int fill_array(int arr[]) {
  int i;
  for (i = 0; i < 100; i++)
    arr[i] = i + 1;
  return 0;
}


x86 assembly (clang, -O0):
<fill_array>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
movl   $0x0,-0xc(%rbp)
cmpl   $0x64,-0xc(%rbp)
jge    1138 <fill_array+0x38>
mov    -0xc(%rbp),%edx
add    $0x1,%edx
mov    -0x8(%rbp),%rax
movslq -0xc(%rbp),%rcx
mov    %edx,(%rax,%rcx,4)
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    110f <fill_array+0xf>
xor    %eax,%eax
pop    %rbp
ret

x86 assembly (clang, -O2):
<fill_array>:
movaps 0xef9(%rip),%xmm0
movups %xmm0,(%rdi)
movaps 0xeff(%rip),%xmm0
movups %xmm0,0x10(%rdi)
movaps 0xf04(%rip),%xmm0
movups %xmm0,0x20(%rdi)
movaps 0xf09(%rip),%xmm0
movups %xmm0,0x30(%rdi)
movaps 0xf0e(%rip),%xmm0
movups %xmm0,0x40(%rdi)
movaps 0xf13(%rip),%xmm0
movups %xmm0,0x50(%rdi)
movaps 0xf18(%rip),%xmm0
movups %xmm0,0x60(%rdi)
movaps 0xf1d(%rip),%xmm0
movups %xmm0,0x70(%rdi)
movaps 0xf22(%rip),%xmm0
movups %xmm0,0x80(%rdi)
movaps 0xf24(%rip),%xmm0
movups %xmm0,0x90(%rdi)
movaps 0xf26(%rip),%xmm0
movups %xmm0,0xa0(%rdi)
movaps 0xf28(%rip),%xmm0
movups %xmm0,0xb0(%rdi)
movaps 0xf2a(%rip),%xmm0
movups %xmm0,0xc0(%rdi)
movaps 0xf2c(%rip),%xmm0
movups %xmm0,0xd0(%rdi)
movaps 0xf2e(%rip),%xmm0
movups %xmm0,0xe0(%rdi)
movaps 0xf30(%rip),%xmm0
movups %xmm0,0xf0(%rdi)
movaps 0xf32(%rip),%xmm0
movups %xmm0,0x100(%rdi)
movaps 0xf34(%rip),%xmm0
movups %xmm0,0x110(%rdi)
movaps 0xf36(%rip),%xmm0
movups %xmm0,0x120(%rdi)
movaps 0xf38(%rip),%xmm0
movups %xmm0,0x130(%rdi)
movaps 0xf3a(%rip),%xmm0
movups %xmm0,0x140(%rdi)
movaps 0xf3c(%rip),%xmm0
movups %xmm0,0x150(%rdi)
movaps 0xf3e(%rip),%xmm0
movups %xmm0,0x160(%rdi)
movaps 0xf40(%rip),%xmm0
movups %xmm0,0x170(%rdi)
movaps 0xf42(%rip),%xmm0
movups %xmm0,0x180(%rdi)
xor    %eax,%eax
ret

LLVM IR (-O0):
define i32 @fill_array(i32* %0) {
%2 = alloca i32*
%3 = alloca i32
store i32* %0, i32** %2
store i32 0, i32* %3
br label %4
4: ; preds = %14, %1
%5 = load i32, i32* %3
%6 = icmp slt i32 %5, 100
br i1 %6, label %7, label %17
7: ; preds = %4
%8 = load i32, i32* %3
%9 = add nsw i32 %8, 1
%10 = load i32*, i32** %2
%11 = load i32, i32* %3
%12 = sext i32 %11 to i64
%13 = getelementptr inbounds i32, i32* %10, i64 %12
store i32 %9, i32* %13
br label %14
14: ; preds = %7
%15 = load i32, i32* %3
%16 = add nsw i32 %15, 1
store i32 %16, i32* %3
br label %4
17: ; preds = %4
ret i32 0
}

LLVM IR (-O2):
define i32 @fill_array(i32* nocapture writeonly %0) {
%2 = bitcast i32* %0 to <4 x i32>*
store <4 x i32> <i32 1, i32 2, i32 3, i32 4>, <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 6, i32 7, i32 8>, <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 9, i32 10, i32 11, i32 12>, <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 13, i32 14, i32 15, i32 16>, <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 17, i32 18, i32 19, i32 20>, <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 21, i32 22, i32 23, i32 24>, <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 25, i32 26, i32 27, i32 28>, <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 29, i32 30, i32 31, i32 32>, <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 33, i32 34, i32 35, i32 36>, <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 37, i32 38, i32 39, i32 40>, <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 41, i32 42, i32 43, i32 44>, <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 45, i32 46, i32 47, i32 48>, <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 49, i32 50, i32 51, i32 52>, <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 53, i32 54, i32 55, i32 56>, <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 57, i32 58, i32 59, i32 60>, <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 61, i32 62, i32 63, i32 64>, <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 65, i32 66, i32 67, i32 68>, <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 69, i32 70, i32 71, i32 72>, <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 73, i32 74, i32 75, i32 76>, <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 77, i32 78, i32 79, i32 80>, <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 81, i32 82, i32 83, i32 84>, <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 85, i32 86, i32 87, i32 88>, <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 89, i32 90, i32 91, i32 92>, <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 93, i32 94, i32 95, i32 96>, <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 97, i32 98, i32 99, i32 100>, <4 x i32>* %50
ret i32 0
}