dilook(a, b, t) int a, b;
char t[26][13];
{
  register i, j;
  i = t[maplow(a) - 'a'][(j = maplow(b) - 'a') / 2];
  if (!(j & 01))
    i >>= 4;
  return (i & 017);
}


x86 assembly (clang, -O0):
<dilook>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %edi,-0x4(%rbp)
mov    %esi,-0x8(%rbp)
mov    %rdx,-0x10(%rbp)
mov    -0x10(%rbp),%rax
mov    %rax,-0x28(%rbp)
mov    -0x4(%rbp),%edi
mov    $0x0,%al
call   1030 <maplow@plt>
mov    %eax,%ecx
mov    -0x28(%rbp),%rax
sub    $0x61,%ecx
movslq %ecx,%rcx
imul   $0xd,%rcx,%rcx
add    %rcx,%rax
mov    %rax,-0x20(%rbp)
mov    -0x8(%rbp),%edi
mov    $0x0,%al
call   1030 <maplow@plt>
sub    $0x61,%eax
mov    %eax,-0x18(%rbp)
mov    $0x2,%ecx
cltd
idiv   %ecx
mov    %eax,%ecx
mov    -0x20(%rbp),%rax
movslq %ecx,%rcx
movsbl (%rax,%rcx,1),%eax
mov    %eax,-0x14(%rbp)
mov    -0x18(%rbp),%eax
and    $0x1,%eax
cmp    $0x0,%eax
jne    118b <dilook+0x7b>
mov    -0x14(%rbp),%eax
sar    $0x4,%eax
mov    %eax,-0x14(%rbp)
mov    -0x14(%rbp),%eax
and    $0xf,%eax
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<dilook>:
push   %rbp
push   %r14
push   %rbx
mov    %rdx,%r14
mov    %esi,%ebp
xor    %eax,%eax
call   1030 <maplow@plt>
movslq %eax,%rbx
mov    %ebp,%edi
xor    %eax,%eax
call   1030 <maplow@plt>
mov    %eax,%ecx
add    $0xffffff9f,%ecx
mov    %ecx,%edx
shr    $0x1f,%edx
add    %edx,%eax
add    $0xffffff9f,%eax
sar    %eax
cltq
lea    (%rbx,%rbx,2),%rdx
add    $0xfffffffffffffedd,%rdx
lea    (%rbx,%rdx,4),%rdx
add    $0xffffffffffffff9f,%rdx
add    %r14,%rdx
movzbl (%rax,%rdx,1),%edx
mov    %edx,%eax
shr    $0x4,%eax
test   $0x1,%cl
cmovne %edx,%eax
and    $0xf,%eax
pop    %rbx
pop    %r14
pop    %rbp
ret

LLVM IR (-O0):
define i32 @dilook(i32 %0, i32 %1, [13 x i8]* %2) {
%4 = alloca i32
%5 = alloca i32
%6 = alloca [13 x i8]*
%7 = alloca i32
%8 = alloca i32
store i32 %0, i32* %4
store i32 %1, i32* %5
store [13 x i8]* %2, [13 x i8]** %6
%9 = load [13 x i8]*, [13 x i8]** %6
%10 = load i32, i32* %4
%11 = call i32 (i32, ...) bitcast (i32 (...)* @maplow to i32 (i32, ...)*)(i32 %10)
%12 = sub nsw i32 %11, 97
%13 = sext i32 %12 to i64
%14 = getelementptr inbounds [13 x i8], [13 x i8]* %9, i64 %13
%15 = load i32, i32* %5
%16 = call i32 (i32, ...) bitcast (i32 (...)* @maplow to i32 (i32, ...)*)(i32 %15)
%17 = sub nsw i32 %16, 97
store i32 %17, i32* %8
%18 = sdiv i32 %17, 2
%19 = sext i32 %18 to i64
%20 = getelementptr inbounds [13 x i8], [13 x i8]* %14, i64 0, i64 %19
%21 = load i8, i8* %20
%22 = sext i8 %21 to i32
store i32 %22, i32* %7
%23 = load i32, i32* %8
%24 = and i32 %23, 1
%25 = icmp ne i32 %24, 0
br i1 %25, label %29, label %26
26: ; preds = %3
%27 = load i32, i32* %7
%28 = ashr i32 %27, 4
store i32 %28, i32* %7
br label %29
29: ; preds = %26, %3
%30 = load i32, i32* %7
%31 = and i32 %30, 15
ret i32 %31
}

LLVM IR (-O2):
define i32 @dilook(i32 %0, i32 %1, [13 x i8]* nocapture %2) {
%4 = tail call i32 (i32, ...) bitcast (i32 (...)* @maplow to i32 (i32, ...)*)(i32 %0)
%5 = add nsw i32 %4, -97
%6 = sext i32 %5 to i64
%7 = tail call i32 (i32, ...) bitcast (i32 (...)* @maplow to i32 (i32, ...)*)(i32 %1)
%8 = add nsw i32 %7, -97
%9 = sdiv i32 %8, 2
%10 = sext i32 %9 to i64
%11 = getelementptr inbounds [13 x i8], [13 x i8]* %2, i64 %6, i64 %10
%12 = load i8, i8* %11
%13 = zext i8 %12 to i32
%14 = and i32 %8, 1
%15 = icmp eq i32 %14, 0
%16 = lshr i32 %13, 4
%17 = select i1 %15, i32 %16, i32 %13
%18 = and i32 %17, 15
ret i32 %18
}