recur(cnt) {
  int i, j, sum;
  if (cnt > 0) {
    return recur(cnt - 1);
  } else {
    sum = 0;
    for (j = 0; j < 20; j++) {
      for (i = 0; i < 100000; i++) {
        sum += 1;
      }
      (void)printf("done loop %d\n", j);
    }
    return sum;
  }
}


x86 assembly (clang, -O0):
<recur>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %edi,-0x8(%rbp)
cmpl   $0x0,-0x8(%rbp)
jle    1148 <recur+0x28>
mov    -0x8(%rbp),%edi
sub    $0x1,%edi
call   1040 <recur@plt>
mov    %eax,-0x4(%rbp)
jmp    11b0 <recur+0x90>
movl   $0x0,-0x14(%rbp)
movl   $0x0,-0x10(%rbp)
cmpl   $0x14,-0x10(%rbp)
jge    11aa <recur+0x8a>
movl   $0x0,-0xc(%rbp)
cmpl   $0x186a0,-0xc(%rbp)
jge    118b <recur+0x6b>
mov    -0x14(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x14(%rbp)
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    1167 <recur+0x47>
mov    -0x10(%rbp),%esi
lea    0xe6b(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    -0x10(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x10(%rbp)
jmp    1156 <recur+0x36>
mov    -0x14(%rbp),%eax
mov    %eax,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<recur>:
push   %rbx
lea    0xee8(%rip),%rbx
mov    %rbx,%rdi
xor    %esi,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x1,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x2,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x3,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x4,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x5,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x6,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x7,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x8,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x9,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0xa,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0xb,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0xc,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0xd,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0xe,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0xf,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x10,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x11,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x12,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %rbx,%rdi
mov    $0x13,%esi
xor    %eax,%eax
call   1030 <printf@plt>
mov    $0x1e8480,%eax
pop    %rbx
ret

LLVM IR (-O0):
@.str = [14 x i8] c"done loop %d\0A\00"
define i32 @recur(i32 %0) {
%2 = alloca i32
%3 = alloca i32
%4 = alloca i32
%5 = alloca i32
%6 = alloca i32
store i32 %0, i32* %3
%7 = load i32, i32* %3
%8 = icmp sgt i32 %7, 0
br i1 %8, label %9, label %13
9: ; preds = %1
%10 = load i32, i32* %3
%11 = sub nsw i32 %10, 1
%12 = call i32 @recur(i32 %11)
store i32 %12, i32* %2
br label %35
13: ; preds = %1
store i32 0, i32* %6
store i32 0, i32* %5
br label %14
14: ; preds = %30, %13
%15 = load i32, i32* %5
%16 = icmp slt i32 %15, 20
br i1 %16, label %17, label %33
17: ; preds = %14
store i32 0, i32* %4
br label %18
18: ; preds = %24, %17
%19 = load i32, i32* %4
%20 = icmp slt i32 %19, 100000
br i1 %20, label %21, label %27
21: ; preds = %18
%22 = load i32, i32* %6
%23 = add nsw i32 %22, 1
store i32 %23, i32* %6
br label %24
24: ; preds = %21
%25 = load i32, i32* %4
%26 = add nsw i32 %25, 1
store i32 %26, i32* %4
br label %18
27: ; preds = %18
%28 = load i32, i32* %5
%29 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 %28)
br label %30
30: ; preds = %27
%31 = load i32, i32* %5
%32 = add nsw i32 %31, 1
store i32 %32, i32* %5
br label %14
33: ; preds = %14
%34 = load i32, i32* %6
store i32 %34, i32* %2
br label %35
35: ; preds = %33, %9
%36 = load i32, i32* %2
ret i32 %36
}

LLVM IR (-O2):
@.str = [14 x i8] c"done loop %d\0A\00"
define i32 @recur(i32 %0) {
%2 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 0)
%3 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 1)
%4 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 2)
%5 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 3)
%6 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 4)
%7 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 5)
%8 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 6)
%9 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 7)
%10 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 8)
%11 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 9)
%12 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 10)
%13 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 11)
%14 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 12)
%15 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 13)
%16 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 14)
%17 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 15)
%18 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 16)
%19 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 17)
%20 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 18)
%21 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i32 19)
ret i32 2000000
}