void doubles_cross_matrix(const double v[3], double V[9]) {
  V[0] = 0;
  V[1] = -v[2];
  V[2] = v[1];
  V[3] = v[2];
  V[4] = 0;
  V[5] = -v[0];
  V[6] = -v[1];
  V[7] = v[0];
  V[8] = 0;
}


x86 assembly (clang, -O0):
<doubles_cross_matrix>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x10(%rbp),%rax
xorps  %xmm0,%xmm0
movsd  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
movsd  0x10(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mov    -0x10(%rbp),%rax
movsd  %xmm0,0x8(%rax)
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm0
mov    -0x10(%rbp),%rax
movsd  %xmm0,0x10(%rax)
mov    -0x8(%rbp),%rax
movsd  0x10(%rax),%xmm0
mov    -0x10(%rbp),%rax
movsd  %xmm0,0x18(%rax)
mov    -0x10(%rbp),%rax
xorps  %xmm0,%xmm0
movsd  %xmm0,0x20(%rax)
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mov    -0x10(%rbp),%rax
movsd  %xmm0,0x28(%rax)
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mov    -0x10(%rbp),%rax
movsd  %xmm0,0x30(%rax)
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm0
mov    -0x10(%rbp),%rax
movsd  %xmm0,0x38(%rax)
mov    -0x10(%rbp),%rax
xorps  %xmm0,%xmm0
movsd  %xmm0,0x40(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<doubles_cross_matrix>:
movq   $0x0,(%rsi)
movsd  0x10(%rdi),%xmm0
movaps 0xeed(%rip),%xmm1
xorps  %xmm1,%xmm0
movlps %xmm0,0x8(%rsi)
movsd  0x8(%rdi),%xmm0
movsd  %xmm0,0x10(%rsi)
movsd  0x10(%rdi),%xmm0
movsd  %xmm0,0x18(%rsi)
movq   $0x0,0x20(%rsi)
movsd  (%rdi),%xmm0
xorps  %xmm1,%xmm0
movlps %xmm0,0x28(%rsi)
movsd  0x8(%rdi),%xmm0
xorps  %xmm1,%xmm0
movlps %xmm0,0x30(%rsi)
movsd  (%rdi),%xmm0
movsd  %xmm0,0x38(%rsi)
movq   $0x0,0x40(%rsi)
ret

LLVM IR (-O0):
define void @doubles_cross_matrix(double* %0, double* %1) {
%3 = alloca double*
%4 = alloca double*
store double* %0, double** %3
store double* %1, double** %4
%5 = load double*, double** %4
%6 = getelementptr inbounds double, double* %5, i64 0
store double 0.000000e+00, double* %6
%7 = load double*, double** %3
%8 = getelementptr inbounds double, double* %7, i64 2
%9 = load double, double* %8
%10 = fneg double %9
%11 = load double*, double** %4
%12 = getelementptr inbounds double, double* %11, i64 1
store double %10, double* %12
%13 = load double*, double** %3
%14 = getelementptr inbounds double, double* %13, i64 1
%15 = load double, double* %14
%16 = load double*, double** %4
%17 = getelementptr inbounds double, double* %16, i64 2
store double %15, double* %17
%18 = load double*, double** %3
%19 = getelementptr inbounds double, double* %18, i64 2
%20 = load double, double* %19
%21 = load double*, double** %4
%22 = getelementptr inbounds double, double* %21, i64 3
store double %20, double* %22
%23 = load double*, double** %4
%24 = getelementptr inbounds double, double* %23, i64 4
store double 0.000000e+00, double* %24
%25 = load double*, double** %3
%26 = getelementptr inbounds double, double* %25, i64 0
%27 = load double, double* %26
%28 = fneg double %27
%29 = load double*, double** %4
%30 = getelementptr inbounds double, double* %29, i64 5
store double %28, double* %30
%31 = load double*, double** %3
%32 = getelementptr inbounds double, double* %31, i64 1
%33 = load double, double* %32
%34 = fneg double %33
%35 = load double*, double** %4
%36 = getelementptr inbounds double, double* %35, i64 6
store double %34, double* %36
%37 = load double*, double** %3
%38 = getelementptr inbounds double, double* %37, i64 0
%39 = load double, double* %38
%40 = load double*, double** %4
%41 = getelementptr inbounds double, double* %40, i64 7
store double %39, double* %41
%42 = load double*, double** %4
%43 = getelementptr inbounds double, double* %42, i64 8
store double 0.000000e+00, double* %43
ret void
}

LLVM IR (-O2):
define void @doubles_cross_matrix(double* nocapture %0, double* nocapture writeonly %1) {
store double 0.000000e+00, double* %1
%3 = getelementptr inbounds double, double* %0, i64 2
%4 = load double, double* %3
%5 = fneg double %4
%6 = getelementptr inbounds double, double* %1, i64 1
store double %5, double* %6
%7 = getelementptr inbounds double, double* %0, i64 1
%8 = load double, double* %7
%9 = getelementptr inbounds double, double* %1, i64 2
store double %8, double* %9
%10 = load double, double* %3
%11 = getelementptr inbounds double, double* %1, i64 3
store double %10, double* %11
%12 = getelementptr inbounds double, double* %1, i64 4
store double 0.000000e+00, double* %12
%13 = load double, double* %0
%14 = fneg double %13
%15 = getelementptr inbounds double, double* %1, i64 5
store double %14, double* %15
%16 = load double, double* %7
%17 = fneg double %16
%18 = getelementptr inbounds double, double* %1, i64 6
store double %17, double* %18
%19 = load double, double* %0
%20 = getelementptr inbounds double, double* %1, i64 7
store double %19, double* %20
%21 = getelementptr inbounds double, double* %1, i64 8
store double 0.000000e+00, double* %21
ret void
}