void m_scl(float *M, const float *v) {
  M[0] = v[0];
  M[4] = 0.f;
  M[8] = 0.f;
  M[12] = 0.f;
  M[1] = 0.f;
  M[5] = v[1];
  M[9] = 0.f;
  M[13] = 0.f;
  M[2] = 0.f;
  M[6] = 0.f;
  M[10] = v[2];
  M[14] = 0.f;
  M[3] = 0.f;
  M[7] = 0.f;
  M[11] = 0.f;
  M[15] = 1.f;
}


x86 assembly (clang, -O0):
<m_scl>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x10(%rbp),%rax
movss  (%rax),%xmm0
mov    -0x8(%rbp),%rax
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x10(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x20(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x30(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x4(%rax)
mov    -0x10(%rbp),%rax
movss  0x4(%rax),%xmm0
mov    -0x8(%rbp),%rax
movss  %xmm0,0x14(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x24(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x34(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x8(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x18(%rax)
mov    -0x10(%rbp),%rax
movss  0x8(%rax),%xmm0
mov    -0x8(%rbp),%rax
movss  %xmm0,0x28(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x38(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0xc(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x1c(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x2c(%rax)
mov    -0x8(%rbp),%rax
movss  0xe24(%rip),%xmm0
movss  %xmm0,0x3c(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<m_scl>:
movss  (%rsi),%xmm0
movss  %xmm0,(%rdi)
movl   $0x0,0x10(%rdi)
movl   $0x0,0x20(%rdi)
movl   $0x0,0x30(%rdi)
movl   $0x0,0x4(%rdi)
movss  0x4(%rsi),%xmm0
movss  %xmm0,0x14(%rdi)
movl   $0x0,0x24(%rdi)
movl   $0x0,0x34(%rdi)
movl   $0x0,0x8(%rdi)
movl   $0x0,0x18(%rdi)
movss  0x8(%rsi),%xmm0
movss  %xmm0,0x28(%rdi)
movabs $0x3f80000000000000,%rax
mov    %rax,0x38(%rdi)
movl   $0x0,0xc(%rdi)
movl   $0x0,0x1c(%rdi)
movl   $0x0,0x2c(%rdi)
ret

LLVM IR (-O0):
define void @m_scl(float* %0, float* %1) {
%3 = alloca float*
%4 = alloca float*
store float* %0, float** %3
store float* %1, float** %4
%5 = load float*, float** %4
%6 = getelementptr inbounds float, float* %5, i64 0
%7 = load float, float* %6
%8 = load float*, float** %3
%9 = getelementptr inbounds float, float* %8, i64 0
store float %7, float* %9
%10 = load float*, float** %3
%11 = getelementptr inbounds float, float* %10, i64 4
store float 0.000000e+00, float* %11
%12 = load float*, float** %3
%13 = getelementptr inbounds float, float* %12, i64 8
store float 0.000000e+00, float* %13
%14 = load float*, float** %3
%15 = getelementptr inbounds float, float* %14, i64 12
store float 0.000000e+00, float* %15
%16 = load float*, float** %3
%17 = getelementptr inbounds float, float* %16, i64 1
store float 0.000000e+00, float* %17
%18 = load float*, float** %4
%19 = getelementptr inbounds float, float* %18, i64 1
%20 = load float, float* %19
%21 = load float*, float** %3
%22 = getelementptr inbounds float, float* %21, i64 5
store float %20, float* %22
%23 = load float*, float** %3
%24 = getelementptr inbounds float, float* %23, i64 9
store float 0.000000e+00, float* %24
%25 = load float*, float** %3
%26 = getelementptr inbounds float, float* %25, i64 13
store float 0.000000e+00, float* %26
%27 = load float*, float** %3
%28 = getelementptr inbounds float, float* %27, i64 2
store float 0.000000e+00, float* %28
%29 = load float*, float** %3
%30 = getelementptr inbounds float, float* %29, i64 6
store float 0.000000e+00, float* %30
%31 = load float*, float** %4
%32 = getelementptr inbounds float, float* %31, i64 2
%33 = load float, float* %32
%34 = load float*, float** %3
%35 = getelementptr inbounds float, float* %34, i64 10
store float %33, float* %35
%36 = load float*, float** %3
%37 = getelementptr inbounds float, float* %36, i64 14
store float 0.000000e+00, float* %37
%38 = load float*, float** %3
%39 = getelementptr inbounds float, float* %38, i64 3
store float 0.000000e+00, float* %39
%40 = load float*, float** %3
%41 = getelementptr inbounds float, float* %40, i64 7
store float 0.000000e+00, float* %41
%42 = load float*, float** %3
%43 = getelementptr inbounds float, float* %42, i64 11
store float 0.000000e+00, float* %43
%44 = load float*, float** %3
%45 = getelementptr inbounds float, float* %44, i64 15
store float 1.000000e+00, float* %45
ret void
}

LLVM IR (-O2):
define void @m_scl(float* nocapture writeonly %0, float* nocapture %1) {
%3 = load float, float* %1
store float %3, float* %0
%4 = getelementptr inbounds float, float* %0, i64 4
store float 0.000000e+00, float* %4
%5 = getelementptr inbounds float, float* %0, i64 8
store float 0.000000e+00, float* %5
%6 = getelementptr inbounds float, float* %0, i64 12
store float 0.000000e+00, float* %6
%7 = getelementptr inbounds float, float* %0, i64 1
store float 0.000000e+00, float* %7
%8 = getelementptr inbounds float, float* %1, i64 1
%9 = load float, float* %8
%10 = getelementptr inbounds float, float* %0, i64 5
store float %9, float* %10
%11 = getelementptr inbounds float, float* %0, i64 9
store float 0.000000e+00, float* %11
%12 = getelementptr inbounds float, float* %0, i64 13
store float 0.000000e+00, float* %12
%13 = getelementptr inbounds float, float* %0, i64 2
store float 0.000000e+00, float* %13
%14 = getelementptr inbounds float, float* %0, i64 6
store float 0.000000e+00, float* %14
%15 = getelementptr inbounds float, float* %1, i64 2
%16 = load float, float* %15
%17 = getelementptr inbounds float, float* %0, i64 10
store float %16, float* %17
%18 = getelementptr inbounds float, float* %0, i64 14
store float 0.000000e+00, float* %18
%19 = getelementptr inbounds float, float* %0, i64 3
store float 0.000000e+00, float* %19
%20 = getelementptr inbounds float, float* %0, i64 7
store float 0.000000e+00, float* %20
%21 = getelementptr inbounds float, float* %0, i64 11
store float 0.000000e+00, float* %21
%22 = getelementptr inbounds float, float* %0, i64 15
store float 1.000000e+00, float* %22
ret void
}