#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 */
size_t strlen(char const *);
int /*<<< orphan*/ strncasecmp(char const *, char const *, size_t const);
const char *_pico_stristr(const char *str, const char *substr) {
  const size_t sublen = strlen(substr);
  while (*str) {
    if (!strncasecmp(str, substr, sublen))
      break;
    str++;
  }
  if (!(*str))
    str = NULL;
  return str;
}


x86 assembly (clang, -O0):
<_pico_stristr>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x10(%rbp),%rdi
call   1030 <strlen@plt>
mov    %rax,-0x18(%rbp)
mov    -0x8(%rbp),%rax
cmpb   $0x0,(%rax)
je     117a <_pico_stristr+0x5a>
mov    -0x8(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x18(%rbp),%rdx
call   1040 <strncasecmp@plt>
cmp    $0x0,%eax
jne    1169 <_pico_stristr+0x49>
jmp    117a <_pico_stristr+0x5a>
mov    -0x8(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x8(%rbp)
jmp    113d <_pico_stristr+0x1d>
mov    -0x8(%rbp),%rax
cmpb   $0x0,(%rax)
jne    118f <_pico_stristr+0x6f>
movq   $0x0,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<_pico_stristr>:
push   %r15
push   %r14
push   %rbx
mov    %rsi,%r14
mov    %rdi,%rbx
mov    %rsi,%rdi
call   1030 <strlen@plt>
cmpb   $0x0,(%rbx)
je     115c <_pico_stristr+0x3c>
mov    %rax,%r15
nopl   0x0(%rax,%rax,1)
mov    %rbx,%rdi
mov    %r14,%rsi
mov    %r15,%rdx
call   1040 <strncasecmp@plt>
test   %eax,%eax
je     115e <_pico_stristr+0x3e>
cmpb   $0x0,0x1(%rbx)
lea    0x1(%rbx),%rbx
jne    1140 <_pico_stristr+0x20>
xor    %ebx,%ebx
mov    %rbx,%rax
pop    %rbx
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
define i8* @_pico_stristr(i8* %0, i8* %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i64
store i8* %0, i8** %3
store i8* %1, i8** %4
%6 = load i8*, i8** %4
%7 = call i64 @strlen(i8* %6)
store i64 %7, i64* %5
br label %8
8: ; preds = %19, %2
%9 = load i8*, i8** %3
%10 = load i8, i8* %9
%11 = icmp ne i8 %10, 0
br i1 %11, label %12, label %22
12: ; preds = %8
%13 = load i8*, i8** %3
%14 = load i8*, i8** %4
%15 = load i64, i64* %5
%16 = call i32 @strncasecmp(i8* %13, i8* %14, i64 %15)
%17 = icmp ne i32 %16, 0
br i1 %17, label %19, label %18
18: ; preds = %12
br label %22
19: ; preds = %12
%20 = load i8*, i8** %3
%21 = getelementptr inbounds i8, i8* %20, i32 1
store i8* %21, i8** %3
br label %8
22: ; preds = %18, %8
%23 = load i8*, i8** %3
%24 = load i8, i8* %23
%25 = icmp ne i8 %24, 0
br i1 %25, label %27, label %26
26: ; preds = %22
store i8* null, i8** %3
br label %27
27: ; preds = %26, %22
%28 = load i8*, i8** %3
ret i8* %28
}

LLVM IR (-O2):
define i8* @_pico_stristr(i8* %0, i8* nocapture %1) {
%3 = tail call i64 @strlen(i8* dereferenceable(1) %1)
%4 = load i8, i8* %0
%5 = icmp eq i8 %4, 0
br i1 %5, label %14, label %6
6: ; preds = %2, %10
%7 = phi i8* [ %11, %10 ], [ %0, %2 ]
%8 = tail call i32 @strncasecmp(i8* %7, i8* %1, i64 %3)
%9 = icmp eq i32 %8, 0
br i1 %9, label %14, label %10
10: ; preds = %6
%11 = getelementptr inbounds i8, i8* %7, i64 1
%12 = load i8, i8* %11
%13 = icmp eq i8 %12, 0
br i1 %13, label %14, label %6
14: ; preds = %10, %6, %2
%15 = phi i8* [ null, %2 ], [ %7, %6 ], [ null, %10 ]
ret i8* %15
}