void copy44d44f(double *src, float *dst) {
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
  *(dst++) = (float)*(src++);
}


x86 assembly (clang, -O0):
<copy44d44f>:
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
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
mov    %rax,%rcx
add    $0x8,%rcx
mov    %rcx,-0x8(%rbp)
movsd  (%rax),%xmm0
cvtsd2ss %xmm0,%xmm0
mov    -0x10(%rbp),%rax
mov    %rax,%rcx
add    $0x4,%rcx
mov    %rcx,-0x10(%rbp)
movss  %xmm0,(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<copy44d44f>:
movupd (%rdi),%xmm0
movupd 0x10(%rdi),%xmm1
cvtpd2ps %xmm1,%xmm1
cvtpd2ps %xmm0,%xmm0
unpcklpd %xmm1,%xmm0
movupd %xmm0,(%rsi)
movupd 0x20(%rdi),%xmm0
movupd 0x30(%rdi),%xmm1
cvtpd2ps %xmm1,%xmm1
cvtpd2ps %xmm0,%xmm0
unpcklpd %xmm1,%xmm0
movupd %xmm0,0x10(%rsi)
movupd 0x40(%rdi),%xmm0
movupd 0x50(%rdi),%xmm1
cvtpd2ps %xmm1,%xmm1
cvtpd2ps %xmm0,%xmm0
unpcklpd %xmm1,%xmm0
movupd %xmm0,0x20(%rsi)
movupd 0x60(%rdi),%xmm0
movupd 0x70(%rdi),%xmm1
cvtpd2ps %xmm1,%xmm1
cvtpd2ps %xmm0,%xmm0
unpcklpd %xmm1,%xmm0
movupd %xmm0,0x30(%rsi)
ret

LLVM IR (-O0):
define void @copy44d44f(double* %0, float* %1) {
%3 = alloca double*
%4 = alloca float*
store double* %0, double** %3
store float* %1, float** %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 = fptrunc double %7 to float
%9 = load float*, float** %4
%10 = getelementptr inbounds float, float* %9, i32 1
store float* %10, float** %4
store float %8, float* %9
%11 = load double*, double** %3
%12 = getelementptr inbounds double, double* %11, i32 1
store double* %12, double** %3
%13 = load double, double* %11
%14 = fptrunc double %13 to float
%15 = load float*, float** %4
%16 = getelementptr inbounds float, float* %15, i32 1
store float* %16, float** %4
store float %14, float* %15
%17 = load double*, double** %3
%18 = getelementptr inbounds double, double* %17, i32 1
store double* %18, double** %3
%19 = load double, double* %17
%20 = fptrunc double %19 to float
%21 = load float*, float** %4
%22 = getelementptr inbounds float, float* %21, i32 1
store float* %22, float** %4
store float %20, float* %21
%23 = load double*, double** %3
%24 = getelementptr inbounds double, double* %23, i32 1
store double* %24, double** %3
%25 = load double, double* %23
%26 = fptrunc double %25 to float
%27 = load float*, float** %4
%28 = getelementptr inbounds float, float* %27, i32 1
store float* %28, float** %4
store float %26, float* %27
%29 = load double*, double** %3
%30 = getelementptr inbounds double, double* %29, i32 1
store double* %30, double** %3
%31 = load double, double* %29
%32 = fptrunc double %31 to float
%33 = load float*, float** %4
%34 = getelementptr inbounds float, float* %33, i32 1
store float* %34, float** %4
store float %32, float* %33
%35 = load double*, double** %3
%36 = getelementptr inbounds double, double* %35, i32 1
store double* %36, double** %3
%37 = load double, double* %35
%38 = fptrunc double %37 to float
%39 = load float*, float** %4
%40 = getelementptr inbounds float, float* %39, i32 1
store float* %40, float** %4
store float %38, float* %39
%41 = load double*, double** %3
%42 = getelementptr inbounds double, double* %41, i32 1
store double* %42, double** %3
%43 = load double, double* %41
%44 = fptrunc double %43 to float
%45 = load float*, float** %4
%46 = getelementptr inbounds float, float* %45, i32 1
store float* %46, float** %4
store float %44, float* %45
%47 = load double*, double** %3
%48 = getelementptr inbounds double, double* %47, i32 1
store double* %48, double** %3
%49 = load double, double* %47
%50 = fptrunc double %49 to float
%51 = load float*, float** %4
%52 = getelementptr inbounds float, float* %51, i32 1
store float* %52, float** %4
store float %50, float* %51
%53 = load double*, double** %3
%54 = getelementptr inbounds double, double* %53, i32 1
store double* %54, double** %3
%55 = load double, double* %53
%56 = fptrunc double %55 to float
%57 = load float*, float** %4
%58 = getelementptr inbounds float, float* %57, i32 1
store float* %58, float** %4
store float %56, float* %57
%59 = load double*, double** %3
%60 = getelementptr inbounds double, double* %59, i32 1
store double* %60, double** %3
%61 = load double, double* %59
%62 = fptrunc double %61 to float
%63 = load float*, float** %4
%64 = getelementptr inbounds float, float* %63, i32 1
store float* %64, float** %4
store float %62, float* %63
%65 = load double*, double** %3
%66 = getelementptr inbounds double, double* %65, i32 1
store double* %66, double** %3
%67 = load double, double* %65
%68 = fptrunc double %67 to float
%69 = load float*, float** %4
%70 = getelementptr inbounds float, float* %69, i32 1
store float* %70, float** %4
store float %68, float* %69
%71 = load double*, double** %3
%72 = getelementptr inbounds double, double* %71, i32 1
store double* %72, double** %3
%73 = load double, double* %71
%74 = fptrunc double %73 to float
%75 = load float*, float** %4
%76 = getelementptr inbounds float, float* %75, i32 1
store float* %76, float** %4
store float %74, float* %75
%77 = load double*, double** %3
%78 = getelementptr inbounds double, double* %77, i32 1
store double* %78, double** %3
%79 = load double, double* %77
%80 = fptrunc double %79 to float
%81 = load float*, float** %4
%82 = getelementptr inbounds float, float* %81, i32 1
store float* %82, float** %4
store float %80, float* %81
%83 = load double*, double** %3
%84 = getelementptr inbounds double, double* %83, i32 1
store double* %84, double** %3
%85 = load double, double* %83
%86 = fptrunc double %85 to float
%87 = load float*, float** %4
%88 = getelementptr inbounds float, float* %87, i32 1
store float* %88, float** %4
store float %86, float* %87
%89 = load double*, double** %3
%90 = getelementptr inbounds double, double* %89, i32 1
store double* %90, double** %3
%91 = load double, double* %89
%92 = fptrunc double %91 to float
%93 = load float*, float** %4
%94 = getelementptr inbounds float, float* %93, i32 1
store float* %94, float** %4
store float %92, float* %93
%95 = load double*, double** %3
%96 = getelementptr inbounds double, double* %95, i32 1
store double* %96, double** %3
%97 = load double, double* %95
%98 = fptrunc double %97 to float
%99 = load float*, float** %4
%100 = getelementptr inbounds float, float* %99, i32 1
store float* %100, float** %4
store float %98, float* %99
ret void
}

LLVM IR (-O2):
define void @copy44d44f(double* nocapture %0, float* nocapture writeonly %1) {
%3 = getelementptr inbounds double, double* %0, i64 4
%4 = bitcast double* %0 to <4 x double>*
%5 = load <4 x double>, <4 x double>* %4
%6 = fptrunc <4 x double> %5 to <4 x float>
%7 = getelementptr inbounds float, float* %1, i64 4
%8 = bitcast float* %1 to <4 x float>*
store <4 x float> %6, <4 x float>* %8
%9 = getelementptr inbounds double, double* %0, i64 8
%10 = bitcast double* %3 to <4 x double>*
%11 = load <4 x double>, <4 x double>* %10
%12 = fptrunc <4 x double> %11 to <4 x float>
%13 = getelementptr inbounds float, float* %1, i64 8
%14 = bitcast float* %7 to <4 x float>*
store <4 x float> %12, <4 x float>* %14
%15 = getelementptr inbounds double, double* %0, i64 12
%16 = bitcast double* %9 to <4 x double>*
%17 = load <4 x double>, <4 x double>* %16
%18 = fptrunc <4 x double> %17 to <4 x float>
%19 = getelementptr inbounds float, float* %1, i64 12
%20 = bitcast float* %13 to <4 x float>*
store <4 x float> %18, <4 x float>* %20
%21 = bitcast double* %15 to <4 x double>*
%22 = load <4 x double>, <4 x double>* %21
%23 = fptrunc <4 x double> %22 to <4 x float>
%24 = bitcast float* %19 to <4 x float>*
store <4 x float> %23, <4 x float>* %24
ret void
}