void cftfsub(int n, double *a) {
  void cft1st(int n, double *a);
  void cftmdl(int n, int l, double *a);
  int j, j1, j2, j3, l;
  double x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;
  l = 2;
  if (n >= 16) {
    cft1st(n, a);
    l = 16;
    while ((l << 3) <= n) {
      cftmdl(n, l, a);
      l <<= 3;
    }
  }
  if ((l << 1) < n) {
    for (j = 0; j < l; j += 2) {
      j1 = j + l;
      j2 = j1 + l;
      j3 = j2 + l;
      x0r = a[j] + a[j1];
      x0i = a[j + 1] + a[j1 + 1];
      x1r = a[j] - a[j1];
      x1i = a[j + 1] - a[j1 + 1];
      x2r = a[j2] + a[j3];
      x2i = a[j2 + 1] + a[j3 + 1];
      x3r = a[j2] - a[j3];
      x3i = a[j2 + 1] - a[j3 + 1];
      a[j] = x0r + x2r;
      a[j + 1] = x0i + x2i;
      a[j2] = x0r - x2r;
      a[j2 + 1] = x0i - x2i;
      a[j1] = x1r - x3i;
      a[j1 + 1] = x1i + x3r;
      a[j3] = x1r + x3i;
      a[j3 + 1] = x1i - x3r;
    }
  } else if ((l << 1) == n) {
    for (j = 0; j < l; j += 2) {
      j1 = j + l;
      x0r = a[j] - a[j1];
      x0i = a[j + 1] - a[j1 + 1];
      a[j] += a[j1];
      a[j + 1] += a[j1 + 1];
      a[j1] = x0r;
      a[j1 + 1] = x0i;
    }
  }
}


x86 assembly (clang, -O0):
<cftfsub>:
push   %rbp
mov    %rsp,%rbp
sub    $0x70,%rsp
mov    %edi,-0x4(%rbp)
mov    %rsi,-0x10(%rbp)
movl   $0x2,-0x24(%rbp)
cmpl   $0x10,-0x4(%rbp)
jl     1184 <cftfsub+0x64>
mov    -0x4(%rbp),%edi
mov    -0x10(%rbp),%rsi
call   1030 <cft1st@plt>
movl   $0x10,-0x24(%rbp)
mov    -0x24(%rbp),%eax
shl    $0x3,%eax
cmp    -0x4(%rbp),%eax
jg     117f <cftfsub+0x5f>
mov    -0x4(%rbp),%edi
mov    -0x24(%rbp),%esi
mov    -0x10(%rbp),%rdx
call   1040 <cftmdl@plt>
mov    -0x24(%rbp),%eax
shl    $0x3,%eax
mov    %eax,-0x24(%rbp)
jmp    1153 <cftfsub+0x33>
jmp    1184 <cftfsub+0x64>
mov    -0x24(%rbp),%eax
shl    $0x1,%eax
cmp    -0x4(%rbp),%eax
jge    13c0 <cftfsub+0x2a0>
movl   $0x0,-0x14(%rbp)
mov    -0x14(%rbp),%eax
cmp    -0x24(%rbp),%eax
jge    13bb <cftfsub+0x29b>
mov    -0x14(%rbp),%eax
add    -0x24(%rbp),%eax
mov    %eax,-0x18(%rbp)
mov    -0x18(%rbp),%eax
add    -0x24(%rbp),%eax
mov    %eax,-0x1c(%rbp)
mov    -0x1c(%rbp),%eax
add    -0x24(%rbp),%eax
mov    %eax,-0x20(%rbp)
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0x10(%rbp),%rax
mov    -0x14(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x18(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
subsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x40(%rbp)
mov    -0x10(%rbp),%rax
mov    -0x14(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x18(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
subsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x48(%rbp)
mov    -0x10(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x20(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x50(%rbp)
mov    -0x10(%rbp),%rax
mov    -0x1c(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x20(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x58(%rbp)
mov    -0x10(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x20(%rbp),%rcx
subsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x60(%rbp)
mov    -0x10(%rbp),%rax
mov    -0x1c(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x20(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
subsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x68(%rbp)
movsd  -0x30(%rbp),%xmm0
addsd  -0x50(%rbp),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x38(%rbp),%xmm0
addsd  -0x58(%rbp),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x14(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x30(%rbp),%xmm0
subsd  -0x50(%rbp),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x38(%rbp),%xmm0
subsd  -0x58(%rbp),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x1c(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x40(%rbp),%xmm0
subsd  -0x68(%rbp),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x48(%rbp),%xmm0
addsd  -0x60(%rbp),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x18(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x40(%rbp),%xmm0
addsd  -0x68(%rbp),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x20(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x48(%rbp),%xmm0
subsd  -0x60(%rbp),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x20(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x14(%rbp),%eax
add    $0x2,%eax
mov    %eax,-0x14(%rbp)
jmp    119a <cftfsub+0x7a>
jmp    14bc <cftfsub+0x39c>
mov    -0x24(%rbp),%eax
shl    $0x1,%eax
cmp    -0x4(%rbp),%eax
jne    14b7 <cftfsub+0x397>
movl   $0x0,-0x14(%rbp)
mov    -0x14(%rbp),%eax
cmp    -0x24(%rbp),%eax
jge    14b2 <cftfsub+0x392>
mov    -0x14(%rbp),%eax
add    -0x24(%rbp),%eax
mov    %eax,-0x18(%rbp)
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
subsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0x10(%rbp),%rax
mov    -0x14(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x18(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
subsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x10(%rbp),%rax
mov    -0x18(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x14(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
addsd  (%rax,%rcx,8),%xmm0
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x30(%rbp),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
movsd  %xmm0,(%rax,%rcx,8)
movsd  -0x38(%rbp),%xmm0
mov    -0x10(%rbp),%rax
mov    -0x18(%rbp),%ecx
add    $0x1,%ecx
movslq %ecx,%rcx
movsd  %xmm0,(%rax,%rcx,8)
mov    -0x14(%rbp),%eax
add    $0x2,%eax
mov    %eax,-0x14(%rbp)
jmp    13d6 <cftfsub+0x2b6>
jmp    14b7 <cftfsub+0x397>
jmp    14bc <cftfsub+0x39c>
add    $0x70,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<cftfsub>:
push   %rbp
push   %r15
push   %r14
push   %rbx
push   %rax
mov    %rsi,%rbx
mov    %edi,%r14d
mov    $0x2,%ebp
cmp    $0x10,%edi
jl     117b <cftfsub+0x5b>
mov    %r14d,%edi
mov    %rbx,%rsi
call   1030 <cft1st@plt>
mov    $0x10,%ebp
cmp    $0x80,%r14d
jb     117b <cftfsub+0x5b>
mov    $0x10,%esi
mov    $0x80,%eax
nopw   0x0(%rax,%rax,1)
mov    %eax,%ebp
mov    %r14d,%edi
mov    %rbx,%rdx
call   1040 <cftmdl@plt>
lea    0x0(,%rbp,8),%eax
mov    %ebp,%esi
cmp    %r14d,%eax
jle    1160 <cftfsub+0x40>
lea    0x0(%rbp,%rbp,1),%r9d
cmp    %r14d,%r9d
jge    12a2 <cftfsub+0x182>
test   %ebp,%ebp
jle    131d <cftfsub+0x1fd>
movabs $0x200000000,%r8
mov    %ebp,%r10d
or     $0x1,%r9
mov    %r10,%rdi
shl    $0x20,%rdi
lea    (%rbx,%r10,8),%r11
lea    (%rdi,%rdi,2),%rcx
lea    (%r10,%r10,2),%rax
lea    (%rbx,%rax,8),%r14
mov    %r10,%r15
shl    $0x4,%r15
add    %rbx,%r15
xor    %eax,%eax
cs nopw 0x0(%rax,%rax,1)
nop
movsd  (%r11,%rax,8),%xmm2
movupd (%rbx,%rax,8),%xmm0
mov    %rdi,%rsi
sar    $0x1d,%rsi
or     $0x8,%rsi
movsd  (%rbx,%rsi,1),%xmm3
movapd %xmm0,%xmm1
subsd  %xmm2,%xmm1
unpcklpd %xmm3,%xmm2
addpd  %xmm0,%xmm2
unpckhpd %xmm0,%xmm0
subsd  %xmm3,%xmm0
movsd  (%r15,%rax,8),%xmm3
movsd  (%r14,%rax,8),%xmm4
lea    (%r9,%rax,1),%ebp
movslq %ebp,%rdx
movsd  (%rbx,%rdx,8),%xmm5
mov    %rcx,%rbp
sar    $0x1d,%rbp
or     $0x8,%rbp
movsd  (%rbx,%rbp,1),%xmm6
movapd %xmm3,%xmm7
unpcklpd %xmm5,%xmm7
subsd  %xmm4,%xmm3
unpcklpd %xmm6,%xmm4
addpd  %xmm7,%xmm4
subsd  %xmm6,%xmm5
movapd %xmm2,%xmm6
addpd  %xmm4,%xmm6
movupd %xmm6,(%rbx,%rax,8)
subpd  %xmm4,%xmm2
movlpd %xmm2,(%r15,%rax,8)
movhpd %xmm2,(%rbx,%rdx,8)
movapd %xmm1,%xmm2
subsd  %xmm5,%xmm2
movsd  %xmm2,(%r11,%rax,8)
movapd %xmm0,%xmm2
addsd  %xmm3,%xmm2
movsd  %xmm2,(%rbx,%rsi,1)
addsd  %xmm1,%xmm5
movsd  %xmm5,(%r14,%rax,8)
subsd  %xmm3,%xmm0
movsd  %xmm0,(%rbx,%rbp,1)
add    $0x2,%rax
add    %r8,%rdi
add    %r8,%rcx
cmp    %r10,%rax
jb     11d0 <cftfsub+0xb0>
jmp    131d <cftfsub+0x1fd>
jne    131d <cftfsub+0x1fd>
test   %ebp,%ebp
jle    131d <cftfsub+0x1fd>
movabs $0x200000000,%rax
mov    %ebp,%ebp
mov    %rbp,%rcx
shl    $0x20,%rcx
lea    (%rbx,%rbp,8),%rsi
xor    %edi,%edi
cs nopw 0x0(%rax,%rax,1)
nopl   0x0(%rax,%rax,1)
movsd  (%rsi,%rdi,8),%xmm0
movupd (%rbx,%rdi,8),%xmm1
movapd %xmm1,%xmm2
subsd  %xmm0,%xmm2
mov    %rcx,%rdx
sar    $0x1d,%rdx
or     $0x8,%rdx
movsd  (%rbx,%rdx,1),%xmm3
unpcklpd %xmm3,%xmm0
addpd  %xmm1,%xmm0
unpckhpd %xmm1,%xmm1
subsd  %xmm3,%xmm1
movupd %xmm0,(%rbx,%rdi,8)
movsd  %xmm2,(%rsi,%rdi,8)
movsd  %xmm1,(%rbx,%rdx,1)
add    $0x2,%rdi
add    %rax,%rcx
cmp    %rbp,%rdi
jb     12d0 <cftfsub+0x1b0>
add    $0x8,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
define void @cftfsub(i32 %0, double* %1) {
%3 = alloca i32
%4 = alloca double*
%5 = alloca i32
%6 = alloca i32
%7 = alloca i32
%8 = alloca i32
%9 = alloca i32
%10 = alloca double
%11 = alloca double
%12 = alloca double
%13 = alloca double
%14 = alloca double
%15 = alloca double
%16 = alloca double
%17 = alloca double
store i32 %0, i32* %3
store double* %1, double** %4
store i32 2, i32* %9
%18 = load i32, i32* %3
%19 = icmp sge i32 %18, 16
br i1 %19, label %20, label %35
20: ; preds = %2
%21 = load i32, i32* %3
%22 = load double*, double** %4
store i32 16, i32* %9
br label %23
23: ; preds = %28, %20
%24 = load i32, i32* %9
%25 = shl i32 %24, 3
%26 = load i32, i32* %3
%27 = icmp sle i32 %25, %26
br i1 %27, label %28, label %34
28: ; preds = %23
%29 = load i32, i32* %3
%30 = load i32, i32* %9
%31 = load double*, double** %4
%32 = load i32, i32* %9
%33 = shl i32 %32, 3
store i32 %33, i32* %9
br label %23
34: ; preds = %23
br label %35
35: ; preds = %34, %2
%36 = load i32, i32* %9
%37 = shl i32 %36, 1
%38 = load i32, i32* %3
%39 = icmp slt i32 %37, %38
br i1 %39, label %40, label %215
40: ; preds = %35
store i32 0, i32* %5
br label %41
41: ; preds = %211, %40
%42 = load i32, i32* %5
%43 = load i32, i32* %9
%44 = icmp slt i32 %42, %43
br i1 %44, label %45, label %214
45: ; preds = %41
%46 = load i32, i32* %5
%47 = load i32, i32* %9
%48 = add nsw i32 %46, %47
store i32 %48, i32* %6
%49 = load i32, i32* %6
%50 = load i32, i32* %9
%51 = add nsw i32 %49, %50
store i32 %51, i32* %7
%52 = load i32, i32* %7
%53 = load i32, i32* %9
%54 = add nsw i32 %52, %53
store i32 %54, i32* %8
%55 = load double*, double** %4
%56 = load i32, i32* %5
%57 = sext i32 %56 to i64
%58 = getelementptr inbounds double, double* %55, i64 %57
%59 = load double, double* %58
%60 = load double*, double** %4
%61 = load i32, i32* %6
%62 = sext i32 %61 to i64
%63 = getelementptr inbounds double, double* %60, i64 %62
%64 = load double, double* %63
%65 = fadd double %59, %64
store double %65, double* %10
%66 = load double*, double** %4
%67 = load i32, i32* %5
%68 = add nsw i32 %67, 1
%69 = sext i32 %68 to i64
%70 = getelementptr inbounds double, double* %66, i64 %69
%71 = load double, double* %70
%72 = load double*, double** %4
%73 = load i32, i32* %6
%74 = add nsw i32 %73, 1
%75 = sext i32 %74 to i64
%76 = getelementptr inbounds double, double* %72, i64 %75
%77 = load double, double* %76
%78 = fadd double %71, %77
store double %78, double* %11
%79 = load double*, double** %4
%80 = load i32, i32* %5
%81 = sext i32 %80 to i64
%82 = getelementptr inbounds double, double* %79, i64 %81
%83 = load double, double* %82
%84 = load double*, double** %4
%85 = load i32, i32* %6
%86 = sext i32 %85 to i64
%87 = getelementptr inbounds double, double* %84, i64 %86
%88 = load double, double* %87
%89 = fsub double %83, %88
store double %89, double* %12
%90 = load double*, double** %4
%91 = load i32, i32* %5
%92 = add nsw i32 %91, 1
%93 = sext i32 %92 to i64
%94 = getelementptr inbounds double, double* %90, i64 %93
%95 = load double, double* %94
%96 = load double*, double** %4
%97 = load i32, i32* %6
%98 = add nsw i32 %97, 1
%99 = sext i32 %98 to i64
%100 = getelementptr inbounds double, double* %96, i64 %99
%101 = load double, double* %100
%102 = fsub double %95, %101
store double %102, double* %13
%103 = load double*, double** %4
%104 = load i32, i32* %7
%105 = sext i32 %104 to i64
%106 = getelementptr inbounds double, double* %103, i64 %105
%107 = load double, double* %106
%108 = load double*, double** %4
%109 = load i32, i32* %8
%110 = sext i32 %109 to i64
%111 = getelementptr inbounds double, double* %108, i64 %110
%112 = load double, double* %111
%113 = fadd double %107, %112
store double %113, double* %14
%114 = load double*, double** %4
%115 = load i32, i32* %7
%116 = add 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* %8
%122 = add nsw i32 %121, 1
%123 = sext i32 %122 to i64
%124 = getelementptr inbounds double, double* %120, i64 %123
%125 = load double, double* %124
%126 = fadd double %119, %125
store double %126, double* %15
%127 = load double*, double** %4
%128 = load i32, i32* %7
%129 = sext i32 %128 to i64
%130 = getelementptr inbounds double, double* %127, i64 %129
%131 = load double, double* %130
%132 = load double*, double** %4
%133 = load i32, i32* %8
%134 = sext i32 %133 to i64
%135 = getelementptr inbounds double, double* %132, i64 %134
%136 = load double, double* %135
%137 = fsub double %131, %136
store double %137, double* %16
%138 = load double*, double** %4
%139 = load i32, i32* %7
%140 = add nsw i32 %139, 1
%141 = sext i32 %140 to i64
%142 = getelementptr inbounds double, double* %138, i64 %141
%143 = load double, double* %142
%144 = load double*, double** %4
%145 = load i32, i32* %8
%146 = add nsw i32 %145, 1
%147 = sext i32 %146 to i64
%148 = getelementptr inbounds double, double* %144, i64 %147
%149 = load double, double* %148
%150 = fsub double %143, %149
store double %150, double* %17
%151 = load double, double* %10
%152 = load double, double* %14
%153 = fadd double %151, %152
%154 = load double*, double** %4
%155 = load i32, i32* %5
%156 = sext i32 %155 to i64
%157 = getelementptr inbounds double, double* %154, i64 %156
store double %153, double* %157
%158 = load double, double* %11
%159 = load double, double* %15
%160 = fadd double %158, %159
%161 = load double*, double** %4
%162 = load i32, i32* %5
%163 = add 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* %10
%167 = load double, double* %14
%168 = fsub double %166, %167
%169 = load double*, double** %4
%170 = load i32, i32* %7
%171 = sext i32 %170 to i64
%172 = getelementptr inbounds double, double* %169, i64 %171
store double %168, double* %172
%173 = load double, double* %11
%174 = load double, double* %15
%175 = fsub double %173, %174
%176 = load double*, double** %4
%177 = load i32, i32* %7
%178 = add nsw i32 %177, 1
%179 = sext i32 %178 to i64
%180 = getelementptr inbounds double, double* %176, i64 %179
store double %175, double* %180
%181 = load double, double* %12
%182 = load double, double* %17
%183 = fsub double %181, %182
%184 = load double*, double** %4
%185 = load i32, i32* %6
%186 = sext i32 %185 to i64
%187 = getelementptr inbounds double, double* %184, i64 %186
store double %183, double* %187
%188 = load double, double* %13
%189 = load double, double* %16
%190 = fadd double %188, %189
%191 = load double*, double** %4
%192 = load i32, i32* %6
%193 = add nsw i32 %192, 1
%194 = sext i32 %193 to i64
%195 = getelementptr inbounds double, double* %191, i64 %194
store double %190, double* %195
%196 = load double, double* %12
%197 = load double, double* %17
%198 = fadd double %196, %197
%199 = load double*, double** %4
%200 = load i32, i32* %8
%201 = sext i32 %200 to i64
%202 = getelementptr inbounds double, double* %199, i64 %201
store double %198, double* %202
%203 = load double, double* %13
%204 = load double, double* %16
%205 = fsub double %203, %204
%206 = load double*, double** %4
%207 = load i32, i32* %8
%208 = add nsw i32 %207, 1
%209 = sext i32 %208 to i64
%210 = getelementptr inbounds double, double* %206, i64 %209
store double %205, double* %210
br label %211
211: ; preds = %45
%212 = load i32, i32* %5
%213 = add nsw i32 %212, 2
store i32 %213, i32* %5
br label %41
214: ; preds = %41
br label %293
215: ; preds = %35
%216 = load i32, i32* %9
%217 = shl i32 %216, 1
%218 = load i32, i32* %3
%219 = icmp eq i32 %217, %218
br i1 %219, label %220, label %292
220: ; preds = %215
store i32 0, i32* %5
br label %221
221: ; preds = %288, %220
%222 = load i32, i32* %5
%223 = load i32, i32* %9
%224 = icmp slt i32 %222, %223
br i1 %224, label %225, label %291
225: ; preds = %221
%226 = load i32, i32* %5
%227 = load i32, i32* %9
%228 = add nsw i32 %226, %227
store i32 %228, i32* %6
%229 = load double*, double** %4
%230 = load i32, i32* %5
%231 = sext i32 %230 to i64
%232 = getelementptr inbounds double, double* %229, i64 %231
%233 = load double, double* %232
%234 = load double*, double** %4
%235 = load i32, i32* %6
%236 = sext i32 %235 to i64
%237 = getelementptr inbounds double, double* %234, i64 %236
%238 = load double, double* %237
%239 = fsub double %233, %238
store double %239, double* %10
%240 = load double*, double** %4
%241 = load i32, i32* %5
%242 = add nsw i32 %241, 1
%243 = sext i32 %242 to i64
%244 = getelementptr inbounds double, double* %240, i64 %243
%245 = load double, double* %244
%246 = load double*, double** %4
%247 = load i32, i32* %6
%248 = add nsw i32 %247, 1
%249 = sext i32 %248 to i64
%250 = getelementptr inbounds double, double* %246, i64 %249
%251 = load double, double* %250
%252 = fsub double %245, %251
store double %252, double* %11
%253 = load double*, double** %4
%254 = load i32, i32* %6
%255 = sext i32 %254 to i64
%256 = getelementptr inbounds double, double* %253, i64 %255
%257 = load double, double* %256
%258 = load double*, double** %4
%259 = load i32, i32* %5
%260 = sext i32 %259 to i64
%261 = getelementptr inbounds double, double* %258, i64 %260
%262 = load double, double* %261
%263 = fadd double %262, %257
store double %263, double* %261
%264 = load double*, double** %4
%265 = load i32, i32* %6
%266 = add nsw i32 %265, 1
%267 = sext i32 %266 to i64
%268 = getelementptr inbounds double, double* %264, i64 %267
%269 = load double, double* %268
%270 = load double*, double** %4
%271 = load i32, i32* %5
%272 = add nsw i32 %271, 1
%273 = sext i32 %272 to i64
%274 = getelementptr inbounds double, double* %270, i64 %273
%275 = load double, double* %274
%276 = fadd double %275, %269
store double %276, double* %274
%277 = load double, double* %10
%278 = load double*, double** %4
%279 = load i32, i32* %6
%280 = sext i32 %279 to i64
%281 = getelementptr inbounds double, double* %278, i64 %280
store double %277, double* %281
%282 = load double, double* %11
%283 = load double*, double** %4
%284 = load i32, i32* %6
%285 = add nsw i32 %284, 1
%286 = sext i32 %285 to i64
%287 = getelementptr inbounds double, double* %283, i64 %286
store double %282, double* %287
br label %288
288: ; preds = %225
%289 = load i32, i32* %5
%290 = add nsw i32 %289, 2
store i32 %290, i32* %5
br label %221
291: ; preds = %221
br label %292
292: ; preds = %291, %215
br label %293
293: ; preds = %292, %214
ret void
}

LLVM IR (-O2):
define void @cftfsub(i32 %0, double* %1) {
%3 = icmp sgt i32 %0, 15
br i1 %3, label %4, label %11
4: ; preds = %2
tail call void @cft1st(i32 %0, double* %1)
%5 = icmp ult i32 %0, 128
br i1 %5, label %11, label %6
6: ; preds = %4, %6
%7 = phi i32 [ %9, %6 ], [ 128, %4 ]
%8 = phi i32 [ %7, %6 ], [ 16, %4 ]
tail call void @cftmdl(i32 %0, i32 %8, double* %1)
%9 = shl i32 %7, 3
%10 = icmp sgt i32 %9, %0
br i1 %10, label %11, label %6
11: ; preds = %6, %4, %2
%12 = phi i32 [ 2, %2 ], [ 16, %4 ], [ %7, %6 ]
%13 = shl i32 %12, 1
%14 = icmp slt i32 %13, %0
br i1 %14, label %15, label %76
15: ; preds = %11
%16 = icmp sgt i32 %12, 0
br i1 %16, label %17, label %105
17: ; preds = %15
%18 = zext i32 %12 to i64
%19 = shl i32 %12, 1
br label %20
20: ; preds = %17, %20
%21 = phi i64 [ 0, %17 ], [ %74, %20 ]
%22 = trunc i64 %21 to i32
%23 = add nuw nsw i64 %21, %18
%24 = add nuw nsw i64 %23, %18
%25 = add i32 %19, %22
%26 = add nuw nsw i64 %24, %18
%27 = getelementptr inbounds double, double* %1, i64 %21
%28 = getelementptr inbounds double, double* %1, i64 %23
%29 = load double, double* %28
%30 = bitcast double* %27 to <2 x double>*
%31 = load <2 x double>, <2 x double>* %30
%32 = shl i64 %23, 32
%33 = ashr exact i64 %32, 32
%34 = or i64 %33, 1
%35 = getelementptr inbounds double, double* %1, i64 %34
%36 = load double, double* %35
%37 = insertelement <2 x double> poison, double %29, i64 0
%38 = insertelement <2 x double> %37, double %36, i64 1
%39 = fadd <2 x double> %31, %38
%40 = extractelement <2 x double> %31, i64 0
%41 = fsub double %40, %29
%42 = extractelement <2 x double> %31, i64 1
%43 = fsub double %42, %36
%44 = getelementptr inbounds double, double* %1, i64 %24
%45 = load double, double* %44
%46 = getelementptr inbounds double, double* %1, i64 %26
%47 = load double, double* %46
%48 = or i32 %25, 1
%49 = sext i32 %48 to i64
%50 = getelementptr inbounds double, double* %1, i64 %49
%51 = load double, double* %50
%52 = shl i64 %26, 32
%53 = ashr exact i64 %52, 32
%54 = or i64 %53, 1
%55 = getelementptr inbounds double, double* %1, i64 %54
%56 = load double, double* %55
%57 = insertelement <2 x double> poison, double %45, i64 0
%58 = insertelement <2 x double> %57, double %51, i64 1
%59 = insertelement <2 x double> poison, double %47, i64 0
%60 = insertelement <2 x double> %59, double %56, i64 1
%61 = fadd <2 x double> %58, %60
%62 = fsub double %45, %47
%63 = fsub double %51, %56
%64 = fadd <2 x double> %39, %61
%65 = bitcast double* %27 to <2 x double>*
store <2 x double> %64, <2 x double>* %65
%66 = fsub <2 x double> %39, %61
%67 = extractelement <2 x double> %66, i64 0
store double %67, double* %44
%68 = fsub <2 x double> %39, %61
%69 = extractelement <2 x double> %68, i64 1
store double %69, double* %50
%70 = fsub double %41, %63
store double %70, double* %28
%71 = fadd double %43, %62
store double %71, double* %35
%72 = fadd double %41, %63
store double %72, double* %46
%73 = fsub double %43, %62
store double %73, double* %55
%74 = add nuw nsw i64 %21, 2
%75 = icmp ult i64 %74, %18
br i1 %75, label %20, label %105
76: ; preds = %11
%77 = icmp eq i32 %13, %0
%78 = icmp sgt i32 %12, 0
%79 = and i1 %77, %78
br i1 %79, label %80, label %105
80: ; preds = %76
%81 = zext i32 %12 to i64
br label %82
82: ; preds = %80, %82
%83 = phi i64 [ 0, %80 ], [ %103, %82 ]
%84 = add nuw nsw i64 %83, %81
%85 = getelementptr inbounds double, double* %1, i64 %83
%86 = getelementptr inbounds double, double* %1, i64 %84
%87 = load double, double* %86
%88 = bitcast double* %85 to <2 x double>*
%89 = load <2 x double>, <2 x double>* %88
%90 = extractelement <2 x double> %89, i64 0
%91 = fsub double %90, %87
%92 = shl i64 %84, 32
%93 = ashr exact i64 %92, 32
%94 = or i64 %93, 1
%95 = getelementptr inbounds double, double* %1, i64 %94
%96 = load double, double* %95
%97 = extractelement <2 x double> %89, i64 1
%98 = fsub double %97, %96
%99 = insertelement <2 x double> poison, double %87, i64 0
%100 = insertelement <2 x double> %99, double %96, i64 1
%101 = fadd <2 x double> %89, %100
%102 = bitcast double* %85 to <2 x double>*
store <2 x double> %101, <2 x double>* %102
store double %91, double* %86
store double %98, double* %95
%103 = add nuw nsw i64 %83, 2
%104 = icmp ult i64 %103, %81
br i1 %104, label %82, label %105
105: ; preds = %82, %20, %15, %76
ret void
}