struct op *dogroup(onlydone)
int onlydone;
{
  register int c;
  register struct op *list;
  c = yylex(01);
  if (c == 271 && onlydone)
    return ((struct op *)0);
  if (c != 270)
    zzerr();
  list = c_list();
  musthave(271, 0);
  return (list);
}


x86 assembly (clang, -O0):
<dogroup>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %edi,-0xc(%rbp)
mov    $0x1,%edi
mov    $0x0,%al
call   1060 <yylex@plt>
mov    %eax,-0x10(%rbp)
cmpl   $0x10f,-0x10(%rbp)
jne    117e <dogroup+0x3e>
cmpl   $0x0,-0xc(%rbp)
je     117e <dogroup+0x3e>
movq   $0x0,-0x8(%rbp)
jmp    11b5 <dogroup+0x75>
cmpl   $0x10e,-0x10(%rbp)
je     1192 <dogroup+0x52>
mov    $0x0,%al
call   1030 <zzerr@plt>
mov    $0x0,%al
call   1040 <c_list@plt>
cltq
mov    %rax,-0x18(%rbp)
mov    $0x10f,%edi
xor    %esi,%esi
mov    $0x0,%al
call   1050 <musthave@plt>
mov    -0x18(%rbp),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<dogroup>:
push   %rbp
push   %rbx
push   %rax
mov    %edi,%ebp
xor    %ebx,%ebx
mov    $0x1,%edi
xor    %eax,%eax
call   1060 <yylex@plt>
test   %ebp,%ebp
je     115e <dogroup+0x1e>
cmp    $0x10f,%eax
je     1184 <dogroup+0x44>
cmp    $0x10e,%eax
je     116c <dogroup+0x2c>
xor    %eax,%eax
call   1030 <zzerr@plt>
xor    %eax,%eax
call   1040 <c_list@plt>
movslq %eax,%rbx
mov    $0x10f,%edi
xor    %esi,%esi
xor    %eax,%eax
call   1050 <musthave@plt>
mov    %rbx,%rax
add    $0x8,%rsp
pop    %rbx
pop    %rbp
ret

LLVM IR (-O0):
%struct.op = type opaque
define %struct.op* @dogroup(i32 %0) {
%2 = alloca %struct.op*
%3 = alloca i32
%4 = alloca i32
%5 = alloca %struct.op*
store i32 %0, i32* %3
%6 = call i32 (i32, ...) bitcast (i32 (...)* @yylex to i32 (i32, ...)*)(i32 1)
store i32 %6, i32* %4
%7 = load i32, i32* %4
%8 = icmp eq i32 %7, 271
br i1 %8, label %9, label %13
9: ; preds = %1
%10 = load i32, i32* %3
%11 = icmp ne i32 %10, 0
br i1 %11, label %12, label %13
12: ; preds = %9
store %struct.op* null, %struct.op** %2
br label %24
13: ; preds = %9, %1
%14 = load i32, i32* %4
%15 = icmp ne i32 %14, 270
br i1 %15, label %16, label %18
16: ; preds = %13
%17 = call i32 (...) @zzerr()
br label %18
18: ; preds = %16, %13
%19 = call i32 (...) @c_list()
%20 = sext i32 %19 to i64
%21 = inttoptr i64 %20 to %struct.op*
store %struct.op* %21, %struct.op** %5
%22 = call i32 (i32, i32, ...) bitcast (i32 (...)* @musthave to i32 (i32, i32, ...)*)(i32 271, i32 0)
%23 = load %struct.op*, %struct.op** %5
store %struct.op* %23, %struct.op** %2
br label %24
24: ; preds = %18, %12
%25 = load %struct.op*, %struct.op** %2
ret %struct.op* %25
}

LLVM IR (-O2):
%struct.op = type opaque
define %struct.op* @dogroup(i32 %0) {
%2 = tail call i32 (i32, ...) bitcast (i32 (...)* @yylex to i32 (i32, ...)*)(i32 1)
%3 = icmp eq i32 %2, 271
%4 = icmp ne i32 %0, 0
%5 = and i1 %4, %3
br i1 %5, label %15, label %6
6: ; preds = %1
%7 = icmp eq i32 %2, 270
br i1 %7, label %10, label %8
8: ; preds = %6
%9 = tail call i32 (...) @zzerr()
br label %10
10: ; preds = %8, %6
%11 = tail call i32 (...) @c_list()
%12 = sext i32 %11 to i64
%13 = inttoptr i64 %12 to %struct.op*
%14 = tail call i32 (i32, i32, ...) bitcast (i32 (...)* @musthave to i32 (i32, i32, ...)*)(i32 271, i32 0)
br label %15
15: ; preds = %1, %10
%16 = phi %struct.op* [ %13, %10 ], [ null, %1 ]
ret %struct.op* %16
}