int main() {
  int count, n;
  char *from, *to;
  char a[39], b[39];
  for (n = 0; n < 39; n++) {
    a[n] = n;
    b[n] = 0;
  }
  from = a;
  to = b;
  count = 39;
  n = (count + 7) / 8;
  switch (count % 8) {
  case 0:
    do {
      *to++ = *from++;
    case 7:
      *to++ = *from++;
    case 6:
      *to++ = *from++;
    case 5:
      *to++ = *from++;
    case 4:
      *to++ = *from++;
    case 3:
      *to++ = *from++;
    case 2:
      *to++ = *from++;
    case 1:
      *to++ = *from++;
    } while (--n > 0);
  }
  for (n = 0; n < 39; n++)
    if (a[n] != b[n])
      return 1;
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
movl   $0x0,-0x4(%rbp)
movl   $0x0,-0xc(%rbp)
cmpl   $0x27,-0xc(%rbp)
jge    1144 <main+0x44>
mov    -0xc(%rbp),%eax
mov    %al,%cl
movslq -0xc(%rbp),%rax
mov    %cl,-0x50(%rbp,%rax,1)
movslq -0xc(%rbp),%rax
movb   $0x0,-0x80(%rbp,%rax,1)
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    1116 <main+0x16>
lea    -0x50(%rbp),%rax
mov    %rax,-0x18(%rbp)
lea    -0x80(%rbp),%rax
mov    %rax,-0x20(%rbp)
movl   $0x27,-0x8(%rbp)
mov    -0x8(%rbp),%ecx
mov    %ecx,%eax
add    $0x7,%eax
add    $0xe,%ecx
test   %eax,%eax
cmovs  %ecx,%eax
sar    $0x3,%eax
mov    %eax,-0xc(%rbp)
mov    -0x8(%rbp),%eax
mov    %eax,%edx
add    $0x7,%edx
test   %eax,%eax
mov    %eax,%ecx
cmovs  %edx,%ecx
and    $0xfffffff8,%ecx
sub    %ecx,%eax
mov    %eax,%ecx
mov    %rcx,-0x88(%rbp)
sub    $0x7,%eax
ja     12da <main+0x1da>
mov    -0x88(%rbp),%rax
lea    0xe5b(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
jmp    11b3 <main+0xb3>
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0x18(%rbp),%rax
mov    %rax,%rcx
add    $0x1,%rcx
mov    %rcx,-0x18(%rbp)
mov    (%rax),%cl
mov    -0x20(%rbp),%rax
mov    %rax,%rdx
add    $0x1,%rdx
mov    %rdx,-0x20(%rbp)
mov    %cl,(%rax)
mov    -0xc(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0xc(%rbp)
cmp    $0x0,%eax
jg     11b3 <main+0xb3>
jmp    12da <main+0x1da>
movl   $0x0,-0xc(%rbp)
cmpl   $0x27,-0xc(%rbp)
jge    1324 <main+0x224>
movslq -0xc(%rbp),%rax
movsbl -0x50(%rbp,%rax,1),%eax
movslq -0xc(%rbp),%rcx
movsbl -0x80(%rbp,%rcx,1),%ecx
cmp    %ecx,%eax
je     1311 <main+0x211>
movl   $0x1,-0x4(%rbp)
jmp    132b <main+0x22b>
jmp    1316 <main+0x216>
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    12e1 <main+0x1e1>
movl   $0x0,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
movaps 0xef9(%rip),%xmm0
movaps %xmm0,-0x28(%rsp)
movaps 0xefd(%rip),%xmm1
movaps %xmm1,-0x18(%rsp)
movl   $0x23222120,-0x8(%rsp)
23
movw   $0x2524,-0x4(%rsp)
movb   $0x26,-0x2(%rsp)
movaps %xmm0,-0x58(%rsp)
movabs $0x1716151413121110,%rax
15 16 17
mov    %rax,-0x48(%rsp)
movl   $0x1b1a1918,-0x40(%rsp)
1b
movb   $0x1c,-0x3c(%rsp)
movzwl -0xb(%rsp),%eax
mov    %ax,-0x3b(%rsp)
mov    -0x9(%rsp),%al
mov    %al,-0x39(%rsp)
movb   $0x20,-0x38(%rsp)
mov    -0x7(%rsp),%al
mov    -0x6(%rsp),%cl
mov    %al,-0x37(%rsp)
mov    %cl,-0x36(%rsp)
mov    -0x5(%rsp),%al
mov    %al,-0x35(%rsp)
mov    -0x4(%rsp),%al
mov    %al,-0x34(%rsp)
mov    -0x3(%rsp),%al
mov    %al,-0x33(%rsp)
mov    -0x2(%rsp),%al
mov    %al,-0x32(%rsp)
mov    $0x2,%ecx
mov    $0x1,%eax
xchg   %ax,%ax
movzbl -0x2a(%rsp,%rcx,1),%edx
cmp    -0x5a(%rsp,%rcx,1),%dl
jne    11cd <main+0xcd>
movzbl -0x29(%rsp,%rcx,1),%edx
cmp    -0x59(%rsp,%rcx,1),%dl
jne    11cd <main+0xcd>
movzbl -0x28(%rsp,%rcx,1),%edx
cmp    -0x58(%rsp,%rcx,1),%dl
jne    11cd <main+0xcd>
add    $0x3,%rcx
cmp    $0x29,%rcx
jne    11a0 <main+0xa0>
xor    %eax,%eax
ret

LLVM IR (-O0):
define i32 @main() {
%1 = alloca i32
%2 = alloca i32
%3 = alloca i32
%4 = alloca i8*
%5 = alloca i8*
%6 = alloca [39 x i8]
%7 = alloca [39 x i8]
store i32 0, i32* %1
store i32 0, i32* %3
br label %8
8: ; preds = %20, %0
%9 = load i32, i32* %3
%10 = icmp slt i32 %9, 39
br i1 %10, label %11, label %23
11: ; preds = %8
%12 = load i32, i32* %3
%13 = trunc i32 %12 to i8
%14 = load i32, i32* %3
%15 = sext i32 %14 to i64
%16 = getelementptr inbounds [39 x i8], [39 x i8]* %6, i64 0, i64 %15
store i8 %13, i8* %16
%17 = load i32, i32* %3
%18 = sext i32 %17 to i64
%19 = getelementptr inbounds [39 x i8], [39 x i8]* %7, i64 0, i64 %18
store i8 0, i8* %19
br label %20
20: ; preds = %11
%21 = load i32, i32* %3
%22 = add nsw i32 %21, 1
store i32 %22, i32* %3
br label %8
23: ; preds = %8
%24 = getelementptr inbounds [39 x i8], [39 x i8]* %6, i64 0, i64 0
store i8* %24, i8** %4
%25 = getelementptr inbounds [39 x i8], [39 x i8]* %7, i64 0, i64 0
store i8* %25, i8** %5
store i32 39, i32* %2
%26 = load i32, i32* %2
%27 = add nsw i32 %26, 7
%28 = sdiv i32 %27, 8
store i32 %28, i32* %3
%29 = load i32, i32* %2
%30 = srem i32 %29, 8
switch i32 %30, label %85 [
i32 0, label %31
i32 7, label %38
i32 6, label %44
i32 5, label %50
i32 4, label %56
i32 3, label %62
i32 2, label %68
i32 1, label %74
]
31: ; preds = %23
br label %32
32: ; preds = %80, %31
%33 = load i8*, i8** %4
%34 = getelementptr inbounds i8, i8* %33, i32 1
store i8* %34, i8** %4
%35 = load i8, i8* %33
%36 = load i8*, i8** %5
%37 = getelementptr inbounds i8, i8* %36, i32 1
store i8* %37, i8** %5
store i8 %35, i8* %36
br label %38
38: ; preds = %23, %32
%39 = load i8*, i8** %4
%40 = getelementptr inbounds i8, i8* %39, i32 1
store i8* %40, i8** %4
%41 = load i8, i8* %39
%42 = load i8*, i8** %5
%43 = getelementptr inbounds i8, i8* %42, i32 1
store i8* %43, i8** %5
store i8 %41, i8* %42
br label %44
44: ; preds = %23, %38
%45 = load i8*, i8** %4
%46 = getelementptr inbounds i8, i8* %45, i32 1
store i8* %46, i8** %4
%47 = load i8, i8* %45
%48 = load i8*, i8** %5
%49 = getelementptr inbounds i8, i8* %48, i32 1
store i8* %49, i8** %5
store i8 %47, i8* %48
br label %50
50: ; preds = %23, %44
%51 = load i8*, i8** %4
%52 = getelementptr inbounds i8, i8* %51, i32 1
store i8* %52, i8** %4
%53 = load i8, i8* %51
%54 = load i8*, i8** %5
%55 = getelementptr inbounds i8, i8* %54, i32 1
store i8* %55, i8** %5
store i8 %53, i8* %54
br label %56
56: ; preds = %23, %50
%57 = load i8*, i8** %4
%58 = getelementptr inbounds i8, i8* %57, i32 1
store i8* %58, i8** %4
%59 = load i8, i8* %57
%60 = load i8*, i8** %5
%61 = getelementptr inbounds i8, i8* %60, i32 1
store i8* %61, i8** %5
store i8 %59, i8* %60
br label %62
62: ; preds = %23, %56
%63 = load i8*, i8** %4
%64 = getelementptr inbounds i8, i8* %63, i32 1
store i8* %64, i8** %4
%65 = load i8, i8* %63
%66 = load i8*, i8** %5
%67 = getelementptr inbounds i8, i8* %66, i32 1
store i8* %67, i8** %5
store i8 %65, i8* %66
br label %68
68: ; preds = %23, %62
%69 = load i8*, i8** %4
%70 = getelementptr inbounds i8, i8* %69, i32 1
store i8* %70, i8** %4
%71 = load i8, i8* %69
%72 = load i8*, i8** %5
%73 = getelementptr inbounds i8, i8* %72, i32 1
store i8* %73, i8** %5
store i8 %71, i8* %72
br label %74
74: ; preds = %23, %68
%75 = load i8*, i8** %4
%76 = getelementptr inbounds i8, i8* %75, i32 1
store i8* %76, i8** %4
%77 = load i8, i8* %75
%78 = load i8*, i8** %5
%79 = getelementptr inbounds i8, i8* %78, i32 1
store i8* %79, i8** %5
store i8 %77, i8* %78
br label %80
80: ; preds = %74
%81 = load i32, i32* %3
%82 = add nsw i32 %81, -1
store i32 %82, i32* %3
%83 = icmp sgt i32 %82, 0
br i1 %83, label %32, label %84
84: ; preds = %80
br label %85
85: ; preds = %84, %23
store i32 0, i32* %3
br label %86
86: ; preds = %103, %85
%87 = load i32, i32* %3
%88 = icmp slt i32 %87, 39
br i1 %88, label %89, label %106
89: ; preds = %86
%90 = load i32, i32* %3
%91 = sext i32 %90 to i64
%92 = getelementptr inbounds [39 x i8], [39 x i8]* %6, i64 0, i64 %91
%93 = load i8, i8* %92
%94 = sext i8 %93 to i32
%95 = load i32, i32* %3
%96 = sext i32 %95 to i64
%97 = getelementptr inbounds [39 x i8], [39 x i8]* %7, i64 0, i64 %96
%98 = load i8, i8* %97
%99 = sext i8 %98 to i32
%100 = icmp ne i32 %94, %99
br i1 %100, label %101, label %102
101: ; preds = %89
store i32 1, i32* %1
br label %107
102: ; preds = %89
br label %103
103: ; preds = %102
%104 = load i32, i32* %3
%105 = add nsw i32 %104, 1
store i32 %105, i32* %3
br label %86
106: ; preds = %86
store i32 0, i32* %1
br label %107
107: ; preds = %106, %101
%108 = load i32, i32* %1
ret i32 %108
}

LLVM IR (-O2):
define i32 @main() {
%1 = alloca [39 x i8]
%2 = alloca [39 x i8]
%3 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 0
%4 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 0
%5 = bitcast [39 x i8]* %1 to <16 x i8>*
store <16 x i8> <i8 0, i8 1, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 8, i8 9, i8 10, i8 11, i8 12, i8 13, i8 14, i8 15>, <16 x i8>* %5
%6 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 16
%7 = bitcast i8* %6 to <16 x i8>*
store <16 x i8> <i8 16, i8 17, i8 18, i8 19, i8 20, i8 21, i8 22, i8 23, i8 24, i8 25, i8 26, i8 27, i8 28, i8 29, i8 30, i8 31>, <16 x i8>* %7
%8 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 32
store i8 32, i8* %8
%9 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 33
store i8 33, i8* %9
%10 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 34
store i8 34, i8* %10
%11 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 35
store i8 35, i8* %11
%12 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 36
store i8 36, i8* %12
%13 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 37
store i8 37, i8* %13
%14 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 38
store i8 38, i8* %14
%15 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 16
%16 = bitcast [39 x i8]* %2 to <16 x i8>*
store <16 x i8> <i8 0, i8 1, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 8, i8 9, i8 10, i8 11, i8 12, i8 13, i8 14, i8 15>, <16 x i8>* %16
store i8 16, i8* %15
%17 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 17
store i8 17, i8* %17
%18 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 18
store i8 18, i8* %18
%19 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 19
store i8 19, i8* %19
%20 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 20
store i8 20, i8* %20
%21 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 21
store i8 21, i8* %21
%22 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 22
store i8 22, i8* %22
%23 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 23
%24 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 24
store i8 23, i8* %23
store i8 24, i8* %24
%25 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 25
store i8 25, i8* %25
%26 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 26
store i8 26, i8* %26
%27 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 27
store i8 27, i8* %27
%28 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 28
store i8 28, i8* %28
%29 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 29
%30 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 29
%31 = load i8, i8* %30
store i8 %31, i8* %29
%32 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 30
%33 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 30
%34 = load i8, i8* %33
store i8 %34, i8* %32
%35 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 31
%36 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 31
%37 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 32
%38 = load i8, i8* %36
%39 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 32
store i8 %38, i8* %35
%40 = load i8, i8* %37
store i8 %40, i8* %39
%41 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 33
%42 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 33
%43 = load i8, i8* %42
store i8 %43, i8* %41
%44 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 34
%45 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 34
%46 = load i8, i8* %45
store i8 %46, i8* %44
%47 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 35
%48 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 35
%49 = load i8, i8* %48
store i8 %49, i8* %47
%50 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 36
%51 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 36
%52 = load i8, i8* %51
store i8 %52, i8* %50
%53 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 37
%54 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 37
%55 = load i8, i8* %54
store i8 %55, i8* %53
%56 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 38
%57 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 38
%58 = load i8, i8* %57
store i8 %58, i8* %56
br label %76
59: ; preds = %76
%60 = add nuw nsw i64 %77, 1
%61 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 %60
%62 = load i8, i8* %61
%63 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 %60
%64 = load i8, i8* %63
%65 = icmp eq i8 %62, %64
br i1 %65, label %66, label %83
66: ; preds = %59
%67 = add nuw nsw i64 %77, 2
%68 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 %67
%69 = load i8, i8* %68
%70 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 %67
%71 = load i8, i8* %70
%72 = icmp eq i8 %69, %71
br i1 %72, label %73, label %83
73: ; preds = %66
%74 = add nuw nsw i64 %77, 3
%75 = icmp eq i64 %74, 39
br i1 %75, label %83, label %76
76: ; preds = %73, %0
%77 = phi i64 [ 0, %0 ], [ %74, %73 ]
%78 = getelementptr inbounds [39 x i8], [39 x i8]* %1, i64 0, i64 %77
%79 = load i8, i8* %78
%80 = getelementptr inbounds [39 x i8], [39 x i8]* %2, i64 0, i64 %77
%81 = load i8, i8* %80
%82 = icmp eq i8 %79, %81
br i1 %82, label %59, label %83
83: ; preds = %73, %66, %59, %76
%84 = phi i32 [ 1, %76 ], [ 1, %59 ], [ 1, %66 ], [ 0, %73 ]
ret i32 %84
}