int equal3x3(double *restrict a, double *restrict b) {
  return *a++ == *b++ && *a++ == *b++ && *a++ == *b++ && *a++ == *b++ &&
         *a++ == *b++ && *a++ == *b++ && *a++ == *b++ && *a++ == *b++ &&
         *a == *b;
}


x86 assembly (clang, -O0):
<equal3x3>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rcx
mov    %rcx,%rax
add    $0x8,%rax
mov    %rax,-0x10(%rbp)
xor    %eax,%eax
ucomisd (%rcx),%xmm0
mov    %al,-0x11(%rbp)
jne    12df <equal3x3+0x1df>
jp     12df <equal3x3+0x1df>
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rax
ucomisd (%rax),%xmm0
sete   %al
setnp  %cl
and    %cl,%al
mov    %al,-0x11(%rbp)
mov    -0x11(%rbp),%al
and    $0x1,%al
movzbl %al,%eax
pop    %rbp
ret

x86 assembly (clang, -O2):
<equal3x3>:
movsd  (%rdi),%xmm0
xor    %eax,%eax
ucomisd (%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x8(%rdi),%xmm0
ucomisd 0x8(%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x10(%rdi),%xmm0
ucomisd 0x10(%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x18(%rdi),%xmm0
ucomisd 0x18(%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x20(%rdi),%xmm0
ucomisd 0x20(%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x28(%rdi),%xmm0
ucomisd 0x28(%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x30(%rdi),%xmm0
ucomisd 0x30(%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x38(%rdi),%xmm0
ucomisd 0x38(%rsi),%xmm0
jne    1183 <equal3x3+0x83>
jp     1183 <equal3x3+0x83>
movsd  0x40(%rsi),%xmm0
cmpeqsd 0x40(%rdi),%xmm0
movq   %xmm0,%rax
and    $0x1,%eax
ret

LLVM IR (-O0):
define i32 @equal3x3(double* noalias %0, double* noalias %1) {
%3 = alloca double*
%4 = alloca double*
store double* %0, double** %3
store double* %1, double** %4
%5 = load double*, double** %3
%6 = getelementptr inbounds double, double* %5, i32 1
store double* %6, double** %3
%7 = load double, double* %5
%8 = load double*, double** %4
%9 = getelementptr inbounds double, double* %8, i32 1
store double* %9, double** %4
%10 = load double, double* %8
%11 = fcmp oeq double %7, %10
br i1 %11, label %12, label %74
12: ; preds = %2
%13 = load double*, double** %3
%14 = getelementptr inbounds double, double* %13, i32 1
store double* %14, double** %3
%15 = load double, double* %13
%16 = load double*, double** %4
%17 = getelementptr inbounds double, double* %16, i32 1
store double* %17, double** %4
%18 = load double, double* %16
%19 = fcmp oeq double %15, %18
br i1 %19, label %20, label %74
20: ; preds = %12
%21 = load double*, double** %3
%22 = getelementptr inbounds double, double* %21, i32 1
store double* %22, double** %3
%23 = load double, double* %21
%24 = load double*, double** %4
%25 = getelementptr inbounds double, double* %24, i32 1
store double* %25, double** %4
%26 = load double, double* %24
%27 = fcmp oeq double %23, %26
br i1 %27, label %28, label %74
28: ; preds = %20
%29 = load double*, double** %3
%30 = getelementptr inbounds double, double* %29, i32 1
store double* %30, double** %3
%31 = load double, double* %29
%32 = load double*, double** %4
%33 = getelementptr inbounds double, double* %32, i32 1
store double* %33, double** %4
%34 = load double, double* %32
%35 = fcmp oeq double %31, %34
br i1 %35, label %36, label %74
36: ; preds = %28
%37 = load double*, double** %3
%38 = getelementptr inbounds double, double* %37, i32 1
store double* %38, double** %3
%39 = load double, double* %37
%40 = load double*, double** %4
%41 = getelementptr inbounds double, double* %40, i32 1
store double* %41, double** %4
%42 = load double, double* %40
%43 = fcmp oeq double %39, %42
br i1 %43, label %44, label %74
44: ; preds = %36
%45 = load double*, double** %3
%46 = getelementptr inbounds double, double* %45, i32 1
store double* %46, double** %3
%47 = load double, double* %45
%48 = load double*, double** %4
%49 = getelementptr inbounds double, double* %48, i32 1
store double* %49, double** %4
%50 = load double, double* %48
%51 = fcmp oeq double %47, %50
br i1 %51, label %52, label %74
52: ; preds = %44
%53 = load double*, double** %3
%54 = getelementptr inbounds double, double* %53, i32 1
store double* %54, double** %3
%55 = load double, double* %53
%56 = load double*, double** %4
%57 = getelementptr inbounds double, double* %56, i32 1
store double* %57, double** %4
%58 = load double, double* %56
%59 = fcmp oeq double %55, %58
br i1 %59, label %60, label %74
60: ; preds = %52
%61 = load double*, double** %3
%62 = getelementptr inbounds double, double* %61, i32 1
store double* %62, double** %3
%63 = load double, double* %61
%64 = load double*, double** %4
%65 = getelementptr inbounds double, double* %64, i32 1
store double* %65, double** %4
%66 = load double, double* %64
%67 = fcmp oeq double %63, %66
br i1 %67, label %68, label %74
68: ; preds = %60
%69 = load double*, double** %3
%70 = load double, double* %69
%71 = load double*, double** %4
%72 = load double, double* %71
%73 = fcmp oeq double %70, %72
br label %74
74: ; preds = %68, %60, %52, %44, %36, %28, %20, %12, %2
%75 = phi i1 [ false, %60 ], [ false, %52 ], [ false, %44 ], [ false, %36 ], [ false, %28 ], [ false, %20 ], [ false, %12 ], [ false, %2 ], [ %73, %68 ]
%76 = zext i1 %75 to i32
ret i32 %76
}

LLVM IR (-O2):
define i32 @equal3x3(double* noalias nocapture %0, double* noalias nocapture %1) {
%3 = load double, double* %0
%4 = load double, double* %1
%5 = fcmp oeq double %3, %4
br i1 %5, label %6, label %55
6: ; preds = %2
%7 = getelementptr inbounds double, double* %1, i64 1
%8 = getelementptr inbounds double, double* %0, i64 1
%9 = load double, double* %8
%10 = load double, double* %7
%11 = fcmp oeq double %9, %10
br i1 %11, label %12, label %55
12: ; preds = %6
%13 = getelementptr inbounds double, double* %1, i64 2
%14 = getelementptr inbounds double, double* %0, i64 2
%15 = load double, double* %14
%16 = load double, double* %13
%17 = fcmp oeq double %15, %16
br i1 %17, label %18, label %55
18: ; preds = %12
%19 = getelementptr inbounds double, double* %1, i64 3
%20 = getelementptr inbounds double, double* %0, i64 3
%21 = load double, double* %20
%22 = load double, double* %19
%23 = fcmp oeq double %21, %22
br i1 %23, label %24, label %55
24: ; preds = %18
%25 = getelementptr inbounds double, double* %1, i64 4
%26 = getelementptr inbounds double, double* %0, i64 4
%27 = load double, double* %26
%28 = load double, double* %25
%29 = fcmp oeq double %27, %28
br i1 %29, label %30, label %55
30: ; preds = %24
%31 = getelementptr inbounds double, double* %1, i64 5
%32 = getelementptr inbounds double, double* %0, i64 5
%33 = load double, double* %32
%34 = load double, double* %31
%35 = fcmp oeq double %33, %34
br i1 %35, label %36, label %55
36: ; preds = %30
%37 = getelementptr inbounds double, double* %1, i64 6
%38 = getelementptr inbounds double, double* %0, i64 6
%39 = load double, double* %38
%40 = load double, double* %37
%41 = fcmp oeq double %39, %40
br i1 %41, label %42, label %55
42: ; preds = %36
%43 = getelementptr inbounds double, double* %1, i64 7
%44 = getelementptr inbounds double, double* %0, i64 7
%45 = load double, double* %44
%46 = load double, double* %43
%47 = fcmp oeq double %45, %46
br i1 %47, label %48, label %55
48: ; preds = %42
%49 = getelementptr inbounds double, double* %1, i64 8
%50 = getelementptr inbounds double, double* %0, i64 8
%51 = load double, double* %50
%52 = load double, double* %49
%53 = fcmp oeq double %51, %52
%54 = zext i1 %53 to i32
br label %55
55: ; preds = %48, %42, %36, %30, %24, %18, %12, %6, %2
%56 = phi i32 [ 0, %42 ], [ 0, %36 ], [ 0, %30 ], [ 0, %24 ], [ 0, %18 ], [ 0, %12 ], [ 0, %6 ], [ 0, %2 ], [ %54, %48 ]
ret i32 %56
}