void mp_squh(int n, int radix, int in[], int out[], int nfft, double inoutfft[],
             int ip[], double w[]) {
  void rdft(int n, int isgn, double *a, int *ip, double *w);
  void mp_mul_i2d(int n, int radix, int nfft, int shift, int in[],
                  double dout[]);
  void mp_mul_csqu(int nfft, double dinout[]);
  void mp_mul_d2i(int n, int radix, int nfft, double din[], int out[]);
  mp_mul_i2d(n, radix, nfft, 0, in, inoutfft);
  rdft(nfft, 1, &inoutfft[1], ip, w);
  mp_mul_csqu(nfft, inoutfft);
  rdft(nfft, -1, &inoutfft[1], ip, w);
  mp_mul_d2i(n, radix, nfft, inoutfft, out);
}


x86 assembly (clang, -O0):
<mp_squh>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    0x18(%rbp),%rax
mov    0x10(%rbp),%rax
mov    %edi,-0x4(%rbp)
mov    %esi,-0x8(%rbp)
mov    %rdx,-0x10(%rbp)
mov    %rcx,-0x18(%rbp)
mov    %r8d,-0x1c(%rbp)
mov    %r9,-0x28(%rbp)
mov    -0x4(%rbp),%edi
mov    -0x8(%rbp),%esi
mov    -0x1c(%rbp),%edx
mov    -0x10(%rbp),%r8
mov    -0x28(%rbp),%r9
xor    %ecx,%ecx
call   1030 <mp_mul_i2d@plt>
mov    -0x1c(%rbp),%edi
mov    -0x28(%rbp),%rdx
add    $0x8,%rdx
mov    0x10(%rbp),%rcx
mov    0x18(%rbp),%r8
mov    $0x1,%esi
call   1050 <rdft@plt>
mov    -0x1c(%rbp),%edi
mov    -0x28(%rbp),%rsi
call   1040 <mp_mul_csqu@plt>
mov    -0x1c(%rbp),%edi
mov    -0x28(%rbp),%rdx
add    $0x8,%rdx
mov    0x10(%rbp),%rcx
mov    0x18(%rbp),%r8
mov    $0xffffffff,%esi
call   1050 <rdft@plt>
mov    -0x4(%rbp),%edi
mov    -0x8(%rbp),%esi
mov    -0x1c(%rbp),%edx
mov    -0x28(%rbp),%rcx
mov    -0x18(%rbp),%r8
call   1060 <mp_mul_d2i@plt>
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<mp_squh>:
push   %rbp
push   %r15
push   %r14
push   %r13
push   %r12
push   %rbx
sub    $0x18,%rsp
mov    %r9,%rbx
mov    %r8d,%ebp
mov    %rcx,0x10(%rsp)
mov    %rdx,%r8
mov    %esi,0xc(%rsp)
mov    %edi,%r12d
mov    0x50(%rsp),%r13
mov    0x58(%rsp),%r14
mov    %ebp,%edx
xor    %ecx,%ecx
call   1030 <mp_mul_i2d@plt>
lea    0x8(%rbx),%r15
mov    %ebp,%edi
mov    $0x1,%esi
mov    %r15,%rdx
mov    %r13,%rcx
mov    %r14,%r8
call   1050 <rdft@plt>
mov    %ebp,%edi
mov    %rbx,%rsi
call   1040 <mp_mul_csqu@plt>
mov    %ebp,%edi
mov    $0xffffffff,%esi
mov    %r15,%rdx
mov    %r13,%rcx
mov    %r14,%r8
call   1050 <rdft@plt>
mov    %r12d,%edi
mov    0xc(%rsp),%esi
mov    %ebp,%edx
mov    %rbx,%rcx
mov    0x10(%rsp),%r8
add    $0x18,%rsp
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
pop    %rbp
jmp    1060 <mp_mul_d2i@plt>

LLVM IR (-O0):
define void @mp_squh(i32 %0, i32 %1, i32* %2, i32* %3, i32 %4, double* %5, i32* %6, double* %7) {
%9 = alloca i32
%10 = alloca i32
%11 = alloca i32*
%12 = alloca i32*
%13 = alloca i32
%14 = alloca double*
%15 = alloca i32*
%16 = alloca double*
store i32 %0, i32* %9
store i32 %1, i32* %10
store i32* %2, i32** %11
store i32* %3, i32** %12
store i32 %4, i32* %13
store double* %5, double** %14
store i32* %6, i32** %15
store double* %7, double** %16
%17 = load i32, i32* %9
%18 = load i32, i32* %10
%19 = load i32, i32* %13
%20 = load i32*, i32** %11
%21 = load double*, double** %14
%22 = load i32, i32* %13
%23 = load double*, double** %14
%24 = getelementptr inbounds double, double* %23, i64 1
%25 = load i32*, i32** %15
%26 = load double*, double** %16
%27 = load i32, i32* %13
%28 = load double*, double** %14
%29 = load i32, i32* %13
%30 = load double*, double** %14
%31 = getelementptr inbounds double, double* %30, i64 1
%32 = load i32*, i32** %15
%33 = load double*, double** %16
%34 = load i32, i32* %9
%35 = load i32, i32* %10
%36 = load i32, i32* %13
%37 = load double*, double** %14
%38 = load i32*, i32** %12
ret void
}

LLVM IR (-O2):
define void @mp_squh(i32 %0, i32 %1, i32* %2, i32* %3, i32 %4, double* %5, i32* %6, double* %7) {
tail call void @mp_mul_i2d(i32 %0, i32 %1, i32 %4, i32 0, i32* %2, double* %5)
%9 = getelementptr inbounds double, double* %5, i64 1
tail call void @rdft(i32 %4, i32 1, double* %9, i32* %6, double* %7)
tail call void @mp_mul_csqu(i32 %4, double* %5)
tail call void @rdft(i32 %4, i32 -1, double* %9, i32* %6, double* %7)
tail call void @mp_mul_d2i(i32 %0, i32 %1, i32 %4, double* %5, i32* %3)
ret void
}