#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 *);
char *find(char *haystack, char needle) {
  int i = 0;
  for (; i < strlen(haystack); i++) {
    if (*(haystack + i) == needle) {
      return &haystack[i + 1];
      break;
    }
  }
  return 0;
}


x86 assembly (clang, -O0):
<find>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %sil,%al
mov    %rdi,-0x10(%rbp)
mov    %al,-0x11(%rbp)
movl   $0x0,-0x18(%rbp)
mov    -0x18(%rbp),%eax
mov    %eax,-0x1c(%rbp)
mov    -0x10(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,%ecx
mov    -0x1c(%rbp),%eax
cmp    %ecx,%eax
jge    1189 <find+0x79>
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
movsbl (%rax,%rcx,1),%eax
movsbl -0x11(%rbp),%ecx
cmp    %ecx,%eax
jne    1176 <find+0x66>
mov    -0x10(%rbp),%rax
mov    -0x18(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
add    %rcx,%rax
mov    %rax,-0x8(%rbp)
jmp    1191 <find+0x81>
jmp    117b <find+0x6b>
mov    -0x18(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x18(%rbp)
jmp    1129 <find+0x19>
movq   $0x0,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<find>:
push   %rbp
push   %r15
push   %r14
push   %rbx
push   %rax
mov    %esi,%r15d
mov    %rdi,%rbx
call   1030 <strlen@plt>
xor    %r14d,%r14d
test   %eax,%eax
jle    1153 <find+0x43>
xor    %ebp,%ebp
nopl   0x0(%rax,%rax,1)
cmp    %r15b,(%rbx,%rbp,1)
je     114b <find+0x3b>
add    $0x1,%rbp
mov    %rbx,%rdi
call   1030 <strlen@plt>
cltq
cmp    %rax,%rbp
jl     1130 <find+0x20>
jmp    1153 <find+0x43>
lea    (%rbx,%rbp,1),%r14
add    $0x1,%r14
mov    %r14,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
define i8* @find(i8* %0, i8 signext %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i8
%6 = alloca i32
store i8* %0, i8** %4
store i8 %1, i8* %5
store i32 0, i32* %6
br label %7
7: ; preds = %29, %2
%8 = load i32, i32* %6
%9 = load i8*, i8** %4
%10 = call i32 @strlen(i8* %9)
%11 = icmp slt i32 %8, %10
br i1 %11, label %12, label %32
12: ; preds = %7
%13 = load i8*, i8** %4
%14 = load i32, i32* %6
%15 = sext i32 %14 to i64
%16 = getelementptr inbounds i8, i8* %13, i64 %15
%17 = load i8, i8* %16
%18 = sext i8 %17 to i32
%19 = load i8, i8* %5
%20 = sext i8 %19 to i32
%21 = icmp eq i32 %18, %20
br i1 %21, label %22, label %28
22: ; preds = %12
%23 = load i8*, i8** %4
%24 = load i32, i32* %6
%25 = add nsw i32 %24, 1
%26 = sext i32 %25 to i64
%27 = getelementptr inbounds i8, i8* %23, i64 %26
store i8* %27, i8** %3
br label %33
28: ; preds = %12
br label %29
29: ; preds = %28
%30 = load i32, i32* %6
%31 = add nsw i32 %30, 1
store i32 %31, i32* %6
br label %7
32: ; preds = %7
store i8* null, i8** %3
br label %33
33: ; preds = %32, %22
%34 = load i8*, i8** %3
ret i8* %34
}

LLVM IR (-O2):
define i8* @find(i8* %0, i8 signext %1) {
%3 = tail call i32 @strlen(i8* %0)
%4 = icmp sgt i32 %3, 0
br i1 %4, label %5, label %18
5: ; preds = %2, %14
%6 = phi i64 [ %10, %14 ], [ 0, %2 ]
%7 = getelementptr inbounds i8, i8* %0, i64 %6
%8 = load i8, i8* %7
%9 = icmp eq i8 %8, %1
%10 = add nuw nsw i64 %6, 1
br i1 %9, label %11, label %14
11: ; preds = %5
%12 = and i64 %10, 4294967295
%13 = getelementptr inbounds i8, i8* %0, i64 %12
br label %18
14: ; preds = %5
%15 = tail call i32 @strlen(i8* %0)
%16 = sext i32 %15 to i64
%17 = icmp slt i64 %10, %16
br i1 %17, label %5, label %18
18: ; preds = %14, %2, %11
%19 = phi i8* [ %13, %11 ], [ null, %2 ], [ null, %14 ]
ret i8* %19
}