void realft(data, n, isign) double data[];
unsigned int n;
int isign;
{
  int i, i1, i2, i3, i4, np3;
  double c1 = .5, c2, h1r, h1i, h2r, h2i;
  double wr, wi, wpr, wpi, wtemp, theta;
  theta = 3.141592653589793 / (double)(n / 2);
  if (isign == 1) {
    c2 = -0.5;
    four1(data, n / 2, 1);
  } else {
    c2 = 0.5;
    theta = -theta;
  }
  wtemp = sin(.5 * theta);
  wpr = -2.0 * wtemp * wtemp;
  wpi = sin(theta);
  wr = 1.0 + wpr;
  wi = wpi;
  np3 = n + 3;
  for (i = 2; i <= (n / 4); 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]);
    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)
movabs $0x3fe0000000000000,%rax
mov    %rax,-0x30(%rbp)
mov    -0xc(%rbp),%eax
shr    %eax
cvtsi2sd %eax,%xmm1
movsd  0xeac(%rip),%xmm0
divsd  %xmm1,%xmm0
movsd  %xmm0,-0x88(%rbp)
ff
cmpl   $0x1,-0x10(%rbp)
jne    1192 <realft+0x72>
movsd  0xe9e(%rip),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x8(%rbp),%rdi
mov    -0xc(%rbp),%esi
shr    $0x1,%esi
mov    $0x1,%edx
mov    $0x0,%al
call   1030 <four1@plt>
jmp    11c6 <realft+0xa6>
movsd  0xe6e(%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  0xe3a(%rip),%xmm0
mulsd  -0x88(%rbp),%xmm0
ff
call   1040 <sin@plt>
movsd  %xmm0,-0x80(%rbp)
movsd  0xe38(%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  0xe07(%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
shr    $0x2,%ecx
cmp    %ecx,%eax
ja     14b0 <realft+0x390>
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
movslq -0x18(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
movslq -0x20(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x40(%rbp)
movsd  -0x30(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
movslq -0x24(%rbp),%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
movslq -0x1c(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
movslq -0x24(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm1
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x50(%rbp)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movslq -0x18(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm1
mov    -0x8(%rbp),%rax
movslq -0x20(%rbp),%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
movslq -0x18(%rbp),%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
movslq -0x1c(%rbp),%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
movslq -0x20(%rbp),%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
movslq -0x24(%rbp),%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    1235 <realft+0x115>
cmpl   $0x1,-0x10(%rbp)
jne    14f6 <realft+0x3d6>
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm0
movsd  %xmm0,-0x40(%rbp)
mov    -0x8(%rbp),%rax
addsd  0x10(%rax),%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x8(%rax)
movsd  -0x40(%rbp),%xmm0
mov    -0x8(%rbp),%rax
subsd  0x10(%rax),%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x10(%rax)
jmp    1555 <realft+0x435>
movsd  -0x30(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm1
movsd  %xmm1,-0x40(%rbp)
mov    -0x8(%rbp),%rax
addsd  0x10(%rax),%xmm1
mulsd  %xmm1,%xmm0
mov    -0x8(%rbp),%rax
movsd  %xmm0,0x8(%rax)
movsd  -0x30(%rbp),%xmm0
movsd  -0x40(%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    -0xc(%rbp),%esi
shr    $0x1,%esi
mov    $0xffffffff,%edx
mov    $0x0,%al
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
shr    %r15d
cvtsi2sd %r15d,%xmm0
mov    %edx,%r14d
mov    %rdi,%rbx
movsd  0xebb(%rip),%xmm1
divsd  %xmm0,%xmm1
cmp    $0x1,%edx
jne    1174 <realft+0x54>
mov    %rbx,%rdi
mov    %r15d,%esi
mov    $0x1,%edx
xor    %eax,%eax
movapd %xmm1,(%rsp)
call   1030 <four1@plt>
movapd (%rsp),%xmm1
movsd  0xe9e(%rip),%xmm0
jmp    1184 <realft+0x64>
xorpd  0xeb4(%rip),%xmm1
movsd  0xe84(%rip),%xmm0
movaps %xmm0,0x20(%rsp)
movapd %xmm1,(%rsp)
movsd  0xe72(%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
jb     1315 <realft+0x1f5>
movsd  0xe50(%rip),%xmm10
movsd  0x18(%rsp),%xmm1
mulsd  %xmm1,%xmm10
mulsd  %xmm1,%xmm10
mov    %ebp,%eax
shr    $0x2,%eax
movsd  0xe3b(%rip),%xmm3
addsd  %xmm10,%xmm3
movapd 0xe3e(%rip),%xmm4
xorpd  %xmm12,%xmm4
shl    $0x4,%rax
movapd %xmm0,%xmm11
unpcklpd %xmm3,%xmm11
unpcklpd %xmm4,%xmm12
unpcklpd %xmm10,%xmm10
unpcklpd %xmm0,%xmm0
add    $0xfffffffffffffff0,%rax
xor    %ecx,%ecx
movapd 0xe1e(%rip),%xmm8
movapd 0xe05(%rip),%xmm9
nopl   0x0(%rax,%rax,1)
lea    -0x1(%rbp),%edx
movslq %edx,%rdx
movslq %ebp,%rbp
movsd  (%rbx,%rdx,8),%xmm3
movhpd (%rbx,%rbp,8),%xmm3
movupd 0x18(%rbx,%rcx,1),%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 %xmm3,0x18(%rbx,%rcx,1)
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,%rbp,8)
mulpd  %xmm0,%xmm2
movapd %xmm11,%xmm1
mulpd  %xmm10,%xmm1
addpd  %xmm2,%xmm1
addpd  %xmm1,%xmm11
add    $0xfffffffe,%ebp
add    $0x10,%rcx
cmp    %rcx,%rax
jne    1230 <realft+0x110>
movsd  0x8(%rbx),%xmm0
movsd  0x10(%rbx),%xmm2
movapd %xmm0,%xmm1
addsd  %xmm2,%xmm1
cmp    $0x1,%r14d
jne    1346 <realft+0x226>
movsd  %xmm1,0x8(%rbx)
subsd  %xmm2,%xmm0
movsd  %xmm0,0x10(%rbx)
add    $0x38,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
ret
subsd  %xmm2,%xmm0
unpcklpd %xmm0,%xmm1
mulpd  0xcea(%rip),%xmm1
movupd %xmm1,0x8(%rbx)
mov    %rbx,%rdi
mov    %r15d,%esi
mov    $0xffffffff,%edx
xor    %eax,%eax
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 = udiv i32 %25, 2
%27 = uitofp 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 %36
31: ; preds = %3
store double -5.000000e-01, double* %14
%32 = load double*, double** %4
%33 = load i32, i32* %5
%34 = udiv i32 %33, 2
%35 = call i32 (double*, i32, i32, ...) bitcast (i32 (...)* @four1 to i32 (double*, i32, i32, ...)*)(double* %32, i32 %34, i32 1)
br label %39
36: ; preds = %3
store double 5.000000e-01, double* %14
%37 = load double, double* %24
%38 = fneg double %37
store double %38, double* %24
br label %39
39: ; preds = %36, %31
%40 = load double, double* %24
%41 = fmul double 5.000000e-01, %40
%42 = call double @sin(double %41)
store double %42, double* %23
%43 = load double, double* %23
%44 = fmul double -2.000000e+00, %43
%45 = load double, double* %23
%46 = fmul double %44, %45
store double %46, double* %21
%47 = load double, double* %24
%48 = call double @sin(double %47)
store double %48, double* %22
%49 = load double, double* %21
%50 = fadd double 1.000000e+00, %49
store double %50, double* %19
%51 = load double, double* %22
store double %51, double* %20
%52 = load i32, i32* %5
%53 = add i32 %52, 3
store i32 %53, i32* %12
store i32 2, i32* %7
br label %54
54: ; preds = %185, %39
%55 = load i32, i32* %7
%56 = load i32, i32* %5
%57 = udiv i32 %56, 4
%58 = icmp ule i32 %55, %57
br i1 %58, label %59, label %188
59: ; preds = %54
%60 = load i32, i32* %12
%61 = load i32, i32* %7
%62 = load i32, i32* %7
%63 = add nsw i32 %61, %62
%64 = sub nsw i32 %63, 1
store i32 %64, i32* %8
%65 = add nsw i32 1, %64
store i32 %65, i32* %9
%66 = sub nsw i32 %60, %65
store i32 %66, i32* %10
%67 = add nsw i32 1, %66
store i32 %67, i32* %11
%68 = load double, double* %13
%69 = load double*, double** %4
%70 = load i32, i32* %8
%71 = sext i32 %70 to i64
%72 = getelementptr inbounds double, double* %69, i64 %71
%73 = load double, double* %72
%74 = load double*, double** %4
%75 = load i32, i32* %10
%76 = sext i32 %75 to i64
%77 = getelementptr inbounds double, double* %74, i64 %76
%78 = load double, double* %77
%79 = fadd double %73, %78
%80 = fmul double %68, %79
store double %80, double* %15
%81 = load double, double* %13
%82 = load double*, double** %4
%83 = load i32, i32* %9
%84 = sext i32 %83 to i64
%85 = getelementptr inbounds double, double* %82, i64 %84
%86 = load double, double* %85
%87 = load double*, double** %4
%88 = load i32, i32* %11
%89 = sext i32 %88 to i64
%90 = getelementptr inbounds double, double* %87, i64 %89
%91 = load double, double* %90
%92 = fsub double %86, %91
%93 = fmul double %81, %92
store double %93, double* %16
%94 = load double, double* %14
%95 = fneg double %94
%96 = load double*, double** %4
%97 = load i32, i32* %9
%98 = sext i32 %97 to i64
%99 = getelementptr inbounds double, double* %96, i64 %98
%100 = load double, double* %99
%101 = load double*, double** %4
%102 = load i32, i32* %11
%103 = sext i32 %102 to i64
%104 = getelementptr inbounds double, double* %101, i64 %103
%105 = load double, double* %104
%106 = fadd double %100, %105
%107 = fmul double %95, %106
store double %107, double* %17
%108 = load double, double* %14
%109 = load double*, double** %4
%110 = load i32, i32* %8
%111 = sext i32 %110 to i64
%112 = getelementptr inbounds double, double* %109, i64 %111
%113 = load double, double* %112
%114 = load double*, double** %4
%115 = load i32, i32* %10
%116 = sext i32 %115 to i64
%117 = getelementptr inbounds double, double* %114, i64 %116
%118 = load double, double* %117
%119 = fsub double %113, %118
%120 = fmul double %108, %119
store double %120, double* %18
%121 = load double, double* %15
%122 = load double, double* %19
%123 = load double, double* %17
%124 = call double @llvm.fmuladd.f64(double %122, double %123, double %121)
%125 = load double, double* %20
%126 = load double, double* %18
%127 = fneg double %125
%128 = call double @llvm.fmuladd.f64(double %127, double %126, double %124)
%129 = load double*, double** %4
%130 = load i32, i32* %8
%131 = sext i32 %130 to i64
%132 = getelementptr inbounds double, double* %129, i64 %131
store double %128, double* %132
%133 = load double, double* %16
%134 = load double, double* %19
%135 = load double, double* %18
%136 = call double @llvm.fmuladd.f64(double %134, double %135, double %133)
%137 = load double, double* %20
%138 = load double, double* %17
%139 = call double @llvm.fmuladd.f64(double %137, double %138, double %136)
%140 = load double*, double** %4
%141 = load i32, i32* %9
%142 = sext i32 %141 to i64
%143 = getelementptr inbounds double, double* %140, i64 %142
store double %139, double* %143
%144 = load double, double* %15
%145 = load double, double* %19
%146 = load double, double* %17
%147 = fneg double %145
%148 = call double @llvm.fmuladd.f64(double %147, double %146, double %144)
%149 = load double, double* %20
%150 = load double, double* %18
%151 = call double @llvm.fmuladd.f64(double %149, double %150, double %148)
%152 = load double*, double** %4
%153 = load i32, i32* %10
%154 = sext i32 %153 to i64
%155 = getelementptr inbounds double, double* %152, i64 %154
store double %151, double* %155
%156 = load double, double* %16
%157 = fneg double %156
%158 = load double, double* %19
%159 = load double, double* %18
%160 = call double @llvm.fmuladd.f64(double %158, double %159, double %157)
%161 = load double, double* %20
%162 = load double, double* %17
%163 = call double @llvm.fmuladd.f64(double %161, double %162, double %160)
%164 = load double*, double** %4
%165 = load i32, i32* %11
%166 = sext i32 %165 to i64
%167 = getelementptr inbounds double, double* %164, i64 %166
store double %163, double* %167
%168 = load double, double* %19
store double %168, double* %23
%169 = load double, double* %21
%170 = load double, double* %20
%171 = load double, double* %22
%172 = fmul double %170, %171
%173 = fneg double %172
%174 = call double @llvm.fmuladd.f64(double %168, double %169, double %173)
%175 = load double, double* %19
%176 = fadd double %174, %175
store double %176, double* %19
%177 = load double, double* %20
%178 = load double, double* %21
%179 = load double, double* %23
%180 = load double, double* %22
%181 = fmul double %179, %180
%182 = call double @llvm.fmuladd.f64(double %177, double %178, double %181)
%183 = load double, double* %20
%184 = fadd double %182, %183
store double %184, double* %20
br label %185
185: ; preds = %59
%186 = load i32, i32* %7
%187 = add nsw i32 %186, 1
store i32 %187, i32* %7
br label %54
188: ; preds = %54
%189 = load i32, i32* %6
%190 = icmp eq i32 %189, 1
br i1 %190, label %191, label %208
191: ; preds = %188
%192 = load double*, double** %4
%193 = getelementptr inbounds double, double* %192, i64 1
%194 = load double, double* %193
store double %194, double* %15
%195 = load double*, double** %4
%196 = getelementptr inbounds double, double* %195, i64 2
%197 = load double, double* %196
%198 = fadd double %194, %197
%199 = load double*, double** %4
%200 = getelementptr inbounds double, double* %199, i64 1
store double %198, double* %200
%201 = load double, double* %15
%202 = load double*, double** %4
%203 = getelementptr inbounds double, double* %202, i64 2
%204 = load double, double* %203
%205 = fsub double %201, %204
%206 = load double*, double** %4
%207 = getelementptr inbounds double, double* %206, i64 2
store double %205, double* %207
br label %233
208: ; preds = %188
%209 = load double, double* %13
%210 = load double*, double** %4
%211 = getelementptr inbounds double, double* %210, i64 1
%212 = load double, double* %211
store double %212, double* %15
%213 = load double*, double** %4
%214 = getelementptr inbounds double, double* %213, i64 2
%215 = load double, double* %214
%216 = fadd double %212, %215
%217 = fmul double %209, %216
%218 = load double*, double** %4
%219 = getelementptr inbounds double, double* %218, i64 1
store double %217, double* %219
%220 = load double, double* %13
%221 = load double, double* %15
%222 = load double*, double** %4
%223 = getelementptr inbounds double, double* %222, i64 2
%224 = load double, double* %223
%225 = fsub double %221, %224
%226 = fmul double %220, %225
%227 = load double*, double** %4
%228 = getelementptr inbounds double, double* %227, i64 2
store double %226, double* %228
%229 = load double*, double** %4
%230 = load i32, i32* %5
%231 = lshr i32 %230, 1
%232 = call i32 (double*, i32, i32, ...) bitcast (i32 (...)* @four1 to i32 (double*, i32, i32, ...)*)(double* %229, i32 %231, i32 -1)
br label %233
233: ; preds = %208, %191
ret void
}

LLVM IR (-O2):
define void @realft(double* %0, i32 %1, i32 %2) {
%4 = lshr i32 %1, 1
%5 = uitofp i32 %4 to double
%6 = fdiv double 0x400921FB54442D18, %5
%7 = icmp eq i32 %2, 1
br i1 %7, label %8, label %10
8: ; preds = %3
%9 = tail call i32 (double*, i32, i32, ...) bitcast (i32 (...)* @four1 to i32 (double*, i32, i32, ...)*)(double* %0, i32 %4, i32 1)
br label %12
10: ; preds = %3
%11 = fneg double %6
br label %12
12: ; preds = %10, %8
%13 = phi double [ -5.000000e-01, %8 ], [ 5.000000e-01, %10 ]
%14 = phi double [ %6, %8 ], [ %11, %10 ]
%15 = fmul double %14, 5.000000e-01
%16 = tail call double @sin(double %15)
%17 = fmul double %16, -2.000000e+00
%18 = fmul double %16, %17
%19 = tail call double @sin(double %14)
%20 = add i32 %1, 3
%21 = icmp ult i32 %1, 8
br i1 %21, label %87, label %22
22: ; preds = %12
%23 = lshr i32 %1, 2
%24 = fadd double %18, 1.000000e+00
%25 = fneg double %13
%26 = add nuw nsw i32 %23, 1
%27 = zext i32 %26 to i64
%28 = insertelement <2 x double> poison, double %19, i64 0
%29 = insertelement <2 x double> %28, double %24, i64 1
%30 = insertelement <2 x double> poison, double %13, i64 0
%31 = insertelement <2 x double> %30, double %25, i64 1
%32 = insertelement <2 x double> poison, double %18, i64 0
%33 = shufflevector <2 x double> %32, <2 x double> poison, <2 x i32> zeroinitializer
%34 = shufflevector <2 x double> %28, <2 x double> poison, <2 x i32> zeroinitializer
br label %35
35: ; preds = %22, %35
%36 = phi i64 [ 2, %22 ], [ %85, %35 ]
%37 = phi <2 x double> [ %29, %22 ], [ %84, %35 ]
%38 = shl nuw nsw i64 %36, 1
%39 = add nsw i64 %38, -1
%40 = trunc i64 %38 to i32
%41 = sub i32 %20, %40
%42 = add nsw i32 %41, 1
%43 = getelementptr inbounds double, double* %0, i64 %39
%44 = sext i32 %41 to i64
%45 = getelementptr inbounds double, double* %0, i64 %44
%46 = load double, double* %45
%47 = bitcast double* %43 to <2 x double>*
%48 = load <2 x double>, <2 x double>* %47
%49 = sext i32 %42 to i64
%50 = getelementptr inbounds double, double* %0, i64 %49
%51 = load double, double* %50
%52 = insertelement <2 x double> poison, double %46, i64 0
%53 = insertelement <2 x double> %52, double %51, i64 1
%54 = fadd <2 x double> %48, %53
%55 = fsub <2 x double> %48, %53
%56 = shufflevector <2 x double> %54, <2 x double> %55, <2 x i32> <i32 0, i32 3>
%57 = fmul <2 x double> %56, <double 5.000000e-01, double 5.000000e-01>
%58 = shufflevector <2 x double> %55, <2 x double> %54, <2 x i32> <i32 0, i32 3>
%59 = fmul <2 x double> %31, %58
%60 = extractelement <2 x double> %37, i64 0
%61 = fneg double %60
%62 = extractelement <2 x double> %37, i64 1
%63 = shufflevector <2 x double> %37, <2 x double> undef, <2 x i32> <i32 1, i32 undef>
%64 = shufflevector <2 x double> %37, <2 x double> poison, <2 x i32> <i32 1, i32 1>
%65 = extractelement <2 x double> %59, i64 1
%66 = extractelement <2 x double> %59, i64 0
%67 = shufflevector <2 x double> %59, <2 x double> undef, <2 x i32> <i32 1, i32 0>
%68 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %64, <2 x double> %67, <2 x double> %57)
%69 = insertelement <2 x double> poison, double %61, i64 0
%70 = shufflevector <2 x double> %69, <2 x double> %37, <2 x i32> <i32 0, i32 2>
%71 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %70, <2 x double> %59, <2 x double> %68)
%72 = bitcast double* %43 to <2 x double>*
store <2 x double> %71, <2 x double>* %72
%73 = fneg double %62
%74 = extractelement <2 x double> %57, i64 0
%75 = tail call double @llvm.fmuladd.f64(double %73, double %65, double %74)
%76 = tail call double @llvm.fmuladd.f64(double %60, double %66, double %75)
store double %76, double* %45
%77 = extractelement <2 x double> %57, i64 1
%78 = fneg double %77
%79 = tail call double @llvm.fmuladd.f64(double %62, double %66, double %78)
%80 = tail call double @llvm.fmuladd.f64(double %60, double %65, double %79)
store double %80, double* %50
%81 = insertelement <2 x double> %63, double %61, i64 1
%82 = fmul <2 x double> %34, %81
%83 = call <2 x double> @llvm.fmuladd.v2f64(<2 x double> %37, <2 x double> %33, <2 x double> %82)
%84 = fadd <2 x double> %37, %83
%85 = add nuw nsw i64 %36, 1
%86 = icmp eq i64 %85, %27
br i1 %86, label %87, label %35
87: ; preds = %35, %12
%88 = getelementptr inbounds double, double* %0, i64 1
%89 = load double, double* %88
%90 = getelementptr inbounds double, double* %0, i64 2
%91 = load double, double* %90
%92 = fadd double %89, %91
br i1 %7, label %93, label %95
93: ; preds = %87
store double %92, double* %88
%94 = fsub double %89, %91
store double %94, double* %90
br label %102
95: ; preds = %87
%96 = fsub double %89, %91
%97 = insertelement <2 x double> poison, double %92, i64 0
%98 = insertelement <2 x double> %97, double %96, i64 1
%99 = fmul <2 x double> %98, <double 5.000000e-01, double 5.000000e-01>
%100 = bitcast double* %88 to <2 x double>*
store <2 x double> %99, <2 x double>* %100
%101 = tail call i32 (double*, i32, i32, ...) bitcast (i32 (...)* @four1 to i32 (double*, i32, i32, ...)*)(double* %0, i32 %4, i32 -1)
br label %102
102: ; preds = %95, %93
ret void
}