void matrix4Scalef(float *mat, float sx, float sy, float sz) {
  mat[15] = 1;
  mat[1] = mat[2] = mat[3] = mat[4] = mat[6] = mat[7] = mat[8] = mat[9] =
      mat[11] = mat[12] = mat[13] = mat[14] = 0;
  mat[0] = sx;
  mat[5] = sy;
  mat[10] = sz;
}


x86 assembly (clang, -O0):
<matrix4Scalef>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
movss  %xmm0,-0xc(%rbp)
movss  %xmm1,-0x10(%rbp)
movss  %xmm2,-0x14(%rbp)
mov    -0x8(%rbp),%rax
movss  0xedd(%rip),%xmm0
movss  %xmm0,0x3c(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x38(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x34(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x30(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x2c(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x24(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x20(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x1c(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x18(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x10(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0xc(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x8(%rax)
mov    -0x8(%rbp),%rax
xorps  %xmm0,%xmm0
movss  %xmm0,0x4(%rax)
movss  -0xc(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movss  %xmm0,(%rax)
movss  -0x10(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movss  %xmm0,0x14(%rax)
movss  -0x14(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movss  %xmm0,0x28(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<matrix4Scalef>:
movl   $0x3f800000,0x3c(%rdi)
xorps  %xmm3,%xmm3
movups %xmm3,0x4(%rdi)
movups %xmm3,0x18(%rdi)
movups %xmm3,0x2c(%rdi)
movss  %xmm0,(%rdi)
movss  %xmm1,0x14(%rdi)
movss  %xmm2,0x28(%rdi)
ret

LLVM IR (-O0):
define void @matrix4Scalef(float* %0, float %1, float %2, float %3) {
%5 = alloca float*
%6 = alloca float
%7 = alloca float
%8 = alloca float
store float* %0, float** %5
store float %1, float* %6
store float %2, float* %7
store float %3, float* %8
%9 = load float*, float** %5
%10 = getelementptr inbounds float, float* %9, i64 15
store float 1.000000e+00, float* %10
%11 = load float*, float** %5
%12 = getelementptr inbounds float, float* %11, i64 14
store float 0.000000e+00, float* %12
%13 = load float*, float** %5
%14 = getelementptr inbounds float, float* %13, i64 13
store float 0.000000e+00, float* %14
%15 = load float*, float** %5
%16 = getelementptr inbounds float, float* %15, i64 12
store float 0.000000e+00, float* %16
%17 = load float*, float** %5
%18 = getelementptr inbounds float, float* %17, i64 11
store float 0.000000e+00, float* %18
%19 = load float*, float** %5
%20 = getelementptr inbounds float, float* %19, i64 9
store float 0.000000e+00, float* %20
%21 = load float*, float** %5
%22 = getelementptr inbounds float, float* %21, i64 8
store float 0.000000e+00, float* %22
%23 = load float*, float** %5
%24 = getelementptr inbounds float, float* %23, i64 7
store float 0.000000e+00, float* %24
%25 = load float*, float** %5
%26 = getelementptr inbounds float, float* %25, i64 6
store float 0.000000e+00, float* %26
%27 = load float*, float** %5
%28 = getelementptr inbounds float, float* %27, i64 4
store float 0.000000e+00, float* %28
%29 = load float*, float** %5
%30 = getelementptr inbounds float, float* %29, i64 3
store float 0.000000e+00, float* %30
%31 = load float*, float** %5
%32 = getelementptr inbounds float, float* %31, i64 2
store float 0.000000e+00, float* %32
%33 = load float*, float** %5
%34 = getelementptr inbounds float, float* %33, i64 1
store float 0.000000e+00, float* %34
%35 = load float, float* %6
%36 = load float*, float** %5
%37 = getelementptr inbounds float, float* %36, i64 0
store float %35, float* %37
%38 = load float, float* %7
%39 = load float*, float** %5
%40 = getelementptr inbounds float, float* %39, i64 5
store float %38, float* %40
%41 = load float, float* %8
%42 = load float*, float** %5
%43 = getelementptr inbounds float, float* %42, i64 10
store float %41, float* %43
ret void
}

LLVM IR (-O2):
define void @matrix4Scalef(float* nocapture writeonly %0, float %1, float %2, float %3) {
%5 = getelementptr inbounds float, float* %0, i64 15
store float 1.000000e+00, float* %5
%6 = getelementptr inbounds float, float* %0, i64 11
%7 = getelementptr inbounds float, float* %0, i64 6
%8 = getelementptr inbounds float, float* %0, i64 1
%9 = bitcast float* %8 to i8*
%10 = bitcast float* %7 to i8*
%11 = bitcast float* %6 to i8*
store float %1, float* %0
%12 = getelementptr inbounds float, float* %0, i64 5
store float %2, float* %12
%13 = getelementptr inbounds float, float* %0, i64 10
store float %3, float* %13
ret void
}