void initialize(int *arr) {
  int i;
  for (i = 0; i < 255; i++)
    arr[i] = 5;
}


x86 assembly (clang, -O0):
<initialize>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
movl   $0x0,-0xc(%rbp)
cmpl   $0xff,-0xc(%rbp)
jge    1139 <initialize+0x39>
mov    -0x8(%rbp),%rax
movslq -0xc(%rbp),%rcx
movl   $0x5,(%rax,%rcx,4)
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    110f <initialize+0xf>
pop    %rbp
ret

x86 assembly (clang, -O2):
<initialize>:
movaps 0xef9(%rip),%xmm0
movups %xmm0,(%rdi)
movups %xmm0,0x10(%rdi)
movups %xmm0,0x20(%rdi)
movups %xmm0,0x30(%rdi)
movups %xmm0,0x40(%rdi)
movups %xmm0,0x50(%rdi)
movups %xmm0,0x60(%rdi)
movups %xmm0,0x70(%rdi)
movups %xmm0,0x80(%rdi)
movups %xmm0,0x90(%rdi)
movups %xmm0,0xa0(%rdi)
movups %xmm0,0xb0(%rdi)
movups %xmm0,0xc0(%rdi)
movups %xmm0,0xd0(%rdi)
movups %xmm0,0xe0(%rdi)
movups %xmm0,0xf0(%rdi)
movups %xmm0,0x100(%rdi)
movups %xmm0,0x110(%rdi)
movups %xmm0,0x120(%rdi)
movups %xmm0,0x130(%rdi)
movups %xmm0,0x140(%rdi)
movups %xmm0,0x150(%rdi)
movups %xmm0,0x160(%rdi)
movups %xmm0,0x170(%rdi)
movups %xmm0,0x180(%rdi)
movups %xmm0,0x190(%rdi)
movups %xmm0,0x1a0(%rdi)
movups %xmm0,0x1b0(%rdi)
movups %xmm0,0x1c0(%rdi)
movups %xmm0,0x1d0(%rdi)
movups %xmm0,0x1e0(%rdi)
movups %xmm0,0x1f0(%rdi)
movups %xmm0,0x200(%rdi)
movups %xmm0,0x210(%rdi)
movups %xmm0,0x220(%rdi)
movups %xmm0,0x230(%rdi)
movups %xmm0,0x240(%rdi)
movups %xmm0,0x250(%rdi)
movups %xmm0,0x260(%rdi)
movups %xmm0,0x270(%rdi)
movups %xmm0,0x280(%rdi)
movups %xmm0,0x290(%rdi)
movups %xmm0,0x2a0(%rdi)
movups %xmm0,0x2b0(%rdi)
movups %xmm0,0x2c0(%rdi)
movups %xmm0,0x2d0(%rdi)
movups %xmm0,0x2e0(%rdi)
movups %xmm0,0x2f0(%rdi)
movups %xmm0,0x300(%rdi)
movups %xmm0,0x310(%rdi)
movups %xmm0,0x320(%rdi)
movups %xmm0,0x330(%rdi)
movups %xmm0,0x340(%rdi)
movups %xmm0,0x350(%rdi)
movups %xmm0,0x360(%rdi)
movups %xmm0,0x370(%rdi)
movups %xmm0,0x380(%rdi)
movups %xmm0,0x390(%rdi)
movups %xmm0,0x3a0(%rdi)
movups %xmm0,0x3b0(%rdi)
movups %xmm0,0x3c0(%rdi)
movups %xmm0,0x3d0(%rdi)
movups %xmm0,0x3e0(%rdi)
movabs $0x500000005,%rax
mov    %rax,0x3f0(%rdi)
movl   $0x5,0x3f8(%rdi)
ret

LLVM IR (-O0):
define void @initialize(i32* %0) {
%2 = alloca i32*
%3 = alloca i32
store i32* %0, i32** %2
store i32 0, i32* %3
br label %4
4: ; preds = %12, %1
%5 = load i32, i32* %3
%6 = icmp slt i32 %5, 255
br i1 %6, label %7, label %15
7: ; preds = %4
%8 = load i32*, i32** %2
%9 = load i32, i32* %3
%10 = sext i32 %9 to i64
%11 = getelementptr inbounds i32, i32* %8, i64 %10
store i32 5, i32* %11
br label %12
12: ; preds = %7
%13 = load i32, i32* %3
%14 = add nsw i32 %13, 1
store i32 %14, i32* %3
br label %4
15: ; preds = %4
ret void
}

LLVM IR (-O2):
define void @initialize(i32* nocapture writeonly %0) {
%2 = bitcast i32* %0 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %2
%3 = getelementptr inbounds i32, i32* %0, i64 4
%4 = bitcast i32* %3 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %4
%5 = getelementptr inbounds i32, i32* %0, i64 8
%6 = bitcast i32* %5 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %6
%7 = getelementptr inbounds i32, i32* %0, i64 12
%8 = bitcast i32* %7 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %8
%9 = getelementptr inbounds i32, i32* %0, i64 16
%10 = bitcast i32* %9 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %10
%11 = getelementptr inbounds i32, i32* %0, i64 20
%12 = bitcast i32* %11 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %12
%13 = getelementptr inbounds i32, i32* %0, i64 24
%14 = bitcast i32* %13 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %14
%15 = getelementptr inbounds i32, i32* %0, i64 28
%16 = bitcast i32* %15 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %16
%17 = getelementptr inbounds i32, i32* %0, i64 32
%18 = bitcast i32* %17 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %18
%19 = getelementptr inbounds i32, i32* %0, i64 36
%20 = bitcast i32* %19 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %20
%21 = getelementptr inbounds i32, i32* %0, i64 40
%22 = bitcast i32* %21 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %22
%23 = getelementptr inbounds i32, i32* %0, i64 44
%24 = bitcast i32* %23 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %24
%25 = getelementptr inbounds i32, i32* %0, i64 48
%26 = bitcast i32* %25 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %26
%27 = getelementptr inbounds i32, i32* %0, i64 52
%28 = bitcast i32* %27 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %28
%29 = getelementptr inbounds i32, i32* %0, i64 56
%30 = bitcast i32* %29 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %30
%31 = getelementptr inbounds i32, i32* %0, i64 60
%32 = bitcast i32* %31 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %32
%33 = getelementptr inbounds i32, i32* %0, i64 64
%34 = bitcast i32* %33 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %34
%35 = getelementptr inbounds i32, i32* %0, i64 68
%36 = bitcast i32* %35 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %36
%37 = getelementptr inbounds i32, i32* %0, i64 72
%38 = bitcast i32* %37 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %38
%39 = getelementptr inbounds i32, i32* %0, i64 76
%40 = bitcast i32* %39 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %40
%41 = getelementptr inbounds i32, i32* %0, i64 80
%42 = bitcast i32* %41 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %42
%43 = getelementptr inbounds i32, i32* %0, i64 84
%44 = bitcast i32* %43 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %44
%45 = getelementptr inbounds i32, i32* %0, i64 88
%46 = bitcast i32* %45 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %46
%47 = getelementptr inbounds i32, i32* %0, i64 92
%48 = bitcast i32* %47 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %48
%49 = getelementptr inbounds i32, i32* %0, i64 96
%50 = bitcast i32* %49 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %50
%51 = getelementptr inbounds i32, i32* %0, i64 100
%52 = bitcast i32* %51 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %52
%53 = getelementptr inbounds i32, i32* %0, i64 104
%54 = bitcast i32* %53 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %54
%55 = getelementptr inbounds i32, i32* %0, i64 108
%56 = bitcast i32* %55 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %56
%57 = getelementptr inbounds i32, i32* %0, i64 112
%58 = bitcast i32* %57 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %58
%59 = getelementptr inbounds i32, i32* %0, i64 116
%60 = bitcast i32* %59 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %60
%61 = getelementptr inbounds i32, i32* %0, i64 120
%62 = bitcast i32* %61 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %62
%63 = getelementptr inbounds i32, i32* %0, i64 124
%64 = bitcast i32* %63 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %64
%65 = getelementptr inbounds i32, i32* %0, i64 128
%66 = bitcast i32* %65 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %66
%67 = getelementptr inbounds i32, i32* %0, i64 132
%68 = bitcast i32* %67 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %68
%69 = getelementptr inbounds i32, i32* %0, i64 136
%70 = bitcast i32* %69 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %70
%71 = getelementptr inbounds i32, i32* %0, i64 140
%72 = bitcast i32* %71 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %72
%73 = getelementptr inbounds i32, i32* %0, i64 144
%74 = bitcast i32* %73 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %74
%75 = getelementptr inbounds i32, i32* %0, i64 148
%76 = bitcast i32* %75 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %76
%77 = getelementptr inbounds i32, i32* %0, i64 152
%78 = bitcast i32* %77 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %78
%79 = getelementptr inbounds i32, i32* %0, i64 156
%80 = bitcast i32* %79 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %80
%81 = getelementptr inbounds i32, i32* %0, i64 160
%82 = bitcast i32* %81 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %82
%83 = getelementptr inbounds i32, i32* %0, i64 164
%84 = bitcast i32* %83 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %84
%85 = getelementptr inbounds i32, i32* %0, i64 168
%86 = bitcast i32* %85 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %86
%87 = getelementptr inbounds i32, i32* %0, i64 172
%88 = bitcast i32* %87 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %88
%89 = getelementptr inbounds i32, i32* %0, i64 176
%90 = bitcast i32* %89 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %90
%91 = getelementptr inbounds i32, i32* %0, i64 180
%92 = bitcast i32* %91 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %92
%93 = getelementptr inbounds i32, i32* %0, i64 184
%94 = bitcast i32* %93 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %94
%95 = getelementptr inbounds i32, i32* %0, i64 188
%96 = bitcast i32* %95 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %96
%97 = getelementptr inbounds i32, i32* %0, i64 192
%98 = bitcast i32* %97 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %98
%99 = getelementptr inbounds i32, i32* %0, i64 196
%100 = bitcast i32* %99 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %100
%101 = getelementptr inbounds i32, i32* %0, i64 200
%102 = bitcast i32* %101 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %102
%103 = getelementptr inbounds i32, i32* %0, i64 204
%104 = bitcast i32* %103 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %104
%105 = getelementptr inbounds i32, i32* %0, i64 208
%106 = bitcast i32* %105 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %106
%107 = getelementptr inbounds i32, i32* %0, i64 212
%108 = bitcast i32* %107 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %108
%109 = getelementptr inbounds i32, i32* %0, i64 216
%110 = bitcast i32* %109 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %110
%111 = getelementptr inbounds i32, i32* %0, i64 220
%112 = bitcast i32* %111 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %112
%113 = getelementptr inbounds i32, i32* %0, i64 224
%114 = bitcast i32* %113 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %114
%115 = getelementptr inbounds i32, i32* %0, i64 228
%116 = bitcast i32* %115 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %116
%117 = getelementptr inbounds i32, i32* %0, i64 232
%118 = bitcast i32* %117 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %118
%119 = getelementptr inbounds i32, i32* %0, i64 236
%120 = bitcast i32* %119 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %120
%121 = getelementptr inbounds i32, i32* %0, i64 240
%122 = bitcast i32* %121 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %122
%123 = getelementptr inbounds i32, i32* %0, i64 244
%124 = bitcast i32* %123 to <4 x i32>*
store <4 x i32> <i32 5, i32 5, i32 5, i32 5>, <4 x i32>* %124
%125 = getelementptr inbounds i32, i32* %0, i64 248
store i32 5, i32* %125
%126 = getelementptr inbounds i32, i32* %0, i64 249
store i32 5, i32* %126
%127 = getelementptr inbounds i32, i32* %0, i64 250
store i32 5, i32* %127
%128 = getelementptr inbounds i32, i32* %0, i64 251
store i32 5, i32* %128
%129 = getelementptr inbounds i32, i32* %0, i64 252
store i32 5, i32* %129
%130 = getelementptr inbounds i32, i32* %0, i64 253
store i32 5, i32* %130
%131 = getelementptr inbounds i32, i32* %0, i64 254
store i32 5, i32* %131
ret void
}