store i64 %n, i64* %n1
  %n2 = load i64, i64* %n1
  %eqtmp = icmp eq i64 %n2, 0
  %0 = sext i1 %eqtmp to i64
  %ifcond = icmp ne i64 %0, 0
  br i1 %ifcond, label %then, label %else

then:                                             ; preds = %entry
  br label %ifcont

else:                                             ; preds = %entry
  %n3 = load i64, i64* %n1
  %n4 = load i64, i64* %n1
  %subtmp = sub i64 %n4, 1
  %calltmp = call i64 @fact(i64 %subtmp)
  %multmp = mul i64 %n3, %calltmp
  br label %ifcont

ifcont:                                           ; preds = %else, %then
  %iftmp = phi i64 [ 1, %then ], [ %multmp, %else ]
  ret i64 %iftmp
}

fact.ltr

(def fact (n)
  (if (= n 0)
    1
    (* n (fact (- n 1)))))

fact.optim.ll

define private i64 @fact(i64 %n) {
entry:
  br label %tailrecurse

tailrecurse:                                      ; preds = %else, %entry
  %accumulator.tr = phi i64 [ 1, %entry ], [ %multmp, %else ]
  %n.tr = phi i64 [ %n, %entry ], [ %subtmp, %else ]
  %eqtmp = icmp eq i64 %n.tr, 0
  br i1 %eqtmp, label %ifcont, label %else

else:                                             ; preds = %tailrecurse
  %subtmp = add i64 %n.tr, -1
  %multmp = mul i64 %accumulator.tr, %n.tr
  br label %tailrecurse

ifcont:                                           ; preds = %tailrecurse
  ret i64 %accumulator.tr
}

fact.optim.s

	.align	4, 0x90
l_fact:                                 ## @fact
	.cfi_startproc
## BB#0:                                ## %entry
	movl	$1, %eax
	jmp	LBB1_1
	.align	4, 0x90
LBB1_2:                                 ## %else
                                        ##   in Loop: Header=BB1_1 Depth=1
	imulq	%rdi, %rax
	decq	%rdi
LBB1_1:                                 ## %tailrecurse
                                        ## =>This Inner Loop Header: Depth=1
	testq	%rdi, %rdi
	jne	LBB1_2
## BB#3:                                ## %ifcont
	retq
	.cfi_endproc

fact.s

	.align	4, 0x90
l_fact:                                 ## @fact
	.cfi_startproc
## BB#0:                                ## %entry
	pushq	%rbx
Ltmp2:
	.cfi_def_cfa_offset 16
	subq	$16, %rsp
Ltmp3:
	.cfi_def_cfa_offset 32
Ltmp4:
	.cfi_offset %rbx, -16
	movq	%rdi, 8(%rsp)
	cmpq	$1, %rdi
	movl	$1, %eax
	jb	LBB1_2
## BB#1:                                ## %else
	movq	8(%rsp), %rbx
	leaq	-1(%rbx), %rdi
	callq	l_fact
	imulq	%rbx, %rax
LBB1_2:                                 ## %ifcont
	addq	$16, %rsp
	popq	%rbx
	retq
	.cfi_endproc