int is_definition(t_num)
int t_num;
{
  if (isletter(t_num) && equals(t_num + 1, "="))
    return 1;
  if (isletter(t_num) && equals(t_num + 1, "(") && isletter(t_num + 2)) {
    t_num += 3;
    while (equals(t_num, ",")) {
      if (!isletter(++t_num))
        return 0;
      t_num += 1;
    }
    return (equals(t_num, ")") && equals(t_num + 1, "="));
  }
  return 0;
}


x86 assembly (clang, -O0):
<is_definition>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %edi,-0x8(%rbp)
mov    -0x8(%rbp),%edi
mov    $0x0,%al
call   1030 <isletter@plt>
cmp    $0x0,%eax
je     1167 <is_definition+0x47>
mov    -0x8(%rbp),%edi
add    $0x1,%edi
lea    0xeb5(%rip),%rsi
mov    $0x0,%al
call   1040 <equals@plt>
cmp    $0x0,%eax
je     1167 <is_definition+0x47>
movl   $0x1,-0x4(%rbp)
jmp    1258 <is_definition+0x138>
mov    -0x8(%rbp),%edi
mov    $0x0,%al
call   1030 <isletter@plt>
cmp    $0x0,%eax
je     1251 <is_definition+0x131>
mov    -0x8(%rbp),%edi
add    $0x1,%edi
lea    0xe7b(%rip),%rsi
mov    $0x0,%al
call   1040 <equals@plt>
cmp    $0x0,%eax
je     1251 <is_definition+0x131>
mov    -0x8(%rbp),%edi
add    $0x2,%edi
mov    $0x0,%al
call   1030 <isletter@plt>
cmp    $0x0,%eax
je     1251 <is_definition+0x131>
mov    -0x8(%rbp),%eax
add    $0x3,%eax
mov    %eax,-0x8(%rbp)
mov    -0x8(%rbp),%edi
lea    0xe44(%rip),%rsi
mov    $0x0,%al
call   1040 <equals@plt>
cmp    $0x0,%eax
je     1203 <is_definition+0xe3>
mov    -0x8(%rbp),%edi
add    $0x1,%edi
mov    %edi,-0x8(%rbp)
mov    $0x0,%al
call   1030 <isletter@plt>
cmp    $0x0,%eax
jne    11f5 <is_definition+0xd5>
movl   $0x0,-0x4(%rbp)
jmp    1258 <is_definition+0x138>
mov    -0x8(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x8(%rbp)
jmp    11b6 <is_definition+0x96>
mov    -0x8(%rbp),%edi
lea    0xdf9(%rip),%rsi
mov    $0x0,%al
call   1040 <equals@plt>
mov    %eax,%ecx
xor    %eax,%eax
cmp    $0x0,%ecx
mov    %al,-0x9(%rbp)
je     1241 <is_definition+0x121>
mov    -0x8(%rbp),%edi
add    $0x1,%edi
lea    0xdcf(%rip),%rsi
mov    $0x0,%al
call   1040 <equals@plt>
cmp    $0x0,%eax
setne  %al
mov    %al,-0x9(%rbp)
mov    -0x9(%rbp),%al
and    $0x1,%al
movzbl %al,%eax
mov    %eax,-0x4(%rbp)
jmp    1258 <is_definition+0x138>
movl   $0x0,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<is_definition>:
push   %rbp
push   %r14
push   %rbx
mov    %edi,%ebx
xor    %eax,%eax
call   1030 <isletter@plt>
test   %eax,%eax
je     114f <is_definition+0x2f>
lea    0x1(%rbx),%edi
lea    0xec5(%rip),%rsi
xor    %eax,%eax
call   1040 <equals@plt>
mov    $0x1,%ebp
test   %eax,%eax
jne    121d <is_definition+0xfd>
mov    %ebx,%edi
xor    %eax,%eax
call   1030 <isletter@plt>
mov    $0x0,%ebp
test   %eax,%eax
je     121d <is_definition+0xfd>
lea    0x1(%rbx),%edi
lea    0xe93(%rip),%rsi
xor    %ebp,%ebp
xor    %eax,%eax
call   1040 <equals@plt>
test   %eax,%eax
je     121d <is_definition+0xfd>
lea    0x2(%rbx),%edi
xor    %ebp,%ebp
xor    %eax,%eax
call   1030 <isletter@plt>
test   %eax,%eax
je     121d <is_definition+0xfd>
lea    0x3(%rbx),%r14d
lea    0xe65(%rip),%rsi
xor    %ebp,%ebp
mov    %r14d,%edi
xor    %eax,%eax
call   1040 <equals@plt>
test   %eax,%eax
je     11e7 <is_definition+0xc7>
add    $0x5,%ebx
lea    0xe4b(%rip),%r14
nopl   0x0(%rax)
lea    -0x1(%rbx),%edi
xor    %eax,%eax
call   1030 <isletter@plt>
test   %eax,%eax
je     121b <is_definition+0xfb>
mov    %ebx,%edi
mov    %r14,%rsi
xor    %eax,%eax
call   1040 <equals@plt>
add    $0x2,%ebx
test   %eax,%eax
jne    11c0 <is_definition+0xa0>
add    $0xfffffffe,%ebx
mov    %ebx,%r14d
lea    0xe18(%rip),%rsi
mov    %r14d,%edi
xor    %eax,%eax
call   1040 <equals@plt>
test   %eax,%eax
je     121d <is_definition+0xfd>
add    $0x1,%r14d
lea    0xdf9(%rip),%rsi
mov    %r14d,%edi
xor    %eax,%eax
call   1040 <equals@plt>
xor    %ebp,%ebp
test   %eax,%eax
setne  %bpl
jmp    121d <is_definition+0xfd>
xor    %ebp,%ebp
mov    %ebp,%eax
pop    %rbx
pop    %r14
pop    %rbp
ret

LLVM IR (-O0):
@.str = [2 x i8] c"=\00"
@.str.1 = [2 x i8] c"(\00"
@.str.2 = [2 x i8] c",\00"
@.str.3 = [2 x i8] c")\00"
define i32 @is_definition(i32 %0) {
%2 = alloca i32
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
%5 = call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %4)
%6 = icmp ne i32 %5, 0
br i1 %6, label %7, label %13
7: ; preds = %1
%8 = load i32, i32* %3
%9 = add nsw i32 %8, 1
%10 = call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %9, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
%11 = icmp ne i32 %10, 0
br i1 %11, label %12, label %13
12: ; preds = %7
store i32 1, i32* %2
br label %56
13: ; preds = %7, %1
%14 = load i32, i32* %3
%15 = call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %14)
%16 = icmp ne i32 %15, 0
br i1 %16, label %17, label %55
17: ; preds = %13
%18 = load i32, i32* %3
%19 = add nsw i32 %18, 1
%20 = call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %19, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.1, i64 0, i64 0))
%21 = icmp ne i32 %20, 0
br i1 %21, label %22, label %55
22: ; preds = %17
%23 = load i32, i32* %3
%24 = add nsw i32 %23, 2
%25 = call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %24)
%26 = icmp ne i32 %25, 0
br i1 %26, label %27, label %55
27: ; preds = %22
%28 = load i32, i32* %3
%29 = add nsw i32 %28, 3
store i32 %29, i32* %3
br label %30
30: ; preds = %40, %27
%31 = load i32, i32* %3
%32 = call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %31, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.2, i64 0, i64 0))
%33 = icmp ne i32 %32, 0
br i1 %33, label %34, label %43
34: ; preds = %30
%35 = load i32, i32* %3
%36 = add nsw i32 %35, 1
store i32 %36, i32* %3
%37 = call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %36)
%38 = icmp ne i32 %37, 0
br i1 %38, label %40, label %39
39: ; preds = %34
store i32 0, i32* %2
br label %56
40: ; preds = %34
%41 = load i32, i32* %3
%42 = add nsw i32 %41, 1
store i32 %42, i32* %3
br label %30
43: ; preds = %30
%44 = load i32, i32* %3
%45 = call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %44, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.3, i64 0, i64 0))
%46 = icmp ne i32 %45, 0
br i1 %46, label %47, label %52
47: ; preds = %43
%48 = load i32, i32* %3
%49 = add nsw i32 %48, 1
%50 = call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %49, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
%51 = icmp ne i32 %50, 0
br label %52
52: ; preds = %47, %43
%53 = phi i1 [ false, %43 ], [ %51, %47 ]
%54 = zext i1 %53 to i32
store i32 %54, i32* %2
br label %56
55: ; preds = %22, %17, %13
store i32 0, i32* %2
br label %56
56: ; preds = %55, %52, %39, %12
%57 = load i32, i32* %2
ret i32 %57
}

LLVM IR (-O2):
@.str = [2 x i8] c"=\00"
@.str.1 = [2 x i8] c"(\00"
@.str.2 = [2 x i8] c",\00"
@.str.3 = [2 x i8] c")\00"
define i32 @is_definition(i32 %0) {
%2 = tail call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %0)
%3 = icmp eq i32 %2, 0
br i1 %3, label %8, label %4
4: ; preds = %1
%5 = add nsw i32 %0, 1
%6 = tail call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %5, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
%7 = icmp eq i32 %6, 0
br i1 %7, label %8, label %41
8: ; preds = %4, %1
%9 = tail call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %0)
%10 = icmp eq i32 %9, 0
br i1 %10, label %41, label %11
11: ; preds = %8
%12 = add nsw i32 %0, 1
%13 = tail call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %12, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.1, i64 0, i64 0))
%14 = icmp eq i32 %13, 0
br i1 %14, label %41, label %15
15: ; preds = %11
%16 = add nsw i32 %0, 2
%17 = tail call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %16)
%18 = icmp eq i32 %17, 0
br i1 %18, label %41, label %19
19: ; preds = %15
%20 = add nsw i32 %0, 3
%21 = tail call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %20, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.2, i64 0, i64 0))
%22 = icmp eq i32 %21, 0
br i1 %22, label %32, label %23
23: ; preds = %19, %28
%24 = phi i32 [ %29, %28 ], [ %20, %19 ]
%25 = add nsw i32 %24, 1
%26 = tail call i32 (i32, ...) bitcast (i32 (...)* @isletter to i32 (i32, ...)*)(i32 %25)
%27 = icmp eq i32 %26, 0
br i1 %27, label %41, label %28
28: ; preds = %23
%29 = add nsw i32 %24, 2
%30 = tail call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %29, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.2, i64 0, i64 0))
%31 = icmp eq i32 %30, 0
br i1 %31, label %32, label %23
32: ; preds = %28, %19
%33 = phi i32 [ %20, %19 ], [ %29, %28 ]
%34 = tail call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %33, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.3, i64 0, i64 0))
%35 = icmp eq i32 %34, 0
br i1 %35, label %41, label %36
36: ; preds = %32
%37 = add nsw i32 %33, 1
%38 = tail call i32 (i32, i8*, ...) bitcast (i32 (...)* @equals to i32 (i32, i8*, ...)*)(i32 %37, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
%39 = icmp ne i32 %38, 0
%40 = zext i1 %39 to i32
br label %41
41: ; preds = %23, %8, %11, %15, %32, %36, %4
%42 = phi i32 [ 1, %4 ], [ 0, %32 ], [ %40, %36 ], [ 0, %15 ], [ 0, %11 ], [ 0, %8 ], [ 0, %23 ]
ret i32 %42
}