#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 d_realft(double data[], unsigned long n, int isign) {
  void d_four1(double data[], unsigned long nn, int isign);
  unsigned long 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;
    d_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] + data[i3]);
    h1i = c1 * (data[i2] - data[i4]);
    h2r = -c2 * (data[i2] + data[i4]);
    h2i = c2 * (data[i1] - data[i3]);
    data[i1] = h1r + wr * h2r - wi * h2i;
    data[i2] = h1i + wr * h2i + wi * h2r;
    data[i3] = h1r - wr * h2r + wi * h2i;
    data[i4] = -h1i + wr * h2i + wi * h2r;
    wr = (wtemp = wr) * wpr - wi * wpi + wr;
    wi = wi * wpr + wtemp * wpi + wi;
  }
  if (isign == 1) {
    data[1] = (h1r = data[1]) + data[2];
    data[2] = h1r - data[2];
  } else {
    data[1] = c1 * ((h1r = data[1]) + data[2]);
    data[2] = c1 * (h1r - data[2]);
    d_four1(data, n >> 1, -1);
  }
}


x86 assembly (clang, -O0):
<d_realft>:
push   %rbp
mov    %rsp,%rbp
sub    $0xb0,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %edx,-0x14(%rbp)
movabs $0x3fe0000000000000,%rax
mov    %rax,-0x50(%rbp)
mov    -0x10(%rbp),%rax
shr    %rax
cvtsi2sd %rax,%xmm1
movsd  0xea8(%rip),%xmm0
divsd  %xmm1,%xmm0
movsd  %xmm0,-0xa8(%rbp)
ff
cmpl   $0x1,-0x14(%rbp)
jne    1196 <d_realft+0x76>
movsd  0xe9a(%rip),%xmm0
movsd  %xmm0,-0x58(%rbp)
mov    -0x8(%rbp),%rdi
mov    -0x10(%rbp),%rsi
shr    $0x1,%rsi
mov    $0x1,%edx
call   1040 <d_four1@plt>
jmp    11ca <d_realft+0xaa>
movsd  0xe6a(%rip),%xmm0
movsd  %xmm0,-0x58(%rbp)
movsd  -0xa8(%rbp),%xmm0
ff
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  %xmm0,-0xa8(%rbp)
ff
movsd  0xe36(%rip),%xmm0
mulsd  -0xa8(%rbp),%xmm0
ff
call   1030 <sin@plt>
movsd  %xmm0,-0xa0(%rbp)
ff
movsd  0xe31(%rip),%xmm0
mulsd  -0xa0(%rbp),%xmm0
ff
mulsd  -0xa0(%rbp),%xmm0
ff
movsd  %xmm0,-0x90(%rbp)
ff
movsd  -0xa8(%rbp),%xmm0
ff
call   1030 <sin@plt>
movsd  %xmm0,-0x98(%rbp)
ff
movsd  0xdf4(%rip),%xmm0
addsd  -0x90(%rbp),%xmm0
ff
movsd  %xmm0,-0x80(%rbp)
movsd  -0x98(%rbp),%xmm0
ff
movsd  %xmm0,-0x88(%rbp)
ff
mov    -0x10(%rbp),%rax
add    $0x3,%rax
mov    %rax,-0x48(%rbp)
movq   $0x2,-0x20(%rbp)
mov    -0x20(%rbp),%rax
mov    -0x10(%rbp),%rcx
shr    $0x2,%rcx
cmp    %rcx,%rax
ja     150c <d_realft+0x3ec>
mov    -0x48(%rbp),%rax
mov    -0x20(%rbp),%rcx
add    -0x20(%rbp),%rcx
sub    $0x1,%rcx
mov    %rcx,-0x28(%rbp)
add    $0x1,%rcx
mov    %rcx,-0x30(%rbp)
sub    %rcx,%rax
mov    %rax,-0x38(%rbp)
add    $0x1,%rax
mov    %rax,-0x40(%rbp)
movsd  -0x50(%rbp),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x28(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x60(%rbp)
movsd  -0x50(%rbp),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x30(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x40(%rbp),%rcx
subsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x68(%rbp)
movsd  -0x58(%rbp),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x30(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x40(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x70(%rbp)
movsd  -0x58(%rbp),%xmm0
mov    -0x8(%rbp),%rax
mov    -0x28(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
subsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x78(%rbp)
movsd  -0x60(%rbp),%xmm0
movsd  -0x80(%rbp),%xmm1
movsd  -0x70(%rbp),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x88(%rbp),%xmm0
ff
movsd  -0x78(%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    -0x28(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x68(%rbp),%xmm0
movsd  -0x80(%rbp),%xmm1
movsd  -0x78(%rbp),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x88(%rbp),%xmm0
ff
movsd  -0x70(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x30(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x60(%rbp),%xmm0
movsd  -0x80(%rbp),%xmm1
movsd  -0x70(%rbp),%xmm2
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x88(%rbp),%xmm0
ff
movsd  -0x78(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x38(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x68(%rbp),%xmm0
movq   %xmm0,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm0
movsd  -0x80(%rbp),%xmm1
movsd  -0x78(%rbp),%xmm2
mulsd  %xmm2,%xmm1
addsd  %xmm0,%xmm1
movsd  -0x88(%rbp),%xmm0
ff
movsd  -0x70(%rbp),%xmm2
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
mov    -0x40(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x80(%rbp),%xmm0
movsd  %xmm0,-0xa0(%rbp)
ff
movsd  -0x90(%rbp),%xmm2
ff
movsd  -0x88(%rbp),%xmm1
ff
mulsd  -0x98(%rbp),%xmm1
ff
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
addsd  -0x80(%rbp),%xmm0
movsd  %xmm0,-0x80(%rbp)
movsd  -0x88(%rbp),%xmm0
ff
movsd  -0x90(%rbp),%xmm2
ff
movsd  -0xa0(%rbp),%xmm1
ff
mulsd  -0x98(%rbp),%xmm1
ff
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
addsd  -0x88(%rbp),%xmm0
ff
movsd  %xmm0,-0x88(%rbp)
ff
mov    -0x20(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x20(%rbp)
jmp    1255 <d_realft+0x135>
cmpl   $0x1,-0x14(%rbp)
jne    1552 <d_realft+0x432>
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm0
movsd  %xmm0,-0x60(%rbp)
mov    -0x8(%rbp),%rax
addsd  0x10(%rax),%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x8(%rax)
movsd  -0x60(%rbp),%xmm0
mov    -0x8(%rbp),%rax
subsd  0x10(%rax),%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x10(%rax)
jmp    15b1 <d_realft+0x491>
movsd  -0x50(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm1
movsd  %xmm1,-0x60(%rbp)
mov    -0x8(%rbp),%rax
addsd  0x10(%rax),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x8(%rax)
movsd  -0x50(%rbp),%xmm0
movsd  -0x60(%rbp),%xmm1
mov    -0x8(%rbp),%rax
subsd  0x10(%rax),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x10(%rax)
mov    -0x8(%rbp),%rdi
mov    -0x10(%rbp),%rsi
shr    $0x1,%rsi
mov    $0xffffffff,%edx
call   1040 <d_four1@plt>
add    $0xb0,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<d_realft>:
push   %rbp
push   %r15
push   %r14
push   %rbx
sub    $0x38,%rsp
mov    %rsi,%rbx
mov    %rsi,%r14
shr    %r14
cvtsi2sd %r14,%xmm0
mov    %edx,%ebp
mov    %rdi,%r15
movsd  0xebb(%rip),%xmm1
divsd  %xmm0,%xmm1
cmp    $0x1,%edx
jne    1172 <d_realft+0x52>
mov    %r15,%rdi
mov    %r14,%rsi
mov    $0x1,%edx
movapd %xmm1,(%rsp)
call   1040 <d_four1@plt>
movapd (%rsp),%xmm1
movsd  0xea0(%rip),%xmm0
jmp    1182 <d_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   1030 <sin@plt>
movsd  %xmm0,0x18(%rsp)
movapd (%rsp),%xmm0
call   1030 <sin@plt>
cmp    $0x8,%rbx
movapd 0x20(%rsp),%xmm12
jb     12fe <d_realft+0x1de>
movsd  0xe51(%rip),%xmm9
movsd  0x18(%rsp),%xmm1
mulsd  %xmm1,%xmm9
mulsd  %xmm1,%xmm9
lea    (%r15,%rbx,8),%rax
add    $0xfffffffffffffff8,%rax
shr    $0x2,%rbx
movsd  0xe35(%rip),%xmm2
addsd  %xmm9,%xmm2
movapd 0xe38(%rip),%xmm1
xorpd  %xmm12,%xmm1
movapd %xmm0,%xmm11
unpcklpd %xmm2,%xmm11
unpcklpd %xmm1,%xmm12
unpcklpd %xmm9,%xmm9
unpcklpd %xmm0,%xmm0
add    $0xffffffffffffffff,%rbx
lea    0x18(%r15),%rcx
movapd 0xe1a(%rip),%xmm8
movapd 0xe01(%rip),%xmm10
nop
movupd (%rcx),%xmm6
movupd (%rax),%xmm5
movapd %xmm6,%xmm7
addpd  %xmm5,%xmm7
subpd  %xmm5,%xmm6
movapd %xmm6,%xmm5
movsd  %xmm7,%xmm5
mulpd  %xmm8,%xmm5
shufpd $0x2,%xmm7,%xmm6
mulpd  %xmm12,%xmm6
movapd %xmm11,%xmm7
xorpd  %xmm10,%xmm7
movapd %xmm11,%xmm2
shufpd $0x1,%xmm7,%xmm2
unpcklpd %xmm11,%xmm7
mulpd  %xmm6,%xmm7
movapd %xmm11,%xmm3
unpcklpd %xmm11,%xmm3
mulpd  %xmm6,%xmm3
shufpd $0x1,%xmm6,%xmm6
movapd %xmm11,%xmm4
unpckhpd %xmm11,%xmm4
movapd %xmm4,%xmm1
mulpd  %xmm6,%xmm1
addpd  %xmm5,%xmm1
addpd  %xmm1,%xmm7
movupd %xmm7,(%rcx)
xorpd  %xmm10,%xmm4
movapd %xmm5,%xmm1
unpckhpd %xmm5,%xmm1
xorpd  %xmm10,%xmm1
shufpd $0x2,%xmm11,%xmm4
unpcklpd %xmm1,%xmm5
mulpd  %xmm6,%xmm4
addpd  %xmm5,%xmm4
addpd  %xmm4,%xmm3
movupd %xmm3,(%rax)
mulpd  %xmm0,%xmm2
movapd %xmm11,%xmm1
mulpd  %xmm9,%xmm1
addpd  %xmm2,%xmm1
addpd  %xmm1,%xmm11
add    $0xfffffffffffffff0,%rax
add    $0x10,%rcx
add    $0xffffffffffffffff,%rbx
jne    1230 <d_realft+0x110>
movsd  0x8(%r15),%xmm0
movsd  0x10(%r15),%xmm2
movapd %xmm0,%xmm1
addsd  %xmm2,%xmm1
cmp    $0x1,%ebp
jne    1332 <d_realft+0x212>
movsd  %xmm1,0x8(%r15)
subsd  %xmm2,%xmm0
movsd  %xmm0,0x10(%r15)
add    $0x38,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
ret
subsd  %xmm2,%xmm0
unpcklpd %xmm0,%xmm1
mulpd  0xcfe(%rip),%xmm1
movupd %xmm1,0x8(%r15)
mov    %r15,%rdi
mov    %r14,%rsi
mov    $0xffffffff,%edx
add    $0x38,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
jmp    1040 <d_four1@plt>

LLVM IR (-O0):
define void @d_realft(double* %0, i64 %1, i32 %2) {
%4 = alloca double*
%5 = alloca i64
%6 = alloca i32
%7 = alloca i64
%8 = alloca i64
%9 = alloca i64
%10 = alloca i64
%11 = alloca i64
%12 = alloca i64
%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 i64 %1, i64* %5
store i32 %2, i32* %6
store double 5.000000e-01, double* %13
%25 = load i64, i64* %5
%26 = lshr i64 %25, 1
%27 = uitofp i64 %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 i64, i64* %5
%34 = lshr i64 %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 i64, i64* %5
%52 = add i64 %51, 3
store i64 %52, i64* %12
store i64 2, i64* %7
br label %53
53: ; preds = %172, %38
%54 = load i64, i64* %7
%55 = load i64, i64* %5
%56 = lshr i64 %55, 2
%57 = icmp ule i64 %54, %56
br i1 %57, label %58, label %175
58: ; preds = %53
%59 = load i64, i64* %12
%60 = load i64, i64* %7
%61 = load i64, i64* %7
%62 = add i64 %60, %61
%63 = sub i64 %62, 1
store i64 %63, i64* %8
%64 = add i64 1, %63
store i64 %64, i64* %9
%65 = sub i64 %59, %64
store i64 %65, i64* %10
%66 = add i64 1, %65
store i64 %66, i64* %11
%67 = load double, double* %13
%68 = load double*, double** %4
%69 = load i64, i64* %8
%70 = getelementptr inbounds double, double* %68, i64 %69
%71 = load double, double* %70
%72 = load double*, double** %4
%73 = load i64, i64* %10
%74 = getelementptr inbounds double, double* %72, i64 %73
%75 = load double, double* %74
%76 = fadd double %71, %75
%77 = fmul double %67, %76
store double %77, double* %15
%78 = load double, double* %13
%79 = load double*, double** %4
%80 = load i64, i64* %9
%81 = getelementptr inbounds double, double* %79, i64 %80
%82 = load double, double* %81
%83 = load double*, double** %4
%84 = load i64, i64* %11
%85 = getelementptr inbounds double, double* %83, i64 %84
%86 = load double, double* %85
%87 = fsub double %82, %86
%88 = fmul double %78, %87
store double %88, double* %16
%89 = load double, double* %14
%90 = fneg double %89
%91 = load double*, double** %4
%92 = load i64, i64* %9
%93 = getelementptr inbounds double, double* %91, i64 %92
%94 = load double, double* %93
%95 = load double*, double** %4
%96 = load i64, i64* %11
%97 = getelementptr inbounds double, double* %95, i64 %96
%98 = load double, double* %97
%99 = fadd double %94, %98
%100 = fmul double %90, %99
store double %100, double* %17
%101 = load double, double* %14
%102 = load double*, double** %4
%103 = load i64, i64* %8
%104 = getelementptr inbounds double, double* %102, i64 %103
%105 = load double, double* %104
%106 = load double*, double** %4
%107 = load i64, i64* %10
%108 = getelementptr inbounds double, double* %106, i64 %107
%109 = load double, double* %108
%110 = fsub double %105, %109
%111 = fmul double %101, %110
store double %111, double* %18
%112 = load double, double* %15
%113 = load double, double* %19
%114 = load double, double* %17
%115 = call double @llvm.fmuladd.f64(double %113, double %114, double %112)
%116 = load double, double* %20
%117 = load double, double* %18
%118 = fneg double %116
%119 = call double @llvm.fmuladd.f64(double %118, double %117, double %115)
%120 = load double*, double** %4
%121 = load i64, i64* %8
%122 = getelementptr inbounds double, double* %120, i64 %121
store double %119, double* %122
%123 = load double, double* %16
%124 = load double, double* %19
%125 = load double, double* %18
%126 = call double @llvm.fmuladd.f64(double %124, double %125, double %123)
%127 = load double, double* %20
%128 = load double, double* %17
%129 = call double @llvm.fmuladd.f64(double %127, double %128, double %126)
%130 = load double*, double** %4
%131 = load i64, i64* %9
%132 = getelementptr inbounds double, double* %130, i64 %131
store double %129, double* %132
%133 = load double, double* %15
%134 = load double, double* %19
%135 = load double, double* %17
%136 = fneg double %134
%137 = call double @llvm.fmuladd.f64(double %136, double %135, double %133)
%138 = load double, double* %20
%139 = load double, double* %18
%140 = call double @llvm.fmuladd.f64(double %138, double %139, double %137)
%141 = load double*, double** %4
%142 = load i64, i64* %10
%143 = getelementptr inbounds double, double* %141, i64 %142
store double %140, double* %143
%144 = load double, double* %16
%145 = fneg double %144
%146 = load double, double* %19
%147 = load double, double* %18
%148 = call double @llvm.fmuladd.f64(double %146, double %147, double %145)
%149 = load double, double* %20
%150 = load double, double* %17
%151 = call double @llvm.fmuladd.f64(double %149, double %150, double %148)
%152 = load double*, double** %4
%153 = load i64, i64* %11
%154 = getelementptr inbounds double, double* %152, i64 %153
store double %151, double* %154
%155 = load double, double* %19
store double %155, double* %23
%156 = load double, double* %21
%157 = load double, double* %20
%158 = load double, double* %22
%159 = fmul double %157, %158
%160 = fneg double %159
%161 = call double @llvm.fmuladd.f64(double %155, double %156, double %160)
%162 = load double, double* %19
%163 = fadd double %161, %162
store double %163, double* %19
%164 = load double, double* %20
%165 = load double, double* %21
%166 = load double, double* %23
%167 = load double, double* %22
%168 = fmul double %166, %167
%169 = call double @llvm.fmuladd.f64(double %164, double %165, double %168)
%170 = load double, double* %20
%171 = fadd double %169, %170
store double %171, double* %20
br label %172
172: ; preds = %58
%173 = load i64, i64* %7
%174 = add i64 %173, 1
store i64 %174, i64* %7
br label %53
175: ; preds = %53
%176 = load i32, i32* %6
%177 = icmp eq i32 %176, 1
br i1 %177, label %178, label %195
178: ; preds = %175
%179 = load double*, double** %4
%180 = getelementptr inbounds double, double* %179, i64 1
%181 = load double, double* %180
store double %181, double* %15
%182 = load double*, double** %4
%183 = getelementptr inbounds double, double* %182, i64 2
%184 = load double, double* %183
%185 = fadd double %181, %184
%186 = load double*, double** %4
%187 = getelementptr inbounds double, double* %186, i64 1
store double %185, double* %187
%188 = load double, double* %15
%189 = load double*, double** %4
%190 = getelementptr inbounds double, double* %189, i64 2
%191 = load double, double* %190
%192 = fsub double %188, %191
%193 = load double*, double** %4
%194 = getelementptr inbounds double, double* %193, i64 2
store double %192, double* %194
br label %219
195: ; preds = %175
%196 = load double, double* %13
%197 = load double*, double** %4
%198 = getelementptr inbounds double, double* %197, i64 1
%199 = load double, double* %198
store double %199, double* %15
%200 = load double*, double** %4
%201 = getelementptr inbounds double, double* %200, i64 2
%202 = load double, double* %201
%203 = fadd double %199, %202
%204 = fmul double %196, %203
%205 = load double*, double** %4
%206 = getelementptr inbounds double, double* %205, i64 1
store double %204, double* %206
%207 = load double, double* %13
%208 = load double, double* %15
%209 = load double*, double** %4
%210 = getelementptr inbounds double, double* %209, i64 2
%211 = load double, double* %210
%212 = fsub double %208, %211
%213 = fmul double %207, %212
%214 = load double*, double** %4
%215 = getelementptr inbounds double, double* %214, i64 2
store double %213, double* %215
%216 = load double*, double** %4
%217 = load i64, i64* %5
%218 = lshr i64 %217, 1
br label %219
219: ; preds = %195, %178
ret void
}

LLVM IR (-O2):
define void @d_realft(double* %0, i64 %1, i32 %2) {
%4 = lshr i64 %1, 1
%5 = uitofp i64 %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 @d_four1(double* %0, i64 %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 i64 %1, 3
%20 = icmp ult i64 %1, 8
br i1 %20, label %77, label %21
21: ; preds = %11
%22 = lshr i64 %1, 2
%23 = fadd double %17, 1.000000e+00
%24 = fneg double %12
%25 = insertelement <2 x double> poison, double %18, i64 0
%26 = insertelement <2 x double> %25, double %23, i64 1
%27 = insertelement <2 x double> poison, double %12, i64 0
%28 = insertelement <2 x double> %27, double %24, i64 1
%29 = insertelement <2 x double> poison, double %17, i64 0
%30 = shufflevector <2 x double> %29, <2 x double> poison, <2 x i32> zeroinitializer
%31 = shufflevector <2 x double> %25, <2 x double> poison, <2 x i32> zeroinitializer
br label %32
32: ; preds = %21, %32
%33 = phi i64 [ 2, %21 ], [ %75, %32 ]
%34 = phi <2 x double> [ %26, %21 ], [ %74, %32 ]
%35 = shl nuw i64 %33, 1
%36 = add nsw i64 %35, -1
%37 = sub i64 %19, %35
%38 = getelementptr inbounds double, double* %0, i64 %36
%39 = getelementptr inbounds double, double* %0, i64 %37
%40 = bitcast double* %38 to <2 x double>*
%41 = load <2 x double>, <2 x double>* %40
%42 = bitcast double* %39 to <2 x double>*
%43 = load <2 x double>, <2 x double>* %42
%44 = fadd <2 x double> %41, %43
%45 = fsub <2 x double> %41, %43
%46 = shufflevector <2 x double> %44, <2 x double> %45, <2 x i32> <i32 0, i32 3>
%47 = fmul <2 x double> %46, <double 5.000000e-01, double 5.000000e-01>
%48 = shufflevector <2 x double> %45, <2 x double> %44, <2 x i32> <i32 0, i32 3>
%49 = fmul <2 x double> %28, %48
%50 = extractelement <2 x double> %34, i64 0
%51 = fneg double %50
%52 = shufflevector <2 x double> %49, <2 x double> poison, <2 x i32> <i32 1, i32 0>
%53 = extractelement <2 x double> %34, i64 1
%54 = shufflevector <2 x double> %34, <2 x double> undef, <2 x i32> <i32 1, i32 undef>
%55 = shufflevector <2 x double> %34, <2 x double> poison, <2 x i32> <i32 1, i32 1>
%56 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %55, <2 x double> %52, <2 x double> %47)
%57 = insertelement <2 x double> poison, double %51, i64 0
%58 = shufflevector <2 x double> %57, <2 x double> %34, <2 x i32> <i32 0, i32 2>
%59 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %58, <2 x double> %49, <2 x double> %56)
%60 = bitcast double* %38 to <2 x double>*
store <2 x double> %59, <2 x double>* %60
%61 = fneg double %53
%62 = extractelement <2 x double> %47, i64 1
%63 = fneg double %62
%64 = insertelement <2 x double> %34, double %61, i64 0
%65 = shufflevector <2 x double> %49, <2 x double> undef, <2 x i32> <i32 1, i32 0>
%66 = insertelement <2 x double> %47, double %63, i64 1
%67 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %64, <2 x double> %65, <2 x double> %66)
%68 = shufflevector <2 x double> %34, <2 x double> undef, <2 x i32> zeroinitializer
%69 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %68, <2 x double> %49, <2 x double> %67)
%70 = bitcast double* %39 to <2 x double>*
store <2 x double> %69, <2 x double>* %70
%71 = insertelement <2 x double> %54, double %51, i64 1
%72 = fmul <2 x double> %31, %71
%73 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %34, <2 x double> %30, <2 x double> %72)
%74 = fadd <2 x double> %34, %73
%75 = add nuw nsw i64 %33, 1
%76 = icmp eq i64 %33, %22
br i1 %76, label %77, label %32
77: ; preds = %32, %11
%78 = getelementptr inbounds double, double* %0, i64 1
%79 = load double, double* %78
%80 = getelementptr inbounds double, double* %0, i64 2
%81 = load double, double* %80
%82 = fadd double %79, %81
br i1 %7, label %83, label %85
83: ; preds = %77
store double %82, double* %78
%84 = fsub double %79, %81
store double %84, double* %80
br label %91
85: ; preds = %77
%86 = fsub double %79, %81
%87 = insertelement <2 x double> poison, double %82, i64 0
%88 = insertelement <2 x double> %87, double %86, i64 1
%89 = fmul <2 x double> %88, <double 5.000000e-01, double 5.000000e-01>
%90 = bitcast double* %78 to <2 x double>*
store <2 x double> %89, <2 x double>* %90
tail call void @d_four1(double* %0, i64 %4, i32 -1)
br label %91
91: ; preds = %85, %83
ret void
}