void twiddleFFT_3(int sofarRadix, int radix, int remainRadix, int groupOffset,
                  double twiddleRe[], double twiddleIm[], double yRe[],
                  double yIm[]) {
  int yIndx[3];
  int groupNo, blockNo, adr;
  double t1_re, t1_im, m1_re, m1_im, m2_re, m2_im, s1_re, s1_im;
  double yr, yi, twr, twi;
  double ar0, ar1, ar2;
  double ai0, ai1, ai2;
  double zr0, zi0;
  adr = groupOffset;
  for (groupNo = 0; groupNo < remainRadix; groupNo++) {
    for (blockNo = 0; blockNo < radix; blockNo++) {
      yIndx[blockNo] = adr;
      adr = adr + sofarRadix;
    }
    ar0 = yRe[yIndx[0]];
    ai0 = yIm[yIndx[0]];
    yr = yRe[yIndx[1]];
    yi = yIm[yIndx[1]];
    twr = twiddleRe[1];
    twi = twiddleIm[1];
    ar1 = twr * yr - twi * yi;
    ai1 = twr * yi + twi * yr;
    yr = yRe[yIndx[2]];
    yi = yIm[yIndx[2]];
    twr = twiddleRe[2];
    twi = twiddleIm[2];
    ar2 = twr * yr - twi * yi;
    ai2 = twr * yi + twi * yr;
    t1_re = ar1 + ar2;
    t1_im = ai1 + ai2;
    zr0 = ar0 + t1_re;
    zi0 = ai0 + t1_im;
    m1_re = -1.5 * t1_re;
    m1_im = -1.5 * t1_im;
    m2_re = 0.8660254037844386467637231707 * (ai1 - ai2);
    m2_im = 0.8660254037844386467637231707 * (ar2 - ar1);
    s1_re = zr0 + m1_re;
    s1_im = zi0 + m1_im;
    yRe[yIndx[0]] = zr0;
    yIm[yIndx[0]] = zi0;
    yRe[yIndx[1]] = s1_re + m2_re;
    yIm[yIndx[1]] = s1_im + m2_im;
    yRe[yIndx[2]] = s1_re - m2_re;
    yIm[yIndx[2]] = s1_im - m2_im;
    groupOffset = groupOffset + sofarRadix * radix;
    adr = groupOffset;
  }
}


x86 assembly (clang, -O0):
<twiddleFFT_3>:
push   %rbp
mov    %rsp,%rbp
sub    $0x58,%rsp
mov    0x18(%rbp),%rax
mov    0x10(%rbp),%rax
mov    %edi,-0x4(%rbp)
mov    %esi,-0x8(%rbp)
mov    %edx,-0xc(%rbp)
mov    %ecx,-0x10(%rbp)
mov    %r8,-0x18(%rbp)
mov    %r9,-0x20(%rbp)
mov    -0x10(%rbp),%eax
mov    %eax,-0x38(%rbp)
movl   $0x0,-0x30(%rbp)
mov    -0x30(%rbp),%eax
cmp    -0xc(%rbp),%eax
jge    1497 <twiddleFFT_3+0x397>
movl   $0x0,-0x34(%rbp)
mov    -0x34(%rbp),%eax
cmp    -0x8(%rbp),%eax
jge    1172 <twiddleFFT_3+0x72>
mov    -0x38(%rbp),%ecx
movslq -0x34(%rbp),%rax
mov    %ecx,-0x2c(%rbp,%rax,4)
mov    -0x38(%rbp),%eax
add    -0x4(%rbp),%eax
mov    %eax,-0x38(%rbp)
mov    -0x34(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x34(%rbp)
jmp    1144 <twiddleFFT_3+0x44>
mov    0x10(%rbp),%rax
movslq -0x2c(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0xa0(%rbp)
ff
mov    0x18(%rbp),%rax
movslq -0x2c(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0xb8(%rbp)
ff
mov    0x10(%rbp),%rax
movslq -0x28(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x80(%rbp)
mov    0x18(%rbp),%rax
movslq -0x28(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x88(%rbp)
ff
mov    -0x18(%rbp),%rax
movsd  0x8(%rax),%xmm0
movsd  %xmm0,-0x90(%rbp)
ff
mov    -0x20(%rbp),%rax
movsd  0x8(%rax),%xmm0
movsd  %xmm0,-0x98(%rbp)
ff
movsd  -0x90(%rbp),%xmm0
ff
movsd  -0x80(%rbp),%xmm2
movsd  -0x98(%rbp),%xmm1
ff
mulsd  -0x88(%rbp),%xmm1
ff
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0xa8(%rbp)
ff
movsd  -0x90(%rbp),%xmm0
ff
movsd  -0x88(%rbp),%xmm2
ff
movsd  -0x98(%rbp),%xmm1
ff
mulsd  -0x80(%rbp),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0xc0(%rbp)
ff
mov    0x10(%rbp),%rax
movslq -0x24(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x80(%rbp)
mov    0x18(%rbp),%rax
movslq -0x24(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x88(%rbp)
ff
mov    -0x18(%rbp),%rax
movsd  0x10(%rax),%xmm0
movsd  %xmm0,-0x90(%rbp)
ff
mov    -0x20(%rbp),%rax
movsd  0x10(%rax),%xmm0
movsd  %xmm0,-0x98(%rbp)
ff
movsd  -0x90(%rbp),%xmm0
ff
movsd  -0x80(%rbp),%xmm2
movsd  -0x98(%rbp),%xmm1
ff
mulsd  -0x88(%rbp),%xmm1
ff
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0xb0(%rbp)
ff
movsd  -0x90(%rbp),%xmm0
ff
movsd  -0x88(%rbp),%xmm2
ff
movsd  -0x98(%rbp),%xmm1
ff
mulsd  -0x80(%rbp),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0xc8(%rbp)
ff
movsd  -0xa8(%rbp),%xmm0
ff
addsd  -0xb0(%rbp),%xmm0
ff
movsd  %xmm0,-0x40(%rbp)
movsd  -0xc0(%rbp),%xmm0
ff
addsd  -0xc8(%rbp),%xmm0
ff
movsd  %xmm0,-0x48(%rbp)
movsd  -0xa0(%rbp),%xmm0
ff
addsd  -0x40(%rbp),%xmm0
movsd  %xmm0,-0xd0(%rbp)
ff
movsd  -0xb8(%rbp),%xmm0
ff
addsd  -0x48(%rbp),%xmm0
movsd  %xmm0,-0xd8(%rbp)
ff
movsd  0xc9c(%rip),%xmm0
mulsd  -0x40(%rbp),%xmm0
movsd  %xmm0,-0x50(%rbp)
movsd  0xc8a(%rip),%xmm0
mulsd  -0x48(%rbp),%xmm0
movsd  %xmm0,-0x58(%rbp)
movsd  -0xc0(%rbp),%xmm1
ff
subsd  -0xc8(%rbp),%xmm1
ff
movsd  0xc60(%rip),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x60(%rbp)
movsd  -0xb0(%rbp),%xmm1
ff
subsd  -0xa8(%rbp),%xmm1
ff
movsd  0xc3f(%rip),%xmm0
mulsd  %xmm1,%xmm0
movsd  %xmm0,-0x68(%rbp)
movsd  -0xd0(%rbp),%xmm0
ff
addsd  -0x50(%rbp),%xmm0
movsd  %xmm0,-0x70(%rbp)
movsd  -0xd8(%rbp),%xmm0
ff
addsd  -0x58(%rbp),%xmm0
movsd  %xmm0,-0x78(%rbp)
movsd  -0xd0(%rbp),%xmm0
ff
mov    0x10(%rbp),%rax
movslq -0x2c(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0xd8(%rbp),%xmm0
ff
mov    0x18(%rbp),%rax
movslq -0x2c(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x70(%rbp),%xmm0
addsd  -0x60(%rbp),%xmm0
mov    0x10(%rbp),%rax
movslq -0x28(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x78(%rbp),%xmm0
addsd  -0x68(%rbp),%xmm0
mov    0x18(%rbp),%rax
movslq -0x28(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x70(%rbp),%xmm0
subsd  -0x60(%rbp),%xmm0
mov    0x10(%rbp),%rax
movslq -0x24(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x78(%rbp),%xmm0
subsd  -0x68(%rbp),%xmm0
mov    0x18(%rbp),%rax
movslq -0x24(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x10(%rbp),%eax
mov    -0x4(%rbp),%ecx
imul   -0x8(%rbp),%ecx
add    %ecx,%eax
mov    %eax,-0x10(%rbp)
mov    -0x10(%rbp),%eax
mov    %eax,-0x38(%rbp)
mov    -0x30(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x30(%rbp)
jmp    1131 <twiddleFFT_3+0x31>
add    $0x58,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<twiddleFFT_3>:
push   %rbp
push   %r15
push   %r14
push   %r13
push   %r12
push   %rbx
mov    %r9,-0x8(%rsp)
mov    %esi,-0x3c(%rsp)
mov    %edx,-0x34(%rsp)
test   %edx,%edx
jle    1404 <twiddleFFT_3+0x304>
mov    0x40(%rsp),%r9
mov    0x38(%rsp),%rax
mov    -0x3c(%rsp),%edx
mov    %edx,%esi
imul   %edi,%esi
mov    %esi,-0x38(%rsp)
mov    %edx,%ebx
mov    %ebx,%edx
and    $0xfffffff8,%edx
lea    -0x8(%rdx),%rsi
mov    %rsi,-0x10(%rsp)
shr    $0x3,%rsi
add    $0x1,%rsi
mov    %rdx,-0x30(%rsp)
imul   %edi,%edx
mov    %rdx,-0x28(%rsp)
movd   %edi,%xmm0
pshufd $0x0,%xmm0,%xmm0
movdqa 0xe94(%rip),%xmm1
pmuludq %xmm0,%xmm1
pshufd $0xe8,%xmm1,%xmm2
movdqa 0xe93(%rip),%xmm1
pmuludq %xmm0,%xmm1
pshufd $0xe8,%xmm1,%xmm8
punpckldq %xmm2,%xmm8
pslld  $0x2,%xmm0
mov    %esi,%ebp
and    $0x3,%ebp
and    $0xfffffffffffffffc,%rsi
mov    %rsi,-0x20(%rsp)
mov    %rbp,-0x18(%rsp)
shl    $0x5,%rbp
xor    %r13d,%r13d
movsd  0xe6c(%rip),%xmm9
movsd  0xe6b(%rip),%xmm10
jmp    12ed <twiddleFFT_3+0x1ed>
cs nopw 0x0(%rax,%rax,1)
nopl   0x0(%rax)
mov    -0x48(%rsp),%r14d
mov    -0x44(%rsp),%r12d
mov    -0x40(%rsp),%r15d
movslq %r14d,%rdx
movslq %r12d,%r11
movsd  (%rax,%r11,8),%xmm5
movsd  (%r9,%r11,8),%xmm7
mov    -0x8(%rsp),%rsi
movsd  0x8(%rsi),%xmm1
movsd  0x10(%rsi),%xmm2
movsd  0x8(%r8),%xmm4
movapd %xmm4,%xmm11
mulsd  %xmm7,%xmm4
mulsd  %xmm1,%xmm7
movsd  0x10(%r8),%xmm3
mulsd  %xmm5,%xmm11
subsd  %xmm7,%xmm11
mulsd  %xmm1,%xmm5
addsd  %xmm5,%xmm4
movslq %r15d,%r10
movsd  (%rax,%r10,8),%xmm1
movsd  (%r9,%r10,8),%xmm7
movapd %xmm3,%xmm5
mulsd  %xmm7,%xmm3
mulsd  %xmm2,%xmm7
mulsd  %xmm1,%xmm5
subsd  %xmm7,%xmm5
mulsd  %xmm2,%xmm1
addsd  %xmm1,%xmm3
movapd %xmm11,%xmm1
addsd  %xmm5,%xmm1
movapd %xmm4,%xmm2
addsd  %xmm3,%xmm2
movsd  (%rax,%rdx,8),%xmm7
addsd  %xmm1,%xmm7
movsd  (%r9,%rdx,8),%xmm6
addsd  %xmm2,%xmm6
mulsd  %xmm9,%xmm1
mulsd  %xmm9,%xmm2
subsd  %xmm3,%xmm4
mulsd  %xmm10,%xmm4
subsd  %xmm11,%xmm5
mulsd  %xmm10,%xmm5
movsd  %xmm7,(%rax,%rdx,8)
subsd  %xmm1,%xmm7
movsd  %xmm6,(%r9,%rdx,8)
subsd  %xmm2,%xmm6
movapd %xmm4,%xmm1
addsd  %xmm7,%xmm1
movsd  %xmm1,(%rax,%r11,8)
movapd %xmm5,%xmm1
addsd  %xmm6,%xmm1
movsd  %xmm1,(%r9,%r11,8)
subsd  %xmm4,%xmm7
movsd  %xmm7,(%rax,%r10,8)
subsd  %xmm5,%xmm6
movsd  %xmm6,(%r9,%r10,8)
add    -0x38(%rsp),%ecx
add    $0x1,%r13d
cmp    -0x34(%rsp),%r13d
je     1404 <twiddleFFT_3+0x304>
cmpl   $0x0,-0x3c(%rsp)
jle    11df <twiddleFFT_3+0xdf>
cmpl   $0x8,-0x3c(%rsp)
jae    1310 <twiddleFFT_3+0x210>
xor    %edx,%edx
mov    %ecx,%esi
jmp    13f0 <twiddleFFT_3+0x2f0>
nopl   0x0(%rax,%rax,1)
movd   %ecx,%xmm4
pshufd $0x0,%xmm4,%xmm4
paddd  %xmm8,%xmm4
cmpq   $0x18,-0x10(%rsp)
jae    132a <twiddleFFT_3+0x22a>
xor    %edx,%edx
jmp    139a <twiddleFFT_3+0x29a>
mov    -0x20(%rsp),%rsi
xor    %edx,%edx
cs nopw 0x0(%rax,%rax,1)
nopl   0x0(%rax,%rax,1)
movdqu %xmm4,-0x48(%rsp,%rdx,4)
paddd  %xmm0,%xmm4
movdqu %xmm4,-0x38(%rsp,%rdx,4)
paddd  %xmm0,%xmm4
movdqu %xmm4,-0x28(%rsp,%rdx,4)
paddd  %xmm0,%xmm4
movdqu %xmm4,-0x18(%rsp,%rdx,4)
paddd  %xmm0,%xmm4
movdqu %xmm4,-0x8(%rsp,%rdx,4)
paddd  %xmm0,%xmm4
movdqu %xmm4,0x8(%rsp,%rdx,4)
paddd  %xmm0,%xmm4
movdqu %xmm4,0x18(%rsp,%rdx,4)
paddd  %xmm0,%xmm4
movdqu %xmm4,0x28(%rsp,%rdx,4)
add    $0x20,%rdx
paddd  %xmm0,%xmm4
add    $0xfffffffffffffffc,%rsi
jne    1340 <twiddleFFT_3+0x240>
cmpq   $0x0,-0x18(%rsp)
je     13cc <twiddleFFT_3+0x2cc>
lea    -0x38(%rsp),%rsi
lea    (%rsi,%rdx,4),%rdx
xor    %esi,%esi
nopl   (%rax)
movdqu %xmm4,-0x10(%rdx,%rsi,1)
paddd  %xmm0,%xmm4
movdqu %xmm4,(%rdx,%rsi,1)
paddd  %xmm0,%xmm4
add    $0x20,%rsi
cmp    %rsi,%rbp
jne    13b0 <twiddleFFT_3+0x2b0>
cmp    %rbx,-0x30(%rsp)
je     11d0 <twiddleFFT_3+0xd0>
mov    -0x28(%rsp),%rdx
lea    (%rcx,%rdx,1),%esi
mov    -0x30(%rsp),%rdx
cs nopw 0x0(%rax,%rax,1)
xchg   %ax,%ax
mov    %esi,-0x48(%rsp,%rdx,4)
add    %edi,%esi
add    $0x1,%rdx
cmp    %rdx,%rbx
jne    13f0 <twiddleFFT_3+0x2f0>
jmp    11d0 <twiddleFFT_3+0xd0>
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
define void @twiddleFFT_3(i32 %0, i32 %1, i32 %2, i32 %3, double* %4, double* %5, double* %6, double* %7) {
%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 [3 x i32]
%18 = alloca i32
%19 = alloca i32
%20 = alloca i32
%21 = alloca double
%22 = alloca double
%23 = alloca double
%24 = alloca double
%25 = alloca double
%26 = alloca double
%27 = alloca double
%28 = alloca double
%29 = alloca double
%30 = alloca double
%31 = alloca double
%32 = alloca double
%33 = alloca double
%34 = alloca double
%35 = alloca double
%36 = alloca double
%37 = alloca double
%38 = alloca double
%39 = alloca double
%40 = alloca double
store i32 %0, i32* %9
store i32 %1, i32* %10
store i32 %2, i32* %11
store i32 %3, i32* %12
store double* %4, double** %13
store double* %5, double** %14
store double* %6, double** %15
store double* %7, double** %16
%41 = load i32, i32* %12
store i32 %41, i32* %20
store i32 0, i32* %18
br label %42
42: ; preds = %217, %8
%43 = load i32, i32* %18
%44 = load i32, i32* %11
%45 = icmp slt i32 %43, %44
br i1 %45, label %46, label %220
46: ; preds = %42
store i32 0, i32* %19
br label %47
47: ; preds = %59, %46
%48 = load i32, i32* %19
%49 = load i32, i32* %10
%50 = icmp slt i32 %48, %49
br i1 %50, label %51, label %62
51: ; preds = %47
%52 = load i32, i32* %20
%53 = load i32, i32* %19
%54 = sext i32 %53 to i64
%55 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 %54
store i32 %52, i32* %55
%56 = load i32, i32* %20
%57 = load i32, i32* %9
%58 = add nsw i32 %56, %57
store i32 %58, i32* %20
br label %59
59: ; preds = %51
%60 = load i32, i32* %19
%61 = add nsw i32 %60, 1
store i32 %61, i32* %19
br label %47
62: ; preds = %47
%63 = load double*, double** %15
%64 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 0
%65 = load i32, i32* %64
%66 = sext i32 %65 to i64
%67 = getelementptr inbounds double, double* %63, i64 %66
%68 = load double, double* %67
store double %68, double* %33
%69 = load double*, double** %16
%70 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 0
%71 = load i32, i32* %70
%72 = sext i32 %71 to i64
%73 = getelementptr inbounds double, double* %69, i64 %72
%74 = load double, double* %73
store double %74, double* %36
%75 = load double*, double** %15
%76 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 1
%77 = load i32, i32* %76
%78 = sext i32 %77 to i64
%79 = getelementptr inbounds double, double* %75, i64 %78
%80 = load double, double* %79
store double %80, double* %29
%81 = load double*, double** %16
%82 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 1
%83 = load i32, i32* %82
%84 = sext i32 %83 to i64
%85 = getelementptr inbounds double, double* %81, i64 %84
%86 = load double, double* %85
store double %86, double* %30
%87 = load double*, double** %13
%88 = getelementptr inbounds double, double* %87, i64 1
%89 = load double, double* %88
store double %89, double* %31
%90 = load double*, double** %14
%91 = getelementptr inbounds double, double* %90, i64 1
%92 = load double, double* %91
store double %92, double* %32
%93 = load double, double* %31
%94 = load double, double* %29
%95 = load double, double* %32
%96 = load double, double* %30
%97 = fmul double %95, %96
%98 = fneg double %97
%99 = call double @llvm.fmuladd.f64(double %93, double %94, double %98)
store double %99, double* %34
%100 = load double, double* %31
%101 = load double, double* %30
%102 = load double, double* %32
%103 = load double, double* %29
%104 = fmul double %102, %103
%105 = call double @llvm.fmuladd.f64(double %100, double %101, double %104)
store double %105, double* %37
%106 = load double*, double** %15
%107 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 2
%108 = load i32, i32* %107
%109 = sext i32 %108 to i64
%110 = getelementptr inbounds double, double* %106, i64 %109
%111 = load double, double* %110
store double %111, double* %29
%112 = load double*, double** %16
%113 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 2
%114 = load i32, i32* %113
%115 = sext i32 %114 to i64
%116 = getelementptr inbounds double, double* %112, i64 %115
%117 = load double, double* %116
store double %117, double* %30
%118 = load double*, double** %13
%119 = getelementptr inbounds double, double* %118, i64 2
%120 = load double, double* %119
store double %120, double* %31
%121 = load double*, double** %14
%122 = getelementptr inbounds double, double* %121, i64 2
%123 = load double, double* %122
store double %123, double* %32
%124 = load double, double* %31
%125 = load double, double* %29
%126 = load double, double* %32
%127 = load double, double* %30
%128 = fmul double %126, %127
%129 = fneg double %128
%130 = call double @llvm.fmuladd.f64(double %124, double %125, double %129)
store double %130, double* %35
%131 = load double, double* %31
%132 = load double, double* %30
%133 = load double, double* %32
%134 = load double, double* %29
%135 = fmul double %133, %134
%136 = call double @llvm.fmuladd.f64(double %131, double %132, double %135)
store double %136, double* %38
%137 = load double, double* %34
%138 = load double, double* %35
%139 = fadd double %137, %138
store double %139, double* %21
%140 = load double, double* %37
%141 = load double, double* %38
%142 = fadd double %140, %141
store double %142, double* %22
%143 = load double, double* %33
%144 = load double, double* %21
%145 = fadd double %143, %144
store double %145, double* %39
%146 = load double, double* %36
%147 = load double, double* %22
%148 = fadd double %146, %147
store double %148, double* %40
%149 = load double, double* %21
%150 = fmul double -1.500000e+00, %149
store double %150, double* %23
%151 = load double, double* %22
%152 = fmul double -1.500000e+00, %151
store double %152, double* %24
%153 = load double, double* %37
%154 = load double, double* %38
%155 = fsub double %153, %154
%156 = fmul double 0x3FEBB67AE8584CAA, %155
store double %156, double* %25
%157 = load double, double* %35
%158 = load double, double* %34
%159 = fsub double %157, %158
%160 = fmul double 0x3FEBB67AE8584CAA, %159
store double %160, double* %26
%161 = load double, double* %39
%162 = load double, double* %23
%163 = fadd double %161, %162
store double %163, double* %27
%164 = load double, double* %40
%165 = load double, double* %24
%166 = fadd double %164, %165
store double %166, double* %28
%167 = load double, double* %39
%168 = load double*, double** %15
%169 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 0
%170 = load i32, i32* %169
%171 = sext i32 %170 to i64
%172 = getelementptr inbounds double, double* %168, i64 %171
store double %167, double* %172
%173 = load double, double* %40
%174 = load double*, double** %16
%175 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 0
%176 = load i32, i32* %175
%177 = sext i32 %176 to i64
%178 = getelementptr inbounds double, double* %174, i64 %177
store double %173, double* %178
%179 = load double, double* %27
%180 = load double, double* %25
%181 = fadd double %179, %180
%182 = load double*, double** %15
%183 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 1
%184 = load i32, i32* %183
%185 = sext i32 %184 to i64
%186 = getelementptr inbounds double, double* %182, i64 %185
store double %181, double* %186
%187 = load double, double* %28
%188 = load double, double* %26
%189 = fadd double %187, %188
%190 = load double*, double** %16
%191 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 1
%192 = load i32, i32* %191
%193 = sext i32 %192 to i64
%194 = getelementptr inbounds double, double* %190, i64 %193
store double %189, double* %194
%195 = load double, double* %27
%196 = load double, double* %25
%197 = fsub double %195, %196
%198 = load double*, double** %15
%199 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 2
%200 = load i32, i32* %199
%201 = sext i32 %200 to i64
%202 = getelementptr inbounds double, double* %198, i64 %201
store double %197, double* %202
%203 = load double, double* %28
%204 = load double, double* %26
%205 = fsub double %203, %204
%206 = load double*, double** %16
%207 = getelementptr inbounds [3 x i32], [3 x i32]* %17, i64 0, i64 2
%208 = load i32, i32* %207
%209 = sext i32 %208 to i64
%210 = getelementptr inbounds double, double* %206, i64 %209
store double %205, double* %210
%211 = load i32, i32* %12
%212 = load i32, i32* %9
%213 = load i32, i32* %10
%214 = mul nsw i32 %212, %213
%215 = add nsw i32 %211, %214
store i32 %215, i32* %12
%216 = load i32, i32* %12
store i32 %216, i32* %20
br label %217
217: ; preds = %62
%218 = load i32, i32* %18
%219 = add nsw i32 %218, 1
store i32 %219, i32* %18
br label %42
220: ; preds = %42
ret void
}

LLVM IR (-O2):
define void @twiddleFFT_3(i32 %0, i32 %1, i32 %2, i32 %3, double* nocapture %4, double* nocapture %5, double* nocapture %6, double* nocapture %7) {
%9 = alloca [3 x i32]
%10 = bitcast [3 x i32]* %9 to i8*
%11 = icmp sgt i32 %2, 0
br i1 %11, label %12, label %171
12: ; preds = %8
%13 = icmp sgt i32 %1, 0
%14 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 0
%15 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 1
%16 = getelementptr inbounds double, double* %4, i64 1
%17 = getelementptr inbounds double, double* %5, i64 1
%18 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 2
%19 = getelementptr inbounds double, double* %4, i64 2
%20 = getelementptr inbounds double, double* %5, i64 2
%21 = mul nsw i32 %1, %0
%22 = zext i32 %1 to i64
%23 = and i64 %22, 4294967288
%24 = add nsw i64 %23, -8
%25 = lshr exact i64 %24, 3
%26 = add nuw nsw i64 %25, 1
%27 = icmp ult i32 %1, 8
%28 = and i64 %22, 4294967288
%29 = trunc i64 %28 to i32
%30 = mul i32 %29, %0
%31 = insertelement <4 x i32> poison, i32 %0, i64 0
%32 = shufflevector <4 x i32> %31, <4 x i32> poison, <4 x i32> zeroinitializer
%33 = mul <4 x i32> %32, <i32 0, i32 1, i32 2, i32 3>
%34 = shl i32 %0, 2
%35 = insertelement <4 x i32> poison, i32 %34, i64 0
%36 = shufflevector <4 x i32> %35, <4 x i32> poison, <4 x i32> zeroinitializer
%37 = and i64 %26, 3
%38 = icmp ult i64 %24, 24
%39 = and i64 %26, 4611686018427387900
%40 = icmp eq i64 %37, 0
%41 = icmp eq i64 %28, %22
br label %42
42: ; preds = %12, %119
%43 = phi i32 [ undef, %12 ], [ %120, %119 ]
%44 = phi i32 [ undef, %12 ], [ %121, %119 ]
%45 = phi i32 [ undef, %12 ], [ %122, %119 ]
%46 = phi i32 [ %3, %12 ], [ %168, %119 ]
%47 = phi i32 [ 0, %12 ], [ %169, %119 ]
br i1 %13, label %48, label %119
48: ; preds = %42
br i1 %27, label %105, label %49
49: ; preds = %48
%50 = add i32 %46, %30
%51 = insertelement <4 x i32> poison, i32 %46, i64 0
%52 = shufflevector <4 x i32> %51, <4 x i32> poison, <4 x i32> zeroinitializer
%53 = add <4 x i32> %52, %33
br i1 %38, label %88, label %54
54: ; preds = %49, %54
%55 = phi i64 [ %84, %54 ], [ 0, %49 ]
%56 = phi <4 x i32> [ %85, %54 ], [ %53, %49 ]
%57 = phi i64 [ %86, %54 ], [ 0, %49 ]
%58 = add <4 x i32> %56, %36
%59 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 %55
%60 = bitcast i32* %59 to <4 x i32>*
store <4 x i32> %56, <4 x i32>* %60
%61 = getelementptr inbounds i32, i32* %59, i64 4
%62 = bitcast i32* %61 to <4 x i32>*
store <4 x i32> %58, <4 x i32>* %62
%63 = or i64 %55, 8
%64 = add <4 x i32> %58, %36
%65 = add <4 x i32> %64, %36
%66 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 %63
%67 = bitcast i32* %66 to <4 x i32>*
store <4 x i32> %64, <4 x i32>* %67
%68 = getelementptr inbounds i32, i32* %66, i64 4
%69 = bitcast i32* %68 to <4 x i32>*
store <4 x i32> %65, <4 x i32>* %69
%70 = or i64 %55, 16
%71 = add <4 x i32> %65, %36
%72 = add <4 x i32> %71, %36
%73 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 %70
%74 = bitcast i32* %73 to <4 x i32>*
store <4 x i32> %71, <4 x i32>* %74
%75 = getelementptr inbounds i32, i32* %73, i64 4
%76 = bitcast i32* %75 to <4 x i32>*
store <4 x i32> %72, <4 x i32>* %76
%77 = or i64 %55, 24
%78 = add <4 x i32> %72, %36
%79 = add <4 x i32> %78, %36
%80 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 %77
%81 = bitcast i32* %80 to <4 x i32>*
store <4 x i32> %78, <4 x i32>* %81
%82 = getelementptr inbounds i32, i32* %80, i64 4
%83 = bitcast i32* %82 to <4 x i32>*
store <4 x i32> %79, <4 x i32>* %83
%84 = add nuw i64 %55, 32
%85 = add <4 x i32> %79, %36
%86 = add i64 %57, 4
%87 = icmp eq i64 %86, %39
br i1 %87, label %88, label %54
88: ; preds = %54, %49
%89 = phi i64 [ 0, %49 ], [ %84, %54 ]
%90 = phi <4 x i32> [ %53, %49 ], [ %85, %54 ]
br i1 %40, label %104, label %91
91: ; preds = %88, %91
%92 = phi i64 [ %100, %91 ], [ %89, %88 ]
%93 = phi <4 x i32> [ %101, %91 ], [ %90, %88 ]
%94 = phi i64 [ %102, %91 ], [ 0, %88 ]
%95 = add <4 x i32> %93, %36
%96 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 %92
%97 = bitcast i32* %96 to <4 x i32>*
store <4 x i32> %93, <4 x i32>* %97
%98 = getelementptr inbounds i32, i32* %96, i64 4
%99 = bitcast i32* %98 to <4 x i32>*
store <4 x i32> %95, <4 x i32>* %99
%100 = add nuw i64 %92, 8
%101 = add <4 x i32> %95, %36
%102 = add i64 %94, 1
%103 = icmp eq i64 %102, %37
br i1 %103, label %104, label %91
104: ; preds = %91, %88
br i1 %41, label %115, label %105
105: ; preds = %48, %104
%106 = phi i64 [ 0, %48 ], [ %28, %104 ]
%107 = phi i32 [ %46, %48 ], [ %50, %104 ]
br label %108
108: ; preds = %105, %108
%109 = phi i64 [ %113, %108 ], [ %106, %105 ]
%110 = phi i32 [ %112, %108 ], [ %107, %105 ]
%111 = getelementptr inbounds [3 x i32], [3 x i32]* %9, i64 0, i64 %109
store i32 %110, i32* %111
%112 = add nsw i32 %110, %0
%113 = add nuw nsw i64 %109, 1
%114 = icmp eq i64 %113, %22
br i1 %114, label %115, label %108
115: ; preds = %108, %104
%116 = load i32, i32* %14
%117 = load i32, i32* %15
%118 = load i32, i32* %18
br label %119
119: ; preds = %115, %42
%120 = phi i32 [ %118, %115 ], [ %43, %42 ]
%121 = phi i32 [ %117, %115 ], [ %44, %42 ]
%122 = phi i32 [ %116, %115 ], [ %45, %42 ]
%123 = sext i32 %122 to i64
%124 = getelementptr inbounds double, double* %6, i64 %123
%125 = load double, double* %124
%126 = getelementptr inbounds double, double* %7, i64 %123
%127 = load double, double* %126
%128 = sext i32 %121 to i64
%129 = getelementptr inbounds double, double* %6, i64 %128
%130 = load double, double* %129
%131 = getelementptr inbounds double, double* %7, i64 %128
%132 = load double, double* %131
%133 = load double, double* %16
%134 = load double, double* %17
%135 = fneg double %134
%136 = fmul double %132, %135
%137 = tail call double @llvm.fmuladd.f64(double %133, double %130, double %136)
%138 = fmul double %130, %134
%139 = tail call double @llvm.fmuladd.f64(double %133, double %132, double %138)
%140 = sext i32 %120 to i64
%141 = getelementptr inbounds double, double* %6, i64 %140
%142 = load double, double* %141
%143 = getelementptr inbounds double, double* %7, i64 %140
%144 = load double, double* %143
%145 = load double, double* %19
%146 = load double, double* %20
%147 = fneg double %146
%148 = fmul double %144, %147
%149 = tail call double @llvm.fmuladd.f64(double %145, double %142, double %148)
%150 = fmul double %142, %146
%151 = tail call double @llvm.fmuladd.f64(double %145, double %144, double %150)
%152 = fadd double %137, %149
%153 = fadd double %139, %151
%154 = fadd double %125, %152
%155 = fadd double %127, %153
%156 = fmul double %152, 1.500000e+00
%157 = fmul double %153, 1.500000e+00
%158 = fsub double %139, %151
%159 = fmul double %158, 0x3FEBB67AE8584CAA
%160 = fsub double %149, %137
%161 = fmul double %160, 0x3FEBB67AE8584CAA
%162 = fsub double %154, %156
%163 = fsub double %155, %157
store double %154, double* %124
store double %155, double* %126
%164 = fadd double %159, %162
store double %164, double* %129
%165 = fadd double %161, %163
store double %165, double* %131
%166 = fsub double %162, %159
store double %166, double* %141
%167 = fsub double %163, %161
store double %167, double* %143
%168 = add nsw i32 %46, %21
%169 = add nuw nsw i32 %47, 1
%170 = icmp eq i32 %169, %2
br i1 %170, label %171, label %42
171: ; preds = %119, %8
ret void
}