#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */

/* Variables and functions */
double sin(double);
void realft(double *data, int n, int isign) {
  void four1(double *data, int nn, int isign);
  int i, i1, i2, i3, i4, np3;
  double c1 = 0.5, c2, h1r, h1i, h2r, h2i;
  double wr, wi, wpr, wpi, wtemp, theta;
  theta = 3.141592653589793 / (double)(n >> 1);
  if (isign == 1) {
    c2 = -0.5;
    four1(data, n >> 1, 1);
  } else {
    c2 = 0.5;
    theta = -theta;
  }
  wtemp = sin(0.5 * theta);
  wpr = -2.0 * wtemp * wtemp;
  wpi = sin(theta);
  wr = 1.0 + wpr;
  wi = wpi;
  np3 = n + 3;
  for (i = 2; i <= (n >> 2); i++) {
    i4 = 1 + (i3 = np3 - (i2 = 1 + (i1 = i + i - 1)));
    h1r = c1 * (data[i1 - 1] + data[i3 - 1]);
    h1i = c1 * (data[i2 - 1] - data[i4 - 1]);
    h2r = -c2 * (data[i2 - 1] + data[i4 - 1]);
    h2i = c2 * (data[i1 - 1] - data[i3 - 1]);
    data[i1 - 1] = h1r + wr * h2r - wi * h2i;
    data[i2 - 1] = h1i + wr * h2i + wi * h2r;
    data[i3 - 1] = h1r - wr * h2r + wi * h2i;
    data[i4 - 1] = -h1i + wr * h2i + wi * h2r;
    wr = (wtemp = wr) * wpr - wi * wpi + wr;
    wi = wi * wpr + wtemp * wpi + wi;
  }
  if (isign == 1) {
    data[0] = (h1r = data[1]) + data[1];
    data[1] = h1r - data[1];
  } else {
    data[0] = c1 * ((h1r = data[0]) + data[1]);
    data[1] = c1 * (h1r - data[1]);
    four1(data, n >> 1, -1);
  }
}


x86 assembly (clang, -O0):
<realft>:
push   %rbp
mov    %rsp,%rbp
sub    $0x90,%rsp
mov    %rdi,-0x8(%rbp)
mov    %esi,-0xc(%rbp)
mov    %edx,-0x10(%rbp)
movsd  0xecb(%rip),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0xc(%rbp),%eax
sar    $0x1,%eax
cvtsi2sd %eax,%xmm1
movsd  0xeac(%rip),%xmm0
divsd  %xmm1,%xmm0
movsd  %xmm0,-0x88(%rbp)
ff
cmpl   $0x1,-0x10(%rbp)
jne    1190 <realft+0x70>
movsd  0xe9e(%rip),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x8(%rbp),%rdi
mov    -0xc(%rbp),%esi
sar    $0x1,%esi
mov    $0x1,%edx
call   1030 <four1@plt>
jmp    11c4 <realft+0xa4>
movsd  0xe70(%rip),%xmm0
movsd  %xmm0,-0x38(%rbp)
movsd  -0x88(%rbp),%xmm0
ff
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  %xmm0,-0x88(%rbp)
ff
movsd  0xe3c(%rip),%xmm0
mulsd  -0x88(%rbp),%xmm0
ff
call   1040 <sin@plt>
movsd  %xmm0,-0x80(%rbp)
movsd  0xe3a(%rip),%xmm0
mulsd  -0x80(%rbp),%xmm0
mulsd  -0x80(%rbp),%xmm0
movsd  %xmm0,-0x70(%rbp)
movsd  -0x88(%rbp),%xmm0
ff
call   1040 <sin@plt>
movsd  %xmm0,-0x78(%rbp)
movsd  0xe09(%rip),%xmm0
addsd  -0x70(%rbp),%xmm0
movsd  %xmm0,-0x60(%rbp)
movsd  -0x78(%rbp),%xmm0
movsd  %xmm0,-0x68(%rbp)
mov    -0xc(%rbp),%eax
add    $0x3,%eax
mov    %eax,-0x28(%rbp)
movl   $0x2,-0x14(%rbp)
mov    -0x14(%rbp),%eax
mov    -0xc(%rbp),%ecx
sar    $0x2,%ecx
cmp    %ecx,%eax
jg     14ea <realft+0x3ca>
mov    -0x28(%rbp),%eax
mov    -0x14(%rbp),%ecx
add    -0x14(%rbp),%ecx
sub    $0x1,%ecx
mov    %ecx,-0x18(%rbp)
add    $0x1,%ecx
mov    %ecx,-0x1c(%rbp)
sub    %ecx,%eax
mov    %eax,-0x20(%rbp)
add    $0x1,%eax
mov    %eax,-0x24(%rbp)
movsd  -0x30(%rbp),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x18(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x20(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
addsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x40(%rbp)
movsd  -0x30(%rbp),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x1c(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x24(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
subsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x48(%rbp)
movsd  -0x38(%rbp),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x1c(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x24(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
addsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x50(%rbp)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x18(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x20(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
subsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x58(%rbp)
movsd  -0x40(%rbp),%xmm0
movsd  -0x60(%rbp),%xmm1
movsd  -0x50(%rbp),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x68(%rbp),%xmm0
movsd  -0x58(%rbp),%xmm2
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x18(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x48(%rbp),%xmm0
movsd  -0x60(%rbp),%xmm1
movsd  -0x58(%rbp),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x68(%rbp),%xmm0
movsd  -0x50(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x1c(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x40(%rbp),%xmm0
movsd  -0x60(%rbp),%xmm1
movsd  -0x50(%rbp),%xmm2
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x68(%rbp),%xmm0
movsd  -0x58(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x20(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x48(%rbp),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  -0x60(%rbp),%xmm1
movsd  -0x58(%rbp),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x68(%rbp),%xmm0
movsd  -0x50(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x24(%rbp),%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x60(%rbp),%xmm0
movsd  %xmm0,-0x80(%rbp)
movsd  -0x70(%rbp),%xmm2
movsd  -0x68(%rbp),%xmm1
mulsd  -0x78(%rbp),%xmm1
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
addsd  -0x60(%rbp),%xmm0
movsd  %xmm0,-0x60(%rbp)
movsd  -0x68(%rbp),%xmm0
movsd  -0x70(%rbp),%xmm2
movsd  -0x80(%rbp),%xmm1
mulsd  -0x78(%rbp),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
addsd  -0x68(%rbp),%xmm0
movsd  %xmm0,-0x68(%rbp)
mov    -0x14(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x14(%rbp)
jmp    1233 <realft+0x113>
cmpl   $0x1,-0x10(%rbp)
jne    152f <realft+0x40f>
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm0
movsd  %xmm0,-0x40(%rbp)
mov    -0x8(%rbp),%rax
addsd  0x8(%rax),%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,(%rax)
movsd  -0x40(%rbp),%xmm0
mov    -0x8(%rbp),%rax
subsd  0x8(%rax),%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x8(%rax)
jmp    158a <realft+0x46a>
movsd  -0x30(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm1
movsd  %xmm1,-0x40(%rbp)
mov    -0x8(%rbp),%rax
addsd  0x8(%rax),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,(%rax)
movsd  -0x30(%rbp),%xmm0
movsd  -0x40(%rbp),%xmm1
mov    -0x8(%rbp),%rax
subsd  0x8(%rax),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x8(%rax)
mov    -0x8(%rbp),%rdi
mov    -0xc(%rbp),%esi
sar    $0x1,%esi
mov    $0xffffffff,%edx
call   1030 <four1@plt>
add    $0x90,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<realft>:
push   %rbp
push   %r15
push   %r14
push   %rbx
sub    $0x38,%rsp
mov    %esi,%ebp
mov    %esi,%r15d
sar    %r15d
cvtsi2sd %r15d,%xmm0
mov    %edx,%r14d
mov    %rdi,%rbx
movsd  0xebb(%rip),%xmm1
divsd  %xmm0,%xmm1
cmp    $0x1,%edx
jne    1172 <realft+0x52>
mov    %rbx,%rdi
mov    %r15d,%esi
mov    $0x1,%edx
movapd %xmm1,(%rsp)
call   1030 <four1@plt>
movapd (%rsp),%xmm1
movsd  0xea0(%rip),%xmm0
jmp    1182 <realft+0x62>
xorpd  0xeb6(%rip),%xmm1
movsd  0xe86(%rip),%xmm0
movaps %xmm0,0x20(%rsp)
movapd %xmm1,(%rsp)
movsd  0xe74(%rip),%xmm0
mulsd  %xmm1,%xmm0
call   1040 <sin@plt>
movsd  %xmm0,0x18(%rsp)
movapd (%rsp),%xmm0
call   1040 <sin@plt>
cmp    $0x8,%ebp
movapd 0x20(%rsp),%xmm12
jl     1315 <realft+0x1f5>
movsd  0xe52(%rip),%xmm10
movsd  0x18(%rsp),%xmm1
mulsd  %xmm1,%xmm10
mulsd  %xmm1,%xmm10
mov    %ebp,%eax
shr    $0x2,%eax
movsd  0xe3d(%rip),%xmm3
addsd  %xmm10,%xmm3
movapd 0xe40(%rip),%xmm4
xorpd  %xmm12,%xmm4
shl    $0x3,%rax
movapd %xmm0,%xmm11
unpcklpd %xmm3,%xmm11
unpcklpd %xmm4,%xmm12
unpcklpd %xmm10,%xmm10
unpcklpd %xmm0,%xmm0
add    $0xfffffffe,%ebp
mov    $0x8,%ecx
movapd 0xe1e(%rip),%xmm8
movapd 0xe05(%rip),%xmm9
nopl   0x0(%rax,%rax,1)
movslq %ebp,%rdx
add    $0x1,%ebp
movslq %ebp,%rsi
movsd  (%rbx,%rdx,8),%xmm3
movhpd (%rbx,%rsi,8),%xmm3
movupd (%rbx,%rcx,2),%xmm6
movapd %xmm6,%xmm4
addpd  %xmm3,%xmm4
subpd  %xmm3,%xmm6
movapd %xmm6,%xmm5
movsd  %xmm4,%xmm5
mulpd  %xmm8,%xmm5
shufpd $0x2,%xmm4,%xmm6
mulpd  %xmm12,%xmm6
movapd %xmm11,%xmm3
xorpd  %xmm9,%xmm3
movapd %xmm11,%xmm7
unpckhpd %xmm11,%xmm7
movapd %xmm6,%xmm4
shufpd $0x1,%xmm6,%xmm4
mulpd  %xmm7,%xmm4
addpd  %xmm5,%xmm4
movapd %xmm11,%xmm2
shufpd $0x1,%xmm3,%xmm2
unpcklpd %xmm11,%xmm3
mulpd  %xmm6,%xmm3
addpd  %xmm4,%xmm3
movapd %xmm7,%xmm4
movapd %xmm11,%xmm1
mulsd  %xmm6,%xmm1
mulsd  %xmm6,%xmm7
unpckhpd %xmm6,%xmm6
movupd %xmm3,(%rbx,%rcx,2)
mulsd  %xmm6,%xmm4
movapd %xmm5,%xmm3
subsd  %xmm4,%xmm3
addsd  %xmm3,%xmm1
movsd  %xmm1,(%rbx,%rdx,8)
unpckhpd %xmm5,%xmm5
subsd  %xmm5,%xmm7
mulsd  %xmm11,%xmm6
addsd  %xmm7,%xmm6
movsd  %xmm6,(%rbx,%rsi,8)
mulpd  %xmm0,%xmm2
movapd %xmm11,%xmm1
mulpd  %xmm10,%xmm1
addpd  %xmm2,%xmm1
addpd  %xmm1,%xmm11
add    $0xfffffffe,%edx
add    $0x8,%rcx
mov    %edx,%ebp
cmp    %rcx,%rax
jne    1230 <realft+0x110>
cmp    $0x1,%r14d
jne    1340 <realft+0x220>
movsd  0x8(%rbx),%xmm0
movapd %xmm0,%xmm1
addsd  %xmm0,%xmm1
movsd  %xmm1,(%rbx)
subsd  %xmm0,%xmm0
movsd  %xmm0,0x8(%rbx)
add    $0x38,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
ret
movsd  (%rbx),%xmm0
movsd  0x8(%rbx),%xmm1
movapd %xmm0,%xmm2
addsd  %xmm1,%xmm2
movsd  0xcaf(%rip),%xmm3
mulsd  %xmm3,%xmm2
movsd  %xmm2,(%rbx)
subsd  %xmm1,%xmm0
mulsd  %xmm3,%xmm0
movsd  %xmm0,0x8(%rbx)
mov    %rbx,%rdi
mov    %r15d,%esi
mov    $0xffffffff,%edx
add    $0x38,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
jmp    1030 <four1@plt>

LLVM IR (-O0):
define void @realft(double* %0, i32 %1, i32 %2) {
%4 = alloca double*
%5 = alloca i32
%6 = alloca i32
%7 = alloca i32
%8 = alloca i32
%9 = alloca i32
%10 = alloca i32
%11 = alloca i32
%12 = alloca i32
%13 = alloca double
%14 = alloca double
%15 = alloca double
%16 = alloca double
%17 = alloca double
%18 = alloca double
%19 = alloca double
%20 = alloca double
%21 = alloca double
%22 = alloca double
%23 = alloca double
%24 = alloca double
store double* %0, double** %4
store i32 %1, i32* %5
store i32 %2, i32* %6
store double 5.000000e-01, double* %13
%25 = load i32, i32* %5
%26 = ashr i32 %25, 1
%27 = sitofp i32 %26 to double
%28 = fdiv double 0x400921FB54442D18, %27
store double %28, double* %24
%29 = load i32, i32* %6
%30 = icmp eq i32 %29, 1
br i1 %30, label %31, label %35
31: ; preds = %3
store double -5.000000e-01, double* %14
%32 = load double*, double** %4
%33 = load i32, i32* %5
%34 = ashr i32 %33, 1
br label %38
35: ; preds = %3
store double 5.000000e-01, double* %14
%36 = load double, double* %24
%37 = fneg double %36
store double %37, double* %24
br label %38
38: ; preds = %35, %31
%39 = load double, double* %24
%40 = fmul double 5.000000e-01, %39
%41 = call double @sin(double %40)
store double %41, double* %23
%42 = load double, double* %23
%43 = fmul double -2.000000e+00, %42
%44 = load double, double* %23
%45 = fmul double %43, %44
store double %45, double* %21
%46 = load double, double* %24
%47 = call double @sin(double %46)
store double %47, double* %22
%48 = load double, double* %21
%49 = fadd double 1.000000e+00, %48
store double %49, double* %19
%50 = load double, double* %22
store double %50, double* %20
%51 = load i32, i32* %5
%52 = add nsw i32 %51, 3
store i32 %52, i32* %12
store i32 2, i32* %7
br label %53
53: ; preds = %196, %38
%54 = load i32, i32* %7
%55 = load i32, i32* %5
%56 = ashr i32 %55, 2
%57 = icmp sle i32 %54, %56
br i1 %57, label %58, label %199
58: ; preds = %53
%59 = load i32, i32* %12
%60 = load i32, i32* %7
%61 = load i32, i32* %7
%62 = add nsw i32 %60, %61
%63 = sub nsw i32 %62, 1
store i32 %63, i32* %8
%64 = add nsw i32 1, %63
store i32 %64, i32* %9
%65 = sub nsw i32 %59, %64
store i32 %65, i32* %10
%66 = add nsw i32 1, %65
store i32 %66, i32* %11
%67 = load double, double* %13
%68 = load double*, double** %4
%69 = load i32, i32* %8
%70 = sub nsw i32 %69, 1
%71 = sext i32 %70 to i64
%72 = getelementptr inbounds double, double* %68, i64 %71
%73 = load double, double* %72
%74 = load double*, double** %4
%75 = load i32, i32* %10
%76 = sub nsw i32 %75, 1
%77 = sext i32 %76 to i64
%78 = getelementptr inbounds double, double* %74, i64 %77
%79 = load double, double* %78
%80 = fadd double %73, %79
%81 = fmul double %67, %80
store double %81, double* %15
%82 = load double, double* %13
%83 = load double*, double** %4
%84 = load i32, i32* %9
%85 = sub nsw i32 %84, 1
%86 = sext i32 %85 to i64
%87 = getelementptr inbounds double, double* %83, i64 %86
%88 = load double, double* %87
%89 = load double*, double** %4
%90 = load i32, i32* %11
%91 = sub nsw i32 %90, 1
%92 = sext i32 %91 to i64
%93 = getelementptr inbounds double, double* %89, i64 %92
%94 = load double, double* %93
%95 = fsub double %88, %94
%96 = fmul double %82, %95
store double %96, double* %16
%97 = load double, double* %14
%98 = fneg double %97
%99 = load double*, double** %4
%100 = load i32, i32* %9
%101 = sub nsw i32 %100, 1
%102 = sext i32 %101 to i64
%103 = getelementptr inbounds double, double* %99, i64 %102
%104 = load double, double* %103
%105 = load double*, double** %4
%106 = load i32, i32* %11
%107 = sub nsw i32 %106, 1
%108 = sext i32 %107 to i64
%109 = getelementptr inbounds double, double* %105, i64 %108
%110 = load double, double* %109
%111 = fadd double %104, %110
%112 = fmul double %98, %111
store double %112, double* %17
%113 = load double, double* %14
%114 = load double*, double** %4
%115 = load i32, i32* %8
%116 = sub nsw i32 %115, 1
%117 = sext i32 %116 to i64
%118 = getelementptr inbounds double, double* %114, i64 %117
%119 = load double, double* %118
%120 = load double*, double** %4
%121 = load i32, i32* %10
%122 = sub nsw i32 %121, 1
%123 = sext i32 %122 to i64
%124 = getelementptr inbounds double, double* %120, i64 %123
%125 = load double, double* %124
%126 = fsub double %119, %125
%127 = fmul double %113, %126
store double %127, double* %18
%128 = load double, double* %15
%129 = load double, double* %19
%130 = load double, double* %17
%131 = call double @llvm.fmuladd.f64(double %129, double %130, double %128)
%132 = load double, double* %20
%133 = load double, double* %18
%134 = fneg double %132
%135 = call double @llvm.fmuladd.f64(double %134, double %133, double %131)
%136 = load double*, double** %4
%137 = load i32, i32* %8
%138 = sub nsw i32 %137, 1
%139 = sext i32 %138 to i64
%140 = getelementptr inbounds double, double* %136, i64 %139
store double %135, double* %140
%141 = load double, double* %16
%142 = load double, double* %19
%143 = load double, double* %18
%144 = call double @llvm.fmuladd.f64(double %142, double %143, double %141)
%145 = load double, double* %20
%146 = load double, double* %17
%147 = call double @llvm.fmuladd.f64(double %145, double %146, double %144)
%148 = load double*, double** %4
%149 = load i32, i32* %9
%150 = sub nsw i32 %149, 1
%151 = sext i32 %150 to i64
%152 = getelementptr inbounds double, double* %148, i64 %151
store double %147, double* %152
%153 = load double, double* %15
%154 = load double, double* %19
%155 = load double, double* %17
%156 = fneg double %154
%157 = call double @llvm.fmuladd.f64(double %156, double %155, double %153)
%158 = load double, double* %20
%159 = load double, double* %18
%160 = call double @llvm.fmuladd.f64(double %158, double %159, double %157)
%161 = load double*, double** %4
%162 = load i32, i32* %10
%163 = sub nsw i32 %162, 1
%164 = sext i32 %163 to i64
%165 = getelementptr inbounds double, double* %161, i64 %164
store double %160, double* %165
%166 = load double, double* %16
%167 = fneg double %166
%168 = load double, double* %19
%169 = load double, double* %18
%170 = call double @llvm.fmuladd.f64(double %168, double %169, double %167)
%171 = load double, double* %20
%172 = load double, double* %17
%173 = call double @llvm.fmuladd.f64(double %171, double %172, double %170)
%174 = load double*, double** %4
%175 = load i32, i32* %11
%176 = sub nsw i32 %175, 1
%177 = sext i32 %176 to i64
%178 = getelementptr inbounds double, double* %174, i64 %177
store double %173, double* %178
%179 = load double, double* %19
store double %179, double* %23
%180 = load double, double* %21
%181 = load double, double* %20
%182 = load double, double* %22
%183 = fmul double %181, %182
%184 = fneg double %183
%185 = call double @llvm.fmuladd.f64(double %179, double %180, double %184)
%186 = load double, double* %19
%187 = fadd double %185, %186
store double %187, double* %19
%188 = load double, double* %20
%189 = load double, double* %21
%190 = load double, double* %23
%191 = load double, double* %22
%192 = fmul double %190, %191
%193 = call double @llvm.fmuladd.f64(double %188, double %189, double %192)
%194 = load double, double* %20
%195 = fadd double %193, %194
store double %195, double* %20
br label %196
196: ; preds = %58
%197 = load i32, i32* %7
%198 = add nsw i32 %197, 1
store i32 %198, i32* %7
br label %53
199: ; preds = %53
%200 = load i32, i32* %6
%201 = icmp eq i32 %200, 1
br i1 %201, label %202, label %219
202: ; preds = %199
%203 = load double*, double** %4
%204 = getelementptr inbounds double, double* %203, i64 1
%205 = load double, double* %204
store double %205, double* %15
%206 = load double*, double** %4
%207 = getelementptr inbounds double, double* %206, i64 1
%208 = load double, double* %207
%209 = fadd double %205, %208
%210 = load double*, double** %4
%211 = getelementptr inbounds double, double* %210, i64 0
store double %209, double* %211
%212 = load double, double* %15
%213 = load double*, double** %4
%214 = getelementptr inbounds double, double* %213, i64 1
%215 = load double, double* %214
%216 = fsub double %212, %215
%217 = load double*, double** %4
%218 = getelementptr inbounds double, double* %217, i64 1
store double %216, double* %218
br label %243
219: ; preds = %199
%220 = load double, double* %13
%221 = load double*, double** %4
%222 = getelementptr inbounds double, double* %221, i64 0
%223 = load double, double* %222
store double %223, double* %15
%224 = load double*, double** %4
%225 = getelementptr inbounds double, double* %224, i64 1
%226 = load double, double* %225
%227 = fadd double %223, %226
%228 = fmul double %220, %227
%229 = load double*, double** %4
%230 = getelementptr inbounds double, double* %229, i64 0
store double %228, double* %230
%231 = load double, double* %13
%232 = load double, double* %15
%233 = load double*, double** %4
%234 = getelementptr inbounds double, double* %233, i64 1
%235 = load double, double* %234
%236 = fsub double %232, %235
%237 = fmul double %231, %236
%238 = load double*, double** %4
%239 = getelementptr inbounds double, double* %238, i64 1
store double %237, double* %239
%240 = load double*, double** %4
%241 = load i32, i32* %5
%242 = ashr i32 %241, 1
br label %243
243: ; preds = %219, %202
ret void
}

LLVM IR (-O2):
define void @realft(double* %0, i32 %1, i32 %2) {
%4 = ashr i32 %1, 1
%5 = sitofp i32 %4 to double
%6 = fdiv double 0x400921FB54442D18, %5
%7 = icmp eq i32 %2, 1
br i1 %7, label %8, label %9
8: ; preds = %3
tail call void @four1(double* %0, i32 %4, i32 1)
br label %11
9: ; preds = %3
%10 = fneg double %6
br label %11
11: ; preds = %9, %8
%12 = phi double [ -5.000000e-01, %8 ], [ 5.000000e-01, %9 ]
%13 = phi double [ %6, %8 ], [ %10, %9 ]
%14 = fmul double %13, 5.000000e-01
%15 = tail call double @sin(double %14)
%16 = fmul double %15, -2.000000e+00
%17 = fmul double %15, %16
%18 = tail call double @sin(double %13)
%19 = add nsw i32 %1, 3
%20 = icmp slt i32 %1, 8
br i1 %20, label %86, label %21
21: ; preds = %11
%22 = lshr i32 %1, 2
%23 = fadd double %17, 1.000000e+00
%24 = fneg double %12
%25 = add nuw nsw i32 %22, 1
%26 = zext i32 %25 to i64
%27 = insertelement <2 x double> poison, double %18, i64 0
%28 = insertelement <2 x double> %27, double %23, i64 1
%29 = insertelement <2 x double> poison, double %12, i64 0
%30 = insertelement <2 x double> %29, double %24, i64 1
%31 = insertelement <2 x double> poison, double %17, i64 0
%32 = shufflevector <2 x double> %31, <2 x double> poison, <2 x i32> zeroinitializer
%33 = shufflevector <2 x double> %27, <2 x double> poison, <2 x i32> zeroinitializer
br label %34
34: ; preds = %21, %34
%35 = phi i64 [ 2, %21 ], [ %84, %34 ]
%36 = phi <2 x double> [ %28, %21 ], [ %83, %34 ]
%37 = shl nuw nsw i64 %35, 1
%38 = trunc i64 %37 to i32
%39 = sub i32 %19, %38
%40 = add nsw i64 %37, -2
%41 = getelementptr inbounds double, double* %0, i64 %40
%42 = add nsw i32 %39, -1
%43 = sext i32 %42 to i64
%44 = getelementptr inbounds double, double* %0, i64 %43
%45 = load double, double* %44
%46 = bitcast double* %41 to <2 x double>*
%47 = load <2 x double>, <2 x double>* %46
%48 = sext i32 %39 to i64
%49 = getelementptr inbounds double, double* %0, i64 %48
%50 = load double, double* %49
%51 = insertelement <2 x double> poison, double %45, i64 0
%52 = insertelement <2 x double> %51, double %50, i64 1
%53 = fadd <2 x double> %47, %52
%54 = fsub <2 x double> %47, %52
%55 = shufflevector <2 x double> %53, <2 x double> %54, <2 x i32> <i32 0, i32 3>
%56 = fmul <2 x double> %55, <double 5.000000e-01, double 5.000000e-01>
%57 = shufflevector <2 x double> %54, <2 x double> %53, <2 x i32> <i32 0, i32 3>
%58 = fmul <2 x double> %30, %57
%59 = extractelement <2 x double> %36, i64 0
%60 = fneg double %59
%61 = extractelement <2 x double> %36, i64 1
%62 = shufflevector <2 x double> %36, <2 x double> undef, <2 x i32> <i32 1, i32 undef>
%63 = shufflevector <2 x double> %36, <2 x double> poison, <2 x i32> <i32 1, i32 1>
%64 = extractelement <2 x double> %58, i64 1
%65 = extractelement <2 x double> %58, i64 0
%66 = shufflevector <2 x double> %58, <2 x double> undef, <2 x i32> <i32 1, i32 0>
%67 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %63, <2 x double> %66, <2 x double> %56)
%68 = insertelement <2 x double> poison, double %60, i64 0
%69 = shufflevector <2 x double> %68, <2 x double> %36, <2 x i32> <i32 0, i32 2>
%70 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %69, <2 x double> %58, <2 x double> %67)
%71 = bitcast double* %41 to <2 x double>*
store <2 x double> %70, <2 x double>* %71
%72 = fneg double %61
%73 = extractelement <2 x double> %56, i64 0
%74 = tail call double @llvm.fmuladd.f64(double %72, double %64, double %73)
%75 = tail call double @llvm.fmuladd.f64(double %59, double %65, double %74)
store double %75, double* %44
%76 = extractelement <2 x double> %56, i64 1
%77 = fneg double %76
%78 = tail call double @llvm.fmuladd.f64(double %61, double %65, double %77)
%79 = tail call double @llvm.fmuladd.f64(double %59, double %64, double %78)
store double %79, double* %49
%80 = insertelement <2 x double> %62, double %60, i64 1
%81 = fmul <2 x double> %33, %80
%82 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %36, <2 x double> %32, <2 x double> %81)
%83 = fadd <2 x double> %36, %82
%84 = add nuw nsw i64 %35, 1
%85 = icmp eq i64 %84, %26
br i1 %85, label %86, label %34
86: ; preds = %34, %11
br i1 %7, label %87, label %92
87: ; preds = %86
%88 = getelementptr inbounds double, double* %0, i64 1
%89 = load double, double* %88
%90 = fadd double %89, %89
store double %90, double* %0
%91 = fsub double %89, %89
store double %91, double* %88
br label %100
92: ; preds = %86
%93 = load double, double* %0
%94 = getelementptr inbounds double, double* %0, i64 1
%95 = load double, double* %94
%96 = fadd double %93, %95
%97 = fmul double %96, 5.000000e-01
store double %97, double* %0
%98 = fsub double %93, %95
%99 = fmul double %98, 5.000000e-01
store double %99, double* %94
tail call void @four1(double* %0, i32 %4, i32 -1)
br label %100
100: ; preds = %92, %87
ret void
}