void inverse_transform44d3d(double *m1, double *m2, double *m3) {
  register double m2r0 = m2[0] - m1[3];
  register double m2r1 = m2[1] - m1[7];
  register double m2r2 = m2[2] - m1[11];
  m3[0] = (float)(m1[0] * m2r0 + m1[4] * m2r1 + m1[8] * m2r2);
  m3[1] = (float)(m1[1] * m2r0 + m1[5] * m2r1 + m1[9] * m2r2);
  m3[2] = (float)(m1[2] * m2r0 + m1[6] * m2r1 + m1[10] * m2r2);
}


x86 assembly (clang, -O0):
<inverse_transform44d3d>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %rdx,-0x18(%rbp)
mov    -0x10(%rbp),%rax
movsd  (%rax),%xmm0
mov    -0x8(%rbp),%rax
subsd  0x18(%rax),%xmm0
movsd  %xmm0,-0x20(%rbp)
mov    -0x10(%rbp),%rax
movsd  0x8(%rax),%xmm0
mov    -0x8(%rbp),%rax
subsd  0x38(%rax),%xmm0
movsd  %xmm0,-0x28(%rbp)
mov    -0x10(%rbp),%rax
movsd  0x10(%rax),%xmm0
mov    -0x8(%rbp),%rax
subsd  0x58(%rax),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm1
movsd  -0x20(%rbp),%xmm2
mov    -0x8(%rbp),%rax
movsd  0x20(%rax),%xmm0
mulsd  -0x28(%rbp),%xmm0
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x8(%rbp),%rax
movsd  0x40(%rax),%xmm0
movsd  -0x30(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
cvtsd2ss %xmm0,%xmm0
cvtss2sd %xmm0,%xmm0
mov    -0x18(%rbp),%rax
movsd  %xmm0,(%rax)
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm1
movsd  -0x20(%rbp),%xmm2
mov    -0x8(%rbp),%rax
movsd  0x28(%rax),%xmm0
mulsd  -0x28(%rbp),%xmm0
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x8(%rbp),%rax
movsd  0x48(%rax),%xmm0
movsd  -0x30(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
cvtsd2ss %xmm0,%xmm0
cvtss2sd %xmm0,%xmm0
mov    -0x18(%rbp),%rax
movsd  %xmm0,0x8(%rax)
mov    -0x8(%rbp),%rax
movsd  0x10(%rax),%xmm1
movsd  -0x20(%rbp),%xmm2
mov    -0x8(%rbp),%rax
movsd  0x30(%rax),%xmm0
mulsd  -0x28(%rbp),%xmm0
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
mov    -0x8(%rbp),%rax
movsd  0x50(%rax),%xmm0
movsd  -0x30(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
cvtsd2ss %xmm0,%xmm0
cvtss2sd %xmm0,%xmm0
mov    -0x18(%rbp),%rax
movsd  %xmm0,0x10(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<inverse_transform44d3d>:
movsd  (%rsi),%xmm0
movsd  0x8(%rsi),%xmm1
subsd  0x18(%rdi),%xmm0
subsd  0x38(%rdi),%xmm1
movsd  0x10(%rsi),%xmm2
subsd  0x58(%rdi),%xmm2
movsd  0x20(%rdi),%xmm3
mulsd  %xmm1,%xmm3
movsd  (%rdi),%xmm4
mulsd  %xmm0,%xmm4
addsd  %xmm3,%xmm4
movsd  0x40(%rdi),%xmm3
mulsd  %xmm2,%xmm3
addsd  %xmm4,%xmm3
cvtsd2ss %xmm3,%xmm3
cvtss2sd %xmm3,%xmm3
movsd  %xmm3,(%rdx)
movsd  0x28(%rdi),%xmm3
mulsd  %xmm1,%xmm3
movsd  0x8(%rdi),%xmm4
mulsd  %xmm0,%xmm4
addsd  %xmm3,%xmm4
movsd  0x48(%rdi),%xmm3
mulsd  %xmm2,%xmm3
addsd  %xmm4,%xmm3
cvtsd2ss %xmm3,%xmm3
cvtss2sd %xmm3,%xmm3
movsd  %xmm3,0x8(%rdx)
mulsd  0x30(%rdi),%xmm1
mulsd  0x10(%rdi),%xmm0
addsd  %xmm1,%xmm0
mulsd  0x50(%rdi),%xmm2
addsd  %xmm0,%xmm2
xorps  %xmm0,%xmm0
cvtsd2ss %xmm2,%xmm0
cvtss2sd %xmm0,%xmm0
movsd  %xmm0,0x10(%rdx)
ret

LLVM IR (-O0):
define void @inverse_transform44d3d(double* %0, double* %1, double* %2) {
%4 = alloca double*
%5 = alloca double*
%6 = alloca double*
%7 = alloca double
%8 = alloca double
%9 = alloca double
store double* %0, double** %4
store double* %1, double** %5
store double* %2, double** %6
%10 = load double*, double** %5
%11 = getelementptr inbounds double, double* %10, i64 0
%12 = load double, double* %11
%13 = load double*, double** %4
%14 = getelementptr inbounds double, double* %13, i64 3
%15 = load double, double* %14
%16 = fsub double %12, %15
store double %16, double* %7
%17 = load double*, double** %5
%18 = getelementptr inbounds double, double* %17, i64 1
%19 = load double, double* %18
%20 = load double*, double** %4
%21 = getelementptr inbounds double, double* %20, i64 7
%22 = load double, double* %21
%23 = fsub double %19, %22
store double %23, double* %8
%24 = load double*, double** %5
%25 = getelementptr inbounds double, double* %24, i64 2
%26 = load double, double* %25
%27 = load double*, double** %4
%28 = getelementptr inbounds double, double* %27, i64 11
%29 = load double, double* %28
%30 = fsub double %26, %29
store double %30, double* %9
%31 = load double*, double** %4
%32 = getelementptr inbounds double, double* %31, i64 0
%33 = load double, double* %32
%34 = load double, double* %7
%35 = load double*, double** %4
%36 = getelementptr inbounds double, double* %35, i64 4
%37 = load double, double* %36
%38 = load double, double* %8
%39 = fmul double %37, %38
%40 = call double @llvm.fmuladd.f64(double %33, double %34, double %39)
%41 = load double*, double** %4
%42 = getelementptr inbounds double, double* %41, i64 8
%43 = load double, double* %42
%44 = load double, double* %9
%45 = call double @llvm.fmuladd.f64(double %43, double %44, double %40)
%46 = fptrunc double %45 to float
%47 = fpext float %46 to double
%48 = load double*, double** %6
%49 = getelementptr inbounds double, double* %48, i64 0
store double %47, double* %49
%50 = load double*, double** %4
%51 = getelementptr inbounds double, double* %50, i64 1
%52 = load double, double* %51
%53 = load double, double* %7
%54 = load double*, double** %4
%55 = getelementptr inbounds double, double* %54, i64 5
%56 = load double, double* %55
%57 = load double, double* %8
%58 = fmul double %56, %57
%59 = call double @llvm.fmuladd.f64(double %52, double %53, double %58)
%60 = load double*, double** %4
%61 = getelementptr inbounds double, double* %60, i64 9
%62 = load double, double* %61
%63 = load double, double* %9
%64 = call double @llvm.fmuladd.f64(double %62, double %63, double %59)
%65 = fptrunc double %64 to float
%66 = fpext float %65 to double
%67 = load double*, double** %6
%68 = getelementptr inbounds double, double* %67, i64 1
store double %66, double* %68
%69 = load double*, double** %4
%70 = getelementptr inbounds double, double* %69, i64 2
%71 = load double, double* %70
%72 = load double, double* %7
%73 = load double*, double** %4
%74 = getelementptr inbounds double, double* %73, i64 6
%75 = load double, double* %74
%76 = load double, double* %8
%77 = fmul double %75, %76
%78 = call double @llvm.fmuladd.f64(double %71, double %72, double %77)
%79 = load double*, double** %4
%80 = getelementptr inbounds double, double* %79, i64 10
%81 = load double, double* %80
%82 = load double, double* %9
%83 = call double @llvm.fmuladd.f64(double %81, double %82, double %78)
%84 = fptrunc double %83 to float
%85 = fpext float %84 to double
%86 = load double*, double** %6
%87 = getelementptr inbounds double, double* %86, i64 2
store double %85, double* %87
ret void
}

LLVM IR (-O2):
define void @inverse_transform44d3d(double* nocapture %0, double* nocapture %1, double* nocapture writeonly %2) {
%4 = load double, double* %1
%5 = getelementptr inbounds double, double* %0, i64 3
%6 = load double, double* %5
%7 = fsub double %4, %6
%8 = getelementptr inbounds double, double* %1, i64 1
%9 = load double, double* %8
%10 = getelementptr inbounds double, double* %0, i64 7
%11 = load double, double* %10
%12 = fsub double %9, %11
%13 = getelementptr inbounds double, double* %1, i64 2
%14 = load double, double* %13
%15 = getelementptr inbounds double, double* %0, i64 11
%16 = load double, double* %15
%17 = fsub double %14, %16
%18 = load double, double* %0
%19 = getelementptr inbounds double, double* %0, i64 4
%20 = load double, double* %19
%21 = fmul double %12, %20
%22 = tail call double @llvm.fmuladd.f64(double %18, double %7, double %21)
%23 = getelementptr inbounds double, double* %0, i64 8
%24 = load double, double* %23
%25 = tail call double @llvm.fmuladd.f64(double %24, double %17, double %22)
%26 = fptrunc double %25 to float
%27 = fpext float %26 to double
store double %27, double* %2
%28 = getelementptr inbounds double, double* %0, i64 1
%29 = load double, double* %28
%30 = getelementptr inbounds double, double* %0, i64 5
%31 = load double, double* %30
%32 = fmul double %12, %31
%33 = tail call double @llvm.fmuladd.f64(double %29, double %7, double %32)
%34 = getelementptr inbounds double, double* %0, i64 9
%35 = load double, double* %34
%36 = tail call double @llvm.fmuladd.f64(double %35, double %17, double %33)
%37 = fptrunc double %36 to float
%38 = fpext float %37 to double
%39 = getelementptr inbounds double, double* %2, i64 1
store double %38, double* %39
%40 = getelementptr inbounds double, double* %0, i64 2
%41 = load double, double* %40
%42 = getelementptr inbounds double, double* %0, i64 6
%43 = load double, double* %42
%44 = fmul double %12, %43
%45 = tail call double @llvm.fmuladd.f64(double %41, double %7, double %44)
%46 = getelementptr inbounds double, double* %0, i64 10
%47 = load double, double* %46
%48 = tail call double @llvm.fmuladd.f64(double %47, double %17, double %45)
%49 = fptrunc double %48 to float
%50 = fpext float %49 to double
%51 = getelementptr inbounds double, double* %2, i64 2
store double %50, double* %51
ret void
}