void mdct_butterfly_first(double *trig, double *x, int points) {
  double *x1 = x + points - 8;
  double *x2 = x + (points >> 1) - 8;
  double r0;
  double r1;
  do {
    r0 = x1[6] - x2[6];
    r1 = x1[7] - x2[7];
    x1[6] += x2[6];
    x1[7] += x2[7];
    x2[6] = (r1 * trig[1] + r0 * trig[0]);
    x2[7] = (r1 * trig[0] - r0 * trig[1]);
    r0 = x1[4] - x2[4];
    r1 = x1[5] - x2[5];
    x1[4] += x2[4];
    x1[5] += x2[5];
    x2[4] = (r1 * trig[5] + r0 * trig[4]);
    x2[5] = (r1 * trig[4] - r0 * trig[5]);
    r0 = x1[2] - x2[2];
    r1 = x1[3] - x2[3];
    x1[2] += x2[2];
    x1[3] += x2[3];
    x2[2] = (r1 * trig[9] + r0 * trig[8]);
    x2[3] = (r1 * trig[8] - r0 * trig[9]);
    r0 = x1[0] - x2[0];
    r1 = x1[1] - x2[1];
    x1[0] += x2[0];
    x1[1] += x2[1];
    x2[0] = (r1 * trig[13] + r0 * trig[12]);
    x2[1] = (r1 * trig[12] - r0 * trig[13]);
    x1 -= 8;
    x2 -= 8;
    trig += 16;
  } while (x2 >= x);
}


x86 assembly (clang, -O0):
<mdct_butterfly_first>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %edx,-0x14(%rbp)
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
shl    $0x3,%rcx
add    %rcx,%rax
add    $0xffffffffffffffc0,%rax
mov    %rax,-0x20(%rbp)
mov    -0x10(%rbp),%rax
mov    -0x14(%rbp),%ecx
sar    $0x1,%ecx
movslq %ecx,%rcx
shl    $0x3,%rcx
add    %rcx,%rax
add    $0xffffffffffffffc0,%rax
mov    %rax,-0x28(%rbp)
mov    -0x20(%rbp),%rax
movsd  0x30(%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  0x30(%rax),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0x20(%rbp),%rax
movsd  0x38(%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  0x38(%rax),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x28(%rbp),%rax
movsd  0x30(%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  0x30(%rax),%xmm0
movsd  %xmm0,0x30(%rax)
mov    -0x28(%rbp),%rax
movsd  0x38(%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  0x38(%rax),%xmm0
movsd  %xmm0,0x38(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x8(%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  (%rax),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,0x30(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  0x8(%rax),%xmm1
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,0x38(%rax)
mov    -0x20(%rbp),%rax
movsd  0x20(%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  0x20(%rax),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0x20(%rbp),%rax
movsd  0x28(%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  0x28(%rax),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x28(%rbp),%rax
movsd  0x20(%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  0x20(%rax),%xmm0
movsd  %xmm0,0x20(%rax)
mov    -0x28(%rbp),%rax
movsd  0x28(%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  0x28(%rax),%xmm0
movsd  %xmm0,0x28(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x28(%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  0x20(%rax),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,0x20(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x20(%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  0x28(%rax),%xmm1
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,0x28(%rax)
mov    -0x20(%rbp),%rax
movsd  0x10(%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  0x10(%rax),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0x20(%rbp),%rax
movsd  0x18(%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  0x18(%rax),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x28(%rbp),%rax
movsd  0x10(%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  0x10(%rax),%xmm0
movsd  %xmm0,0x10(%rax)
mov    -0x28(%rbp),%rax
movsd  0x18(%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  0x18(%rax),%xmm0
movsd  %xmm0,0x18(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x48(%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  0x40(%rax),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,0x10(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x40(%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  0x48(%rax),%xmm1
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,0x18(%rax)
mov    -0x20(%rbp),%rax
movsd  (%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  (%rax),%xmm0
movsd  %xmm0,-0x30(%rbp)
mov    -0x20(%rbp),%rax
movsd  0x8(%rax),%xmm0
mov    -0x28(%rbp),%rax
subsd  0x8(%rax),%xmm0
movsd  %xmm0,-0x38(%rbp)
mov    -0x28(%rbp),%rax
movsd  (%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  (%rax),%xmm0
movsd  %xmm0,(%rax)
mov    -0x28(%rbp),%rax
movsd  0x8(%rax),%xmm0
mov    -0x20(%rbp),%rax
addsd  0x8(%rax),%xmm0
movsd  %xmm0,0x8(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x68(%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  0x60(%rax),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,(%rax)
movsd  -0x38(%rbp),%xmm0
mov    -0x8(%rbp),%rax
movsd  0x60(%rax),%xmm2
movsd  -0x30(%rbp),%xmm1
mov    -0x8(%rbp),%rax
mulsd  0x68(%rax),%xmm1
movq   %xmm1,%rax
movabs $0x8000000000000000,%rcx
xor    %rcx,%rax
movq   %rax,%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
mov    -0x28(%rbp),%rax
movsd  %xmm0,0x8(%rax)
mov    -0x20(%rbp),%rax
add    $0xffffffffffffffc0,%rax
mov    %rax,-0x20(%rbp)
mov    -0x28(%rbp),%rax
add    $0xffffffffffffffc0,%rax
mov    %rax,-0x28(%rbp)
mov    -0x8(%rbp),%rax
add    $0x80,%rax
mov    %rax,-0x8(%rbp)
mov    -0x28(%rbp),%rax
cmp    -0x10(%rbp),%rax
jae    1142 <mdct_butterfly_first+0x42>
pop    %rbp
ret

x86 assembly (clang, -O2):
<mdct_butterfly_first>:
movslq %edx,%rcx
lea    (%rsi,%rcx,8),%rax
add    $0xfffffffffffffff8,%rax
sar    %ecx
movslq %ecx,%rcx
lea    (%rsi,%rcx,8),%rcx
add    $0xffffffffffffffc0,%rcx
add    $0x68,%rdi
nopl   0x0(%rax)
movsd  0x30(%rcx),%xmm0
movsd  -0x8(%rax),%xmm1
movsd  (%rax),%xmm2
movapd %xmm1,%xmm3
subsd  %xmm0,%xmm3
movapd %xmm2,%xmm4
subsd  0x38(%rcx),%xmm4
addsd  %xmm0,%xmm1
movsd  %xmm1,-0x8(%rax)
addsd  0x38(%rcx),%xmm2
movsd  %xmm2,(%rax)
movsd  -0x68(%rdi),%xmm0
mulsd  %xmm3,%xmm0
movsd  -0x60(%rdi),%xmm1
mulsd  %xmm4,%xmm1
addsd  %xmm0,%xmm1
movsd  %xmm1,0x30(%rcx)
mulsd  -0x60(%rdi),%xmm3
mulsd  -0x68(%rdi),%xmm4
subsd  %xmm3,%xmm4
movsd  %xmm4,0x38(%rcx)
movsd  0x20(%rcx),%xmm0
movsd  -0x18(%rax),%xmm1
movsd  -0x10(%rax),%xmm2
movapd %xmm1,%xmm3
subsd  %xmm0,%xmm3
movapd %xmm2,%xmm4
subsd  0x28(%rcx),%xmm4
addsd  %xmm0,%xmm1
movsd  %xmm1,-0x18(%rax)
addsd  0x28(%rcx),%xmm2
movsd  %xmm2,-0x10(%rax)
movsd  -0x48(%rdi),%xmm0
mulsd  %xmm3,%xmm0
movsd  -0x40(%rdi),%xmm1
mulsd  %xmm4,%xmm1
addsd  %xmm0,%xmm1
movsd  %xmm1,0x20(%rcx)
mulsd  -0x40(%rdi),%xmm3
mulsd  -0x48(%rdi),%xmm4
subsd  %xmm3,%xmm4
movsd  %xmm4,0x28(%rcx)
movsd  0x10(%rcx),%xmm0
movsd  -0x28(%rax),%xmm1
movsd  -0x20(%rax),%xmm2
movapd %xmm1,%xmm3
subsd  %xmm0,%xmm3
movapd %xmm2,%xmm4
subsd  0x18(%rcx),%xmm4
addsd  %xmm0,%xmm1
movsd  %xmm1,-0x28(%rax)
addsd  0x18(%rcx),%xmm2
movsd  %xmm2,-0x20(%rax)
movsd  -0x28(%rdi),%xmm0
mulsd  %xmm3,%xmm0
movsd  -0x20(%rdi),%xmm1
mulsd  %xmm4,%xmm1
addsd  %xmm0,%xmm1
movsd  %xmm1,0x10(%rcx)
mulsd  -0x20(%rdi),%xmm3
mulsd  -0x28(%rdi),%xmm4
subsd  %xmm3,%xmm4
movsd  %xmm4,0x18(%rcx)
movsd  (%rcx),%xmm0
movsd  -0x38(%rax),%xmm1
movsd  -0x30(%rax),%xmm2
movapd %xmm1,%xmm3
subsd  %xmm0,%xmm3
movapd %xmm2,%xmm4
subsd  0x8(%rcx),%xmm4
addsd  %xmm0,%xmm1
movsd  %xmm1,-0x38(%rax)
addsd  0x8(%rcx),%xmm2
movsd  %xmm2,-0x30(%rax)
movsd  -0x8(%rdi),%xmm0
mulsd  %xmm3,%xmm0
movsd  (%rdi),%xmm1
mulsd  %xmm4,%xmm1
addsd  %xmm0,%xmm1
movsd  %xmm1,(%rcx)
mulsd  (%rdi),%xmm3
mulsd  -0x8(%rdi),%xmm4
subsd  %xmm3,%xmm4
movsd  %xmm4,0x8(%rcx)
add    $0xffffffffffffffc0,%rcx
add    $0xffffffffffffffc0,%rax
sub    $0xffffffffffffff80,%rdi
cmp    %rsi,%rcx
jae    1120 <mdct_butterfly_first+0x20>
ret

LLVM IR (-O0):
define void @mdct_butterfly_first(double* %0, double* %1, i32 %2) {
%4 = alloca double*
%5 = alloca double*
%6 = alloca i32
%7 = alloca double*
%8 = alloca double*
%9 = alloca double
%10 = alloca double
store double* %0, double** %4
store double* %1, double** %5
store i32 %2, i32* %6
%11 = load double*, double** %5
%12 = load i32, i32* %6
%13 = sext i32 %12 to i64
%14 = getelementptr inbounds double, double* %11, i64 %13
%15 = getelementptr inbounds double, double* %14, i64 -8
store double* %15, double** %7
%16 = load double*, double** %5
%17 = load i32, i32* %6
%18 = ashr i32 %17, 1
%19 = sext i32 %18 to i64
%20 = getelementptr inbounds double, double* %16, i64 %19
%21 = getelementptr inbounds double, double* %20, i64 -8
store double* %21, double** %8
br label %22
22: ; preds = %241, %3
%23 = load double*, double** %7
%24 = getelementptr inbounds double, double* %23, i64 6
%25 = load double, double* %24
%26 = load double*, double** %8
%27 = getelementptr inbounds double, double* %26, i64 6
%28 = load double, double* %27
%29 = fsub double %25, %28
store double %29, double* %9
%30 = load double*, double** %7
%31 = getelementptr inbounds double, double* %30, i64 7
%32 = load double, double* %31
%33 = load double*, double** %8
%34 = getelementptr inbounds double, double* %33, i64 7
%35 = load double, double* %34
%36 = fsub double %32, %35
store double %36, double* %10
%37 = load double*, double** %8
%38 = getelementptr inbounds double, double* %37, i64 6
%39 = load double, double* %38
%40 = load double*, double** %7
%41 = getelementptr inbounds double, double* %40, i64 6
%42 = load double, double* %41
%43 = fadd double %42, %39
store double %43, double* %41
%44 = load double*, double** %8
%45 = getelementptr inbounds double, double* %44, i64 7
%46 = load double, double* %45
%47 = load double*, double** %7
%48 = getelementptr inbounds double, double* %47, i64 7
%49 = load double, double* %48
%50 = fadd double %49, %46
store double %50, double* %48
%51 = load double, double* %10
%52 = load double*, double** %4
%53 = getelementptr inbounds double, double* %52, i64 1
%54 = load double, double* %53
%55 = load double, double* %9
%56 = load double*, double** %4
%57 = getelementptr inbounds double, double* %56, i64 0
%58 = load double, double* %57
%59 = fmul double %55, %58
%60 = call double @llvm.fmuladd.f64(double %51, double %54, double %59)
%61 = load double*, double** %8
%62 = getelementptr inbounds double, double* %61, i64 6
store double %60, double* %62
%63 = load double, double* %10
%64 = load double*, double** %4
%65 = getelementptr inbounds double, double* %64, i64 0
%66 = load double, double* %65
%67 = load double, double* %9
%68 = load double*, double** %4
%69 = getelementptr inbounds double, double* %68, i64 1
%70 = load double, double* %69
%71 = fmul double %67, %70
%72 = fneg double %71
%73 = call double @llvm.fmuladd.f64(double %63, double %66, double %72)
%74 = load double*, double** %8
%75 = getelementptr inbounds double, double* %74, i64 7
store double %73, double* %75
%76 = load double*, double** %7
%77 = getelementptr inbounds double, double* %76, i64 4
%78 = load double, double* %77
%79 = load double*, double** %8
%80 = getelementptr inbounds double, double* %79, i64 4
%81 = load double, double* %80
%82 = fsub double %78, %81
store double %82, double* %9
%83 = load double*, double** %7
%84 = getelementptr inbounds double, double* %83, i64 5
%85 = load double, double* %84
%86 = load double*, double** %8
%87 = getelementptr inbounds double, double* %86, i64 5
%88 = load double, double* %87
%89 = fsub double %85, %88
store double %89, double* %10
%90 = load double*, double** %8
%91 = getelementptr inbounds double, double* %90, i64 4
%92 = load double, double* %91
%93 = load double*, double** %7
%94 = getelementptr inbounds double, double* %93, i64 4
%95 = load double, double* %94
%96 = fadd double %95, %92
store double %96, double* %94
%97 = load double*, double** %8
%98 = getelementptr inbounds double, double* %97, i64 5
%99 = load double, double* %98
%100 = load double*, double** %7
%101 = getelementptr inbounds double, double* %100, i64 5
%102 = load double, double* %101
%103 = fadd double %102, %99
store double %103, double* %101
%104 = load double, double* %10
%105 = load double*, double** %4
%106 = getelementptr inbounds double, double* %105, i64 5
%107 = load double, double* %106
%108 = load double, double* %9
%109 = load double*, double** %4
%110 = getelementptr inbounds double, double* %109, i64 4
%111 = load double, double* %110
%112 = fmul double %108, %111
%113 = call double @llvm.fmuladd.f64(double %104, double %107, double %112)
%114 = load double*, double** %8
%115 = getelementptr inbounds double, double* %114, i64 4
store double %113, double* %115
%116 = load double, double* %10
%117 = load double*, double** %4
%118 = getelementptr inbounds double, double* %117, i64 4
%119 = load double, double* %118
%120 = load double, double* %9
%121 = load double*, double** %4
%122 = getelementptr inbounds double, double* %121, i64 5
%123 = load double, double* %122
%124 = fmul double %120, %123
%125 = fneg double %124
%126 = call double @llvm.fmuladd.f64(double %116, double %119, double %125)
%127 = load double*, double** %8
%128 = getelementptr inbounds double, double* %127, i64 5
store double %126, double* %128
%129 = load double*, double** %7
%130 = getelementptr inbounds double, double* %129, i64 2
%131 = load double, double* %130
%132 = load double*, double** %8
%133 = getelementptr inbounds double, double* %132, i64 2
%134 = load double, double* %133
%135 = fsub double %131, %134
store double %135, double* %9
%136 = load double*, double** %7
%137 = getelementptr inbounds double, double* %136, i64 3
%138 = load double, double* %137
%139 = load double*, double** %8
%140 = getelementptr inbounds double, double* %139, i64 3
%141 = load double, double* %140
%142 = fsub double %138, %141
store double %142, double* %10
%143 = load double*, double** %8
%144 = getelementptr inbounds double, double* %143, i64 2
%145 = load double, double* %144
%146 = load double*, double** %7
%147 = getelementptr inbounds double, double* %146, i64 2
%148 = load double, double* %147
%149 = fadd double %148, %145
store double %149, double* %147
%150 = load double*, double** %8
%151 = getelementptr inbounds double, double* %150, i64 3
%152 = load double, double* %151
%153 = load double*, double** %7
%154 = getelementptr inbounds double, double* %153, i64 3
%155 = load double, double* %154
%156 = fadd double %155, %152
store double %156, double* %154
%157 = load double, double* %10
%158 = load double*, double** %4
%159 = getelementptr inbounds double, double* %158, i64 9
%160 = load double, double* %159
%161 = load double, double* %9
%162 = load double*, double** %4
%163 = getelementptr inbounds double, double* %162, i64 8
%164 = load double, double* %163
%165 = fmul double %161, %164
%166 = call double @llvm.fmuladd.f64(double %157, double %160, double %165)
%167 = load double*, double** %8
%168 = getelementptr inbounds double, double* %167, i64 2
store double %166, double* %168
%169 = load double, double* %10
%170 = load double*, double** %4
%171 = getelementptr inbounds double, double* %170, i64 8
%172 = load double, double* %171
%173 = load double, double* %9
%174 = load double*, double** %4
%175 = getelementptr inbounds double, double* %174, i64 9
%176 = load double, double* %175
%177 = fmul double %173, %176
%178 = fneg double %177
%179 = call double @llvm.fmuladd.f64(double %169, double %172, double %178)
%180 = load double*, double** %8
%181 = getelementptr inbounds double, double* %180, i64 3
store double %179, double* %181
%182 = load double*, double** %7
%183 = getelementptr inbounds double, double* %182, i64 0
%184 = load double, double* %183
%185 = load double*, double** %8
%186 = getelementptr inbounds double, double* %185, i64 0
%187 = load double, double* %186
%188 = fsub double %184, %187
store double %188, double* %9
%189 = load double*, double** %7
%190 = getelementptr inbounds double, double* %189, i64 1
%191 = load double, double* %190
%192 = load double*, double** %8
%193 = getelementptr inbounds double, double* %192, i64 1
%194 = load double, double* %193
%195 = fsub double %191, %194
store double %195, double* %10
%196 = load double*, double** %8
%197 = getelementptr inbounds double, double* %196, i64 0
%198 = load double, double* %197
%199 = load double*, double** %7
%200 = getelementptr inbounds double, double* %199, i64 0
%201 = load double, double* %200
%202 = fadd double %201, %198
store double %202, double* %200
%203 = load double*, double** %8
%204 = getelementptr inbounds double, double* %203, i64 1
%205 = load double, double* %204
%206 = load double*, double** %7
%207 = getelementptr inbounds double, double* %206, i64 1
%208 = load double, double* %207
%209 = fadd double %208, %205
store double %209, double* %207
%210 = load double, double* %10
%211 = load double*, double** %4
%212 = getelementptr inbounds double, double* %211, i64 13
%213 = load double, double* %212
%214 = load double, double* %9
%215 = load double*, double** %4
%216 = getelementptr inbounds double, double* %215, i64 12
%217 = load double, double* %216
%218 = fmul double %214, %217
%219 = call double @llvm.fmuladd.f64(double %210, double %213, double %218)
%220 = load double*, double** %8
%221 = getelementptr inbounds double, double* %220, i64 0
store double %219, double* %221
%222 = load double, double* %10
%223 = load double*, double** %4
%224 = getelementptr inbounds double, double* %223, i64 12
%225 = load double, double* %224
%226 = load double, double* %9
%227 = load double*, double** %4
%228 = getelementptr inbounds double, double* %227, i64 13
%229 = load double, double* %228
%230 = fmul double %226, %229
%231 = fneg double %230
%232 = call double @llvm.fmuladd.f64(double %222, double %225, double %231)
%233 = load double*, double** %8
%234 = getelementptr inbounds double, double* %233, i64 1
store double %232, double* %234
%235 = load double*, double** %7
%236 = getelementptr inbounds double, double* %235, i64 -8
store double* %236, double** %7
%237 = load double*, double** %8
%238 = getelementptr inbounds double, double* %237, i64 -8
store double* %238, double** %8
%239 = load double*, double** %4
%240 = getelementptr inbounds double, double* %239, i64 16
store double* %240, double** %4
br label %241
241: ; preds = %22
%242 = load double*, double** %8
%243 = load double*, double** %5
%244 = icmp uge double* %242, %243
br i1 %244, label %22, label %245
245: ; preds = %241
ret void
}

LLVM IR (-O2):
define void @mdct_butterfly_first(double* nocapture %0, double* %1, i32 %2) {
%4 = sext i32 %2 to i64
%5 = getelementptr inbounds double, double* %1, i64 %4
%6 = ashr i32 %2, 1
%7 = sext i32 %6 to i64
%8 = getelementptr inbounds double, double* %1, i64 %7
%9 = getelementptr inbounds double, double* %8, i64 -8
br label %10
10: ; preds = %10, %3
%11 = phi double* [ %9, %3 ], [ %108, %10 ]
%12 = phi double* [ %5, %3 ], [ %14, %10 ]
%13 = phi double* [ %0, %3 ], [ %109, %10 ]
%14 = getelementptr inbounds double, double* %12, i64 -8
%15 = getelementptr inbounds double, double* %12, i64 -2
%16 = load double, double* %15
%17 = getelementptr inbounds double, double* %11, i64 6
%18 = load double, double* %17
%19 = fsub double %16, %18
%20 = getelementptr inbounds double, double* %12, i64 -1
%21 = load double, double* %20
%22 = getelementptr inbounds double, double* %11, i64 7
%23 = load double, double* %22
%24 = fsub double %21, %23
%25 = fadd double %16, %18
store double %25, double* %15
%26 = load double, double* %22
%27 = fadd double %21, %26
store double %27, double* %20
%28 = getelementptr inbounds double, double* %13, i64 1
%29 = load double, double* %28
%30 = load double, double* %13
%31 = fmul double %19, %30
%32 = tail call double @llvm.fmuladd.f64(double %24, double %29, double %31)
store double %32, double* %17
%33 = load double, double* %13
%34 = load double, double* %28
%35 = fneg double %19
%36 = fmul double %34, %35
%37 = tail call double @llvm.fmuladd.f64(double %24, double %33, double %36)
store double %37, double* %22
%38 = getelementptr inbounds double, double* %12, i64 -4
%39 = load double, double* %38
%40 = getelementptr inbounds double, double* %11, i64 4
%41 = load double, double* %40
%42 = fsub double %39, %41
%43 = getelementptr inbounds double, double* %12, i64 -3
%44 = load double, double* %43
%45 = getelementptr inbounds double, double* %11, i64 5
%46 = load double, double* %45
%47 = fsub double %44, %46
%48 = fadd double %39, %41
store double %48, double* %38
%49 = load double, double* %45
%50 = fadd double %44, %49
store double %50, double* %43
%51 = getelementptr inbounds double, double* %13, i64 5
%52 = load double, double* %51
%53 = getelementptr inbounds double, double* %13, i64 4
%54 = load double, double* %53
%55 = fmul double %42, %54
%56 = tail call double @llvm.fmuladd.f64(double %47, double %52, double %55)
store double %56, double* %40
%57 = load double, double* %53
%58 = load double, double* %51
%59 = fneg double %42
%60 = fmul double %58, %59
%61 = tail call double @llvm.fmuladd.f64(double %47, double %57, double %60)
store double %61, double* %45
%62 = getelementptr inbounds double, double* %12, i64 -6
%63 = load double, double* %62
%64 = getelementptr inbounds double, double* %11, i64 2
%65 = load double, double* %64
%66 = fsub double %63, %65
%67 = getelementptr inbounds double, double* %12, i64 -5
%68 = load double, double* %67
%69 = getelementptr inbounds double, double* %11, i64 3
%70 = load double, double* %69
%71 = fsub double %68, %70
%72 = fadd double %63, %65
store double %72, double* %62
%73 = load double, double* %69
%74 = fadd double %68, %73
store double %74, double* %67
%75 = getelementptr inbounds double, double* %13, i64 9
%76 = load double, double* %75
%77 = getelementptr inbounds double, double* %13, i64 8
%78 = load double, double* %77
%79 = fmul double %66, %78
%80 = tail call double @llvm.fmuladd.f64(double %71, double %76, double %79)
store double %80, double* %64
%81 = load double, double* %77
%82 = load double, double* %75
%83 = fneg double %66
%84 = fmul double %82, %83
%85 = tail call double @llvm.fmuladd.f64(double %71, double %81, double %84)
store double %85, double* %69
%86 = load double, double* %14
%87 = load double, double* %11
%88 = fsub double %86, %87
%89 = getelementptr inbounds double, double* %12, i64 -7
%90 = load double, double* %89
%91 = getelementptr inbounds double, double* %11, i64 1
%92 = load double, double* %91
%93 = fsub double %90, %92
%94 = fadd double %86, %87
store double %94, double* %14
%95 = load double, double* %91
%96 = fadd double %90, %95
store double %96, double* %89
%97 = getelementptr inbounds double, double* %13, i64 13
%98 = load double, double* %97
%99 = getelementptr inbounds double, double* %13, i64 12
%100 = load double, double* %99
%101 = fmul double %88, %100
%102 = tail call double @llvm.fmuladd.f64(double %93, double %98, double %101)
store double %102, double* %11
%103 = load double, double* %99
%104 = load double, double* %97
%105 = fneg double %88
%106 = fmul double %104, %105
%107 = tail call double @llvm.fmuladd.f64(double %93, double %103, double %106)
store double %107, double* %91
%108 = getelementptr inbounds double, double* %11, i64 -8
%109 = getelementptr inbounds double, double* %13, i64 16
%110 = icmp ult double* %108, %1
br i1 %110, label %111, label %10
111: ; preds = %10
ret void
}