int f(a)
int a;
{
  switch (a & 7) {
  case 7:
    printf("7\n");
  case 6:
    printf("6\n");
  case 5:
    printf("5\n");
  case 4:
    printf("4\n");
  case 3:
    printf("3\n");
  case 2:
    printf("2\n");
  case 1:
    printf("1\n");
  }
}


x86 assembly (clang, -O0):
<f>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %edi,-0x8(%rbp)
mov    -0x8(%rbp),%eax
and    $0x7,%eax
add    $0xffffffff,%eax
mov    %eax,%ecx
mov    %rcx,-0x10(%rbp)
sub    $0x6,%eax
ja     11a9 <f+0x99>
mov    -0x10(%rbp),%rax
lea    0xec2(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xece(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xec3(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xeb8(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xead(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xea2(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xe97(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xe8c(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    -0x4(%rbp),%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<f>:
and    $0x7,%edi
add    $0xffffffff,%edi
cmp    $0x6,%edi
ja     1184 <f+0x74>
push   %rax
lea    0xedd(%rip),%rax
movslq (%rax,%rdi,4),%rcx
add    %rax,%rcx
jmp    *%rcx
lea    0xef5(%rip),%rdi
call   1030 <puts@plt>
lea    0xee7(%rip),%rdi
call   1030 <puts@plt>
lea    0xed9(%rip),%rdi
call   1030 <puts@plt>
lea    0xecb(%rip),%rdi
call   1030 <puts@plt>
lea    0xebd(%rip),%rdi
call   1030 <puts@plt>
lea    0xeaf(%rip),%rdi
call   1030 <puts@plt>
lea    0xea1(%rip),%rdi
call   1030 <puts@plt>
add    $0x8,%rsp
ret

LLVM IR (-O0):
@.str = [3 x i8] c"7\0A\00"
@.str.1 = [3 x i8] c"6\0A\00"
@.str.2 = [3 x i8] c"5\0A\00"
@.str.3 = [3 x i8] c"4\0A\00"
@.str.4 = [3 x i8] c"3\0A\00"
@.str.5 = [3 x i8] c"2\0A\00"
@.str.6 = [3 x i8] c"1\0A\00"
define i32 @f(i32 %0) {
%2 = alloca i32
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
%5 = and i32 %4, 7
switch i32 %5, label %20 [
i32 7, label %6
i32 6, label %8
i32 5, label %10
i32 4, label %12
i32 3, label %14
i32 2, label %16
i32 1, label %18
]
6: ; preds = %1
%7 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0))
br label %8
8: ; preds = %1, %6
%9 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0))
br label %10
10: ; preds = %1, %8
%11 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0))
br label %12
12: ; preds = %1, %10
%13 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.3, i64 0, i64 0))
br label %14
14: ; preds = %1, %12
%15 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.4, i64 0, i64 0))
br label %16
16: ; preds = %1, %14
%17 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.5, i64 0, i64 0))
br label %18
18: ; preds = %1, %16
%19 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.6, i64 0, i64 0))
br label %20
20: ; preds = %18, %1
%21 = load i32, i32* %2
ret i32 %21
}

LLVM IR (-O2):
@str = [2 x i8] c"1\00"
@str.7 = [2 x i8] c"2\00"
@str.8 = [2 x i8] c"3\00"
@str.9 = [2 x i8] c"4\00"
@str.10 = [2 x i8] c"5\00"
@str.11 = [2 x i8] c"6\00"
@str.12 = [2 x i8] c"7\00"
define i32 @f(i32 %0) {
%2 = and i32 %0, 7
switch i32 %2, label %17 [
i32 7, label %3
i32 6, label %5
i32 5, label %7
i32 4, label %9
i32 3, label %11
i32 2, label %13
i32 1, label %15
]
3: ; preds = %1
%4 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([2 x i8], [2 x i8]* @str.12, i64 0, i64 0))
br label %5
5: ; preds = %1, %3
%6 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([2 x i8], [2 x i8]* @str.11, i64 0, i64 0))
br label %7
7: ; preds = %1, %5
%8 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([2 x i8], [2 x i8]* @str.10, i64 0, i64 0))
br label %9
9: ; preds = %1, %7
%10 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([2 x i8], [2 x i8]* @str.9, i64 0, i64 0))
br label %11
11: ; preds = %1, %9
%12 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([2 x i8], [2 x i8]* @str.8, i64 0, i64 0))
br label %13
13: ; preds = %1, %11
%14 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([2 x i8], [2 x i8]* @str.7, i64 0, i64 0))
br label %15
15: ; preds = %1, %13
%16 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([2 x i8], [2 x i8]* @str, i64 0, i64 0))
br label %17
17: ; preds = %15, %1
ret i32 undef
}