#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 last_char_occurance(char *string, char ch) {
  int i, index = -1;
  for (i = 0; i < strlen(string); i++) {
    if (string[i] == ch) {
      index = i;
    }
  }
  return index;
}


x86 assembly (clang, -O0):
<last_char_occurance>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %sil,%al
mov    %rdi,-0x8(%rbp)
mov    %al,-0x9(%rbp)
movl   $0xffffffff,-0x14(%rbp)
movl   $0x0,-0x10(%rbp)
mov    -0x10(%rbp),%eax
mov    %eax,-0x18(%rbp)
mov    -0x8(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,%ecx
mov    -0x18(%rbp),%eax
cmp    %ecx,%eax
jge    117d <last_char_occurance+0x6d>
mov    -0x8(%rbp),%rax
movslq -0x10(%rbp),%rcx
movsbl (%rax,%rcx,1),%eax
movsbl -0x9(%rbp),%ecx
cmp    %ecx,%eax
jne    116a <last_char_occurance+0x5a>
mov    -0x10(%rbp),%eax
mov    %eax,-0x14(%rbp)
jmp    116f <last_char_occurance+0x5f>
mov    -0x10(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x10(%rbp)
jmp    1130 <last_char_occurance+0x20>
mov    -0x14(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<last_char_occurance>:
push   %rbp
push   %r15
push   %r14
push   %rbx
push   %rax
mov    %esi,%r14d
mov    %rdi,%r15
call   1030 <strlen@plt>
mov    $0xffffffff,%ebp
test   %eax,%eax
jle    114a <last_char_occurance+0x3a>
xor    %ebx,%ebx
nopl   (%rax)
cmp    %r14b,(%r15,%rbx,1)
cmove  %ebx,%ebp
add    $0x1,%rbx
mov    %r15,%rdi
call   1030 <strlen@plt>
cltq
cmp    %rax,%rbx
jl     1130 <last_char_occurance+0x20>
mov    %ebp,%eax
add    $0x8,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
ret

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

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