#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */

/* Variables and functions */
int strlen(char *);
int is_number(char *buffer) {
  int i;
  for (i = 0; i < strlen(buffer); i++) {
    if (!(buffer[i] <= '9' && buffer[i] >= '0')) {
      return 0;
    }
  }
  return 1;
}


x86 assembly (clang, -O0):
<is_number>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x10(%rbp)
movl   $0x0,-0x14(%rbp)
mov    -0x14(%rbp),%eax
mov    %eax,-0x18(%rbp)
mov    -0x10(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,%ecx
mov    -0x18(%rbp),%eax
cmp    %ecx,%eax
jge    1188 <is_number+0x78>
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsbl (%rax,%rcx,1),%eax
cmp    $0x39,%eax
jg     1169 <is_number+0x59>
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsbl (%rax,%rcx,1),%eax
cmp    $0x30,%eax
jge    1175 <is_number+0x65>
movl   $0x0,-0x4(%rbp)
jmp    118f <is_number+0x7f>
jmp    117a <is_number+0x6a>
mov    -0x14(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x14(%rbp)
jmp    1123 <is_number+0x13>
movl   $0x1,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<is_number>:
push   %rbp
push   %r14
push   %rbx
mov    %rdi,%rbx
call   1030 <strlen@plt>
mov    $0x1,%r14d
test   %eax,%eax
jle    1152 <is_number+0x42>
xor    %ebp,%ebp
nopl   0x0(%rax,%rax,1)
movzbl (%rbx,%rbp,1),%eax
add    $0xd0,%al
cmp    $0xa,%al
jae    114f <is_number+0x3f>
add    $0x1,%rbp
mov    %rbx,%rdi
call   1030 <strlen@plt>
cltq
cmp    %rax,%rbp
jl     1130 <is_number+0x20>
jmp    1152 <is_number+0x42>
xor    %r14d,%r14d
mov    %r14d,%eax
pop    %rbx
pop    %r14
pop    %rbp
ret

LLVM IR (-O0):
define i32 @is_number(i8* %0) {
%2 = alloca i32
%3 = alloca i8*
%4 = alloca i32
store i8* %0, i8** %3
store i32 0, i32* %4
br label %5
5: ; preds = %28, %1
%6 = load i32, i32* %4
%7 = load i8*, i8** %3
%8 = call i32 @strlen(i8* %7)
%9 = icmp slt i32 %6, %8
br i1 %9, label %10, label %31
10: ; preds = %5
%11 = load i8*, i8** %3
%12 = load i32, i32* %4
%13 = sext i32 %12 to i64
%14 = getelementptr inbounds i8, i8* %11, i64 %13
%15 = load i8, i8* %14
%16 = sext i8 %15 to i32
%17 = icmp sle i32 %16, 57
br i1 %17, label %18, label %26
18: ; preds = %10
%19 = load i8*, i8** %3
%20 = load i32, i32* %4
%21 = sext i32 %20 to i64
%22 = getelementptr inbounds i8, i8* %19, i64 %21
%23 = load i8, i8* %22
%24 = sext i8 %23 to i32
%25 = icmp sge i32 %24, 48
br i1 %25, label %27, label %26
26: ; preds = %18, %10
store i32 0, i32* %2
br label %32
27: ; preds = %18
br label %28
28: ; preds = %27
%29 = load i32, i32* %4
%30 = add nsw i32 %29, 1
store i32 %30, i32* %4
br label %5
31: ; preds = %5
store i32 1, i32* %2
br label %32
32: ; preds = %31, %26
%33 = load i32, i32* %2
ret i32 %33
}

LLVM IR (-O2):
define i32 @is_number(i8* %0) {
%2 = tail call i32 @strlen(i8* %0)
%3 = icmp sgt i32 %2, 0
br i1 %3, label %8, label %15
4: ; preds = %8
%5 = tail call i32 @strlen(i8* %0)
%6 = sext i32 %5 to i64
%7 = icmp slt i64 %14, %6
br i1 %7, label %8, label %15
8: ; preds = %1, %4
%9 = phi i64 [ %14, %4 ], [ 0, %1 ]
%10 = getelementptr inbounds i8, i8* %0, i64 %9
%11 = load i8, i8* %10
%12 = add i8 %11, -48
%13 = icmp ult i8 %12, 10
%14 = add nuw nsw i64 %9, 1
br i1 %13, label %4, label %15
15: ; preds = %8, %4, %1
%16 = phi i32 [ 1, %1 ], [ 1, %4 ], [ 0, %8 ]
ret i32 %16
}